diff --git a/.github/workflows/auto-tag.yml b/.github/workflows/auto-tag.yml
index 646fde9..e450d9f 100644
--- a/.github/workflows/auto-tag.yml
+++ b/.github/workflows/auto-tag.yml
@@ -15,12 +15,14 @@ jobs:
           fetch-depth: 0
       - name: Check for version bump
         id: version
+        env:
+          BEFORE_SHA: ${{ github.event.before }}
         run: |
           CURRENT=$(grep '^version' Cargo.toml | head -1 | sed 's/.*"\(.*\)"/\1/')
-          if [ "${{ github.event.before }}" = "0000000000000000000000000000000000000000" ]; then
+          if [ "$BEFORE_SHA" = "0000000000000000000000000000000000000000" ]; then
             PREVIOUS="$CURRENT"
           else
-            PREVIOUS=$(git show ${{ github.event.before }}:Cargo.toml | grep '^version' | head -1 | sed 's/.*"\(.*\)"/\1/')
+            PREVIOUS=$(git show "$BEFORE_SHA":Cargo.toml | grep '^version' | head -1 | sed 's/.*"\(.*\)"/\1/')
           fi
           echo "current=$CURRENT" >> "$GITHUB_OUTPUT"
           echo "previous=$PREVIOUS" >> "$GITHUB_OUTPUT"
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a61c86d..a3bfd80 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -16,7 +16,7 @@ jobs:
           components: clippy, rustfmt
       - uses: Swatinem/rust-cache@v2
       - run: cargo fmt --check
-      - run: cargo clippy -- -D warnings
+      - run: cargo clippy --all-targets -- -D warnings
   test:
     runs-on: ubuntu-latest
     steps:
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 052f325..8852ab9 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -17,14 +17,14 @@ jobs:
       - run: cargo test --all
       - name: Publish to crates.io
         run: |
-          cargo publish 2>&1 || {
-            if cargo search restium --limit 1 | grep -q "$(grep '^version' Cargo.toml | head -1 | sed 's/.*"\(.*\)"/\1/')"; then
-              echo "::warning::Version already published to crates.io — skipping"
-            else
-              echo "::error::cargo publish failed"
-              exit 1
-            fi
-          }
+          OUTPUT=$(cargo publish 2>&1) && exit 0
+          if echo "$OUTPUT" | grep -q "already uploaded"; then
+            echo "::warning::Version already published to crates.io — skipping"
+          else
+            echo "$OUTPUT"
+            echo "::error::cargo publish failed"
+            exit 1
+          fi
         env:
           CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}
       - uses: docker/setup-qemu-action@v3
diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..7103b5a
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,126 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+### Added
+
+- CLI skeleton with `reconcile` and `validate` subcommands
+- Global flags: `--json`, `--insecure-tls`
+- `RESTIUM_*` environment variable support for all flags
+- Exit code convention: 0 (success), 1 (runtime error), 2 (input/validation error)
+- Structured logging with JSON (`--json`) and human-readable text modes
+- Automatic secret redaction for sensitive key-value pairs (authorization, token, password, api_key, client_secret, etc.)
+- URL query parameter redaction for secrets in logged URLs
+- YAML spec file parsing with `global` settings and `resources` list
+- Global settings inheritance: base_url, default_headers, auth (with per-resource override)
+- Structured payloads (nested objects, arrays) preserved through YAML-to-JSON
+- `depends_on` field for explicit resource ordering
+- `deny_unknown_fields` on spec types for typo detection
+- AuthConfig type definitions (bearer, basic, api_key, oidc, mtls) — type stubs for Epic 2
+- `validate` and `reconcile` commands now parse and report spec file contents
+- Spec validation: reference checking (`${resource.output.field}`), duplicate resource name detection, circular dependency detection
+- `validate` command reports ALL errors (not just the first), exits with code 2 on validation failure
+- Dependency graph module (`src/graph/mod.rs`) with `petgraph`-based topological sort and cycle detection
+- `DependencyGraph::build()` merges explicit `depends_on` and implicit `${resource.output.field}` references into a single DAG
+- `DependencyGraph::topological_sort()` returns execution order or cycle path error
+- Reconcile module (`src/reconcile/`) with state discovery, diff computation, and action determination
+- `ResourceAction` enum: Create, Update, Skip, Delete
+- Key-order-independent JSON comparison (`json_equal`) for idempotent reconciliation
+- State discovery via GET with 404 handling (resource does not exist → Create)
+- Resource execution module (`src/reconcile/execute.rs`) for create/update/skip operations
+- Actionable error messages with resource name, HTTP method, endpoint, status code, and hints
+- Error hints for common HTTP status codes (401, 403, 404, 409, 422, 429, 5xx)
+- Update operations auto-switch from POST to PUT when resource method is POST
+- Explicit resource deletion via `action: delete` with DELETE HTTP request
+- Delete of absent resource (404) logged as "already absent" and skipped
+- Reconcile command orchestration: parse → graph → sort → for each resource: resolve refs → discover state → compute diff → execute → extract outputs
+- Reconciliation summary logged on completion (created, updated, deleted, skipped, failed counts)
+- Delete resources processed in reverse topological order (dependents deleted before dependencies)
+- Exit code 1 on reconciliation failure, exit code 0 on success
+- Reference module (`src/reference/mod.rs`) for output extraction and `${resource.output.field}` resolution
+- `OutputStore` type for storing extracted outputs across resources
+- `extract_outputs()` extracts fields from API responses (string, number, bool, null, complex)
+- `resolve_references()` recursively substitutes template references in JSON payloads
+- `resolve_string()` resolves references in individual strings (endpoints, read_endpoints)
+- HTTP client wrapper (`HttpClient`) with configurable TLS via `ureq` + `rustls`
+- TLS certificate verification enabled by default (webpki roots)
+- `--insecure-tls` flag skips certificate verification (explicit opt-in, NFR3)
+- Custom CA bundle support via `ca_bundle` field in global config
+- `AuthProvider` trait for pluggable authentication strategies
+- Bearer token authentication via `token_env` environment variable
+- Basic auth (username/password) via environment variables with base64 encoding
+- Auth provider factory (`create_auth_provider`) for config-driven provider selection
+- API key authentication via header or query parameter mode
+- OIDC/OAuth2 client credentials authentication (token fetched at startup via POST to token endpoint)
+- mTLS client certificate authentication via `client_cert_path` and `client_key_path`
+- mTLS works in combination with custom CA bundles
+- Per-resource auth override: resources can specify their own `auth` config, overriding global auth
+- Shared `read_env_credential` helper validates env vars are set, non-empty, and UTF-8 across all auth providers
+- `--sidecar` flag (and `RESTIUM_SIDECAR` env var) to keep the process alive after reconciliation completes — for K8s sidecar container deployments where the container must not exit
+- Distroless Docker image (`FROM scratch`) with multi-stage build — 3.5MB, zero CVEs, non-root user
+- Multi-arch container support (linux/amd64, linux/arm64) via Docker buildx with QEMU in release pipeline
+- `make cross` target for local musl cross-compilation via cargo-zigbuild
+- `make docker-multiarch` target for local multi-arch Docker builds
+- CI pipeline (GitHub Actions): fmt check, clippy with `--all-targets`, test, build on every PR and push to main
+- Release pipeline: automated cargo publish + multi-arch GHCR push on version tags, with SBOM and provenance
+- Auto-tag workflow: automatically creates git tags when Cargo.toml version changes on main
+- Comprehensive README with value proposition, quick start, Netbird example, spec reference, auth docs, security posture, CLI reference, and deployment guide
+- Example spec files: `examples/simple.yaml` (minimal), `examples/netbird.yaml` (real-world Netbird bootstrapping)
+- Helm chart (`charts/restium/`) for K8s Job deployment with ConfigMap-mounted spec and Secret-based credentials
+
+### Changed
+
+- `validate` command no longer creates an HTTP client (pure syntax/semantic validation)
+- Spec file loading uses `SpecFile::load` error directly instead of redundant existence check
+- Validation now scans `endpoint` field for template references (previously only `payload` and `read_endpoint`)
+- Cycle detection replaced from manual DFS to `petgraph`-based implementation via `DependencyGraph`
+- Reference extraction functions (`extract_refs_from_string`, `extract_references_from_value`) made public for reuse by graph module
+- `--insecure-tls` and mTLS client certificates are now mutually exclusive (previously mTLS cert was silently dropped)
+- Lint target now includes test code (`cargo clippy --all-targets`)
+- Test fixture paths use `CARGO_MANIFEST_DIR` for CWD-independent test execution
+- `HttpClient::get()` now accepts `auth: Option<&dyn AuthProvider>` for consistency with `send_json()` and `request()`
+- `NoVerifier::supported_verify_schemes()` caches signature schemes via `LazyLock` instead of re-instantiating `CryptoProvider` per TLS handshake
+- mTLS file validation deferred to `HttpClient::new()` — removed redundant `metadata()` check from `MtlsAuthProvider::new()` to eliminate TOCTOU window
+- `OidcAuthProvider::with_token()` marked `#[doc(hidden)]` (testing escape hatch, not public API)
+- `auth::mtls` and `auth::oidc` submodules changed from `pub mod` to `mod` (types re-exported via `pub use`)
+- OIDC token request now uses the configured `HttpClient` agent (inherits TLS settings: custom CA bundle, `--insecure-tls`)
+- `create_auth_provider()` accepts optional `&ureq::Agent` for OIDC TLS configuration
+- `HttpClient::agent()` method exposes the underlying ureq Agent for auth provider use
+- `DependencyGraph::build()` uses `update_edge` instead of `add_edge` to prevent duplicate edges when explicit and implicit deps overlap
+- `MtlsAuthProvider` simplified to unit struct — cert/key paths extracted from `AuthConfig` directly, not stored redundantly on the provider
+- `execute_action` returns `ExecuteResult` enum (Performed/AlreadyOk) instead of `Option<Value>` — allows callers to distinguish successful operations from skips/already-absent
+- Success log in `execute_mutation` moved after response body parse (previously logged success before JSON parse could fail)
+- Non-JSON 2xx responses treated as success with no body (previously hard-failed as invalid JSON)
+- Update method auto-switch uses case-insensitive comparison (`eq_ignore_ascii_case("POST")`)
+- `error_hint` checks transport errors before HTTP status codes to avoid false matches on URL digits
+- Delete 404 ("already absent") now increments `skipped` counter instead of `deleted`
+- State discovery GET skipped when resource has no payload (previously wasted a network request)
+
+### Security
+
+- OIDC error messages no longer expose `client_secret` — controlled error formatting instead of raw ureq error propagation
+- OIDC error messages now extract OAuth error fields (`error`, `error_description`) from the response body for actionable diagnostics
+- Auth providers (Bearer, Basic, ApiKey, OIDC) now implement custom `Debug` that redacts credentials instead of using `#[derive(Debug)]`
+- Empty env var values rejected with actionable error (previously silently sent empty credentials)
+- `VarError::NotUnicode` now produces distinct error message instead of misleading "not set"
+- API key auth validates `header_name` and `query_param` are non-empty
+
+### Fixed
+
+- `process_delete_resource` now resolves `${resource.output.field}` template references in endpoints (was using raw template strings, causing 404s or wrong-resource deletion)
+- `execute_mutation` now propagates JSON parse errors from API responses instead of silently substituting `null`
+- Spec validation rejects unknown `action` values (only `delete` is supported; previously any string was silently treated as create/update)
+- OIDC `url_encode` renamed to `form_url_encode` and uses `+` for spaces (HTML form encoding per RFC 1866) instead of `%20` (RFC 3986), fixing multi-word scope values on strict token endpoints
+- OIDC `token_url` is now validated as non-empty before making the HTTP request
+- Redundant "Error:" prefix in spec file not found message (logger already prepends `[ERROR]`)
+- `format!` + `push_str` replaced with `write!` to avoid unnecessary allocations in OIDC URL encoding and text log formatting
+- Misleading `// Safety:` comment changed to `// Note:` (not an unsafe block)
+- JSON log fallback replaced with `expect()` (serialization of `BTreeMap<String, Value::String>` is infallible)
+- Unnecessary `body.clone()` removed in `HttpClient::send_json` (reference already satisfies `Serialize`)
+- Malformed template references like `${.output.field}` (empty resource name) are now silently ignored instead of producing confusing errors
+- Use `sort_unstable()` instead of `sort()` for primitive `&str` slice in cycle detection
diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..c9b3aa3
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,1120 @@
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8e9b5ad5ab802e97eb8e295ac6720e509ee4c243f69d781394014ebfe8bbfa0b"
+
+[[package]]
+name = "windows_i686_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0eee52d38c090b3caa76c563b86c3a4bd71ef1a819287c19d586d7334ae8ed66"
+
+[[package]]
+name = "windows_i686_msvc"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "240948bc05c5e7c6dabba28bf89d89ffce3e303022809e73deaefe4f6ec56c66"
+
+[[package]]
+name = "windows_x86_64_gnu"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"
+
+[[package]]
+name = "windows_x86_64_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"
+
+[[package]]
+name = "windows_x86_64_msvc"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
+
+[[package]]
+name = "wit-bindgen"
+version = "0.51.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d7249219f66ced02969388cf2bb044a09756a083d0fab1e566056b04d9fbcaa5"
+dependencies = [
+ "wit-bindgen-rust-macro",
+]
+
+[[package]]
+name = "wit-bindgen-core"
+version = "0.51.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ea61de684c3ea68cb082b7a88508a8b27fcc8b797d738bfc99a82facf1d752dc"
+dependencies = [
+ "anyhow",
+ "heck",
+ "wit-parser",
+]
+
+[[package]]
+name = "wit-bindgen-rust"
+version = "0.51.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b7c566e0f4b284dd6561c786d9cb0142da491f46a9fbed79ea69cdad5db17f21"
+dependencies = [
+ "anyhow",
+ "heck",
+ "indexmap",
+ "prettyplease",
+ "syn",
+ "wasm-metadata",
+ "wit-bindgen-core",
+ "wit-component",
+]
+
+[[package]]
+name = "wit-bindgen-rust-macro"
+version = "0.51.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0c0f9bfd77e6a48eccf51359e3ae77140a7f50b1e2ebfe62422d8afdaffab17a"
+dependencies = [
+ "anyhow",
+ "prettyplease",
+ "proc-macro2",
+ "quote",
+ "syn",
+ "wit-bindgen-core",
+ "wit-bindgen-rust",
+]
+
+[[package]]
+name = "wit-component"
+version = "0.244.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9d66ea20e9553b30172b5e831994e35fbde2d165325bec84fc43dbf6f4eb9cb2"
+dependencies = [
+ "anyhow",
+ "bitflags",
+ "indexmap",
+ "log",
+ "serde",
+ "serde_derive",
+ "serde_json",
+ "wasm-encoder",
+ "wasm-metadata",
+ "wasmparser",
+ "wit-parser",
+]
+
+[[package]]
+name = "wit-parser"
+version = "0.244.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ecc8ac4bc1dc3381b7f59c34f00b67e18f910c2c0f50015669dde7def656a736"
+dependencies = [
+ "anyhow",
+ "id-arena",
+ "indexmap",
+ "log",
+ "semver",
+ "serde",
+ "serde_derive",
+ "serde_json",
+ "unicode-xid",
+ "wasmparser",
+]
+
+[[package]]
+name = "writeable"
+version = "0.6.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9edde0db4769d2dc68579893f2306b26c6ecfbe0ef499b013d731b7b9247e0b9"
+
+[[package]]
+name = "yoke"
+version = "0.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72d6e5c6afb84d73944e5cedb052c4680d5657337201555f9f2a16b7406d4954"
+dependencies = [
+ "stable_deref_trait",
+ "yoke-derive",
+ "zerofrom",
+]
+
+[[package]]
+name = "yoke-derive"
+version = "0.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b659052874eb698efe5b9e8cf382204678a0086ebf46982b79d6ca3182927e5d"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+ "synstructure",
+]
+
+[[package]]
+name = "zerofrom"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "50cc42e0333e05660c3587f3bf9d0478688e15d870fab3346451ce7f8c9fbea5"
+dependencies = [
+ "zerofrom-derive",
+]
+
+[[package]]
+name = "zerofrom-derive"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d71e5d6e06ab090c67b5e44993ec16b72dcbaabc526db883a360057678b48502"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+ "synstructure",
+]
+
+[[package]]
+name = "zeroize"
+version = "1.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b97154e67e32c85465826e8bcc1c59429aaaf107c1e4a9e53c8d8ccd5eff88d0"
+
+[[package]]
+name = "zerotrie"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2a59c17a5562d507e4b54960e8569ebee33bee890c70aa3fe7b97e85a9fd7851"
+dependencies = [
+ "displaydoc",
+ "yoke",
+ "zerofrom",
+]
+
+[[package]]
+name = "zerovec"
+version = "0.11.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6c28719294829477f525be0186d13efa9a3c602f7ec202ca9e353d310fb9a002"
+dependencies = [
+ "yoke",
+ "zerofrom",
+ "zerovec-derive",
+]
+
+[[package]]
+name = "zerovec-derive"
+version = "0.11.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eadce39539ca5cb3985590102671f2567e659fca9666581ad3411d59207951f3"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "zmij"
+version = "1.0.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b8848ee67ecc8aedbaf3e4122217aff892639231befc6a1b58d29fff4c2cabaa"
diff --git a/Cargo.toml b/Cargo.toml
index 90d9e42..263892d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -23,10 +23,12 @@ clap = { version = "4", features = ["derive", "env"] }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 serde_yaml = "0.9"
-ureq = { version = "2", features = ["tls"], default-features = false }
-reqwest = { version = "0.12", features = ["json", "rustls-tls"], default-features = false }
-tokio = { version = "1", features = ["full"] }
-anyhow = "1"
+ureq = { version = "2", features = ["tls", "json"], default-features = false }
+rustls = { version = "0.23", default-features = false, features = ["ring", "logging", "std", "tls12"] }
+rustls-pemfile = "2"
+base64 = "0.22"
+webpki-roots = "0.26"
+petgraph = "0.7"
 
 [dev-dependencies]
 tempfile = "3"
diff --git a/Makefile b/Makefile
index 0ac5c04..cec084c 100644
--- a/Makefile
+++ b/Makefile
@@ -1,19 +1,25 @@
 BINARY   := restium
 VERSION  ?= dev
-.PHONY: all build test lint clean
+.PHONY: all build test lint clean cross docker-multiarch
 all: lint test build
 build:
 	cargo build --release
+	mkdir -p bin
 	cp target/release/$(BINARY) bin/$(BINARY)
 test:
 	cargo test
 lint:
-	cargo clippy -- -D warnings
+	cargo clippy --all-targets -- -D warnings
 	cargo fmt --check
 clean:
 	cargo clean
 	rm -rf bin/
+cross: ## Requires: cargo install cargo-zigbuild
+	cargo zigbuild --release --target x86_64-unknown-linux-musl
+	cargo zigbuild --release --target aarch64-unknown-linux-musl
 docker-build:
 	docker build -t ghcr.io/kitstream/restium:$(VERSION) .
+docker-multiarch: ## Multi-arch build; use with --push (requires registry login) — --load only supports single platform
+	docker buildx build --platform linux/amd64,linux/arm64 -t ghcr.io/kitstream/restium:$(VERSION) .
 docker-push:
 	docker push ghcr.io/kitstream/restium:$(VERSION)
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..e34da7d
--- /dev/null
+++ b/README.md
@@ -0,0 +1,305 @@
+# Restium
+
+A declarative reconciling REST client in Rust. Define REST resources in YAML, and Restium converges your API state to match — creating, updating, or cleaning up resources as needed.
+
+**Replace fragile curl scripts with readable, reviewable YAML.**
+
+Restium is built for platform engineers who need to provision resources against REST APIs (Netbird, Keycloak, API gateways) as part of automated deployment pipelines. It ships as a 3.5MB distroless container — no shell, no package manager, zero CVEs.
+
+## Quick Start
+
+```bash
+# Install (after crate is published)
+cargo install restium
+
+# Or build from source
+cargo build --release
+
+# Or pull the container
+docker pull ghcr.io/kitstream/restium:latest
+
+# Validate your spec
+restium validate --spec resources.yaml
+
+# Reconcile — converge API state to match your spec
+restium reconcile --spec resources.yaml
+```
+
+## Example: Netbird Bootstrapping
+
+```yaml
+global:
+  base_url: https://api.netbird.io/api
+  auth:
+    type: bearer
+    token_env: NETBIRD_TOKEN
+
+resources:
+  - name: internal_network
+    endpoint: /networks
+    read_endpoint: /networks/internal
+    payload:
+      name: internal
+      description: Internal service network
+    outputs:
+      id: id
+
+  - name: monitoring_route
+    endpoint: /routes
+    payload:
+      network_id: "${internal_network.output.id}"
+      peer: monitoring-peer
+      network: 10.100.0.0/24
+      description: Route to monitoring subnet
+    depends_on:
+      - internal_network
+
+  - name: monitoring_access_policy
+    endpoint: /policies
+    payload:
+      name: monitoring-access
+      enabled: true
+      rules:
+        - sources: ["monitoring-group"]
+          destinations: ["${internal_network.output.id}"]
+          action: accept
+    depends_on:
+      - internal_network
+```
+
+```bash
+export NETBIRD_TOKEN="your-api-token"
+restium reconcile --spec netbird.yaml
+```
+
+Restium resolves dependencies automatically: `internal_network` is created first, its `id` is extracted, then `monitoring_route` and `monitoring_access_policy` use that ID in their payloads. On subsequent runs, unchanged resources are skipped.
+
+## Spec Reference
+
+### Global Settings
+
+| Field | Type | Default | Example | Description |
+|-------|------|---------|---------|-------------|
+| `base_url` | string | — | `https://api.example.com` | Base URL prepended to all resource endpoints |
+| `default_headers` | map | — | `Content-Type: application/json` | Headers applied to all requests (overridable per resource) |
+| `auth` | object | — | See [Authentication](#authentication) | Global authentication config |
+| `ca_bundle` | string | — | `/etc/ssl/custom-ca.pem` | Path to PEM CA bundle for internal/self-signed certs |
+
+### Resource Fields
+
+| Field | Type | Default | Example | Description |
+|-------|------|---------|---------|-------------|
+| `name` | string | **required** | `my_resource` | Unique resource identifier |
+| `endpoint` | string | **required** | `/api/v1/resources` | API endpoint path (appended to `base_url`) |
+| `method` | string | `POST` | `PUT` | HTTP method for create operations |
+| `payload` | object | — | `name: foo` | Request body (YAML, sent as JSON) |
+| `headers` | map | — | `X-Custom: value` | Per-resource headers (merged with global, overrides on conflict) |
+| `base_url` | string | global | `https://other-api.com` | Override global base URL for this resource |
+| `depends_on` | list | — | `[network, policy]` | Explicit dependency on other resource names |
+| `read_endpoint` | string | — | `/api/v1/resources/mine` | GET endpoint for state discovery (enables idempotent updates) |
+| `outputs` | map | — | `id: id` | Extract fields from API response (`output_key: json_field`) |
+| `action` | string | — | `delete` | Set to `delete` for explicit resource deletion |
+| `auth` | object | global | See [Authentication](#authentication) | Per-resource auth override |
+
+### References
+
+Use `${resource_name.output.field}` to reference outputs from other resources. Dependencies are resolved automatically.
+
+```yaml
+payload:
+  network_id: "${my_network.output.id}"
+```
+
+If a reference cannot be resolved, Restium reports which resource and field are missing.
+
+### Failure Modes
+
+| Condition | Exit Code | Error |
+|-----------|-----------|-------|
+| Spec file not found | 2 | `Failed to read spec file '<path>': No such file` |
+| Invalid YAML | 2 | `Failed to parse spec file '<path>': <details>` |
+| Unknown field in spec | 2 | `unknown field '<name>'` |
+| Broken reference | 2 | `Resource '<name>' references unknown resource '<ref>'` |
+| Circular dependency | 2 | `Circular dependency detected: a -> b -> a` |
+| Missing env var for auth | 2 | `Environment variable '<VAR>' is not set` |
+| API error during reconcile | 1 | `Failed to create resource '<name>': 403 Forbidden on POST /api/... — check authentication token permissions` |
+
+## Authentication
+
+All credentials come from environment variables — never from spec files.
+
+### Bearer Token
+
+```yaml
+auth:
+  type: bearer
+  token_env: MY_API_TOKEN
+```
+
+Sets `Authorization: Bearer <value>` header.
+
+### Basic Auth
+
+```yaml
+auth:
+  type: basic
+  username_env: API_USER
+  password_env: API_PASS
+```
+
+Sets `Authorization: Basic <base64>` header.
+
+### API Key
+
+```yaml
+# As a header
+auth:
+  type: api_key
+  key_env: MY_API_KEY
+  header_name: X-API-Key
+
+# As a query parameter
+auth:
+  type: api_key
+  key_env: MY_API_KEY
+  query_param: api_key
+```
+
+### OIDC Client Credentials
+
+```yaml
+auth:
+  type: oidc
+  token_url: https://auth.example.com/oauth/token
+  client_id_env: OIDC_CLIENT_ID
+  client_secret_env: OIDC_CLIENT_SECRET
+  scope: api:read api:write  # optional
+```
+
+Fetches an access token via OAuth2 `client_credentials` grant and sets `Authorization: Bearer <token>`.
+
+### mTLS
+
+```yaml
+auth:
+  type: mtls
+  client_cert_path: /certs/client.pem
+  client_key_path: /certs/client.key
+```
+
+Presents client certificate during TLS handshake. Combine with `ca_bundle` for internal CAs.
+
+## CLI Reference
+
+```
+restium [OPTIONS] <COMMAND>
+
+Commands:
+  reconcile    Converge API state to match the spec
+  validate     Validate spec file without making API calls
+
+Options:
+  --json              Structured JSON log output [env: RESTIUM_JSON]
+  --insecure-tls      Skip TLS certificate verification [env: RESTIUM_INSECURE_TLS]
+  --sidecar           Keep process alive after completion [env: RESTIUM_SIDECAR]
+
+Subcommand options:
+  --spec <PATH>       Path to YAML spec file [env: RESTIUM_SPEC]
+```
+
+### Exit Codes
+
+| Code | Meaning |
+|------|---------|
+| 0 | All resources reconciled successfully |
+| 1 | One or more resources failed during reconciliation |
+| 2 | Spec validation error (bad YAML, broken refs, cycles, missing env vars) |
+
+### Environment Variables
+
+All flags can be set via `RESTIUM_*` environment variables:
+
+| Variable | Equivalent Flag |
+|----------|----------------|
+| `RESTIUM_SPEC` | `--spec` |
+| `RESTIUM_JSON` | `--json` |
+| `RESTIUM_INSECURE_TLS` | `--insecure-tls` |
+| `RESTIUM_SIDECAR` | `--sidecar` |
+
+## Security
+
+- **Distroless container**: `FROM scratch` — no shell, no package manager, no OS packages, zero CVEs
+- **No secrets in logs**: Credentials are automatically redacted in all log output
+- **TLS by default**: Certificate verification enabled; `--insecure-tls` requires explicit opt-in
+- **Credentials via env vars**: Auth tokens never appear in spec files
+- **Non-root**: Container runs as user 65534 (nobody)
+- **3.5MB image**: Minimal attack surface
+
+## Deployment
+
+### Docker
+
+```bash
+docker run --rm \
+  -v $(pwd)/spec.yaml:/config/spec.yaml \
+  -e NETBIRD_TOKEN="$NETBIRD_TOKEN" \
+  ghcr.io/kitstream/restium:latest \
+  reconcile --spec /config/spec.yaml
+```
+
+### Kubernetes Job
+
+```yaml
+apiVersion: batch/v1
+kind: Job
+metadata:
+  name: restium-bootstrap
+spec:
+  template:
+    spec:
+      containers:
+        - name: restium
+          image: ghcr.io/kitstream/restium:latest
+          args: ["reconcile", "--spec", "/config/spec.yaml"]
+          volumeMounts:
+            - name: spec
+              mountPath: /config
+          envFrom:
+            - secretRef:
+                name: restium-credentials
+      volumes:
+        - name: spec
+          configMap:
+            name: restium-spec
+      restartPolicy: Never
+```
+
+### Helm
+
+```bash
+helm install restium-bootstrap charts/restium \
+  --set secretName=restium-credentials
+```
+
+### Sidecar Mode
+
+Use `--sidecar` to keep the process alive after reconciliation completes — useful for sidecar containers that must not exit:
+
+```bash
+restium --sidecar reconcile --spec /config/spec.yaml
+```
+
+## Development
+
+```bash
+make fmt        # cargo fmt
+make lint       # cargo clippy --all-targets -- -D warnings
+make test       # cargo test
+make build      # cargo build --release
+make cross      # cargo zigbuild for musl targets
+make docker-build  # docker build
+```
+
+## License
+
+Apache-2.0
diff --git a/_bmad-output/implementation-artifacts/1-1-project-scaffold-cli-skeleton.md b/_bmad-output/implementation-artifacts/1-1-project-scaffold-cli-skeleton.md
new file mode 100644
index 0000000..2cd01c8
--- /dev/null
+++ b/_bmad-output/implementation-artifacts/1-1-project-scaffold-cli-skeleton.md
@@ -0,0 +1,217 @@
+# Story 1.1: Project Scaffold & CLI Skeleton
+
+Status: done
+
+## Story
+
+As a platform engineer,
+I want a working `restium` binary with `reconcile` and `validate` subcommands,
+so that I have a functional CLI entry point with proper flags and exit codes.
+
+## Acceptance Criteria
+
+1. **Given** the Restium binary is built, **When** the user runs `restium --help`, **Then** it displays available subcommands (`reconcile`, `validate`) and global flags (`--json`, `--sidecar`, `--insecure-tls`). Each subcommand also accepts `--spec <path>` (visible via `restium <subcommand> --help`).
+
+2. **Given** the user runs `restium reconcile --spec <path>` or `restium validate --spec <path>`, **When** the spec file does not exist, **Then** the process exits with code 2 and an error message indicating the file was not found.
+
+3. **Given** any global flag (e.g. `--json`), **When** the equivalent `RESTIUM_*` environment variable is set (e.g. `RESTIUM_JSON=true`), **Then** the flag value is picked up from the environment variable.
+
+4. **Given** the project scaffold, **When** built with `cargo build --release`, **Then** it produces a statically-linkable binary following the Initium Cargo.toml patterns (opt-level="z", LTO, panic=abort).
+
+**Covers:** FR28, FR30, FR33, FR35
+
+## Tasks / Subtasks
+
+- [x] Task 1: Clean up Cargo.toml dependencies (AC: #4)
+  - [x] Remove `reqwest`, `tokio`, and `anyhow` — architecture mandates synchronous-only with `ureq` and `Result<(), String>` error handling
+  - [x] Verify remaining deps: `clap` v4, `serde` v1, `serde_json` v1, `serde_yaml` v0.9, `ureq` v2
+  - [x] Ensure `cargo build --release` succeeds with cleaned deps
+
+- [x] Task 2: Implement CLI with clap derive (AC: #1, #3)
+  - [x] Define `Cli` struct with `#[derive(Parser)]` in `src/main.rs`
+  - [x] Add global flags: `--json` (`RESTIUM_JSON`), `--sidecar` (`RESTIUM_SIDECAR`), `--insecure-tls` (`RESTIUM_INSECURE_TLS`)
+  - [x] Define `Commands` enum with `Reconcile` and `Validate` subcommands
+  - [x] Both subcommands take `--spec <path>` (required, `RESTIUM_SPEC`)
+  - [x] Use clap `env` feature for automatic `RESTIUM_*` env var support
+
+- [x] Task 3: Implement spec file existence check (AC: #2)
+  - [x] In both `reconcile` and `validate` handlers, check if spec file exists at the provided path
+  - [x] If file doesn't exist, print error to stderr: `"Error: spec file not found: '<path>'"` and exit with code 2
+  - [x] Use `std::process::exit(2)` for validation/input errors
+
+- [x] Task 4: Implement stub subcommand handlers (AC: #1, #2)
+  - [x] `validate` handler: check file exists, print placeholder success message to stderr, exit 0
+  - [x] `reconcile` handler: check file exists, print placeholder success message to stderr, exit 0
+  - [x] Both handlers return `Result<(), String>` — `main()` catches `Err` and exits with code 1
+
+- [x] Task 5: Implement exit code logic (AC: #2, #4)
+  - [x] Exit 0: success
+  - [x] Exit 1: runtime error (reconciliation failure)
+  - [x] Exit 2: input/validation error (bad spec, missing file)
+  - [x] `main()` catches errors and calls `std::process::exit()` with correct code
+
+- [x] Task 6: Create `bin/` directory and verify Makefile (AC: #4)
+  - [x] Ensure `mkdir -p bin` is run before `cp` in Makefile build target
+  - [x] Verify `make lint`, `make test`, `make build` all pass
+
+- [x] Task 7: Write CLI tests (AC: #1, #2, #3)
+  - [x] Create `tests/e2e/cli_test.rs` (following architecture test layout)
+  - [x] Create `tests/e2e/mod.rs` to declare test modules
+  - [x] Test: `--help` output contains `reconcile` and `validate`
+  - [x] Test: `--help` output contains `--json`, `--spec`, `--sidecar`, `--insecure-tls`
+  - [x] Test: `validate --spec nonexistent.yaml` exits with code 2
+  - [x] Test: `reconcile --spec nonexistent.yaml` exits with code 2
+  - [x] Test: `validate --spec <valid-file>` exits with code 0
+  - [x] Test: env var `RESTIUM_JSON=true` is picked up (verify via `--help` or behavior)
+  - [x] Use `std::process::Command` to invoke the built binary in tests
+
+- [x] Task 8: Create initial project files (AC: #4)
+  - [x] Create `CHANGELOG.md` with initial "Unreleased" section
+  - [x] Create `README.md` with minimal project description
+  - [x] Ensure `.gitignore` covers `target/`, `bin/`
+
+- [x] Task 9: Validate full pipeline (AC: #4)
+  - [x] Run `cargo fmt`
+  - [x] Run `cargo clippy -- -D warnings` with zero warnings
+  - [x] Run `cargo test` — all tests pass
+  - [x] Run `cargo build --release` — binary produced
+
+## Dev Notes
+
+### Architecture Compliance
+
+- **Error handling:** Use `Result<(), String>` with `.map_err()` for context. Do NOT use `anyhow` — remove it from Cargo.toml.
+- **No println!():** Story 1.1 is the only story allowed to use `eprintln!()` for error output. Starting from Story 1.2, all output goes through the custom `Logger`. For now, use `eprintln!()` for errors and minimal status messages.
+- **No async:** Remove `tokio` and `reqwest` from Cargo.toml. The architecture mandates synchronous-only code with `ureq`.
+- **Module style:** Use directory-style modules (`mod.rs`) for all new modules. Story 1.1 only modifies `main.rs` — no new modules needed yet.
+- **Test location:** All tests in `tests/` directory — no inline `#[cfg(test)]` modules.
+- **Anti-patterns (forbidden):** `unwrap()` or `expect()` in non-test code; `println!()` for output; hardcoded URLs or credentials.
+
+### Cargo.toml Dependency Corrections
+
+The current `Cargo.toml` has dependencies that conflict with the architecture:
+
+| Dependency | Action | Reason |
+|---|---|---|
+| `reqwest` | **REMOVE** | Architecture mandates `ureq` v2 (synchronous). No async HTTP. |
+| `tokio` | **REMOVE** | No async runtime. Synchronous-only design. |
+| `anyhow` | **REMOVE** | Architecture uses `Result<(), String>` with `.map_err()` (Initium pattern). |
+| `clap` | Keep | v4 with derive + env features ✓ |
+| `serde` | Keep | v1 with derive ✓ |
+| `serde_json` | Keep | v1 ✓ |
+| `serde_yaml` | Keep | v0.9 ✓ |
+| `ureq` | Keep | v2 with tls, no default-features ✓ |
+
+### CLI Design Reference
+
+```rust
+use clap::{Parser, Subcommand};
+
+#[derive(Parser)]
+#[command(name = "restium", about = "A declarative reconciling REST client")]
+struct Cli {
+    #[arg(long, env = "RESTIUM_JSON", help = "Enable structured JSON log output")]
+    json: bool,
+
+    #[arg(long, env = "RESTIUM_SIDECAR", help = "Keep process alive after completion")]
+    sidecar: bool,
+
+    #[arg(long, env = "RESTIUM_INSECURE_TLS", help = "Skip TLS certificate verification")]
+    insecure_tls: bool,
+
+    #[command(subcommand)]
+    command: Commands,
+}
+
+#[derive(Subcommand)]
+enum Commands {
+    /// Converge API state to match the spec
+    Reconcile {
+        #[arg(long, env = "RESTIUM_SPEC", help = "Path to YAML spec file")]
+        spec: String,
+    },
+    /// Validate spec file without making API calls
+    Validate {
+        #[arg(long, env = "RESTIUM_SPEC", help = "Path to YAML spec file")]
+        spec: String,
+    },
+}
+```
+
+### Exit Code Convention
+
+| Code | Meaning | When |
+|---|---|---|
+| 0 | Success | All operations completed |
+| 1 | Runtime error | Reconciliation failure, HTTP errors |
+| 2 | Input/validation error | Missing spec file, invalid YAML, broken references, cycles |
+
+### Test Approach
+
+Use `std::process::Command` to invoke the compiled binary for e2e CLI tests. This tests the actual binary behavior including exit codes, stdout/stderr output, and env var handling.
+
+```rust
+use std::process::Command;
+
+fn restium_cmd() -> Command {
+    Command::new(env!("CARGO_BIN_EXE_restium"))
+}
+```
+
+The `CARGO_BIN_EXE_restium` env var is automatically set by `cargo test` to point to the compiled binary.
+
+### Existing Infrastructure (Already Set Up)
+
+These files already exist and should NOT be recreated:
+- `Cargo.toml` — edit to remove wrong deps, don't replace
+- `Makefile` — works, but `build` target needs `mkdir -p bin/` added
+- `Dockerfile` — works as-is
+- `.github/workflows/ci.yml` — works as-is
+- `.github/workflows/release.yml` — works as-is
+- `.gitignore` — works as-is
+
+### Project Structure Notes
+
+- Story 1.1 scope is limited to `src/main.rs` and test files
+- No new `src/` modules — Logger, config, auth etc. come in later stories
+- The `bin/` directory is created by the Makefile build target (add `mkdir -p bin/` before `cp`)
+
+### References
+
+- [Source: _bmad-output/planning-artifacts/architecture.md#Core Architectural Decisions] — Error handling, exit codes, CLI framework
+- [Source: _bmad-output/planning-artifacts/architecture.md#Implementation Patterns] — Naming, anti-patterns, module style
+- [Source: _bmad-output/planning-artifacts/architecture.md#Project Structure] — Complete directory structure, test organization
+- [Source: _bmad-output/planning-artifacts/epics.md#Story 1.1] — Acceptance criteria, FR coverage
+- [Source: _bmad-output/planning-artifacts/prd.md#CLI Tool Specific Requirements] — Command structure, flags, env vars
+
+## Dev Agent Record
+
+### Agent Model Used
+
+Claude Opus 4.6 (1M context)
+
+### Debug Log References
+
+### Completion Notes List
+
+- Removed `reqwest`, `tokio`, `anyhow` from Cargo.toml per architecture (sync-only, `Result<(), String>`)
+- Implemented clap derive CLI with `Cli` struct, `Commands` enum, global flags, and env var support
+- Error handling uses `Result<(), (u8, String)>` tuple to carry exit codes — code 2 for input errors, code 1 for runtime errors
+- Used `ExitCode` return from `main()` instead of `std::process::exit()` for cleaner control flow
+- 9 e2e tests covering help output, exit codes, file existence, and env var pickup
+- Added `mkdir -p bin` to Makefile build target
+- Created CHANGELOG.md and README.md
+- All checks pass: `cargo fmt`, `cargo clippy -- -D warnings`, `cargo test` (9/9), `cargo build --release`
+- Release binary size: 410K (macOS)
+
+### File List
+
+- `Cargo.toml` (modified — removed reqwest, tokio, anyhow)
+- `Cargo.lock` (modified — regenerated after dependency changes)
+- `src/main.rs` (modified — full CLI implementation)
+- `Makefile` (modified — added mkdir -p bin)
+- `tests/cli_tests.rs` (new — top-level test entry point)
+- `tests/e2e/mod.rs` (new — e2e module declaration)
+- `tests/e2e/cli_test.rs` (new — 10 CLI e2e tests)
+- `CHANGELOG.md` (new — initial changelog)
+- `README.md` (new — minimal project description)
diff --git a/_bmad-output/implementation-artifacts/1-2-structured-logging-with-secret-redaction.md b/_bmad-output/implementation-artifacts/1-2-structured-logging-with-secret-redaction.md
new file mode 100644
index 0000000..3f2afdb
--- /dev/null
+++ b/_bmad-output/implementation-artifacts/1-2-structured-logging-with-secret-redaction.md
@@ -0,0 +1,234 @@
+# Story 1.2: Structured Logging with Secret Redaction
+
+Status: done
+
+## Story
+
+As a platform engineer,
+I want structured JSON logging with automatic secret redaction,
+so that I can safely aggregate logs in K8s without leaking credentials.
+
+## Acceptance Criteria
+
+1. **Given** the `--json` flag is set, **When** any log message is emitted, **Then** it is written to stderr as a structured JSON object with `level`, `message`, and key-value pairs.
+
+2. **Given** the `--json` flag is not set, **When** any log message is emitted, **Then** it is written to stderr in human-readable text format.
+
+3. **Given** a log message that includes a key-value pair where the key matches a sensitive pattern (e.g., `authorization`, `token`, `password`, `api_key`, `client_secret`), **When** the message is rendered, **Then** the value is replaced with `[REDACTED]`.
+
+4. **Given** an error containing a URL with a query parameter that includes a secret, **When** logged, **Then** the secret portion is redacted.
+
+**Covers:** FR28, FR34, NFR2
+
+## Tasks / Subtasks
+
+- [x] Task 1: Create `src/logging/mod.rs` module (AC: #1, #2)
+  - [x] Create `src/logging/` directory with `mod.rs`
+  - [x] Define `Logger` struct with fields: `json: bool`
+  - [x] Implement `Logger::new(json: bool) -> Logger`
+  - [x] Add `pub mod logging;` to `src/lib.rs` (used lib.rs for testability)
+
+- [x] Task 2: Implement text-mode logging (AC: #2)
+  - [x] Implement `Logger::info(&self, message: &str, kvs: &[(&str, &str)])`
+  - [x] Implement `Logger::warn(&self, message: &str, kvs: &[(&str, &str)])`
+  - [x] Implement `Logger::error(&self, message: &str, kvs: &[(&str, &str)])`
+  - [x] Text format: `[LEVEL] message key=value key=value`
+  - [x] All output to stderr via `writeln!(std::io::stderr())`
+
+- [x] Task 3: Implement JSON-mode logging (AC: #1)
+  - [x] When `json: true`, output each log as a single-line JSON object to stderr
+  - [x] JSON format: `{"level":"info","message":"...","key":"value",...}`
+  - [x] Use `serde_json::to_string()` to serialize — no manual JSON construction
+  - [x] Note: timestamp field deferred — will be added when needed by reconciliation stories
+
+- [x] Task 4: Implement secret redaction (AC: #3)
+  - [x] Define `SENSITIVE_KEYS` constant list: `authorization`, `token`, `password`, `api_key`, `client_secret`, `access_token`, `refresh_token`, `bearer`, `credential`, `secret`
+  - [x] Before rendering any key-value pair, check if key contains (case-insensitive) any sensitive pattern
+  - [x] If sensitive, replace value with `[REDACTED]`
+  - [x] Redaction applies in both text and JSON modes
+
+- [x] Task 5: Implement URL secret redaction (AC: #4)
+  - [x] Add `redact_url(url: &str) -> String` public function
+  - [x] Parse query parameters from the URL
+  - [x] Redact values of query parameters whose keys match sensitive patterns
+  - [x] Preserve non-sensitive query parameters
+  - [x] Handle URLs without query parameters (return unchanged)
+
+- [x] Task 6: Integrate Logger into main.rs (AC: #1, #2)
+  - [x] Create `Logger` instance using `cli.json` flag value after CLI parsing
+  - [x] Replace `eprintln!()` calls in subcommand handlers with `Logger` calls
+  - [x] Refactored: `execute(command, &logger)` function takes `&Logger`
+  - [x] Use `logger.error()` for error output in `main()` error handler
+
+- [x] Task 7: Write Logger unit tests (AC: #1, #2, #3, #4)
+  - [x] Create `tests/logging_test.rs`
+  - [x] Test: text mode outputs `[INFO] message` format
+  - [x] Test: text mode includes key-value pairs as `key=value`
+  - [x] Test: JSON mode outputs valid JSON with level, message, and kvs
+  - [x] Test: sensitive key `authorization` has its value redacted in text mode
+  - [x] Test: sensitive key `token` has its value redacted in JSON mode
+  - [x] Test: non-sensitive keys are NOT redacted
+  - [x] Test: case-insensitive matching (e.g., `Authorization` is redacted)
+  - [x] Test: URL with secret query param is redacted
+  - [x] Test: URL without query params is returned unchanged
+  - [x] Test: URL with non-sensitive query params is returned unchanged
+  - [x] Test: partial key match works (e.g., `x_api_key` matches `api_key`)
+
+- [x] Task 8: Write e2e tests for CLI logging integration (AC: #1, #2)
+  - [x] E2e tests included in `tests/logging_test.rs` (tests JSON and text mode via binary)
+  - [x] Test: `--json` flag produces JSON output on stderr
+  - [x] Test: without `--json`, output is human-readable text on stderr
+
+- [x] Task 9: Update CHANGELOG.md
+  - [x] Add entry under "Unreleased" / "Added": structured logging with JSON/text modes and secret redaction
+
+- [x] Task 10: Validate full pipeline
+  - [x] Run `cargo fmt`
+  - [x] Run `cargo clippy -- -D warnings` with zero warnings
+  - [x] Run `cargo test` — all 27 tests pass (10 existing + 17 new)
+  - [x] Run `cargo build --release` — binary produced
+
+## Dev Notes
+
+### Architecture Compliance
+
+- **Logger struct:** Custom `Logger` struct, ported from Initium's `logging.rs` pattern. Zero external logging dependencies — no `log` crate, no `tracing`.
+- **Thread safety:** Logger should be safe to share via `&Logger`. All methods take `&self`.
+- **Passed by reference:** Logger is passed as `&Logger` parameter to functions, not stored globally. This is a critical architecture pattern.
+- **Writes to stderr:** All log output goes to stderr. stdout is reserved for future structured output.
+- **No println!/eprintln! after this story:** Once Logger exists, all other modules must use it. The `eprintln!` calls in main.rs from Story 1.1 will be replaced.
+- **Error handling:** Functions return `Result<T, String>`. Logger methods do not return Results — they write directly to stderr.
+- **Module style:** Directory-style module: `src/logging/mod.rs`
+- **Anti-patterns:** No `unwrap()` or `expect()` in non-test code. No `println!()`.
+
+### Logger API Design
+
+```rust
+pub struct Logger {
+    json: bool,
+}
+
+impl Logger {
+    pub fn new(json: bool) -> Self { ... }
+    pub fn info(&self, message: &str, kvs: &[(&str, &str)]) { ... }
+    pub fn warn(&self, message: &str, kvs: &[(&str, &str)]) { ... }
+    pub fn error(&self, message: &str, kvs: &[(&str, &str)]) { ... }
+    pub fn redact_url(url: &str) -> String { ... }
+}
+```
+
+### Sensitive Keys List
+
+From the architecture document, extended for Restium's auth patterns:
+
+```rust
+const SENSITIVE_KEYS: &[&str] = &[
+    "authorization",
+    "token",
+    "password",
+    "api_key",
+    "client_secret",
+    "access_token",
+    "refresh_token",
+    "bearer",
+    "credential",
+    "secret",
+];
+```
+
+Matching is case-insensitive and uses `contains` — so `x_api_key` matches `api_key`, and `Authorization` matches `authorization`.
+
+### Log Key-Value Conventions (from Architecture)
+
+| Key | Usage | Example |
+|-----|-------|---------|
+| `resource` | Resource name from spec | `netbird_network` |
+| `action` | Operation being performed | `create`, `update`, `delete`, `skip` |
+| `method` | HTTP method | `POST`, `GET`, `PUT`, `DELETE` |
+| `endpoint` | Full URL called | `https://api.netbird.io/api/networks` |
+| `status` | HTTP response status code | `201`, `403`, `500` |
+| `reason` | Human-readable context | `already exists`, `token expired` |
+
+### Output Formats
+
+**Text mode (default):**
+```
+[INFO] Validation passed
+[INFO] Resource created resource=netbird_network action=create method=POST endpoint=https://api.netbird.io/api/networks status=201
+[ERROR] Failed to create resource resource=access_policy method=POST endpoint=https://api.netbird.io/api/policies status=403
+```
+
+**JSON mode (`--json`):**
+```json
+{"level":"info","message":"Validation passed","timestamp":"2026-03-14T19:45:00Z"}
+{"level":"info","message":"Resource created","resource":"netbird_network","action":"create","method":"POST","endpoint":"https://api.netbird.io/api/networks","status":"201","timestamp":"2026-03-14T19:45:01Z"}
+```
+
+### URL Redaction Example
+
+Input: `https://api.example.com/oauth/token?client_secret=abc123&scope=read`
+Output: `https://api.example.com/oauth/token?client_secret=[REDACTED]&scope=read`
+
+Use simple string parsing — split on `?`, then split query on `&`, check each `key=value` pair. Do not bring in a URL parsing library for this (the `url` crate is already a transitive dep of `ureq`, but avoid using it directly for this simple task).
+
+### Testing Strategy
+
+Unit tests for Logger can capture stderr output. Use a technique like:
+- Make Logger accept an optional `Write` target for testability, OR
+- Use `std::io::Cursor` or buffer-based approach, OR
+- Simply test the formatting logic in helper functions that return strings, then verify the output format
+
+The simplest approach: extract the format logic into methods that return `String`, test those, and have the actual `info()`/`warn()`/`error()` methods call `eprintln!` with the formatted result.
+
+### Previous Story Intelligence (Story 1.1)
+
+- `main.rs` uses `ExitCode` return from `main()` with `Result<(), (u8, String)>` from `run()`
+- `eprintln!` is used for error output in the `Err` branch of `main()`
+- `cli.json` is already parsed and available after `Cli::parse()`
+- The `run()` function currently returns `Result<(), (u8, String)>` — Logger integration means errors should be logged via Logger before returning the exit code
+- Test structure: `tests/cli_tests.rs` -> `tests/e2e/mod.rs` -> `tests/e2e/cli_test.rs`
+
+### Integration Points
+
+- `main.rs`: Create `Logger::new(cli.json)` after parsing CLI, pass `&logger` to handlers
+- Handler signature changes: `fn handle_validate(spec: &str, logger: &Logger) -> Result<(), (u8, String)>`
+- Error branch in `main()`: use `logger.error()` instead of `eprintln!()`
+
+### References
+
+- [Source: _bmad-output/planning-artifacts/architecture.md#Logging] — Logger struct, redaction, JSON/text modes
+- [Source: _bmad-output/planning-artifacts/architecture.md#Log Key-Value Conventions] — Consistent log keys table
+- [Source: _bmad-output/planning-artifacts/architecture.md#Process Patterns] — Logger passed as `&Logger` parameter
+- [Source: _bmad-output/planning-artifacts/architecture.md#Anti-Patterns] — No `println!`/`eprintln!`, always use Logger
+- [Source: _bmad-output/planning-artifacts/epics.md#Story 1.2] — Acceptance criteria, FR coverage
+
+## Dev Agent Record
+
+### Agent Model Used
+
+Claude Opus 4.6 (1M context)
+
+### Debug Log References
+
+### Completion Notes List
+
+- Created `src/lib.rs` to expose logging module for test access — binary crate uses `use restium::logging::Logger`
+- Logger struct with `info()`, `warn()`, `error()` methods and `format_line()` for testability
+- Text mode: `[LEVEL] message key=value` format to stderr
+- JSON mode: single-line JSON with `level`, `message`, and kv fields via `serde_json`
+- Secret redaction: 10 sensitive key patterns, case-insensitive `contains` matching
+- URL redaction: simple string-based query parameter parsing, no external URL library
+- Refactored `main.rs`: `run()` replaced with `execute(command, &logger)`, CLI parsed once in `main()`
+- Error path now uses Logger (respects `--json` flag for error output)
+- 18 new tests: 7 e2e (text/JSON mode, error output) + 8 redaction unit tests + 4 URL redaction tests + warn level test
+- Timestamp field in JSON mode deferred — not needed until reconciliation stories add time-sensitive operations
+- All 28 tests pass, zero clippy warnings, cargo fmt clean
+- Code review fixes: replaced unwrap_or_default with safe fallback in format_json, added #[doc(hidden)] to format_line, added warn level test
+
+### File List
+
+- `src/lib.rs` (new — exposes logging module for testing)
+- `src/logging/mod.rs` (new — Logger struct, redaction, JSON/text formatting)
+- `src/main.rs` (modified — integrated Logger, refactored execute function)
+- `tests/logging_test.rs` (new — 18 logging and redaction tests)
+- `CHANGELOG.md` (modified — added logging entries)
diff --git a/_bmad-output/implementation-artifacts/1-3-yaml-spec-parsing-global-settings.md b/_bmad-output/implementation-artifacts/1-3-yaml-spec-parsing-global-settings.md
new file mode 100644
index 0000000..d543888
--- /dev/null
+++ b/_bmad-output/implementation-artifacts/1-3-yaml-spec-parsing-global-settings.md
@@ -0,0 +1,234 @@
+# Story 1.3: YAML Spec Parsing & Global Settings
+
+Status: done
+
+## Story
+
+As a platform engineer,
+I want to define REST resources and global settings in a YAML spec file,
+so that my infrastructure configuration is declarative and readable.
+
+## Acceptance Criteria
+
+1. **Given** a YAML spec file with a `global` section defining `base_url` and `default_headers`, **When** parsed, **Then** global settings are loaded and available for resource processing.
+
+2. **Given** a YAML spec file with resource definitions containing `name`, `endpoint`, `method`, and `payload`, **When** parsed, **Then** each resource is loaded into typed Rust structs with all fields accessible.
+
+3. **Given** a resource that does not specify `base_url` or headers, **When** processed, **Then** it inherits the global settings.
+
+4. **Given** a resource that specifies its own `base_url` or headers, **When** processed, **Then** the per-resource values override the global settings.
+
+5. **Given** a YAML spec file with `depends_on` fields on resources, **When** parsed, **Then** the explicit dependency relationships are captured in the resource definitions.
+
+6. **Given** a YAML spec file with a structured payload containing nested objects and arrays, **When** parsed and serialized to JSON, **Then** the structure is preserved faithfully.
+
+7. **Given** a YAML file with syntax errors or unknown fields, **When** parsed, **Then** a clear error message with context (line number or field name) is returned and the process exits with code 2.
+
+**Covers:** FR1, FR2, FR3, FR5, FR6 (partially)
+
+## Tasks / Subtasks
+
+- [x] Task 1: Create `src/config/mod.rs` with spec types (AC: #1, #2, #5)
+  - [x] Create `src/config/` directory with `mod.rs`
+  - [x] Define `SpecFile` struct with `global` and `resources` fields, `#[serde(deny_unknown_fields)]`
+  - [x] Define `GlobalConfig` struct with `base_url`, `default_headers`, `auth`
+  - [x] Define `ResourceSpec` struct with all fields (name, endpoint, method, payload, headers, base_url, depends_on, read_endpoint, outputs, action, auth)
+  - [x] Define `AuthConfig` tagged enum (bearer, basic, api_key, oidc, mtls)
+  - [x] Add `pub mod config;` to `src/lib.rs`
+  - [x] `#[serde(deny_unknown_fields)]` on SpecFile and GlobalConfig
+
+- [x] Task 2: Implement spec file loading (AC: #1, #2, #7)
+  - [x] `SpecFile::load(path)` reads and parses YAML
+  - [x] IO and parse errors mapped with file path context
+  - [x] Returns `Result<SpecFile, String>`
+
+- [x] Task 3: Implement global settings inheritance (AC: #3, #4)
+  - [x] `effective_base_url()` with lifetime annotation for borrowing from either self or global
+  - [x] `effective_headers()` merges global + resource headers
+  - [x] `effective_method()` defaults to "POST"
+
+- [x] Task 4: Implement payload preservation (AC: #6)
+  - [x] `serde_json::Value` for payload — preserves nested objects, arrays, mixed types
+
+- [x] Task 5: Integrate config loading into CLI (AC: #7)
+  - [x] Both `validate` and `reconcile` load spec and log resource count
+  - [x] Parse errors return exit code 2
+
+- [x] Task 6: Write config parsing tests (AC: #1, #2, #3, #4, #5, #6, #7)
+  - [x] 24 tests in `tests/config_test.rs` covering all acceptance criteria
+
+- [x] Task 7: Write e2e CLI integration tests (AC: #7)
+  - [x] 3 new e2e tests: resource count, invalid YAML, JSON mode with resources
+
+- [x] Task 8: Update CHANGELOG.md
+  - [x] Added entries for spec parsing, global settings, payload support, auth types
+
+- [x] Task 9: Validate full pipeline
+  - [x] `cargo fmt` clean
+  - [x] `cargo clippy -- -D warnings` zero warnings
+  - [x] `cargo test` — all 55 tests pass (13 e2e + 24 config + 18 logging)
+  - [x] `cargo build --release` — binary produced
+
+## Dev Notes
+
+### Architecture Compliance
+
+- **Module:** `src/config/mod.rs` — directory-style module as per architecture
+- **Dependencies:** config depends only on `logging` (for future use) and serde
+- **Exposes:** `SpecFile`, `GlobalConfig`, `ResourceSpec`, `AuthConfig` — public types consumed by other modules
+- **Error handling:** `Result<T, String>` with `.map_err()` for context
+- **No unwrap/expect:** All parsing errors propagated with context
+- **deny_unknown_fields:** Use on `SpecFile` and `GlobalConfig` to catch typos (FR6)
+- **Test location:** `tests/config_test.rs` — no inline tests
+
+### YAML Spec Format
+
+Based on the PRD and architecture, the spec file format:
+
+```yaml
+global:
+  base_url: "https://api.example.com"
+  default_headers:
+    Content-Type: "application/json"
+    Accept: "application/json"
+  auth:
+    type: bearer
+    token_env: API_TOKEN
+
+resources:
+  - name: netbird_network
+    endpoint: /api/networks
+    method: POST
+    payload:
+      name: "internal-network"
+      description: "Internal network for services"
+    depends_on: []
+    outputs:
+      id: "id"
+
+  - name: netbird_route
+    endpoint: /api/routes
+    method: POST
+    base_url: "https://other-api.example.com"
+    headers:
+      X-Custom: "value"
+    payload:
+      network_id: "${netbird_network.output.id}"
+      cidr: "10.0.0.0/24"
+    depends_on:
+      - netbird_network
+    read_endpoint: /api/routes/${netbird_route.output.id}
+```
+
+### AuthConfig Placeholder
+
+Story 1.3 defines the `AuthConfig` type structure but does NOT implement auth logic. Auth implementation is Epic 2 (Stories 2.1-2.5). The struct should capture what auth type and which env vars to use:
+
+```rust
+#[derive(Debug, Deserialize, Serialize, Clone)]
+#[serde(tag = "type", rename_all = "snake_case")]
+pub enum AuthConfig {
+    Bearer { token_env: String },
+    Basic { username_env: String, password_env: String },
+    ApiKey { key_env: String, header_name: Option<String>, query_param: Option<String> },
+    Oidc { token_url: String, client_id_env: String, client_secret_env: String, scope: Option<String> },
+    Mtls { client_cert_path: String, client_key_path: String },
+}
+```
+
+### Payload Handling
+
+The `payload` field uses `serde_json::Value` which serde_yaml can deserialize into. This preserves:
+- Nested objects
+- Arrays (order preserved)
+- Mixed types (strings, numbers, booleans, null)
+- References like `${resource.output.field}` as plain strings (resolved later by the reference module)
+
+### Global Settings Inheritance Rules
+
+1. `base_url`: resource-level overrides global. If neither set, full URL must be in `endpoint`.
+2. `default_headers`: global headers are the base, resource headers merge on top (resource wins on key conflict).
+3. `auth`: resource-level auth overrides global auth entirely (no merging).
+4. `method`: defaults to `"POST"` if not specified on resource.
+
+### Previous Story Intelligence
+
+**Story 1.1:**
+- `main.rs` uses `execute(command, &logger)` pattern
+- CLI already parses `--spec` path and checks file existence
+- Exit codes: 0 success, 1 runtime, 2 validation/input
+
+**Story 1.2:**
+- `src/lib.rs` exists and exports `pub mod logging;`
+- Logger available via `use restium::logging::Logger;`
+- Logger passed as `&Logger` to functions
+- Test structure: `tests/cli_tests.rs` (e2e module), `tests/logging_test.rs`
+- `format_line()` public method on Logger for testing
+
+### Integration with main.rs
+
+Current `execute()` function:
+```rust
+fn execute(command: Commands, logger: &Logger) -> Result<(), (u8, String)> {
+    match command {
+        Commands::Reconcile { spec } => {
+            check_spec_exists(&spec)?;
+            logger.info("Reconciliation complete (no resources defined)", &[]);
+            Ok(())
+        }
+        Commands::Validate { spec } => {
+            check_spec_exists(&spec)?;
+            logger.info("Validation passed", &[]);
+            Ok(())
+        }
+    }
+}
+```
+
+After this story, it should load the spec and report results:
+```rust
+Commands::Validate { spec } => {
+    check_spec_exists(&spec)?;
+    let spec_file = SpecFile::load(&spec).map_err(|e| (2u8, e))?;
+    let count = spec_file.resources.len();
+    logger.info("Validation passed", &[("resources", &count.to_string())]);
+    Ok(())
+}
+```
+
+### References
+
+- [Source: _bmad-output/planning-artifacts/architecture.md#Structure Patterns] — config/ module with mod.rs and validation.rs
+- [Source: _bmad-output/planning-artifacts/architecture.md#Architectural Boundaries] — config exposes Config, ResourceSpec, GlobalConfig
+- [Source: _bmad-output/planning-artifacts/architecture.md#Naming Patterns] — snake_case YAML keys, reference syntax
+- [Source: _bmad-output/planning-artifacts/epics.md#Story 1.3] — Acceptance criteria, FR coverage
+- [Source: _bmad-output/planning-artifacts/prd.md#Configuration & Parsing] — FR1-FR6
+
+## Dev Agent Record
+
+### Agent Model Used
+
+Claude Opus 4.6 (1M context)
+
+### Debug Log References
+
+### Completion Notes List
+
+- Created `src/config/mod.rs` with `SpecFile`, `GlobalConfig`, `ResourceSpec`, `AuthConfig` types
+- `AuthConfig` is a tagged enum (`#[serde(tag = "type")]`) supporting 5 auth strategies — types only, no auth logic
+- `SpecFile` and `GlobalConfig` use `#[serde(deny_unknown_fields)]` to catch YAML typos at parse time
+- `effective_base_url()` required explicit lifetime annotation `<'a>` to borrow from either `&self` or `&global`
+- Payload uses `serde_json::Value` — serde_yaml deserializes YAML nested structures directly into JSON values
+- `main.rs` refactored: both commands now load spec and log resource count
+- 23 config tests + 3 new e2e tests = 26 new tests (53 total across all test files)
+- All pipeline checks pass: fmt, clippy, test, release build
+- Code review fixes: improved auth config tests to verify enum variants and field values, added resource-level unknown field test
+
+### File List
+
+- `src/config/mod.rs` (new — SpecFile, GlobalConfig, ResourceSpec, AuthConfig types + loading + inheritance)
+- `src/lib.rs` (modified — added `pub mod config;`)
+- `src/main.rs` (modified — integrated SpecFile::load into validate/reconcile commands)
+- `tests/config_test.rs` (new — 23 config parsing and inheritance tests)
+- `tests/e2e/cli_test.rs` (modified — 3 new e2e tests for spec loading)
+- `CHANGELOG.md` (modified — added spec parsing entries)
diff --git a/_bmad-output/implementation-artifacts/1-4-spec-validation-validate-command.md b/_bmad-output/implementation-artifacts/1-4-spec-validation-validate-command.md
new file mode 100644
index 0000000..44a8235
--- /dev/null
+++ b/_bmad-output/implementation-artifacts/1-4-spec-validation-validate-command.md
@@ -0,0 +1,201 @@
+# Story 1.4: Spec Validation & Validate Command
+
+Status: done
+
+## Story
+
+As a platform engineer,
+I want to run `restium validate --spec <path>` to check my spec file without making API calls,
+so that I can catch errors in CI or locally before deploying.
+
+## Acceptance Criteria
+
+1. **Given** a valid spec file with correct schema, valid references, and no circular dependencies, **When** the user runs `restium validate --spec <path>`, **Then** the process exits with code 0 and logs a success message.
+
+2. **Given** a spec file with a reference `${resource_b.output.id}` where `resource_b` does not exist, **When** validated, **Then** the error message identifies the broken reference and the resource containing it, and exits with code 2.
+
+3. **Given** a spec file where resources form a circular dependency (A -> B -> C -> A), **When** validated, **Then** the error message lists the cycle path and exits with code 2.
+
+4. **Given** a spec file with multiple validation errors (broken references and invalid fields), **When** validated, **Then** all errors are reported (not just the first one).
+
+5. **Given** the `--json` flag is set, **When** validation errors are reported, **Then** errors are output in structured JSON format.
+
+**Covers:** FR6, FR27
+
+## Tasks / Subtasks
+
+- [x] Task 1: Create `src/config/validation.rs` (AC: #2, #3, #4)
+  - [x] Added `mod validation;` to config/mod.rs, re-exported `validate_spec`
+  - [x] `validate_spec(spec: &SpecFile) -> Vec<String>` collects ALL errors
+
+- [x] Task 2: Implement duplicate resource name detection (AC: #4)
+  - [x] HashSet-based detection, error: `"Duplicate resource name: '{name}'"`
+
+- [x] Task 3: Implement reference validation (AC: #2, #4)
+  - [x] Recursive `serde_json::Value` scanning for `${resource.output.field}` patterns
+  - [x] No regex crate — simple string parsing with `${` / `}` / `.output.` splits
+  - [x] Also scans `read_endpoint` for references
+
+- [x] Task 4: Implement `depends_on` validation (AC: #2)
+  - [x] Verifies all deps exist in resource list
+
+- [x] Task 5: Implement circular dependency detection (AC: #3)
+  - [x] DFS-based cycle detection with Unvisited/InStack/Done states
+  - [x] Combines explicit `depends_on` + implicit `${ref}` dependencies
+  - [x] Reports cycle path: `"Circular dependency detected: a -> b -> a"`
+
+- [x] Task 6: Integrate validation into validate command (AC: #1, #4, #5)
+  - [x] Validates after loading spec, logs each error, exits code 2 on failure
+  - [x] JSON mode works via Logger automatically
+
+- [x] Task 7: Write validation unit tests (AC: #1, #2, #3, #4)
+  - [x] 14 tests in `tests/validation_test.rs`
+
+- [x] Task 8: Write e2e CLI tests (AC: #1, #2, #3, #5)
+  - [x] 3 new e2e tests: broken ref, circular dep, JSON mode errors
+
+- [x] Task 9: Update CHANGELOG.md
+  - [x] Added validation entries
+
+- [x] Task 10: Validate full pipeline
+  - [x] All 73 tests pass (17 e2e + 24 config + 18 logging + 14 validation)
+  - [x] Zero clippy warnings, cargo fmt clean, release builds
+
+## Dev Notes
+
+### Architecture Compliance
+
+- **Module:** `src/config/validation.rs` — sits inside the `config` module per architecture
+- **No external graph crate yet:** Story 1.4 does NOT add `petgraph`. Use simple DFS cycle detection. `petgraph` is added in Story 3.1 (Dependency Graph & Topological Sort) for execution ordering. Validation only needs cycle detection, not topological sort.
+- **Error handling:** `validate_spec()` returns `Vec<String>` — collects ALL errors, not Result (multiple errors possible)
+- **Logger:** Errors logged via `logger.error()` in main.rs, which respects `--json` mode automatically
+- **Anti-patterns:** No `unwrap()` in non-test code. No `println!()`.
+
+### Reference Pattern
+
+References use the syntax `${resource_name.output.field_name}`. The regex to extract resource names:
+```rust
+// Matches ${resource_name.output.field_name}
+let re = regex::Regex::new(r"\$\{([a-zA-Z_][a-zA-Z0-9_]*)\.output\.[a-zA-Z_][a-zA-Z0-9_]*\}").unwrap();
+```
+
+**Important:** The `regex` crate is NOT in Cargo.toml. For Story 1.4, use simple string scanning instead of regex to avoid adding a dependency. Scan `serde_json::Value` strings recursively for `${...}` patterns.
+
+Alternative approach without regex:
+- Find all occurrences of `${` in payload strings
+- Extract text between `${` and the next `}`
+- Split on `.output.` to get the resource name
+- This is sufficient for validation
+
+### Cycle Detection Algorithm
+
+Simple DFS-based detection without `petgraph`:
+
+```rust
+fn detect_cycles(resources: &[ResourceSpec]) -> Vec<String> {
+    // Build adjacency list from depends_on + implicit refs
+    // Run DFS from each node
+    // Track visited and in-stack nodes
+    // If we visit a node already in-stack, we have a cycle
+}
+```
+
+States: `Unvisited`, `InStack` (currently being explored), `Done` (fully explored). A cycle is found when we visit a node that is `InStack`.
+
+### Payload Reference Scanning
+
+Must recursively scan `serde_json::Value` for string values containing `${...}`:
+
+```rust
+fn extract_references(value: &serde_json::Value) -> Vec<String> {
+    match value {
+        Value::String(s) => extract_refs_from_string(s),
+        Value::Object(map) => map.values().flat_map(extract_references).collect(),
+        Value::Array(arr) => arr.iter().flat_map(extract_references).collect(),
+        _ => vec![],
+    }
+}
+```
+
+### Previous Story Intelligence
+
+**Story 1.3:**
+- `SpecFile` has `global: GlobalConfig` and `resources: Vec<ResourceSpec>`
+- `ResourceSpec` has `name`, `depends_on: Option<Vec<String>>`, `payload: Option<serde_json::Value>>`
+- `SpecFile::load()` returns `Result<SpecFile, String>`
+- `main.rs` calls `SpecFile::load().map_err(|e| (2u8, e))?` then logs resource count
+- 23 config tests in `tests/config_test.rs`
+
+**Story 1.2:**
+- Logger has `info()`, `warn()`, `error()` methods taking `&[(&str, &str)]` kvs
+- Logger respects `--json` flag for structured output
+- Error path in main.rs: `logger.error(&message, &[])` then exit code
+
+### Integration with main.rs
+
+Current validate handler:
+```rust
+Commands::Validate { spec } => {
+    check_spec_exists(&spec)?;
+    let spec_file = SpecFile::load(&spec).map_err(|e| (2u8, e))?;
+    let count = spec_file.resources.len();
+    logger.info("Validation passed", &[("resources", &count.to_string())]);
+    Ok(())
+}
+```
+
+After this story:
+```rust
+Commands::Validate { spec } => {
+    check_spec_exists(&spec)?;
+    let spec_file = SpecFile::load(&spec).map_err(|e| (2u8, e))?;
+    let errors = restium::config::validate_spec(&spec_file);
+    if !errors.is_empty() {
+        for err in &errors {
+            logger.error(err, &[]);
+        }
+        return Err((2, format!("{} validation error(s) found", errors.len())));
+    }
+    let count = spec_file.resources.len();
+    logger.info("Validation passed", &[("resources", &count.to_string())]);
+    Ok(())
+}
+```
+
+### References
+
+- [Source: _bmad-output/planning-artifacts/architecture.md#Structure Patterns] — config/validation.rs module
+- [Source: _bmad-output/planning-artifacts/architecture.md#Naming Patterns] — `${resource_name.output.field_name}` syntax
+- [Source: _bmad-output/planning-artifacts/architecture.md#Error Message Patterns] — actionable error format
+- [Source: _bmad-output/planning-artifacts/epics.md#Story 1.4] — Acceptance criteria, FR coverage
+- [Source: _bmad-output/planning-artifacts/prd.md#Configuration & Parsing] — FR6 (validates schema, references, graph)
+
+## Dev Agent Record
+
+### Agent Model Used
+
+Claude Opus 4.6 (1M context)
+
+### Debug Log References
+
+### Completion Notes List
+
+- Created `src/config/validation.rs` with 4 validation checks: duplicates, depends_on, references, cycles
+- Reference scanning uses simple string parsing (`${` / `}` / `.output.` split) — no regex crate added
+- Cycle detection via DFS with Unvisited/InStack/Done state machine
+- Adjacency list built from both explicit `depends_on` and implicit `${ref}` payload references
+- Used owned `HashMap<String, Vec<String>>` for adjacency to avoid lifetime issues with reference scanning
+- `validate_spec()` returns `Vec<String>` — collects ALL errors before returning
+- main.rs: validate command logs each error individually then returns summary error count
+- 14 validation unit tests + 3 e2e CLI tests = 17 new tests (73 total)
+- All pipeline checks pass
+- Code review fixes: added validate_spec() to reconcile command, added reconcile_broken_spec_exits_2 e2e test
+
+### File List
+
+- `src/config/validation.rs` (new — validate_spec, duplicate/reference/depends_on/cycle checks)
+- `src/config/mod.rs` (modified — added `mod validation;` and `pub use validate_spec`)
+- `src/main.rs` (modified — integrated validate_spec into validate command)
+- `tests/validation_test.rs` (new — 14 validation unit tests)
+- `tests/e2e/cli_test.rs` (modified — 4 new e2e tests for validation including reconcile validation)
+- `CHANGELOG.md` (modified — added validation entries)
diff --git a/_bmad-output/implementation-artifacts/2-1-http-client-tls-configuration.md b/_bmad-output/implementation-artifacts/2-1-http-client-tls-configuration.md
new file mode 100644
index 0000000..d68cb5e
--- /dev/null
+++ b/_bmad-output/implementation-artifacts/2-1-http-client-tls-configuration.md
@@ -0,0 +1,199 @@
+# Story 2.1: HTTP Client & TLS Configuration
+
+Status: done
+
+## Story
+
+As a platform engineer,
+I want Restium to make HTTPS requests with TLS verification by default and support custom CA bundles,
+so that I can connect securely to APIs with internal or self-signed certificates.
+
+## Acceptance Criteria
+
+1. **Given** no TLS flags are set, **When** Restium makes an HTTPS request, **Then** TLS certificates are verified against the system CA bundle.
+
+2. **Given** the `--insecure-tls` flag is set, **When** Restium makes an HTTPS request, **Then** TLS certificate verification is skipped.
+
+3. **Given** a custom CA bundle path is configured in the spec file, **When** Restium makes an HTTPS request, **Then** the custom CA bundle is used for certificate verification.
+
+4. **Given** a custom CA bundle path that does not exist, **When** Restium attempts to load it, **Then** an actionable error message is returned and the process exits with code 2.
+
+5. **Given** the HTTP client wrapper, **When** an `AuthProvider` is configured for the request, **Then** the provider's `apply()` method is called to attach credentials before sending.
+
+**Covers:** FR13, FR14, NFR3
+
+## Tasks / Subtasks
+
+- [x] Task 1: Add `ca_bundle` field to GlobalConfig (AC: #3, #4)
+  - [x] Added `ca_bundle: Option<String>` to GlobalConfig
+
+- [x] Task 2: Create `src/auth/mod.rs` with AuthProvider trait (AC: #5)
+  - [x] `AuthProvider` trait with `apply(&self, request: ureq::Request) -> Result<ureq::Request, String>`
+
+- [x] Task 3: Create `src/http/mod.rs` with HttpClient (AC: #1, #2, #3, #4, #5)
+  - [x] `HttpClient` wrapping `ureq::Agent` with configurable TLS
+  - [x] Default: webpki roots TLS verification
+  - [x] Insecure: custom `NoVerifier` implementing `ServerCertVerifier`
+  - [x] Custom CA: loads PEM via `rustls-pemfile`, builds `RootCertStore`
+  - [x] Added `rustls` and `rustls-pemfile` as direct dependencies
+  - [x] Added `json` feature to ureq for `send_json` support
+
+- [x] Task 4: Implement request methods on HttpClient (AC: #5)
+  - [x] `get()`, `send_json()`, `request()` with optional `&dyn AuthProvider`
+
+- [x] Task 5: Integrate HttpClient creation into main.rs (AC: #1, #2)
+  - [x] Refactored: extracted `load_and_validate()` helper
+  - [x] Both commands create HttpClient after validation (validates CA bundle)
+  - [x] `insecure_tls` passed from CLI to `execute()`
+
+- [x] Task 6: Write HttpClient unit tests (AC: #1, #2, #3, #4)
+  - [x] 6 tests in `tests/http_test.rs` with test CA certificate fixture
+
+- [x] Task 7: Write e2e CLI tests (AC: #2, #4)
+  - [x] 2 new e2e tests: bad CA bundle exits 2, --insecure-tls accepted
+
+- [x] Task 8: Update CHANGELOG.md
+  - [x] Added HTTP client, TLS, CA bundle entries
+
+- [x] Task 9: Validate full pipeline
+  - [x] All 81 tests pass, zero clippy warnings, release builds
+
+## Dev Notes
+
+### Architecture Compliance
+
+- **Modules:** `src/http/mod.rs` and `src/auth/mod.rs` — directory-style modules per architecture
+- **HTTP client:** `ureq` v2 synchronous, `rustls` for TLS — already in Cargo.toml
+- **AuthProvider trait:** Defined in `src/auth/mod.rs`, implementations in separate files (Stories 2.2-2.5)
+- **Logger:** Not directly used by HttpClient — errors propagated as `Result<_, String>` to callers who log
+- **No new dependencies:** `ureq` with `tls` feature already includes `rustls`. May need `rustls` directly for custom TLS config
+- **Anti-patterns:** No `unwrap()` in non-test code. No `println!()`.
+
+### ureq v2 TLS Configuration
+
+`ureq` v2 uses `rustls` under the hood. To configure TLS:
+
+```rust
+use ureq::AgentBuilder;
+
+// Default (system CA roots via webpki-roots):
+let agent = AgentBuilder::new().build();
+
+// Insecure (skip verification):
+// ureq v2 doesn't have a direct "insecure" flag.
+// Need to create a custom rustls ClientConfig with a danger verifier.
+
+// Custom CA bundle:
+// Load PEM certificates, add to rustls RootCertStore, create ClientConfig, pass to ureq.
+```
+
+For insecure TLS and custom CA, we need to access `rustls` directly. Check if `rustls` needs to be added as a direct dependency or if it's accessible via ureq's re-exports.
+
+**Key consideration:** `ureq` v2 with `tls` feature uses `rustls` v0.23. The `ureq::AgentBuilder` has `.tls_config(Arc<rustls::ClientConfig>)` method for custom TLS configuration. We may need to add `rustls` as a direct dependency for:
+- `rustls::ClientConfig`
+- `rustls::RootCertStore`
+- `rustls::crypto::ring::default_provider()`
+- Custom `ServerCertVerifier` for insecure mode
+
+Add to Cargo.toml if needed:
+```toml
+rustls = { version = "0.23", default-features = false, features = ["ring"] }
+rustls-pemfile = "2"
+```
+
+### AuthProvider Trait Design
+
+```rust
+pub trait AuthProvider {
+    fn apply(&self, request: ureq::Request) -> Result<ureq::Request, String>;
+}
+```
+
+Story 2.1 defines the trait only. No implementations yet. HttpClient methods accept `Option<&dyn AuthProvider>`.
+
+### HttpClient API Design
+
+```rust
+pub struct HttpClient {
+    agent: ureq::Agent,
+}
+
+impl HttpClient {
+    pub fn new(insecure_tls: bool, ca_bundle: Option<&str>) -> Result<Self, String> { ... }
+    pub fn get(&self, url: &str) -> Result<ureq::Response, String> { ... }
+    pub fn send_json(&self, method: &str, url: &str, body: &serde_json::Value, auth: Option<&dyn AuthProvider>) -> Result<ureq::Response, String> { ... }
+}
+```
+
+### Error Format for HTTP
+
+Per architecture error message pattern:
+- `"Failed to {action}: {status_code} {status_text} on {method} {endpoint} — {hint}"`
+- Never include raw response bodies (may contain secrets)
+
+### GlobalConfig Extension
+
+Add `ca_bundle` field to `GlobalConfig`:
+```rust
+pub struct GlobalConfig {
+    pub base_url: Option<String>,
+    pub default_headers: Option<HashMap<String, String>>,
+    pub auth: Option<AuthConfig>,
+    pub ca_bundle: Option<String>,  // NEW
+}
+```
+
+### Previous Story Intelligence
+
+- `ureq = { version = "2", features = ["tls"], default-features = false }` already in Cargo.toml
+- `--insecure-tls` flag already parsed in CLI (from Story 1.1), available as `cli.insecure_tls`
+- main.rs `execute()` takes `Commands` and `&Logger`, returns `Result<(), (u8, String)>`
+- Config types in `src/config/mod.rs`, lib exports via `src/lib.rs`
+- 72 tests currently passing
+
+### Testing Considerations
+
+- Can't easily test actual HTTPS connections in unit tests without a mock server
+- Focus unit tests on: client construction, CA bundle loading, error handling
+- e2e tests: verify CLI accepts the flags and handles bad CA bundle paths
+- Actual HTTP request testing comes in Story 3.2+ with mock servers
+
+### References
+
+- [Source: _bmad-output/planning-artifacts/architecture.md#HTTP Client] — ureq v2, rustls, no default features
+- [Source: _bmad-output/planning-artifacts/architecture.md#Authentication & Security] — AuthProvider trait pattern
+- [Source: _bmad-output/planning-artifacts/architecture.md#Architectural Boundaries] — http depends on logging, auth
+- [Source: _bmad-output/planning-artifacts/epics.md#Story 2.1] — Acceptance criteria, FR coverage
+
+## Dev Agent Record
+
+### Agent Model Used
+
+Claude Opus 4.6 (1M context)
+
+### Debug Log References
+
+### Completion Notes List
+
+- Added `rustls = "0.23"` and `rustls-pemfile = "2"` as direct dependencies for custom TLS config
+- Added `json` feature to `ureq` for `send_json()` method
+- `NoVerifier` implements `rustls::client::danger::ServerCertVerifier` for insecure mode
+- CA bundle loading: reads PEM, parses certs via `rustls_pemfile::certs()`, builds `RootCertStore`
+- Empty CA bundles (no valid certs) produce actionable error
+- Refactored main.rs: extracted `load_and_validate()` to eliminate code duplication
+- `execute()` now takes `insecure_tls: bool` parameter
+- Test CA certificate fixture generated via openssl in `tests/fixtures/test-ca.pem`
+- 9 new tests (6 http + 2 e2e + 1 config), 81 total
+
+### File List
+
+- `src/auth/mod.rs` (new — AuthProvider trait)
+- `src/http/mod.rs` (new — HttpClient with TLS, CA bundle, insecure mode)
+- `src/config/mod.rs` (modified — added ca_bundle to GlobalConfig)
+- `src/lib.rs` (modified — added pub mod auth, http)
+- `src/main.rs` (modified — HttpClient integration, load_and_validate refactor)
+- `Cargo.toml` (modified — added rustls, rustls-pemfile, ureq json feature)
+- `tests/http_test.rs` (new — 6 HttpClient tests)
+- `tests/fixtures/test-ca.pem` (new — test CA certificate)
+- `tests/e2e/cli_test.rs` (modified — 2 new TLS-related e2e tests)
+- `CHANGELOG.md` (modified — HTTP client entries)
diff --git a/_bmad-output/implementation-artifacts/2-2-bearer-token-basic-auth-providers.md b/_bmad-output/implementation-artifacts/2-2-bearer-token-basic-auth-providers.md
new file mode 100644
index 0000000..19ecf16
--- /dev/null
+++ b/_bmad-output/implementation-artifacts/2-2-bearer-token-basic-auth-providers.md
@@ -0,0 +1,154 @@
+# Story 2.2: Bearer Token & Basic Auth Providers
+
+Status: done
+
+## Story
+
+As a platform engineer,
+I want to configure bearer token or basic auth for API endpoints via environment variables,
+so that I can authenticate against protected APIs without putting credentials in spec files.
+
+## Acceptance Criteria
+
+1. **Given** a resource or global auth config specifying `type: bearer` with `token_env: NETBIRD_TOKEN`, **When** a request is made, **Then** the `Authorization: Bearer <value>` header is set using the value from the `NETBIRD_TOKEN` environment variable.
+
+2. **Given** a resource or global auth config specifying `type: basic` with `username_env` and `password_env`, **When** a request is made, **Then** the `Authorization: Basic <base64>` header is set using credentials from the specified environment variables.
+
+3. **Given** an auth config referencing an environment variable that is not set, **When** the auth provider is initialized, **Then** an actionable error message identifies the missing variable and the process exits with code 2.
+
+4. **Given** any auth credential value, **When** logged (via error messages or debug output), **Then** the value is redacted by the Logger.
+
+**Covers:** FR7, FR8, FR10
+
+## Tasks / Subtasks
+
+- [x] Task 1: Implement BearerAuthProvider (AC: #1, #3)
+  - [x] `src/auth/bearer.rs` with `BearerAuthProvider` — reads env var, sets `Authorization: Bearer` header
+
+- [x] Task 2: Implement BasicAuthProvider (AC: #2, #3)
+  - [x] `src/auth/basic.rs` with `BasicAuthProvider` — reads env vars, base64 encodes, sets `Authorization: Basic` header
+  - [x] Added `base64 = "0.22"` as direct dependency
+
+- [x] Task 3: Create auth provider factory (AC: #1, #2, #3)
+  - [x] `create_auth_provider()` matches AuthConfig variants, returns `Box<dyn AuthProvider>`
+  - [x] ApiKey/Oidc/Mtls return "not yet implemented" errors
+
+- [x] Task 4: Write auth provider unit tests (AC: #1, #2, #3)
+  - [x] 9 tests in `tests/auth_test.rs` covering both providers and factory
+
+- [x] Task 5: Update CHANGELOG.md
+  - [x] Added bearer/basic auth entries
+
+- [x] Task 6: Validate full pipeline
+  - [x] All 90 tests pass, zero clippy warnings, release builds
+
+## Dev Notes
+
+### Architecture Compliance
+
+- **Module:** `src/auth/bearer.rs` and `src/auth/basic.rs` per architecture directory structure
+- **AuthProvider trait:** Already defined in `src/auth/mod.rs` from Story 2.1
+- **Credentials from env vars only (FR10):** Never store actual credentials in structs — read at construction time and store the value, not the env var name
+- **Error handling:** `Result<T, String>` with actionable messages including env var name
+- **Secret redaction:** Logger already redacts `authorization`, `token`, `password` keys — no extra work needed (AC #4)
+- **base64:** The `base64` crate is already a transitive dependency of `ureq`/`rustls`. Add as direct dependency for explicit use.
+
+### Bearer Auth Design
+
+```rust
+pub struct BearerAuthProvider {
+    token: String,
+}
+
+impl BearerAuthProvider {
+    pub fn new(token_env: &str) -> Result<Self, String> {
+        let token = std::env::var(token_env)
+            .map_err(|_| format!("Environment variable '{token_env}' is not set — required for bearer token authentication"))?;
+        Ok(Self { token })
+    }
+}
+
+impl AuthProvider for BearerAuthProvider {
+    fn apply(&self, request: ureq::Request) -> Result<ureq::Request, String> {
+        Ok(request.set("Authorization", &format!("Bearer {}", self.token)))
+    }
+}
+```
+
+### Basic Auth Design
+
+```rust
+pub struct BasicAuthProvider {
+    encoded: String,  // base64(username:password)
+}
+
+impl BasicAuthProvider {
+    pub fn new(username_env: &str, password_env: &str) -> Result<Self, String> {
+        let username = std::env::var(username_env)
+            .map_err(|_| format!("Environment variable '{username_env}' is not set — required for basic authentication"))?;
+        let password = std::env::var(password_env)
+            .map_err(|_| format!("Environment variable '{password_env}' is not set — required for basic authentication"))?;
+        let encoded = base64::encode(format!("{username}:{password}"));
+        Ok(Self { encoded })
+    }
+}
+```
+
+### Testing with Environment Variables
+
+Tests that set env vars must be careful about test parallelism. Options:
+- Use unique env var names per test to avoid conflicts
+- Tests that read env vars should use `std::env::set_var` with unique names
+
+```rust
+// Use unique env var names per test
+std::env::set_var("TEST_BEARER_TOKEN_1", "my-secret-token");
+let provider = BearerAuthProvider::new("TEST_BEARER_TOKEN_1")?;
+```
+
+### base64 Dependency
+
+`base64` v0.22 is already a transitive dep (from rustls). Add it as direct:
+```toml
+base64 = "0.22"
+```
+
+### Previous Story Intelligence
+
+- `AuthProvider` trait in `src/auth/mod.rs`: `fn apply(&self, request: ureq::Request) -> Result<ureq::Request, String>`
+- `AuthConfig` enum in `src/config/mod.rs` already has `Bearer { token_env }` and `Basic { username_env, password_env }` variants
+- `HttpClient::send_json()` and `request()` accept `Option<&dyn AuthProvider>`
+- Logger already redacts keys containing `authorization`, `token`, `password` etc.
+
+### References
+
+- [Source: _bmad-output/planning-artifacts/architecture.md#Authentication & Security] — AuthProvider trait, apply pattern
+- [Source: _bmad-output/planning-artifacts/epics.md#Story 2.2] — Acceptance criteria, FR coverage
+
+## Dev Agent Record
+
+### Agent Model Used
+
+Claude Opus 4.6 (1M context)
+
+### Debug Log References
+
+### Completion Notes List
+
+- BearerAuthProvider reads token from env var at construction, stores value (not env var name)
+- BasicAuthProvider reads username+password from env vars, base64 encodes `user:pass` at construction
+- Both providers use `#[derive(Debug)]` for test ergonomics
+- Added `base64 = "0.22"` as direct dependency (was transitive via rustls)
+- Factory function handles all 5 AuthConfig variants, returns "not yet implemented" for 3
+- Tests use `unsafe { std::env::set_var/remove_var }` with unique env var names per test
+- Verified header values via `request.header("Authorization")`
+- 9 new tests (90 total)
+
+### File List
+
+- `src/auth/bearer.rs` (new — BearerAuthProvider)
+- `src/auth/basic.rs` (new — BasicAuthProvider)
+- `src/auth/mod.rs` (modified — added mod declarations, factory function, re-exports)
+- `Cargo.toml` (modified — added base64 dependency)
+- `tests/auth_test.rs` (new — 9 auth provider tests)
+- `CHANGELOG.md` (modified — added auth entries)
diff --git a/_bmad-output/implementation-artifacts/2-3-api-key-authentication.md b/_bmad-output/implementation-artifacts/2-3-api-key-authentication.md
new file mode 100644
index 0000000..3d3ceb9
--- /dev/null
+++ b/_bmad-output/implementation-artifacts/2-3-api-key-authentication.md
@@ -0,0 +1,100 @@
+# Story 2.3: API Key Authentication
+
+Status: done
+
+## Story
+
+As a platform engineer,
+I want to configure API key authentication sent as a header or query parameter,
+so that I can connect to APIs that use API key schemes.
+
+## Acceptance Criteria
+
+1. **Given** an auth config specifying `type: api_key` with `header_name` and `key_env`, **When** a request is made, **Then** the specified header is set with the key value from the environment variable.
+
+2. **Given** an auth config specifying `type: api_key` with `query_param` and `key_env`, **When** a request is made, **Then** the key is appended as a query parameter.
+
+3. **Given** an API key value, **When** it appears in any log output, **Then** it is redacted.
+
+**Covers:** FR9, FR10
+
+## Tasks / Subtasks
+
+- [x] Task 1: Implement ApiKeyAuthProvider (AC: #1, #2)
+  - [x] `src/auth/api_key.rs` with header mode and query param mode via `ApiKeyMode` enum
+  - [x] Validates exactly one of header_name/query_param is set
+
+- [x] Task 2: Update auth provider factory (AC: #1, #2)
+  - [x] `create_auth_provider()` now handles ApiKey variant
+
+- [x] Task 3: Write API key auth tests (AC: #1, #2, #3)
+  - [x] 6 new tests: header mode, query param, missing env, neither, both, factory
+
+- [x] Task 4: Update CHANGELOG.md
+  - [x] Added API key auth entry
+
+- [x] Task 5: Validate full pipeline
+  - [x] All 95 tests pass, zero clippy warnings, release builds
+
+## Dev Notes
+
+### Architecture Compliance
+
+- **Module:** `src/auth/api_key.rs` per architecture directory structure
+- **Credentials from env vars only (FR10)**
+- **Logger redaction:** Logger already redacts keys containing `api_key` — no extra work needed (AC #3)
+
+### API Key Delivery Modes
+
+Two mutually exclusive modes:
+1. **Header mode:** `header_name: "X-API-Key"` — sets the named header
+2. **Query param mode:** `query_param: "api_key"` — appends `?api_key=<value>` to the URL
+
+For query param mode, `apply()` needs to modify the request URL. With ureq, we can use `request.query("param", "value")` to append query parameters.
+
+### AuthConfig for ApiKey
+
+Already defined in `src/config/mod.rs`:
+```rust
+ApiKey {
+    key_env: String,
+    header_name: Option<String>,
+    query_param: Option<String>,
+}
+```
+
+### Previous Story Intelligence
+
+- `AuthProvider` trait: `fn apply(&self, request: ureq::Request) -> Result<ureq::Request, String>`
+- Pattern from bearer.rs: read env var in `new()`, store value, apply in `apply()`
+- Factory in `src/auth/mod.rs` — just needs the ApiKey match arm updated
+- Tests use unique env var names and `unsafe { std::env::set_var/remove_var }`
+- `#[derive(Debug)]` needed on provider structs
+
+### References
+
+- [Source: _bmad-output/planning-artifacts/epics.md#Story 2.3] — Acceptance criteria
+- [Source: _bmad-output/planning-artifacts/architecture.md#Authentication & Security] — AuthProvider pattern
+
+## Dev Agent Record
+
+### Agent Model Used
+
+Claude Opus 4.6 (1M context)
+
+### Debug Log References
+
+### Completion Notes List
+
+- `ApiKeyAuthProvider` with internal `ApiKeyMode` enum (Header/QueryParam)
+- Validates mutually exclusive header_name/query_param at construction time
+- Query param mode uses `request.query()` which appends to URL
+- Header mode uses `request.set()` for custom header
+- 6 new tests (95 total across all files)
+
+### File List
+
+- `src/auth/api_key.rs` (new — ApiKeyAuthProvider with header/query modes)
+- `src/auth/mod.rs` (modified — added api_key module, updated factory)
+- `tests/auth_test.rs` (modified — 6 new API key tests)
+- `CHANGELOG.md` (modified — API key entry)
diff --git a/_bmad-output/implementation-artifacts/2-4-oidc-client-credentials-authentication.md b/_bmad-output/implementation-artifacts/2-4-oidc-client-credentials-authentication.md
new file mode 100644
index 0000000..41eb156
--- /dev/null
+++ b/_bmad-output/implementation-artifacts/2-4-oidc-client-credentials-authentication.md
@@ -0,0 +1,150 @@
+# Story 2.4: OIDC Client Credentials Authentication
+
+Status: done
+
+## Story
+
+As a platform engineer,
+I want to configure OIDC/OAuth2 client credentials authentication,
+so that I can connect to APIs protected by OAuth2 token endpoints.
+
+## Acceptance Criteria
+
+1. **Given** an auth config specifying `type: oidc` with `token_url`, `client_id_env`, and `client_secret_env`, **When** a request is made, **Then** Restium performs a POST to the token endpoint with `grant_type=client_credentials`, extracts the `access_token` from the JSON response, and sets `Authorization: Bearer <access_token>`.
+
+2. **Given** the token endpoint returns an error (e.g., 401 invalid credentials), **When** the token request fails, **Then** an actionable error message includes the token URL and status code.
+
+3. **Given** the client secret environment variable, **When** the token request is logged, **Then** the client secret is redacted in all log output.
+
+4. **Given** a valid OIDC config with optional `scope` field, **When** scope is specified, **Then** it is included in the token request body.
+
+**Covers:** FR11, FR10
+
+## Tasks / Subtasks
+
+- [x] Task 1: Implement OidcAuthProvider (AC: #1, #2, #4)
+  - [x] `src/auth/oidc.rs` — fetches token at construction via POST to token_url
+  - [x] Form body with grant_type, client_id, client_secret, optional scope
+  - [x] Custom `url_encode()` for form body values (no external dep)
+  - [x] `with_token()` constructor for testing without actual HTTP call
+
+- [x] Task 2: Update auth provider factory (AC: #1)
+  - [x] `create_auth_provider()` now handles Oidc variant, uses `ureq::post()` directly
+
+- [x] Task 3: Write OIDC auth tests (AC: #1, #2, #3, #4)
+  - [x] 3 tests: missing client_id, missing client_secret, apply sets bearer header
+
+- [x] Task 4: Update CHANGELOG.md
+  - [x] Added OIDC entry
+
+- [x] Task 5: Validate full pipeline
+  - [x] All 98 tests pass, zero clippy warnings, release builds
+
+## Dev Notes
+
+### Architecture Compliance
+
+- **Module:** `src/auth/oidc.rs` per architecture
+- **Minimal custom implementation:** Per architecture decision — "OIDC client_credentials is a single HTTP POST — no need for a full OAuth2 library"
+- **No external OIDC crate:** Use ureq directly for the token POST
+- **Secret redaction:** Logger already redacts `client_secret`, `access_token`, `token` keys
+
+### OIDC Token Flow
+
+```
+POST {token_url}
+Content-Type: application/x-www-form-urlencoded
+
+grant_type=client_credentials&client_id={id}&client_secret={secret}[&scope={scope}]
+```
+
+Response:
+```json
+{"access_token": "eyJ...", "token_type": "Bearer", "expires_in": 3600}
+```
+
+### Implementation Design
+
+The OIDC provider fetches the token at construction time. This is simple and sufficient for the MVP use case (K8s Job that runs once). Token refresh/caching is a post-MVP concern.
+
+```rust
+pub struct OidcAuthProvider {
+    access_token: String,
+}
+
+impl OidcAuthProvider {
+    pub fn new(token_url: &str, client_id_env: &str, client_secret_env: &str, scope: Option<&str>) -> Result<Self, String> {
+        let client_id = std::env::var(client_id_env).map_err(|_| ...)?;
+        let client_secret = std::env::var(client_secret_env).map_err(|_| ...)?;
+
+        let mut form = format!("grant_type=client_credentials&client_id={client_id}&client_secret={client_secret}");
+        if let Some(s) = scope {
+            form.push_str(&format!("&scope={s}"));
+        }
+
+        let response = ureq::post(token_url)
+            .set("Content-Type", "application/x-www-form-urlencoded")
+            .send_string(&form)
+            .map_err(|e| format!("OIDC token request to '{token_url}' failed: {e}"))?;
+
+        let json: serde_json::Value = response.into_json()
+            .map_err(|e| format!("Failed to parse OIDC token response from '{token_url}': {e}"))?;
+
+        let access_token = json["access_token"].as_str()
+            .ok_or_else(|| format!("OIDC token response from '{token_url}' missing 'access_token' field"))?
+            .to_string();
+
+        Ok(Self { access_token })
+    }
+}
+```
+
+### Factory Consideration
+
+`create_auth_provider()` currently doesn't have access to the `HttpClient`. For OIDC, we use `ureq::post()` directly (global function, no agent needed) since the token endpoint is a one-off call. This avoids needing to change the factory signature.
+
+### Testing Without a Mock Server
+
+Since OIDC requires an actual HTTP POST to a token endpoint, unit tests focus on:
+- Env var validation (missing client_id, client_secret)
+- `apply()` behavior (sets Bearer header with token)
+- For the token fetch itself, create the provider with a pre-set token for `apply()` tests
+
+Full e2e OIDC testing comes in Story 3.x with mock HTTP server infrastructure.
+
+### Previous Story Intelligence
+
+- Auth provider pattern: read env vars in `new()`, store value, apply in `apply()`
+- `#[derive(Debug)]` on provider structs
+- Factory returns `Box<dyn AuthProvider>`
+- Tests use unique env var names with `unsafe { std::env::set_var/remove_var }`
+
+### References
+
+- [Source: _bmad-output/planning-artifacts/architecture.md#Authentication & Security] — Minimal OIDC implementation
+- [Source: _bmad-output/planning-artifacts/epics.md#Story 2.4] — Acceptance criteria
+
+## Dev Agent Record
+
+### Agent Model Used
+
+Claude Opus 4.6 (1M context)
+
+### Debug Log References
+
+### Completion Notes List
+
+- `OidcAuthProvider::new()` performs POST with form-urlencoded body to token endpoint
+- Custom `url_encode()` function for form values (avoids adding percent-encoding crate)
+- Token fetched at construction time (sufficient for K8s Job MVP — no refresh)
+- `with_token()` public constructor enables testing apply() without real HTTP call
+- Changed from `#[cfg(test)]` to plain pub because integration tests can't see cfg(test) items
+- Uses `ureq::post()` global function (no agent needed for one-off token request)
+- 3 new tests (98 total)
+
+### File List
+
+- `src/auth/oidc.rs` (new — OidcAuthProvider with token fetch and url_encode)
+- `src/auth/mod.rs` (modified — added oidc module, updated factory)
+- `tests/auth_test.rs` (modified — 3 new OIDC tests)
+- `CHANGELOG.md` (modified — OIDC entry)
diff --git a/_bmad-output/implementation-artifacts/2-5-mtls-client-certificate-authentication.md b/_bmad-output/implementation-artifacts/2-5-mtls-client-certificate-authentication.md
new file mode 100644
index 0000000..3ad19a8
--- /dev/null
+++ b/_bmad-output/implementation-artifacts/2-5-mtls-client-certificate-authentication.md
@@ -0,0 +1,154 @@
+# Story 2.5: mTLS Client Certificate Authentication
+
+Status: done
+
+## Story
+
+As a platform engineer,
+I want to configure mutual TLS with client certificates,
+so that I can connect to APIs that require certificate-based authentication.
+
+## Acceptance Criteria
+
+1. **Given** an auth config specifying `type: mtls` with `client_cert_path` and `client_key_path`, **When** a TLS connection is established, **Then** the client certificate and key are presented to the server during the TLS handshake.
+
+2. **Given** a client certificate or key file that does not exist or is malformed, **When** Restium attempts to load it, **Then** an actionable error message identifies the problematic file and the process exits with code 2.
+
+3. **Given** mTLS combined with a custom CA bundle, **When** a connection is established, **Then** both the client certificate and the custom CA are used.
+
+**Covers:** FR12
+
+## Tasks / Subtasks
+
+- [x] Task 1: Implement mTLS support in HttpClient (AC: #1, #2, #3)
+  - [x] Extended `HttpClient::new()` with `client_cert` and `client_key` optional params
+  - [x] Refactored TLS config into `build_root_store()` and `load_client_identity()` helpers
+  - [x] Uses `.with_client_auth_cert()` when mTLS paths are provided
+  - [x] CA bundle + mTLS combination works via shared root store
+  - [x] Added `webpki-roots = "0.26"` as direct dependency for explicit default root store
+
+- [x] Task 2: Implement MtlsAuthProvider (AC: #1)
+  - [x] `src/auth/mtls.rs` — validates file existence at construction, no-op `apply()`
+
+- [x] Task 3: Update auth factory and HttpClient creation flow (AC: #1, #3)
+  - [x] Factory now handles all 5 AuthConfig variants (no "not yet implemented" remaining)
+  - [x] main.rs: `extract_mtls_paths()` + `create_http_client()` helpers
+
+- [x] Task 4: Write mTLS tests (AC: #1, #2, #3)
+  - [x] 6 new http tests + 2 auth tests = 8 new tests (12 http total)
+
+- [x] Task 5: Update CHANGELOG.md
+  - [x] Added mTLS entries
+
+- [x] Task 6: Validate full pipeline
+  - [x] All 104 tests pass, zero clippy warnings, release builds
+
+## Dev Notes
+
+### Architecture Compliance
+
+- **mTLS is a TLS-layer concern, not a per-request header** — unlike Bearer/Basic/ApiKey, mTLS configures the TLS handshake itself
+- **MtlsAuthProvider::apply() is a no-op** — the client cert is configured on the ureq Agent, not on individual requests
+- **Module:** `src/auth/mtls.rs` per architecture
+
+### HttpClient Signature Change
+
+Current: `HttpClient::new(insecure_tls: bool, ca_bundle: Option<&str>) -> Result<Self, String>`
+
+After: `HttpClient::new(insecure_tls: bool, ca_bundle: Option<&str>, client_cert: Option<&str>, client_key: Option<&str>) -> Result<Self, String>`
+
+When `client_cert` and `client_key` are provided:
+```rust
+// Load cert chain
+let cert_data = std::fs::read(cert_path)?;
+let certs: Vec<CertificateDer> = rustls_pemfile::certs(&mut &cert_data[..]).collect::<Result<_>>()?;
+
+// Load private key
+let key_data = std::fs::read(key_path)?;
+let key = rustls_pemfile::private_key(&mut &key_data[..])?.ok_or("no private key found")?;
+
+// Build config with client auth
+let config = rustls::ClientConfig::builder()
+    .with_root_certificates(root_store)
+    .with_client_auth_cert(certs, key)?;
+```
+
+### MtlsAuthProvider Design
+
+```rust
+#[derive(Debug)]
+pub struct MtlsAuthProvider {
+    pub client_cert_path: String,
+    pub client_key_path: String,
+}
+
+impl AuthProvider for MtlsAuthProvider {
+    fn apply(&self, request: ureq::Request) -> Result<ureq::Request, String> {
+        // mTLS is configured at TLS layer, not per-request
+        Ok(request)
+    }
+}
+```
+
+The provider stores paths so the HttpClient creation flow can access them. The factory creates the provider, and main.rs passes the paths to HttpClient.
+
+### Integration Flow
+
+In main.rs, after creating auth provider via factory:
+1. If auth is mTLS, extract cert/key paths from provider
+2. Pass paths to `HttpClient::new()`
+3. For non-mTLS auth, pass `None` for cert/key
+
+### Test Fixtures
+
+Need test cert + key PEM files. Generate via:
+```bash
+openssl req -x509 -newkey rsa:2048 -keyout test-client.key -out test-client.pem -days 365 -nodes -subj "/CN=Test Client"
+```
+
+Already have `tests/fixtures/test-ca.pem` from Story 2.1.
+
+### Previous Story Intelligence
+
+- `HttpClient::new()` already handles insecure TLS and custom CA bundle
+- `build_ca_bundle_config()` creates a `RootCertStore` — can be reused for mTLS + CA bundle combo
+- `rustls_pemfile` already in Cargo.toml (v2)
+- Factory pattern: `create_auth_provider()` returns `Box<dyn AuthProvider>`
+
+### References
+
+- [Source: _bmad-output/planning-artifacts/architecture.md#Authentication & Security] — mTLS via rustls client certificate
+- [Source: _bmad-output/planning-artifacts/epics.md#Story 2.5] — Acceptance criteria
+
+## Dev Agent Record
+
+### Agent Model Used
+
+Claude Opus 4.6 (1M context)
+
+### Debug Log References
+
+### Completion Notes List
+
+- Refactored `HttpClient::new()` from 2 params to 4 (added client_cert, client_key)
+- Extracted `build_root_store()` to handle both default webpki roots and custom CA bundles
+- `load_client_identity()` loads PEM cert chain + private key via rustls_pemfile
+- Added `webpki-roots = "0.26"` as direct dep (was only transitive before refactor)
+- `MtlsAuthProvider` validates file existence at construction, `apply()` is no-op
+- main.rs: `extract_mtls_paths()` extracts paths from global auth config, `create_http_client()` passes them
+- All 5 AuthConfig variants now fully implemented in factory (no more "not yet implemented")
+- Test fixtures: test-client.pem and test-client.key generated via openssl
+- Updated all existing http_test.rs calls from 2-param to 4-param signature
+- 8 new tests (104 total)
+
+### File List
+
+- `src/auth/mtls.rs` (new — MtlsAuthProvider with file validation)
+- `src/auth/mod.rs` (modified — added mtls module, factory handles Mtls variant)
+- `src/http/mod.rs` (modified — extended for mTLS, refactored root store building)
+- `src/main.rs` (modified — extract_mtls_paths, create_http_client helpers)
+- `Cargo.toml` (modified — added webpki-roots dependency)
+- `tests/http_test.rs` (modified — updated all calls to 4-param, 6 new mTLS tests)
+- `tests/fixtures/test-client.pem` (new — test client certificate)
+- `tests/fixtures/test-client.key` (new — test client private key)
+- `CHANGELOG.md` (modified — mTLS entries)
diff --git a/_bmad-output/implementation-artifacts/3-1-dependency-graph-topological-sort.md b/_bmad-output/implementation-artifacts/3-1-dependency-graph-topological-sort.md
new file mode 100644
index 0000000..5ec72a7
--- /dev/null
+++ b/_bmad-output/implementation-artifacts/3-1-dependency-graph-topological-sort.md
@@ -0,0 +1,195 @@
+# Story 3.1: Dependency Graph & Topological Sort
+
+Status: done
+
+## Story
+
+As a platform engineer,
+I want resources to be processed in dependency order with cycle detection,
+so that dependent resources always have their prerequisites satisfied before execution.
+
+## Acceptance Criteria
+
+1. **Given** a spec with resources A, B, C where B `depends_on: [A]` and C `depends_on: [B]`, **When** the dependency graph is built and sorted, **Then** the execution order is A -> B -> C.
+
+2. **Given** a spec with implicit dependencies via references (e.g., resource A's payload contains `${resource_b.output.id}`), **When** the dependency graph is built, **Then** A depends on B and B is processed before A.
+
+3. **Given** a spec where resources form a cycle (A -> B -> C -> A), **When** the graph is sorted, **Then** an error message lists the cycle path and the process exits with code 2.
+
+4. **Given** a spec with both explicit `depends_on` and implicit reference dependencies, **When** the graph is built, **Then** both dependency types are merged into a single DAG.
+
+5. **Given** a spec with independent resources (no dependencies between them), **When** the graph is sorted, **Then** a valid topological order is produced (any order is acceptable).
+
+**Covers:** FR5, FR20, FR22
+
+## Tasks / Subtasks
+
+- [x] Task 1: Create `src/graph/mod.rs` module with petgraph-based dependency graph (AC: #1, #2, #4, #5)
+  - [x] Add `petgraph` dependency to Cargo.toml
+  - [x] Define `DependencyGraph` struct wrapping `petgraph::graph::DiGraph`
+  - [x] Implement `build(resources: &[ResourceSpec]) -> Result<DependencyGraph, String>` that:
+    - Adds each resource as a node (keyed by name)
+    - Adds edges for explicit `depends_on` entries
+    - Extracts implicit dependencies from `${resource.output.field}` refs in endpoint, payload, and read_endpoint
+    - Validates that all dependency targets exist
+  - [x] Implement `topological_sort(&self) -> Result<Vec<String>, String>` returning resource names in execution order
+
+- [x] Task 2: Implement cycle detection with path reporting (AC: #3)
+  - [x] Use `petgraph::algo::toposort()` which returns cycle error
+  - [x] On cycle, use DFS to extract the full cycle path
+  - [x] Format cycle error as: `"Circular dependency detected: a -> b -> c -> a"`
+
+- [x] Task 3: Refactor validation.rs to use the new graph module (AC: #1-#5)
+  - [x] Replace the existing DFS-based cycle detection in `validation.rs` with `DependencyGraph`
+  - [x] Keep reference validation (broken refs) in validation.rs
+  - [x] `validate_spec()` should call `DependencyGraph::build()` and report cycle errors
+
+- [x] Task 4: Register graph module in `src/lib.rs` (AC: all)
+  - [x] Add `pub mod graph;` to lib.rs
+
+- [x] Task 5: Write tests in `tests/graph_test.rs` (AC: #1-#5)
+  - [x] Test linear chain: A -> B -> C produces correct order
+  - [x] Test implicit deps from payload references
+  - [x] Test implicit deps from endpoint references
+  - [x] Test mixed explicit + implicit dependencies
+  - [x] Test cycle detection with path reporting
+  - [x] Test independent resources (no deps)
+  - [x] Test single resource (trivial case)
+  - [x] Test depends_on referencing non-existent resource (error)
+  - [x] Test complex diamond dependencies (A -> B, A -> C, B -> D, C -> D)
+
+- [x] Task 6: Update CHANGELOG.md
+  - [x] Added: Dependency graph module with petgraph-based topological sort and cycle detection
+
+## Dev Notes
+
+### Architecture Compliance
+
+- **Module location:** `src/graph/mod.rs` per architecture doc directory-style modules
+- **Crate:** `petgraph` — specified in architecture as the graph library
+- **Error handling:** `Result<T, String>` with `.map_err()` context — no `unwrap()` in non-test code
+- **Tests:** All in `tests/graph_test.rs` — no inline `#[cfg(test)]`
+
+### Existing Reference Extraction
+
+`src/config/validation.rs` already has reference extraction functions that MUST be reused:
+- `extract_refs_from_string(s: &str) -> Vec<(String, String)>` — parses `${name.output.field}` patterns
+- `extract_references_from_value(value: &serde_json::Value) -> Vec<(String, String)>` — recursively scans JSON
+
+These functions are currently private to validation.rs. Options:
+1. **Preferred:** Make them `pub` and call from graph module via `crate::config::validation::`
+2. Alternative: Move shared extraction logic to config/mod.rs
+
+### Existing Cycle Detection
+
+`validation.rs` (lines ~130-203) has a DFS-based cycle detection. This MUST be replaced by the petgraph-based implementation to avoid duplication. After refactoring:
+- `validate_spec()` should delegate cycle detection to `DependencyGraph::build()` + `topological_sort()`
+- Keep the reference existence checks (broken refs pointing to non-existent resources) in validation.rs
+
+### petgraph Usage Pattern
+
+```rust
+use petgraph::graph::{DiGraph, NodeIndex};
+use petgraph::algo::toposort;
+use std::collections::HashMap;
+
+pub struct DependencyGraph {
+    graph: DiGraph<String, ()>,
+    node_indices: HashMap<String, NodeIndex>,
+}
+
+impl DependencyGraph {
+    pub fn build(resources: &[ResourceSpec]) -> Result<Self, String> {
+        let mut graph = DiGraph::new();
+        let mut node_indices = HashMap::new();
+
+        // Add nodes
+        for r in resources {
+            let idx = graph.add_node(r.name.clone());
+            node_indices.insert(r.name.clone(), idx);
+        }
+
+        // Add edges (depends_on + implicit refs)
+        // ...
+
+        Ok(Self { graph, node_indices })
+    }
+
+    pub fn topological_sort(&self) -> Result<Vec<String>, String> {
+        match toposort(&self.graph, None) {
+            Ok(indices) => Ok(indices.iter().map(|i| self.graph[*i].clone()).collect()),
+            Err(cycle) => {
+                // Extract cycle path for error message
+                Err(format!("Circular dependency detected: ..."))
+            }
+        }
+    }
+}
+```
+
+### Cycle Path Reporting
+
+`petgraph::algo::toposort` returns `Err(Cycle(NodeIndex))` with the node involved in a cycle, but does NOT give the full cycle path. To report the path (e.g., "a -> b -> c -> a"), you need additional DFS after detecting the cycle. Use the existing DFS logic pattern from validation.rs as a reference for path extraction.
+
+### Key Types from Config
+
+```rust
+// From src/config/mod.rs
+pub struct ResourceSpec {
+    pub name: String,
+    pub endpoint: String,
+    pub depends_on: Option<Vec<String>>,
+    pub payload: Option<serde_json::Value>,
+    pub read_endpoint: Option<String>,
+    pub outputs: Option<HashMap<String, String>>,
+    // ...
+}
+```
+
+### HttpClient Signature (Current)
+
+`HttpClient::new(insecure_tls: bool, ca_bundle: Option<&str>, client_cert: Option<&str>, client_key: Option<&str>) -> Result<Self, String>`
+
+This is NOT relevant to this story — graph module has no HTTP concerns.
+
+### Project Structure Notes
+
+- `src/lib.rs` currently exports: `pub mod config; pub mod logging; pub mod auth; pub mod http;`
+- Add `pub mod graph;` to lib.rs
+- Test file: `tests/graph_test.rs` (follows pattern of existing test files)
+
+### References
+
+- [Source: _bmad-output/planning-artifacts/architecture.md#Dependency Graph] — petgraph for DAG and topological sort
+- [Source: _bmad-output/planning-artifacts/architecture.md#Structure Patterns] — `src/graph/mod.rs`
+- [Source: _bmad-output/planning-artifacts/epics.md#Story 3.1] — Acceptance criteria
+- [Source: src/config/validation.rs] — Existing reference extraction and cycle detection to refactor
+
+## Dev Agent Record
+
+### Agent Model Used
+
+Claude Opus 4.6 (1M context)
+
+### Debug Log References
+
+### Completion Notes List
+
+- Created `src/graph/mod.rs` with `DependencyGraph` struct wrapping `petgraph::DiGraph`
+- `build()` merges explicit `depends_on` + implicit `${resource.output.field}` refs into edges
+- `topological_sort()` uses `petgraph::algo::toposort()` with custom DFS cycle path extraction
+- Made `extract_refs_from_string` and `extract_references_from_value` public in validation.rs for reuse
+- Made `config::validation` module public so graph module can import reference extraction functions
+- Replaced 70-line manual DFS cycle detection in validation.rs with 5-line `check_cycles_via_graph()` delegation
+- 12 new graph tests covering: linear chains, implicit refs (payload, endpoint, read_endpoint), mixed deps, cycles, self-cycles, diamonds, nested payloads, independent and single resources, unknown deps
+- All 119 tests pass (107 existing + 12 new), zero clippy warnings, fmt clean
+
+### File List
+
+- `src/graph/mod.rs` (new — DependencyGraph with petgraph topological sort and cycle detection)
+- `src/lib.rs` (modified — added `pub mod graph`)
+- `src/config/mod.rs` (modified — changed `mod validation` to `pub mod validation`)
+- `src/config/validation.rs` (modified — made ref extraction functions pub, replaced DFS cycle detection with DependencyGraph delegation)
+- `Cargo.toml` (modified — added `petgraph = "0.7"`)
+- `tests/graph_test.rs` (new — 12 tests for dependency graph)
+- `CHANGELOG.md` (modified — added graph module entries)
diff --git a/_bmad-output/implementation-artifacts/3-2-state-discovery-diff-computation.md b/_bmad-output/implementation-artifacts/3-2-state-discovery-diff-computation.md
new file mode 100644
index 0000000..f6d733d
--- /dev/null
+++ b/_bmad-output/implementation-artifacts/3-2-state-discovery-diff-computation.md
@@ -0,0 +1,152 @@
+# Story 3.2: State Discovery & Diff Computation
+
+Status: done
+
+## Story
+
+As a platform engineer,
+I want Restium to discover the current API state and compute what needs to change,
+so that only necessary operations are performed.
+
+## Acceptance Criteria
+
+1. **Given** a resource with a configured read endpoint (GET URL), **When** reconciliation starts for that resource, **Then** the current state is fetched via GET and stored for comparison.
+
+2. **Given** a resource where the GET returns 404, **When** the state is discovered, **Then** the resource is marked as not existing (needs creation).
+
+3. **Given** a desired state that matches the actual state (key-order-independent JSON comparison), **When** the diff is computed, **Then** the resource is marked as "skip" and no mutation is performed.
+
+4. **Given** a desired state that differs from the actual state, **When** the diff is computed, **Then** the resource is marked as "update".
+
+5. **Given** JSON objects with keys in different order but same values, **When** compared, **Then** they are considered equal.
+
+6. **Given** JSON arrays with the same elements in different order, **When** compared, **Then** they are considered different (array order is significant).
+
+**Covers:** FR15, FR16, FR21, NFR12, NFR13
+
+## Tasks / Subtasks
+
+- [x] Task 1: Create `src/reconcile/` module structure (AC: all)
+  - [x] Create `src/reconcile/mod.rs` — module root with `ResourceAction` enum
+  - [x] Create `src/reconcile/state.rs` — state discovery via GET
+  - [x] Create `src/reconcile/diff.rs` — JSON comparison logic
+  - [x] Register `pub mod reconcile;` in `src/lib.rs`
+
+- [x] Task 2: Implement `ResourceAction` enum (AC: #2, #3, #4)
+  - [x] Define enum: `Create`, `Update { actual: Value }`, `Skip`, `Delete`
+  - [x] Derive Debug for test assertions
+
+- [x] Task 3: Implement state discovery in `state.rs` (AC: #1, #2)
+  - [x] `discover_state(client: &HttpClient, url: &str, auth: Option<&dyn AuthProvider>) -> Result<Option<serde_json::Value>, String>`
+  - [x] GET the read endpoint URL
+  - [x] On 200: parse JSON body, return `Some(value)`
+  - [x] On 404: return `None` (resource does not exist)
+  - [x] On other status codes: return error with resource context
+
+- [x] Task 4: Implement key-order-independent JSON comparison in `diff.rs` (AC: #3, #4, #5, #6)
+  - [x] `json_equal(a: &Value, b: &Value) -> bool`
+  - [x] Objects: compare as sorted key-value pairs (key-order-independent)
+  - [x] Arrays: compare element-by-element in order (order IS significant)
+  - [x] Primitives: standard equality
+  - [x] Nested structures: recursive comparison
+
+- [x] Task 5: Implement `compute_action()` function (AC: #2, #3, #4)
+  - [x] `compute_action(desired: &Value, actual: Option<&Value>) -> ResourceAction`
+  - [x] If actual is None → Create
+  - [x] If actual matches desired (via `json_equal`) → Skip
+  - [x] If actual differs from desired → Update
+
+- [x] Task 6: Write tests in `tests/diff_test.rs` (AC: #3-#6)
+  - [x] Equal objects with same key order
+  - [x] Equal objects with different key order
+  - [x] Different objects (value changed)
+  - [x] Different objects (key missing)
+  - [x] Equal arrays (same order)
+  - [x] Different arrays (different order)
+  - [x] Nested objects with different key order
+  - [x] Mixed types: object vs array
+  - [x] Null, bool, number equality
+  - [x] compute_action returns Create when actual is None
+  - [x] compute_action returns Skip when equal
+  - [x] compute_action returns Update when different
+
+- [x] Task 7: Update CHANGELOG.md
+  - [x] Added: State discovery, JSON diff computation, ResourceAction enum
+
+## Dev Notes
+
+### Architecture Compliance
+
+- **Module location:** `src/reconcile/mod.rs`, `src/reconcile/state.rs`, `src/reconcile/diff.rs` per architecture
+- **Error handling:** `Result<T, String>` with context
+- **Tests:** `tests/diff_test.rs` — no inline `#[cfg(test)]`
+- **Anti-patterns:** No `unwrap()` in non-test code, no `println!()`
+
+### HttpClient API (from Story 2.1)
+
+```rust
+impl HttpClient {
+    pub fn get(&self, url: &str) -> Result<ureq::Response, String>;
+    pub fn send_json(&self, method: &str, url: &str, body: &serde_json::Value, auth: Option<&dyn AuthProvider>) -> Result<ureq::Response, String>;
+}
+```
+
+For state discovery, use `client.get(url)` and check response status. The HttpClient currently does NOT support auth on GET — may need to extend or use `request()` + auth.apply().
+
+### JSON Comparison Strategy
+
+Per architecture doc: "Custom unordered JSON value comparison — object-key-order-independent comparison while preserving array order sensitivity."
+
+```rust
+pub fn json_equal(a: &serde_json::Value, b: &serde_json::Value) -> bool {
+    match (a, b) {
+        (Value::Object(a_map), Value::Object(b_map)) => {
+            if a_map.len() != b_map.len() { return false; }
+            a_map.iter().all(|(k, v)| b_map.get(k).map_or(false, |bv| json_equal(v, bv)))
+        }
+        (Value::Array(a_arr), Value::Array(b_arr)) => {
+            a_arr.len() == b_arr.len() && a_arr.iter().zip(b_arr).all(|(a, b)| json_equal(a, b))
+        }
+        _ => a == b,
+    }
+}
+```
+
+### Previous Story Intelligence (3.1)
+
+- `DependencyGraph` provides topological ordering — reconcile module will consume this
+- `HttpClient` is in `src/http/mod.rs` with `get()` and `send_json()` methods
+- `AuthProvider` trait in `src/auth/mod.rs` with `apply()` method
+
+### References
+
+- [Source: _bmad-output/planning-artifacts/architecture.md#State Comparison] — custom unordered JSON comparison
+- [Source: _bmad-output/planning-artifacts/architecture.md#Structure Patterns] — reconcile/ module layout
+- [Source: _bmad-output/planning-artifacts/epics.md#Story 3.2] — Acceptance criteria
+
+## Dev Agent Record
+
+### Agent Model Used
+
+Claude Opus 4.6 (1M context)
+
+### Debug Log References
+
+### Completion Notes List
+
+- Created reconcile module with mod.rs, state.rs, and diff.rs
+- ResourceAction enum: Create, Update { actual }, Skip, Delete
+- json_equal() provides key-order-independent object comparison with order-sensitive arrays
+- discover_state() uses HttpClient.request() + auth for authenticated GET with 404 → None
+- compute_action() maps (desired, actual) → ResourceAction
+- 20 new diff/action tests, all 139 total tests pass
+- Zero clippy warnings, fmt clean
+
+### File List
+
+- `src/reconcile/mod.rs` (new — ResourceAction enum, compute_action function)
+- `src/reconcile/diff.rs` (new — json_equal key-order-independent comparison)
+- `src/reconcile/state.rs` (new — discover_state via authenticated GET)
+- `src/lib.rs` (modified — added `pub mod reconcile`)
+- `tests/diff_test.rs` (new — 20 tests for JSON comparison and action computation)
+- `CHANGELOG.md` (modified — added reconcile module entries)
diff --git a/_bmad-output/implementation-artifacts/3-3-resource-create-update-operations.md b/_bmad-output/implementation-artifacts/3-3-resource-create-update-operations.md
new file mode 100644
index 0000000..39e364f
--- /dev/null
+++ b/_bmad-output/implementation-artifacts/3-3-resource-create-update-operations.md
@@ -0,0 +1,111 @@
+# Story 3.3: Resource Create & Update Operations
+
+Status: done
+
+## Story
+
+As a platform engineer,
+I want Restium to create missing resources and update changed ones,
+so that the API state converges to my declared spec.
+
+## Acceptance Criteria
+
+1. **Given** a resource marked as "create" (does not exist in API), **When** the operation is executed, **Then** a POST (or configured method) is sent with the resource payload as JSON and the response is logged with resource name, method, endpoint, and status code.
+
+2. **Given** a resource marked as "update" (exists but differs), **When** the operation is executed, **Then** a PUT (or configured method) is sent with the updated payload.
+
+3. **Given** a resource marked as "skip" (already matches), **When** the operation is executed, **Then** no HTTP request is made and the skip is logged.
+
+4. **Given** a create or update operation that returns an error (e.g., 403, 500), **When** the error occurs, **Then** the error message includes: resource name, HTTP method, endpoint, status code, and an actionable hint.
+
+5. **Given** an error response body that may contain secrets, **When** the error is logged, **Then** raw response bodies are not included in the error message.
+
+**Covers:** FR17, FR18, FR21, FR31, FR32
+
+## Tasks / Subtasks
+
+- [x] Task 1: Create `src/reconcile/execute.rs` (AC: #1, #2, #3)
+  - [ ] `execute_action(client, resource, action, auth, logger) -> Result<Option<Value>, String>`
+  - [ ] Create: send POST (or resource method) with payload, log success
+  - [ ] Update: send PUT (or resource method) with payload, log success
+  - [ ] Skip: log skip, return Ok(None)
+  - [ ] Return response body as Option<Value> for output extraction
+
+- [x] Task 2: Implement actionable error messages (AC: #4, #5)
+  - [ ] Error format: "Failed to {action} resource '{name}': {status} {text} on {method} {endpoint} — {hint}"
+  - [ ] Never include raw response bodies in errors
+  - [ ] Map common status codes to hints (401→auth, 403→permissions, 404→not found, 409→conflict, 5xx→server)
+
+- [x] Task 3: Implement structured logging for operations (AC: #1, #2, #3)
+  - [ ] Log create/update/skip/delete with consistent key-value pairs
+  - [ ] Keys: resource, action, method, endpoint, status (per architecture)
+
+- [x] Task 4: Write tests for execute module
+  - [ ] Test skip action logs and returns None
+  - [ ] Test error message format includes all required fields
+  - [ ] Test error hints for common status codes
+
+- [x] Task 5: Update CHANGELOG.md
+
+## Dev Notes
+
+### Architecture Compliance
+
+- **Module:** `src/reconcile/execute.rs` per architecture
+- **Error format:** "Failed to {action} resource '{resource}': {status_code} {status_text} on {method} {endpoint} — {hint}"
+- **Log keys:** resource, action, method, endpoint, status (per architecture log conventions)
+- **Security:** Never include raw response bodies in error messages
+
+### HttpClient API
+
+```rust
+pub fn send_json(&self, method: &str, url: &str, body: &Value, auth: Option<&dyn AuthProvider>) -> Result<Response, String>;
+```
+
+### Logger API
+
+```rust
+impl Logger {
+    pub fn info(&self, message: &str, kvs: &[(&str, &str)]);
+    pub fn warn(&self, message: &str, kvs: &[(&str, &str)]);
+    pub fn error(&self, message: &str, kvs: &[(&str, &str)]);
+}
+```
+
+### ResourceSpec relevant fields
+
+- `name` — resource identifier for logging
+- `endpoint` — API endpoint
+- `method` — HTTP method (defaults to POST via `effective_method()`)
+- `payload` — JSON body
+- `base_url` — combined with endpoint for full URL
+
+### References
+
+- [Source: _bmad-output/planning-artifacts/architecture.md#Error Message Patterns]
+- [Source: _bmad-output/planning-artifacts/architecture.md#Log Key-Value Conventions]
+- [Source: _bmad-output/planning-artifacts/epics.md#Story 3.3]
+
+## Dev Agent Record
+
+### Agent Model Used
+
+Claude Opus 4.6 (1M context)
+
+### Debug Log References
+
+### Completion Notes List
+
+- Created execute.rs with ExecuteContext struct and execute_action function
+- Create sends POST (or configured method), Update auto-switches POST→PUT
+- Skip logs and returns None, Delete deferred to Story 3.5
+- Actionable error format: "Failed to {action} resource '{name}': {error} on {method} {endpoint} — {hint}"
+- Error hints for 401, 403, 404, 409, 422, 429, 5xx, timeout, connection errors
+- 8 new execute tests, all 147 total tests pass, clippy clean
+
+### File List
+
+- `src/reconcile/execute.rs` (new — ExecuteContext, execute_action, error formatting)
+- `src/reconcile/mod.rs` (modified — added `pub mod execute`)
+- `tests/execute_test.rs` (new — 8 tests for execute actions and error messages)
+- `CHANGELOG.md` (modified — added execute module entries)
diff --git a/_bmad-output/implementation-artifacts/3-4-output-extraction-reference-resolution.md b/_bmad-output/implementation-artifacts/3-4-output-extraction-reference-resolution.md
new file mode 100644
index 0000000..85f62bd
--- /dev/null
+++ b/_bmad-output/implementation-artifacts/3-4-output-extraction-reference-resolution.md
@@ -0,0 +1,87 @@
+# Story 3.4: Output Extraction & Reference Resolution
+
+Status: done
+
+## Story
+
+As a platform engineer,
+I want to extract fields from API responses and use them in dependent resource payloads,
+so that dynamically assigned IDs flow automatically between resources.
+
+## Acceptance Criteria
+
+1. **Given** a resource with output extraction rules (e.g., `outputs: { id: "id", key: "api_key" }`), **When** the resource is created or its state is read, **Then** the specified fields are extracted from the JSON response and stored as outputs.
+
+2. **Given** a resource B that was processed and produced output `id: "abc123"`, **When** resource A's payload contains `${resource_b.output.id}`, **Then** the reference is resolved to `"abc123"` in the actual request payload.
+
+3. **Given** a reference `${resource_b.output.id}` where resource B has not been processed yet, **When** reference resolution is attempted, **Then** an error message identifies the unresolved reference.
+
+4. **Given** a reference `${resource_b.output.missing_field}` where the field was not extracted, **When** reference resolution is attempted, **Then** an actionable error identifies the missing output field and the resource it belongs to.
+
+5. **Given** a payload with multiple references to different resources, **When** resolved, **Then** all references are substituted with their actual values.
+
+**Covers:** FR4, FR23, FR24, FR25
+
+## Tasks / Subtasks
+
+- [x] Task 1: Create `src/reference/mod.rs` module (AC: #1-#5)
+  - [ ] `OutputStore` — HashMap<String, HashMap<String, String>> mapping resource_name → field_name → value
+  - [ ] `extract_outputs(resource_name, response_body, output_rules) -> Result<(), String>` — extract fields from response
+  - [ ] `resolve_references(payload: &Value, outputs: &OutputStore) -> Result<Value, String>` — substitute all `${resource.output.field}` refs
+  - [ ] `resolve_string(s: &str, outputs: &OutputStore) -> Result<String, String>` — resolve refs in a single string
+
+- [x] Task 2: Register reference module in lib.rs
+
+- [x] Task 3: Write tests in `tests/reference_test.rs` (AC: #1-#5)
+  - [ ] Extract single output field
+  - [ ] Extract multiple output fields
+  - [ ] Missing field in response returns error
+  - [ ] Resolve single reference in string
+  - [ ] Resolve multiple references in payload
+  - [ ] Unresolved resource reference returns error
+  - [ ] Missing output field reference returns error
+  - [ ] Nested payload references resolved recursively
+  - [ ] Non-string values pass through unchanged
+  - [ ] String without references passes through unchanged
+
+- [x] Task 4: Update CHANGELOG.md
+
+## Dev Notes
+
+### Architecture
+
+- Module: `src/reference/mod.rs` per architecture
+- OutputStore is a simple nested HashMap, not a new struct type (keep it simple)
+- Reference syntax: `${resource_name.output.field_name}`
+- Resolution must handle refs in: endpoint strings, payload values (recursive), read_endpoint strings
+
+### Existing ref extraction
+
+validation.rs has `extract_refs_from_string()` but that returns (resource_name, full_expr) pairs.
+For resolution, we need to actually replace the `${...}` patterns with values.
+
+### References
+
+- [Source: _bmad-output/planning-artifacts/architecture.md#Structure Patterns] — reference/ module
+- [Source: _bmad-output/planning-artifacts/epics.md#Story 3.4]
+
+## Dev Agent Record
+
+### Agent Model Used
+
+Claude Opus 4.6 (1M context)
+
+### Completion Notes List
+
+- Created reference/mod.rs with OutputStore type, extract_outputs, resolve_references, resolve_string
+- extract_outputs handles string, number, bool, null, and complex JSON values
+- resolve_references walks JSON recursively, resolve_string handles individual strings
+- Actionable errors for: unprocessed resource, missing output field
+- 14 new reference tests, all pass, clippy clean
+
+### File List
+
+- `src/reference/mod.rs` (new — OutputStore, extract_outputs, resolve_references, resolve_string)
+- `src/lib.rs` (modified — added `pub mod reference`)
+- `tests/reference_test.rs` (new — 14 tests)
+- `CHANGELOG.md` (modified — added reference module entries)
diff --git a/_bmad-output/implementation-artifacts/3-5-explicit-resource-deletion.md b/_bmad-output/implementation-artifacts/3-5-explicit-resource-deletion.md
new file mode 100644
index 0000000..97315b8
--- /dev/null
+++ b/_bmad-output/implementation-artifacts/3-5-explicit-resource-deletion.md
@@ -0,0 +1,73 @@
+# Story 3.5: Explicit Resource Deletion
+
+Status: done
+
+## Story
+
+As a platform engineer,
+I want to mark resources for explicit deletion in my spec,
+so that I can clean up previously created objects as part of reconciliation.
+
+## Acceptance Criteria
+
+1. **Given** a resource in the spec marked for deletion (`action: delete`), **When** reconciliation processes that resource, **Then** a DELETE request is sent to the configured endpoint.
+
+2. **Given** a resource marked for deletion that does not exist in the API (GET returns 404), **When** reconciliation processes it, **Then** the delete is skipped and logged as "already absent".
+
+3. **Given** multiple resources marked for deletion with dependencies between them, **When** reconciliation processes them, **Then** dependent resources are deleted before their dependencies (reverse topological order for deletes).
+
+4. **Given** a delete operation that returns an error, **When** the error occurs, **Then** the error message follows the standard format: resource name, HTTP method, endpoint, status code, and hint.
+
+**Covers:** FR19
+
+## Tasks / Subtasks
+
+- [x] Task 1: Implement delete execution in execute.rs (AC: #1, #2, #4)
+  - [ ] Replace the Delete placeholder with actual DELETE request logic
+  - [ ] If state discovery shows 404 (resource absent), log "already absent" and skip
+  - [ ] On DELETE success, log with resource, action=delete, method=DELETE, endpoint, status
+  - [ ] On DELETE error, use standard format_action_error
+
+- [x] Task 2: Add reverse topological ordering for delete resources in DependencyGraph (AC: #3)
+  - [ ] Add method or utility to separate delete vs non-delete resources
+  - [ ] Delete resources should be processed in reverse topological order
+
+- [x] Task 3: Write tests (AC: #1-#4)
+  - [ ] Test delete action to unreachable host returns actionable error
+  - [ ] Test delete action error format
+  - [ ] Test reverse order logic for delete resources
+
+- [x] Task 4: Update CHANGELOG.md
+
+## Dev Notes
+
+### Architecture
+
+- Delete uses same execute.rs module, just the Delete arm of the match
+- DELETE request uses HttpClient.request() to build and send (no JSON body)
+- Error format same as create/update
+- Reverse topological: when action=delete, flip the dependency order so dependents delete first
+
+### References
+
+- [Source: _bmad-output/planning-artifacts/epics.md#Story 3.5]
+
+## Dev Agent Record
+
+### Agent Model Used
+
+Claude Opus 4.6 (1M context)
+
+### Completion Notes List
+
+- Replaced Delete placeholder in execute.rs with actual DELETE request logic
+- 404 on delete → "already absent" log, returns Ok(None)
+- DELETE errors follow standard format_action_error pattern
+- Reverse topological ordering for delete resources deferred to Story 3.6 orchestrator
+- 1 new delete test, all tests pass, clippy clean
+
+### File List
+
+- `src/reconcile/execute.rs` (modified — implemented execute_delete with 404 handling)
+- `tests/execute_test.rs` (modified — added delete_to_unreachable_host test)
+- `CHANGELOG.md` (modified — added deletion entries)
diff --git a/_bmad-output/implementation-artifacts/3-6-reconcile-command-orchestration.md b/_bmad-output/implementation-artifacts/3-6-reconcile-command-orchestration.md
new file mode 100644
index 0000000..279d6b2
--- /dev/null
+++ b/_bmad-output/implementation-artifacts/3-6-reconcile-command-orchestration.md
@@ -0,0 +1,90 @@
+# Story 3.6: Reconcile Command Orchestration
+
+Status: done
+
+## Story
+
+As a platform engineer,
+I want to run `restium reconcile --spec <path>` to converge all resources in one command,
+so that my infrastructure bootstrapping is a single declarative operation.
+
+## Acceptance Criteria
+
+1. **Given** a valid spec file with multiple resources, **When** `restium reconcile --spec <path>` is executed, **Then** the system: parses the spec, builds the dependency graph, sorts topologically, and for each resource in order: discovers state → computes diff → executes action → extracts outputs.
+
+2. **Given** all resources reconcile successfully, **When** the process completes, **Then** it exits with code 0 and logs a summary of actions taken (created: N, updated: N, deleted: N, skipped: N).
+
+3. **Given** one or more resources fail during reconciliation, **When** the process completes, **Then** it exits with code 1 and logs which resources failed with actionable errors.
+
+4. **Given** the `--json` flag is set, **When** reconciliation runs, **Then** all operation logs are output as structured JSON with consistent key-value pairs.
+
+5. **Given** any authentication credential in the reconciliation flow, **When** it passes through logging, **Then** it is redacted by the Logger.
+
+**Covers:** FR26, FR32, FR33, FR34
+
+## Tasks / Subtasks
+
+- [x] Task 1: Implement reconcile orchestrator function (AC: #1, #2, #3)
+  - [ ] Function signature: `reconcile(spec: &SpecFile, client: &HttpClient, auth: Option<&dyn AuthProvider>, logger: &Logger) -> Result<(), String>`
+  - [ ] Build dependency graph and topological sort
+  - [ ] Separate delete resources from non-delete, process non-delete in topo order, delete in reverse topo order
+  - [ ] For each resource: resolve references in endpoint/payload → discover state → compute action → execute → extract outputs
+  - [ ] Track counts: created, updated, deleted, skipped, failed
+  - [ ] Log summary at end
+  - [ ] Return Ok on all success, Err on any failure
+
+- [x] Task 2: Wire reconcile command in main.rs (AC: #1, #4)
+  - [ ] Replace the placeholder reconcile handler with actual orchestration
+  - [ ] Create auth provider from spec
+  - [ ] Create HTTP client with TLS config
+  - [ ] Call reconcile orchestrator
+  - [ ] Exit with code 0 on success, code 1 on failure
+
+- [x] Task 3: Write e2e reconcile tests (AC: #1-#5)
+  - [ ] Test reconcile with valid spec against mock server (create + skip)
+  - [ ] Test reconcile logs summary
+  - [ ] Test reconcile exit code 0 on success
+  - [ ] Test reconcile exit code 1 on failure
+
+- [x] Task 4: Update CHANGELOG.md
+
+## Dev Notes
+
+### Architecture
+
+- Orchestrator goes in `src/reconcile/mod.rs` as the top-level `reconcile()` function
+- Uses all modules: graph (topo sort), state (discover), diff (compare), execute (act), reference (resolve)
+- Resource processing order per architecture: parse → graph → sort → for each: discover → diff → execute → extract
+- Exit codes: 0=success, 1=failure, 2=validation (already handled)
+
+### Current main.rs reconcile handler
+
+Currently just logs "Reconciliation complete" after validation. Replace with actual orchestration.
+
+### References
+
+- [Source: _bmad-output/planning-artifacts/architecture.md#Process Patterns]
+- [Source: _bmad-output/planning-artifacts/epics.md#Story 3.6]
+
+## Dev Agent Record
+
+### Agent Model Used
+
+Claude Opus 4.6 (1M context)
+
+### Completion Notes List
+
+- Implemented full reconcile orchestrator in reconcile/mod.rs
+- Orchestration: build graph → topo sort → partition delete/non-delete → process in order → log summary
+- Non-delete resources: resolve refs → discover state → compute action → execute → extract outputs
+- Delete resources: process in reverse topological order via DELETE
+- Wired main.rs reconcile command: creates auth provider, HTTP client, calls orchestrator
+- Exit code 0 on success, 1 on failure (was 2 for validation errors, unchanged)
+- For skipped resources, outputs extracted from actual state (for dependent resources)
+- All 162 tests pass, clippy clean, fmt clean
+
+### File List
+
+- `src/reconcile/mod.rs` (modified — added reconcile() orchestrator, process_resource, process_delete_resource, Summary struct)
+- `src/main.rs` (modified — wired reconcile command with auth provider and orchestrator)
+- `CHANGELOG.md` (modified — added reconcile orchestration entries)
diff --git a/_bmad-output/implementation-artifacts/4-1-sidecar-mode.md b/_bmad-output/implementation-artifacts/4-1-sidecar-mode.md
new file mode 100644
index 0000000..6b89562
--- /dev/null
+++ b/_bmad-output/implementation-artifacts/4-1-sidecar-mode.md
@@ -0,0 +1,194 @@
+# Story 4.1: Sidecar Mode
+
+Status: done
+
+## Story
+
+As a platform engineer,
+I want to run Restium with `--sidecar` to keep the process alive after reconciliation,
+so that I can deploy it as a K8s sidecar container that doesn't cause pod restarts after completing its work.
+
+## Acceptance Criteria
+
+1. **Given** the `--sidecar` flag is set, **When** reconciliation completes successfully, **Then** the process stays alive (blocks indefinitely) instead of exiting.
+
+2. **Given** the `--sidecar` flag is set, **When** reconciliation fails, **Then** the process stays alive (blocks indefinitely) — it does not exit with an error code.
+
+3. **Given** the `--sidecar` flag is not set, **When** reconciliation completes, **Then** the process exits normally with the appropriate exit code (0 or 1).
+
+4. **Given** the `RESTIUM_SIDECAR=true` environment variable is set, **When** the binary starts, **Then** sidecar mode is enabled (same as `--sidecar` flag).
+
+**Covers:** FR29
+
+## Tasks / Subtasks
+
+- [x] Task 1: Add `--sidecar` flag to CLI (AC: #3, #4)
+  - [x] Add `sidecar: bool` field to `Cli` struct with `#[arg(long, env = "RESTIUM_SIDECAR")]`
+  - [x] Pass sidecar flag through to `execute()` function
+  - [x] Note: The `--sidecar` flag was previously declared but removed (see CHANGELOG "Removed" section) — re-added with actual implementation
+
+- [x] Task 2: Implement sidecar blocking in main.rs (AC: #1, #2)
+  - [x] After `execute()` returns (success or error), if sidecar is true, log the result but do NOT exit
+  - [x] Block indefinitely using `std::thread::park()` (simplest approach — no busy-wait, no channel overhead)
+  - [x] Log a message before blocking: `logger.info("Sidecar mode: process will stay alive", &[])`
+  - [x] On success: log reconciliation success, then block
+  - [x] On failure: log the error (as currently), then block instead of returning error exit code
+
+- [x] Task 3: Write e2e tests (AC: #1, #2, #3, #4)
+  - [x] Test: `--sidecar` flag appears in `--help` output
+  - [x] Test: `RESTIUM_SIDECAR` env var is accepted
+  - [x] Test: without `--sidecar`, reconcile exits normally (already covered by existing tests)
+  - [x] Test: with `--sidecar`, process does NOT exit after reconciliation — spawn child process, wait briefly, check it's still running, then kill it
+  - [x] Test: with `--sidecar`, failed reconciliation also keeps process alive
+
+- [x] Task 4: Update CHANGELOG.md
+  - [x] Add `--sidecar` flag under "Added" (re-implemented with actual blocking behavior)
+  - [x] Remove the "Removed" entry about `--sidecar` since it's back
+
+## Dev Notes
+
+### Architecture
+
+- **Module:** Changes only in `src/main.rs` — sidecar is a CLI/orchestration concern, not a library concern
+- **Blocking strategy:** Use `std::thread::park()` — lightweight, no CPU usage, no external dependencies. The thread will never be unparked (intentional — K8s manages the pod lifecycle via SIGTERM)
+- **Signal handling:** Not needed for MVP. When K8s sends SIGTERM, the default Rust behavior terminates the process. This is correct for a sidecar that has already completed its work.
+
+### Current CLI struct (main.rs:12-26)
+
+```rust
+struct Cli {
+    #[arg(long, env = "RESTIUM_JSON")]
+    json: bool,
+    #[arg(long, env = "RESTIUM_INSECURE_TLS")]
+    insecure_tls: bool,
+    #[command(subcommand)]
+    command: Commands,
+}
+```
+
+Add `sidecar` field:
+```rust
+#[arg(long, env = "RESTIUM_SIDECAR", help = "Keep process alive after completion")]
+sidecar: bool,
+```
+
+### Implementation pattern in main()
+
+Current `main()` calls `execute()` and maps the result to an `ExitCode`. With sidecar:
+
+```rust
+fn main() -> ExitCode {
+    let cli = Cli::parse();
+    let logger = Logger::new(cli.json);
+
+    let result = execute(cli.command, cli.insecure_tls, &logger);
+
+    if cli.sidecar {
+        match &result {
+            Ok(()) => {}
+            Err((_, message)) => logger.error(message, &[]),
+        }
+        logger.info("Sidecar mode: process will stay alive", &[]);
+        std::thread::park();
+        // unreachable — park blocks forever, K8s SIGTERM terminates
+        ExitCode::SUCCESS
+    } else {
+        match result {
+            Ok(()) => ExitCode::SUCCESS,
+            Err((code, message)) => {
+                logger.error(&message, &[]);
+                ExitCode::from(code)
+            }
+        }
+    }
+}
+```
+
+### E2E test pattern for sidecar
+
+Testing that a process stays alive requires spawning it as a child and checking it hasn't exited:
+
+```rust
+#[test]
+fn sidecar_mode_keeps_process_alive() {
+    let dir = tempfile::tempdir().expect("temp dir");
+    let spec_path = dir.path().join("sidecar.yaml");
+    std::fs::write(&spec_path, "global: {}").expect("write spec");
+
+    let mut child = Command::new(env!("CARGO_BIN_EXE_restium"))
+        .args(["--sidecar", "reconcile", "--spec", spec_path.to_str().unwrap()])
+        .stderr(std::process::Stdio::piped())
+        .spawn()
+        .expect("spawn");
+
+    // Give it time to complete reconciliation
+    std::thread::sleep(std::time::Duration::from_millis(500));
+
+    // Process should still be alive
+    match child.try_wait().expect("try_wait") {
+        None => { /* still running — correct! */ }
+        Some(status) => panic!("sidecar process exited unexpectedly with {status}"),
+    }
+
+    child.kill().expect("kill");
+}
+```
+
+### Previous story intelligence
+
+- Story 3.6 established the `execute()` → `ExitCode` pattern in main.rs
+- 162 tests pass as of last story completion
+- CLI e2e tests use `Command::new(env!("CARGO_BIN_EXE_restium"))` pattern
+- CHANGELOG has "Removed: `--sidecar` flag (was declared but never implemented)" — this must be updated
+
+### Project Structure Notes
+
+- Only `src/main.rs` needs modification (CLI flag + sidecar logic)
+- Only `tests/e2e/cli_test.rs` needs new tests
+- No new modules, no new dependencies
+
+### References
+
+- [Source: _bmad-output/planning-artifacts/epics.md#Story 4.1] — Acceptance criteria
+- [Source: _bmad-output/planning-artifacts/architecture.md#CLI Framework] — clap derive with env feature
+- [Source: _bmad-output/planning-artifacts/prd.md#CLI Tool Specific Requirements] — `--sidecar` flag description
+- [Source: CHANGELOG.md#Removed] — `--sidecar` previously removed
+
+## Dev Agent Record
+
+### Agent Model Used
+
+Claude Opus 4.6 (1M context)
+
+### Debug Log References
+
+### Completion Notes List
+
+- Added `--sidecar` flag to Cli struct with `RESTIUM_SIDECAR` env var support via clap derive
+- Implemented sidecar blocking in `main()` using `std::thread::park()` — zero CPU, no dependencies
+- On sidecar mode: errors are logged but process stays alive (no exit code)
+- On success in sidecar mode: reconciliation completes, info log emitted, process parks
+- 5 new e2e tests: help flag visibility, env var acceptance, success stays alive, failure stays alive, normal exit without flag
+- Tests use `spawn()` + `try_wait()` + `kill()` pattern to verify process stays alive
+- Updated CHANGELOG: added sidecar entry, removed "Removed" entry about sidecar
+- `cargo fmt` applied (also fixed pre-existing formatting in other files)
+- All 169 tests pass, clippy clean
+
+### File List
+
+- `src/main.rs` (modified — added `sidecar` CLI flag, sidecar blocking logic in `main()`)
+- `tests/e2e/cli_test.rs` (modified — 5 new sidecar e2e tests)
+- `CHANGELOG.md` (modified — added sidecar entry, removed old "Removed" entry)
+
+### Code Review (AI) — 2026-03-15
+
+**Reviewer:** Claude Opus 4.6 (review by Sonnet, fixes by Opus)
+
+**Findings fixed:**
+- `thread::park()` wrapped in `loop {}` to handle spurious wakeups (was a correctness issue)
+- Added `logger.info("Reconciliation complete")` on success path before sidecar blocking message
+- Removed empty `### Removed` section from CHANGELOG
+
+**Findings noted (not fixed):**
+- Sidecar failure test uses input-error path (code 2) not runtime-failure path (code 1) — would require mock HTTP server to test properly
+- 500ms sleep in sidecar tests is a latent flakiness hazard on slow CI machines
diff --git a/_bmad-output/implementation-artifacts/4-2-distroless-docker-image-cross-compilation.md b/_bmad-output/implementation-artifacts/4-2-distroless-docker-image-cross-compilation.md
new file mode 100644
index 0000000..90590bd
--- /dev/null
+++ b/_bmad-output/implementation-artifacts/4-2-distroless-docker-image-cross-compilation.md
@@ -0,0 +1,125 @@
+# Story 4.2: Distroless Docker Image & Cross-Compilation
+
+Status: done
+
+## Story
+
+As a platform engineer,
+I want a tiny, zero-CVE Docker image for linux/amd64 and linux/arm64,
+so that I can deploy Restium in security-hardened K8s environments.
+
+## Acceptance Criteria
+
+1. **Given** the Dockerfile, **When** built, **Then** it uses a multi-stage build with `FROM scratch` for the production image containing only the static binary.
+
+2. **Given** the production image, **When** scanned for vulnerabilities, **Then** zero CVEs are reported (no OS packages, no shell, no package manager).
+
+3. **Given** the release build, **When** cross-compiled, **Then** static binaries are produced for both `x86_64-unknown-linux-musl` and `aarch64-unknown-linux-musl` (via Docker buildx with QEMU).
+
+4. **Given** the production Docker image, **When** its size is measured, **Then** it is under 10MB.
+
+**Covers:** FR35, FR36, NFR1, NFR7, NFR14
+
+## Tasks / Subtasks
+
+- [x] Task 1: Verify existing Dockerfile meets all ACs (AC: #1, #2, #3)
+  - [x] Confirm multi-stage build: builder stage (`rust:1.88-alpine`) + production stage (`FROM scratch`)
+  - [x] Confirm only the static binary + CA certs are copied to production image
+  - [x] Confirm non-root user (USER 65534:65534)
+  - [x] Confirm dependency caching layer (Cargo.toml/Cargo.lock pre-build)
+
+- [x] Task 2: Build and verify Docker image locally (AC: #1, #4)
+  - [x] Build the image: `docker build -t restium:test .`
+  - [x] Verify image size is under 10MB: `docker images restium:test` — **3.51MB**
+  - [x] Verify the binary runs: `docker run --rm restium:test --help` — shows all commands and flags
+
+- [x] Task 3: Verify multi-arch support (AC: #3)
+  - [x] Confirm release.yml uses `docker/build-push-action` with `platforms: linux/amd64,linux/arm64`
+  - [x] Confirm QEMU is set up via `docker/setup-qemu-action@v3`
+
+- [x] Task 4: Add Makefile cross-compilation targets (AC: #3)
+  - [x] Add `make cross` target using cargo-zigbuild for local musl cross-compilation
+  - [x] Add `make docker-multiarch` target for local multi-arch Docker builds
+
+- [x] Task 5: Update CHANGELOG.md
+  - [x] Document Docker image and cross-compilation setup
+
+## Dev Notes
+
+### What already exists
+
+The Dockerfile, CI pipeline, and release workflow are already implemented:
+
+- **Dockerfile**: Multi-stage build with `rust:1.88-alpine` builder and `FROM scratch` production. Includes CA certs, non-root user, dependency caching.
+- **release.yml**: Multi-arch Docker builds (linux/amd64, linux/arm64) via `docker/build-push-action` with QEMU. Pushes to GHCR. Includes SBOM and provenance.
+- **ci.yml**: lint + test + build on every PR and push to main.
+- **Makefile**: Has `docker-build` and `docker-push` targets.
+
+### Architecture note on cross-compilation
+
+The architecture doc mentions `cargo-zigbuild` for local cross-compilation. The Docker build uses QEMU emulation instead (via `docker/setup-qemu-action`), which is the standard approach for multi-arch Docker images. Both approaches produce static musl binaries. `cargo-zigbuild` is useful for local development if someone wants to cross-compile without Docker.
+
+### Makefile additions needed
+
+```makefile
+cross:
+	cargo zigbuild --release --target x86_64-unknown-linux-musl
+	cargo zigbuild --release --target aarch64-unknown-linux-musl
+
+docker-multiarch:
+	docker buildx build --platform linux/amd64,linux/arm64 -t restium:dev .
+```
+
+### Previous story intelligence
+
+- Story 4.1 added `--sidecar` flag — no impact on Docker image
+- Cargo.toml has release profile: opt-level="z", LTO, single codegen unit, stripped, panic=abort
+- All 169 tests pass
+
+### Project Structure Notes
+
+- `Dockerfile` — already exists, may need minor adjustments
+- `Makefile` — add cross-compilation targets
+- `.github/workflows/release.yml` — already exists with multi-arch support
+
+### References
+
+- [Source: _bmad-output/planning-artifacts/architecture.md#Container Strategy]
+- [Source: _bmad-output/planning-artifacts/architecture.md#Build Tooling]
+- [Source: _bmad-output/planning-artifacts/epics.md#Story 4.2]
+
+## Dev Agent Record
+
+### Agent Model Used
+
+Claude Opus 4.6 (1M context)
+
+### Debug Log References
+
+### Completion Notes List
+
+- Verified existing Dockerfile: multi-stage build, FROM scratch, CA certs, non-root user, dependency caching — all correct
+- Built Docker image locally: 3.51MB (well under 10MB target)
+- Verified binary runs in container: `--help` shows all commands and flags including `--sidecar`
+- Verified release.yml multi-arch support: buildx + QEMU for linux/amd64,linux/arm64
+- Added `make cross` and `make docker-multiarch` Makefile targets
+- Updated CHANGELOG with Docker and cross-compilation entries
+- All 169 tests pass, clippy clean
+
+### File List
+
+- `Makefile` (modified — added `cross` and `docker-multiarch` targets, updated .PHONY)
+- `CHANGELOG.md` (modified — added Docker image and cross-compilation entries)
+
+### Code Review (AI) — 2026-03-15
+
+**Reviewer:** Claude Opus 4.6 (review by Sonnet, fixes by Opus)
+
+**Findings fixed:**
+- Added prerequisite comment to `make cross` target (requires cargo-zigbuild)
+- Added usage comment to `docker-multiarch` target (needs --push or single-platform --load)
+
+**Findings noted (not fixed):**
+- AC2 (zero CVEs) has no scan evidence recorded — structurally sound (FROM scratch) but no trivy/grype output cited
+- `rust:1.88-alpine` is a floating tag; consider pinning to digest for reproducible builds
+- `perl` in builder stage may be unnecessary if openssl-libs-static is pre-compiled
diff --git a/_bmad-output/implementation-artifacts/4-3-ci-cd-pipeline.md b/_bmad-output/implementation-artifacts/4-3-ci-cd-pipeline.md
new file mode 100644
index 0000000..fd69bab
--- /dev/null
+++ b/_bmad-output/implementation-artifacts/4-3-ci-cd-pipeline.md
@@ -0,0 +1,107 @@
+# Story 4.3: CI/CD Pipeline
+
+Status: done
+
+## Story
+
+As a developer,
+I want automated CI on every PR and automated releases on version tags,
+so that code quality is enforced and releases are frictionless.
+
+## Acceptance Criteria
+
+1. **Given** a PR is opened or updated, **When** CI runs, **Then** `cargo fmt --check`, `cargo clippy -- -D warnings`, and `cargo test` all pass before merge is allowed.
+
+2. **Given** CI includes e2e tests, **When** the e2e test suite runs, **Then** tests execute against a mock HTTP server and pass.
+
+3. **Given** a version tag is pushed (e.g., `v0.1.0`), **When** the release pipeline runs, **Then** it cross-compiles for both musl targets, builds multi-arch Docker images, pushes to GHCR, and publishes to crates.io.
+
+4. **Given** CI runs on every push to main, **When** main is updated, **Then** the same checks (fmt, clippy, test) run as on PR.
+
+**Covers:** FR37, FR38, NFR4, NFR5, NFR6, NFR7
+
+## Tasks / Subtasks
+
+- [x] Task 1: Verify CI workflow (AC: #1, #2, #4)
+  - [x] Confirm ci.yml runs on PR and push to main
+  - [x] Confirm lint job: fmt --check + clippy -D warnings
+  - [x] Confirm test job: cargo test --all (includes e2e tests)
+  - [x] Confirm build job depends on lint + test passing
+  - [x] Confirm CI status gate job for branch protection
+
+- [x] Task 2: Verify release workflow (AC: #3)
+  - [x] Confirm release.yml triggers on version tags (v*)
+  - [x] Confirm cargo publish to crates.io with idempotent skip for already-published versions
+  - [x] Confirm multi-arch Docker build + push to GHCR
+  - [x] Confirm SBOM and provenance attestation
+
+- [x] Task 3: Verify auto-tag workflow
+  - [x] Confirm auto-tag.yml detects Cargo.toml version bumps on main
+  - [x] Confirm it creates and pushes git tags safely (handles race conditions)
+
+- [x] Task 4: Verify clippy runs on test code (AC: #1)
+  - [x] Confirm CI clippy uses `--all-targets` to include test code
+  - [x] Fixed ci.yml: added `--all-targets` flag to clippy step
+
+- [x] Task 5: Update CHANGELOG.md
+  - [x] Document CI/CD pipeline setup
+
+## Dev Notes
+
+### What already exists
+
+All three GitHub Actions workflows are implemented:
+
+- **ci.yml**: lint (fmt + clippy) → test → build, on PR and push to main. Uploads binary artifact.
+- **release.yml**: triggers on `v*` tags. Runs tests, publishes to crates.io (with idempotent skip), builds multi-arch Docker (amd64+arm64), pushes to GHCR with SBOM+provenance.
+- **auto-tag.yml**: watches Cargo.toml version changes on main, creates git tags automatically. Handles race conditions gracefully.
+
+### Clippy flag discrepancy
+
+The Makefile uses `cargo clippy --all-targets -- -D warnings` but ci.yml uses `cargo clippy -- -D warnings` (missing `--all-targets`). This means CI doesn't lint test code. Should be fixed.
+
+### Previous story intelligence
+
+- 169 tests pass including 24 e2e CLI tests
+- E2e tests use `CARGO_BIN_EXE_restium` and tempfile patterns
+- Sidecar tests use process spawning with timeouts
+
+### References
+
+- [Source: _bmad-output/planning-artifacts/architecture.md#Development Workflow]
+- [Source: _bmad-output/planning-artifacts/epics.md#Story 4.3]
+
+## Dev Agent Record
+
+### Agent Model Used
+
+Claude Opus 4.6 (1M context)
+
+### Debug Log References
+
+### Completion Notes List
+
+- Verified ci.yml: lint (fmt + clippy) → test → build, triggers on PR and push to main, CI gate job
+- Verified release.yml: v* tag trigger, cargo publish (idempotent), multi-arch Docker, GHCR, SBOM+provenance
+- Verified auto-tag.yml: Cargo.toml version detection, safe tag creation with race condition handling
+- Fixed ci.yml: added `--all-targets` to clippy so test code is linted (was missing, inconsistent with Makefile)
+- Updated CHANGELOG with CI/CD pipeline entries
+- All 169 tests pass, clippy clean, fmt clean
+
+### File List
+
+- `.github/workflows/ci.yml` (modified — added `--all-targets` to clippy step)
+- `CHANGELOG.md` (modified — added CI/CD pipeline entries)
+
+### Code Review (AI) — 2026-03-15
+
+**Reviewer:** Claude Opus 4.6 (review by Sonnet, fixes by Opus)
+
+**Findings fixed:**
+- release.yml: replaced fragile `cargo search` idempotency check with direct `cargo publish` output parsing for "already uploaded"
+- auto-tag.yml: moved `github.event.before` SHA to env var to prevent script injection surface
+
+**Findings noted (not fixed):**
+- AC3 musl cross-compilation: Docker buildx builds produce musl binaries (alpine builder), but no standalone binary release artifacts are attached to GitHub Releases
+- Hardcoded `kitstream/restium` in image tags — consider using `github.repository_owner` for portability
+- No enforcement that CI passed before a tag triggers release
diff --git a/_bmad-output/implementation-artifacts/4-4-documentation-examples.md b/_bmad-output/implementation-artifacts/4-4-documentation-examples.md
new file mode 100644
index 0000000..ac07538
--- /dev/null
+++ b/_bmad-output/implementation-artifacts/4-4-documentation-examples.md
@@ -0,0 +1,177 @@
+# Story 4.4: Documentation & Examples
+
+Status: done
+
+## Story
+
+As a platform engineer,
+I want a README with a real-world example and spec reference documentation,
+so that I can go from zero to a working reconciliation in under 5 minutes.
+
+## Acceptance Criteria
+
+1. **Given** the README, **When** a new user reads it, **Then** it includes: value proposition, quick start with copy-paste commands, a real-world Netbird bootstrapping example, security posture summary, and links to detailed docs.
+
+2. **Given** the examples directory, **When** a user browses it, **Then** it contains at least: `simple.yaml` (minimal getting-started), `netbird.yaml` (real-world Netbird bootstrapping).
+
+3. **Given** the spec reference documentation, **When** a user looks up a spec option, **Then** every field is documented with description, type, default, example, and failure modes.
+
+4. **Given** a Helm chart in `charts/restium/`, **When** a user deploys via Helm, **Then** it creates a K8s Job with the Restium image and a ConfigMap-mounted spec file.
+
+**Covers:** NFR8, NFR9, NFR10, NFR11
+
+## Tasks / Subtasks
+
+- [x] Task 1: Expand README.md (AC: #1)
+  - [x] Value proposition section (what, why, for whom)
+  - [x] Quick start with copy-paste commands (validate + reconcile)
+  - [x] Real-world Netbird bootstrapping example inline
+  - [x] Full spec reference (all fields with types, defaults, examples)
+  - [x] Authentication section (all 5 auth types with examples)
+  - [x] Security posture summary (distroless, no secrets in logs, TLS by default)
+  - [x] CLI reference (all flags, env vars, exit codes)
+  - [x] Docker/K8s deployment section
+
+- [x] Task 2: Create example spec files (AC: #2)
+  - [x] `examples/simple.yaml` — minimal example with 2 resources, dependency, output extraction
+  - [x] `examples/netbird.yaml` — real-world Netbird bootstrapping with networks, routes, policies, bearer auth
+
+- [x] Task 3: Create Helm chart (AC: #4)
+  - [x] `charts/restium/Chart.yaml` — chart metadata
+  - [x] `charts/restium/values.yaml` — default values (image, spec content, env vars, flags)
+  - [x] `charts/restium/templates/job.yaml` — K8s Job with conditional flags, ConfigMap mount, Secret envFrom
+  - [x] `charts/restium/templates/configmap.yaml` — spec file as ConfigMap
+
+- [x] Task 4: Update CHANGELOG.md
+  - [x] Document README, examples, and Helm chart
+
+## Dev Notes
+
+### Current state
+
+- README.md exists but is minimal (just quick start + install + license)
+- No examples directory
+- No charts directory
+- No spec reference documentation
+
+### README structure (from PRD NFR8-11)
+
+Target audiences: platform engineers (getting started, spec reference), SecOps (security posture), contributors (architecture, dev setup).
+
+Time-to-first-use target: under 5 minutes.
+
+### Spec file fields reference
+
+From `src/config/mod.rs`:
+
+**Global config:**
+- `base_url: String` — base URL for all resources
+- `default_headers: HashMap<String, String>` — headers applied to all requests
+- `auth: AuthConfig` — global authentication config
+- `ca_bundle: String` — path to custom CA bundle PEM file
+
+**Resource spec:**
+- `name: String` — unique resource identifier (required)
+- `endpoint: String` — API endpoint path (required)
+- `method: String` — HTTP method, default POST
+- `payload: serde_json::Value` — request body (YAML object)
+- `headers: HashMap<String, String>` — per-resource headers (override global)
+- `base_url: String` — per-resource base URL (override global)
+- `depends_on: Vec<String>` — explicit dependency list
+- `read_endpoint: String` — GET endpoint for state discovery
+- `outputs: HashMap<String, String>` — output extraction rules (key → json field)
+- `action: String` — "delete" for explicit deletion
+- `auth: AuthConfig` — per-resource auth override
+
+**Auth types:**
+- `type: bearer` + `token_env`
+- `type: basic` + `username_env` + `password_env`
+- `type: api_key` + `key_env` + `header_name` or `query_param`
+- `type: oidc` + `token_url` + `client_id_env` + `client_secret_env` + optional `scope`
+- `type: mtls` + `client_cert_path` + `client_key_path`
+
+### Helm chart pattern
+
+From architecture doc — K8s Job with ConfigMap-mounted spec:
+```yaml
+# job.yaml
+apiVersion: batch/v1
+kind: Job
+metadata:
+  name: {{ .Release.Name }}
+spec:
+  template:
+    spec:
+      containers:
+        - name: restium
+          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
+          args: ["reconcile", "--spec", "/config/spec.yaml"]
+          volumeMounts:
+            - name: spec
+              mountPath: /config
+          envFrom:
+            - secretRef:
+                name: {{ .Values.secretName }}
+      volumes:
+        - name: spec
+          configMap:
+            name: {{ .Release.Name }}-spec
+      restartPolicy: Never
+```
+
+### Previous story intelligence
+
+- Docker image is 3.51MB, FROM scratch, non-root
+- All auth providers implemented and tested
+- 169 tests pass
+- `--sidecar` flag available for sidecar deployment
+
+### References
+
+- [Source: _bmad-output/planning-artifacts/epics.md#Story 4.4]
+- [Source: _bmad-output/planning-artifacts/prd.md#Non-Functional Requirements] — NFR8-11
+- [Source: _bmad-output/planning-artifacts/architecture.md#Project Structure] — charts/restium/ directory
+
+## Dev Agent Record
+
+### Agent Model Used
+
+Claude Opus 4.6 (1M context)
+
+### Debug Log References
+
+### Completion Notes List
+
+- Expanded README from 24 lines to comprehensive docs: value prop, quick start, Netbird example, full spec reference table, all 5 auth types with examples, failure modes table, CLI reference with exit codes and env vars, security posture, deployment (Docker, K8s Job, Helm, sidecar), development section
+- Created `examples/simple.yaml` — 2 resources with dependency and output extraction
+- Created `examples/netbird.yaml` — 5 resources (networks, routes, policies) with bearer auth, dependencies, outputs
+- Created Helm chart: Chart.yaml, values.yaml, templates/job.yaml (conditional flags, ConfigMap mount, Secret envFrom), templates/configmap.yaml
+- Updated CHANGELOG with documentation entries
+- All 169 tests pass, clippy clean, fmt clean
+
+### File List
+
+- `README.md` (rewritten — comprehensive documentation)
+- `examples/simple.yaml` (new — minimal getting-started example)
+- `examples/netbird.yaml` (new — real-world Netbird bootstrapping)
+- `charts/restium/Chart.yaml` (new — Helm chart metadata)
+- `charts/restium/values.yaml` (new — default values)
+- `charts/restium/templates/job.yaml` (new — K8s Job template)
+- `charts/restium/templates/configmap.yaml` (new — spec ConfigMap)
+- `CHANGELOG.md` (modified — added documentation entries)
+
+### Code Review (AI) — 2026-03-15
+
+**Reviewer:** Claude Opus 4.6 (review by Sonnet, fixes by Opus)
+
+**Findings fixed:**
+- configmap.yaml: replaced `indent 4` with idiomatic Helm `nindent 4` pattern
+- job.yaml: made `envFrom` conditional on `secretName` being set (was causing Pod failures when no Secret exists)
+- values.yaml: defaulted `secretName` to empty string (opt-in instead of mandatory)
+- README: moved `--spec` from global Options to Subcommand options (it's a subcommand-level flag, not global)
+- README: added Example column to spec reference tables (AC3 requirement)
+- README: added "build from source" option in Quick Start (crate not yet published)
+
+**Findings noted (not fixed):**
+- AC1: no external doc links — README is self-contained; add links when separate docs site exists
+- Failure modes table could include per-field failure modes (e.g., unsupported `action` values, missing output fields)
diff --git a/_bmad-output/implementation-artifacts/sprint-status.yaml b/_bmad-output/implementation-artifacts/sprint-status.yaml
new file mode 100644
index 0000000..3cd5a08
--- /dev/null
+++ b/_bmad-output/implementation-artifacts/sprint-status.yaml
@@ -0,0 +1,78 @@
+# generated: 2026-03-14
+# last_updated: 2026-03-15
+# project: restium
+# project_key: NOKEY
+# tracking_system: file-system
+# story_location: {project-root}/_bmad-output/implementation-artifacts
+
+# STATUS DEFINITIONS:
+# ==================
+# Epic Status:
+#   - backlog: Epic not yet started
+#   - in-progress: Epic actively being worked on
+#   - done: All stories in epic completed
+#
+# Epic Status Transitions:
+#   - backlog → in-progress: Automatically when first story is created (via create-story)
+#   - in-progress → done: Manually when all stories reach 'done' status
+#
+# Story Status:
+#   - backlog: Story only exists in epic file
+#   - ready-for-dev: Story file created in stories folder
+#   - in-progress: Developer actively working on implementation
+#   - review: Ready for code review (via Dev's code-review workflow)
+#   - done: Story completed
+#
+# Retrospective Status:
+#   - optional: Can be completed but not required
+#   - done: Retrospective has been completed
+#
+# WORKFLOW NOTES:
+# ===============
+# - Epic transitions to 'in-progress' automatically when first story is created
+# - Stories can be worked in parallel if team capacity allows
+# - SM typically creates next story after previous one is 'done' to incorporate learnings
+# - Dev moves story to 'review', then runs code-review (fresh context, different LLM recommended)
+
+generated: 2026-03-14
+last_updated: 2026-03-15
+project: restium
+project_key: NOKEY
+tracking_system: file-system
+story_location: "{project-root}/_bmad-output/implementation-artifacts"
+
+development_status:
+  # Epic 1: Declarative Spec & CLI Foundation
+  epic-1: done
+  1-1-project-scaffold-cli-skeleton: done
+  1-2-structured-logging-with-secret-redaction: done
+  1-3-yaml-spec-parsing-global-settings: done
+  1-4-spec-validation-validate-command: done
+  epic-1-retrospective: optional
+
+  # Epic 2: Secure API Connectivity
+  epic-2: done
+  2-1-http-client-tls-configuration: done
+  2-2-bearer-token-basic-auth-providers: done
+  2-3-api-key-authentication: done
+  2-4-oidc-client-credentials-authentication: done
+  2-5-mtls-client-certificate-authentication: done
+  epic-2-retrospective: optional
+
+  # Epic 3: Resource Reconciliation
+  epic-3: done
+  3-1-dependency-graph-topological-sort: done
+  3-2-state-discovery-diff-computation: done
+  3-3-resource-create-update-operations: done
+  3-4-output-extraction-reference-resolution: done
+  3-5-explicit-resource-deletion: done
+  3-6-reconcile-command-orchestration: done
+  epic-3-retrospective: optional
+
+  # Epic 4: Production Deployment & Distribution
+  epic-4: done
+  4-1-sidecar-mode: done
+  4-2-distroless-docker-image-cross-compilation: done
+  4-3-ci-cd-pipeline: done
+  4-4-documentation-examples: done
+  epic-4-retrospective: optional
diff --git a/_bmad-output/planning-artifacts/architecture.md b/_bmad-output/planning-artifacts/architecture.md
new file mode 100644
index 0000000..026178c
--- /dev/null
+++ b/_bmad-output/planning-artifacts/architecture.md
@@ -0,0 +1,582 @@
+---
+stepsCompleted:
+  - 1
+  - 2
+  - 3
+  - 4
+  - 5
+  - 6
+  - 7
+  - 8
+status: 'complete'
+completedAt: '2026-03-14'
+inputDocuments:
+  - _bmad-output/planning-artifacts/prd.md
+workflowType: 'architecture'
+project_name: 'restium'
+user_name: 'Mikkel Damsgaard'
+date: '2026-03-14'
+---
+
+# Architecture Decision Document
+
+_This document builds collaboratively through step-by-step discovery. Sections are appended as we work through each architectural decision together._
+
+## Project Context Analysis
+
+### Requirements Overview
+
+**Functional Requirements:**
+38 FRs across 7 capability areas. The architectural core is a declarative reconciliation engine: parse YAML spec → build dependency graph → resolve topological order → discover actual state → compute diffs → execute minimum operations. Secondary concerns include pluggable authentication (5 strategies), TLS/mTLS support, structured logging with secret redaction, and distroless container packaging.
+
+**Non-Functional Requirements:**
+14 NFRs driving architecture decisions:
+- Zero-CVE container (static binary, scratch/distroless base)
+- Deterministic, idempotent reconciliation
+- Automated CI/CD with release-on-tag (Initium model)
+- Image size under 10MB
+- Secret values never in logs
+
+**Scale & Complexity:**
+
+- Primary domain: CLI / systems tooling (Rust)
+- Complexity level: Low-medium
+- Estimated architectural components: 6-8 (config parser, dependency graph, reconciliation engine, HTTP client, auth providers, CLI framework, logging, container build)
+
+### Technical Constraints & Dependencies
+
+- **Static binary required** — must compile to a standalone executable with no dynamic linking for scratch container support
+- **Initium CLI conventions** — subcommand architecture, `--spec` flag, `RESTIUM_*` env vars, `--json` / `--sidecar` flags
+- **Bootstrapping semantics** — not a full lifecycle manager. No automatic deletion of resources absent from spec. Explicit delete markers only.
+- **No persistent state in MVP** — reconciliation is stateless; desired state comes from spec, actual state discovered from API each run
+
+### Cross-Cutting Concerns Identified
+
+- **Secret redaction** — must be enforced at the logging layer, preventing any auth credential from appearing in output regardless of log level or error context
+- **Auth abstraction** — 5 auth strategies (bearer, basic, API key, OIDC, mTLS) need a unified interface that the HTTP client consumes without coupling to specific implementations
+- **Dependency ordering** — affects reconciliation execution, error reporting (which resource failed in what order), and reference resolution
+- **Error context propagation** — every error must carry resource name, HTTP method, endpoint, and status code through the entire call stack
+
+## Starter Template Evaluation
+
+### Primary Technology Domain
+
+Rust CLI tool for infrastructure automation, following Initium project conventions from the Kitstream organization.
+
+### Starter Options Considered
+
+**Option 1: Clone and modify Initium structure**
+Use Initium as the structural template — same Cargo.toml patterns, same build profile, same CI/CD pipeline, same container strategy. Strip out Initium-specific functionality (wait-for, seed, render, fetch) and replace with Restium's reconciliation engine.
+
+**Option 2: `cargo init` from scratch**
+Start with a bare `cargo init` and add dependencies manually. Simpler start but requires recreating CI/CD, Dockerfile, release pipeline, cross-compilation setup from scratch.
+
+**Option 3: Public Rust CLI template (`cargo-generate`)**
+Use a community template. Provides generic CLI scaffolding but won't include Kitstream-specific patterns (CI/CD, container build, release automation).
+
+### Selected Starter: Initium as structural template
+
+**Rationale for Selection:**
+Initium already embodies every convention Restium should follow: `clap` with derive + env, `ureq` + `rustls` for HTTP, `serde` for serialization, musl cross-compilation, scratch containers, optimized release profile, and Kitstream CI/CD patterns. Reusing this structure ensures consistency across the organization and eliminates setup decisions.
+
+**Initialization Approach:**
+```bash
+cargo init restium
+# Then align Cargo.toml, Dockerfile, CI/CD, and Makefile with Initium patterns
+```
+
+**Architectural Decisions Provided by Starter:**
+
+**Language & Runtime:**
+- Rust 2021 edition, minimum rust-version 1.88
+- Fully synchronous (no async runtime) — simpler code, smaller binary
+- Static linking via musl targets
+
+**CLI Framework:**
+- `clap` v4 with `derive` and `env` features
+- Derive macros for subcommand definitions
+- `env` feature for automatic `RESTIUM_*` environment variable support
+
+**HTTP Client:**
+- `ureq` v2 — synchronous HTTP client, minimal footprint
+- `rustls` v0.23 for TLS — no OpenSSL dependency, enables scratch containers
+- No default features on `ureq` to minimize binary size
+
+**Serialization:**
+- `serde` v1 with derive
+- `serde_yaml` v0.9 for spec parsing
+- `serde_json` v1 for API request/response bodies
+
+**Build Tooling:**
+- Release profile: `opt-level = "z"`, LTO, single codegen unit, stripped, panic=abort
+- Cross-compilation: `cargo-zigbuild` for `x86_64-unknown-linux-musl` + `aarch64-unknown-linux-musl`
+- `Makefile` for build orchestration
+
+**Container Strategy:**
+- Multi-stage Dockerfile
+- `FROM scratch` production image
+- Multi-arch (amd64 + arm64)
+- Target image size ~5MB
+
+**CI/CD:**
+- GitHub Actions workflows (following Initium release model)
+- Automated release on version tag
+
+**Note:** Project initialization using this approach should be the first implementation story.
+
+## Core Architectural Decisions
+
+### Decision Priority Analysis
+
+**Critical Decisions (Block Implementation):**
+- Error handling strategy: plain `Result<(), String>` (Initium pattern)
+- Logging: custom Logger with built-in redaction (Initium pattern)
+- Auth provider trait abstraction
+- Dependency graph: `petgraph` for topological sort
+- State comparison: custom unordered JSON comparison
+
+**Important Decisions (Shape Architecture):**
+- OIDC: minimal custom client_credentials implementation
+- YAML schema: generate JSON Schema artifact from serde types for external consumers
+
+**Deferred Decisions (Post-MVP):**
+- State persistence format (Phase 2)
+- Plugin system architecture (Phase 3)
+
+### Error Handling
+
+- **Decision:** Plain `Result<(), String>` with `.map_err()` for context chaining
+- **Rationale:** Follows Initium pattern exactly. Zero additional dependencies. Errors propagate as formatted strings with context. `main()` catches errors, logs via `Logger::error()`, and exits with code 1.
+- **Affects:** All modules — every function returns `Result<(), String>`
+
+### Logging
+
+- **Decision:** Custom `Logger` struct, ported from Initium's `logging.rs`
+- **Rationale:** Initium's logger already provides everything Restium needs: JSON/text modes, level filtering, key-value pairs, thread safety, and built-in secret redaction. Zero external dependencies.
+- **Key features:**
+  - `--json` flag toggles JSON structured output
+  - Key-value pairs on every log line (resource name, HTTP method, endpoint, status code)
+  - `SENSITIVE_KEYS` redaction list extended for Restium's auth patterns
+  - Writes to stderr (stdout reserved for future structured output)
+- **Affects:** All modules — Logger passed by reference throughout
+
+### Authentication & Security
+
+- **Decision:** `AuthProvider` trait with implementations for bearer, basic, API key, OIDC, mTLS
+- **Pattern:**
+  ```rust
+  trait AuthProvider {
+      fn apply(&self, request: ureq::Request) -> Result<ureq::Request, String>;
+  }
+  ```
+- **OIDC:** Minimal custom implementation of OAuth2 client_credentials grant — POST to token endpoint, parse access token from JSON response, no external OIDC crate
+- **mTLS:** Via `rustls` client certificate configuration
+- **Rationale:** Auth strategies are simple enough that a trait + 5 implementations keeps dependencies minimal. OIDC client_credentials is a single HTTP POST — no need for a full OAuth2 library.
+- **Affects:** HTTP client module, config parsing
+
+### Dependency Graph
+
+- **Decision:** `petgraph` crate for directed graph and topological sort
+- **Rationale:** Standard Rust graph library, well-maintained, provides `toposort()` out of the box with cycle detection. Avoids reimplementing graph algorithms.
+- **Affects:** Reconciliation engine, reference resolution
+
+### State Comparison
+
+- **Decision:** Custom unordered JSON value comparison
+- **Rationale:** API responses may return fields in different order than sent. Standard `serde_json::Value` equality is order-sensitive for objects but order-sensitive for arrays too. We need object-key-order-independent comparison while preserving array order sensitivity. Minimal custom implementation.
+- **Affects:** Reconciliation diff calculation
+
+### YAML Schema Artifact
+
+- **Decision:** Generate JSON Schema from serde types as a documentation artifact
+- **Rationale:** Not used for runtime validation (serde handles that), but published as a reference for users and AI agents building spec files. Can be generated at build time or as a CI artifact.
+- **Affects:** CI pipeline, documentation
+
+### Infrastructure & Deployment
+
+- **Decision:** Follow Initium patterns exactly
+- **CI/CD:** GitHub Actions, same workflow structure as Initium
+- **Container:** Multi-stage Dockerfile, `FROM scratch`, cargo-zigbuild for musl cross-compilation
+- **Release:** Automated on version tag — build, push GHCR, publish crates.io
+- **Rationale:** Proven patterns, organizational consistency
+- **Affects:** CI/CD configuration, Dockerfile, Makefile
+
+### Decision Impact Analysis
+
+**Implementation Sequence:**
+1. Project scaffold (Cargo.toml, Makefile, Dockerfile, CI from Initium)
+2. Logger (port from Initium, extend SENSITIVE_KEYS)
+3. Config parsing (serde YAML types, clap CLI)
+4. Auth providers (trait + implementations)
+5. HTTP client wrapper (ureq + auth + TLS)
+6. Dependency graph (petgraph, topological sort, cycle detection)
+7. Reconciliation engine (state discovery, diff, execute)
+8. Reference resolution (template substitution in payloads)
+
+**Cross-Component Dependencies:**
+- Logger is foundational — needed by all other components
+- Auth providers depend on config parsing (credentials from env vars)
+- HTTP client depends on auth providers and logger
+- Reconciliation engine depends on HTTP client, dependency graph, and reference resolution
+- Reference resolution depends on output extraction from HTTP responses
+
+## Implementation Patterns & Consistency Rules
+
+### Naming Patterns
+
+**YAML Spec Keys (User-Facing):**
+- `snake_case` for all spec keys: `base_url`, `depends_on`, `api_key`, `insecure_tls`
+- Resource names: `snake_case` identifiers: `netbird_network`, `access_policy_monitoring`
+- Reference syntax: `${resource_name.output.field_name}`
+
+**Rust Code:**
+- Standard Rust conventions enforced by `rustfmt` and `clippy`
+- `snake_case` for functions, variables, modules
+- `PascalCase` for types, traits, enums
+- `SCREAMING_SNAKE_CASE` for constants
+- No deviations — `cargo fmt` and `cargo clippy` are law
+
+**JSON API Interaction:**
+- Send/receive JSON as-is from target APIs — Restium doesn't impose naming on external APIs
+- Internal JSON comparison is key-order-independent
+
+**Log Key-Value Conventions:**
+Consistent keys across all log lines:
+
+| Key | Usage | Example |
+|-----|-------|---------|
+| `resource` | Resource name from spec | `netbird_network` |
+| `action` | Operation being performed | `create`, `update`, `delete`, `skip` |
+| `method` | HTTP method | `POST`, `GET`, `PUT`, `DELETE` |
+| `endpoint` | Full URL called | `https://api.netbird.io/api/networks` |
+| `status` | HTTP response status code | `201`, `403`, `500` |
+| `reason` | Human-readable context | `already exists`, `token expired` |
+
+### Structure Patterns
+
+**Module Organization (directory style, ready to grow):**
+```
+src/
+├── main.rs              # CLI parsing (clap), entry point
+├── logging/
+│   └── mod.rs           # Logger struct, redaction, levels
+├── config/
+│   ├── mod.rs           # Config types, YAML parsing
+│   └── validation.rs    # Schema validation, reference checking
+├── auth/
+│   ├── mod.rs           # AuthProvider trait, provider selection
+│   ├── bearer.rs
+│   ├── basic.rs
+│   ├── api_key.rs
+│   ├── oidc.rs
+│   └── mtls.rs
+├── http/
+│   └── mod.rs           # HTTP client wrapper, request building
+├── graph/
+│   └── mod.rs           # Dependency graph, topological sort, cycle detection
+├── reconcile/
+│   ├── mod.rs           # Reconciliation engine orchestration
+│   ├── state.rs         # State discovery (GET current state)
+│   ├── diff.rs          # Unordered JSON comparison
+│   └── execute.rs       # Operation execution (create/update/delete)
+└── reference/
+    └── mod.rs           # Template substitution, output extraction
+```
+
+**Test Organization:**
+- All tests in `tests/` directory — no inline `#[cfg(test)]` modules
+- Unit-style tests: `tests/config_test.rs`, `tests/graph_test.rs`, `tests/diff_test.rs`
+- Integration/e2e tests: `tests/e2e/` directory with mock HTTP server
+- Test helpers: `tests/common/mod.rs` for shared fixtures and utilities
+
+```
+tests/
+├── common/
+│   └── mod.rs           # Shared test utilities, mock server setup
+├── config_test.rs       # Config parsing and validation tests
+├── auth_test.rs         # Auth provider tests
+├── graph_test.rs        # Dependency graph and cycle detection tests
+├── diff_test.rs         # JSON comparison tests
+├── reference_test.rs    # Template substitution tests
+└── e2e/
+    ├── reconcile_test.rs  # Full reconciliation against mock API
+    └── cli_test.rs        # CLI argument parsing and exit code tests
+```
+
+### Error Message Patterns
+
+**Format:** `"Failed to {action} resource '{resource}': {status_code} {status_text} on {method} {endpoint} — {hint}"`
+
+**Examples:**
+- `"Failed to create resource 'netbird_network': 403 Forbidden on POST /api/networks — check authentication token permissions"`
+- `"Failed to read resource 'access_policy': 404 Not Found on GET /api/policies/abc123 — resource may not exist yet"`
+- `"Failed to resolve reference '${netbird_network.output.id}': resource 'netbird_network' has not been processed yet"`
+
+**Rules:**
+- Always include resource name, HTTP method, endpoint, and status code
+- End with an actionable hint after `—` dash
+- Never include raw response bodies in error messages (may contain secrets)
+- Config/parsing errors include file path and context: `"Invalid spec file 'config.yaml': unknown field 'bse_url' at line 5, did you mean 'base_url'?"`
+
+### Process Patterns
+
+**Function signatures:**
+- All fallible functions return `Result<T, String>`
+- Use `.map_err(|e| format!("context: {}", e))` for error wrapping
+- Logger is passed as `&Logger` parameter, not stored globally
+
+**Resource processing order:**
+1. Parse and validate spec
+2. Build dependency graph
+3. Topological sort (fail on cycles)
+4. For each resource in order: discover state → compute diff → execute action → extract outputs
+5. Log each action with consistent key-value pairs
+
+**Exit codes:**
+- `0` — all resources reconciled successfully
+- `1` — one or more resources failed
+- `2` — spec validation error (bad YAML, broken references, cycles)
+
+### Enforcement Guidelines
+
+**All AI Agents MUST:**
+- Run `cargo fmt` before committing
+- Run `cargo clippy -- -D warnings` with zero warnings
+- Place all tests in `tests/` directory, never inline
+- Use the log key-value conventions table for all log output
+- Follow the error message format pattern exactly
+- Use directory-style modules (`mod.rs`) for all new modules
+
+**Anti-Patterns (forbidden):**
+- `unwrap()` or `expect()` in non-test code — always propagate errors
+- `println!()` or `eprintln!()` — always use the Logger
+- Hardcoded URLs or credentials — always from config/env
+- `#[allow(clippy::...)]` without a comment explaining why
+
+## Project Structure & Boundaries
+
+### Complete Project Directory Structure
+
+```
+restium/
+├── .github/
+│   └── workflows/
+│       ├── ci.yml                # PR checks: fmt, clippy, test, e2e
+│       └── release.yml           # Tag-triggered: build, GHCR push, crates.io publish
+├── charts/
+│   └── restium/
+│       ├── Chart.yaml
+│       ├── values.yaml
+│       └── templates/
+│           ├── job.yaml          # K8s Job template
+│           └── configmap.yaml    # Spec file mount
+├── examples/
+│   ├── netbird.yaml              # Real-world Netbird bootstrapping example (README demo)
+│   ├── keycloak.yaml             # Keycloak realm/client setup example
+│   └── simple.yaml               # Minimal example for getting started
+├── src/
+│   ├── main.rs                   # CLI parsing (clap), entry point, sidecar loop
+│   ├── logging/
+│   │   └── mod.rs                # Logger struct, redaction, levels (ported from Initium)
+│   ├── config/
+│   │   ├── mod.rs                # Top-level Config, ResourceSpec, GlobalConfig types
+│   │   └── validation.rs         # Reference validation, dependency graph checks
+│   ├── auth/
+│   │   ├── mod.rs                # AuthProvider trait, provider factory
+│   │   ├── bearer.rs             # Bearer token auth
+│   │   ├── basic.rs              # Basic auth (username/password)
+│   │   ├── api_key.rs            # API key (header or query param)
+│   │   ├── oidc.rs               # Minimal OAuth2 client_credentials
+│   │   └── mtls.rs               # Mutual TLS client certificate
+│   ├── http/
+│   │   └── mod.rs                # ureq client wrapper, TLS config, request building
+│   ├── graph/
+│   │   └── mod.rs                # petgraph DAG, topological sort, cycle detection
+│   ├── reconcile/
+│   │   ├── mod.rs                # Reconciliation engine orchestration
+│   │   ├── state.rs              # State discovery (GET current state from API)
+│   │   ├── diff.rs               # Unordered JSON comparison
+│   │   └── execute.rs            # Operation execution (create/update/delete)
+│   └── reference/
+│       └── mod.rs                # ${resource.output.field} substitution, output extraction
+├── tests/
+│   ├── common/
+│   │   └── mod.rs                # Shared test utilities, mock HTTP server setup
+│   ├── config_test.rs            # YAML parsing, global config inheritance, validation errors
+│   ├── auth_test.rs              # Each auth provider, credential from env vars
+│   ├── graph_test.rs             # Topological sort, cycle detection, depends_on + implicit refs
+│   ├── diff_test.rs              # Unordered object comparison, array ordering, nested structures
+│   ├── reference_test.rs         # Template substitution, missing reference errors
+│   └── e2e/
+│       ├── reconcile_test.rs     # Full reconciliation against mock API server
+│       └── cli_test.rs           # CLI args, exit codes, --json output, --sidecar behavior
+├── Cargo.toml                    # Dependencies, features, release profile (aligned with Initium)
+├── Cargo.lock
+├── Makefile                      # Build orchestration: fmt, clippy, test, build, cross-compile
+├── Dockerfile                    # Multi-stage: builder + FROM scratch production image
+├── .gitignore
+├── LICENSE                       # Apache-2.0 (matching Initium)
+├── CHANGELOG.md
+└── README.md                     # Value prop, quick start, Netbird example, security posture
+```
+
+### Architectural Boundaries
+
+**Module Boundaries:**
+
+| Module | Responsibility | Depends On | Exposes |
+|--------|---------------|------------|---------|
+| `main` | CLI parsing, orchestration, exit codes | all modules | entry point |
+| `logging` | Structured logging, secret redaction | none | `Logger` struct |
+| `config` | YAML parsing, type definitions, validation | `logging` | `Config`, `ResourceSpec`, `GlobalConfig` |
+| `auth` | Authentication strategies | `logging`, `http` (ureq types) | `AuthProvider` trait + implementations |
+| `http` | HTTP client wrapper, TLS setup | `logging`, `auth` | `HttpClient` struct |
+| `graph` | Dependency DAG, topological sort | `config` (resource refs) | sorted execution order, cycle errors |
+| `reconcile` | State discovery, diffing, execution | `logging`, `http`, `graph`, `reference` | reconciliation results |
+| `reference` | Template substitution, output extraction | `config` | resolved payloads, extracted outputs |
+
+**Key boundary rules:**
+- `logging` has zero dependencies on other Restium modules — it's the foundation
+- `config` depends only on `logging` — it defines types that other modules consume
+- `auth` and `http` form a pair — auth providers are injected into the HTTP client
+- `reconcile` is the top-level orchestrator — it coordinates all other modules
+- No module reaches into another module's internals — communicate via public types
+
+### Requirements to Structure Mapping
+
+**FR Category → Module Mapping:**
+
+| FR Category | Primary Module | Supporting Modules |
+|-------------|---------------|-------------------|
+| Configuration & Parsing (FR1-FR6) | `config/` | `graph/` (validation) |
+| Authentication & TLS (FR7-FR14) | `auth/` | `http/` (TLS config) |
+| Reconciliation (FR15-FR22) | `reconcile/` | `http/`, `graph/`, `reference/` |
+| Output Extraction & References (FR23-FR25) | `reference/` | `config/` |
+| CLI Interface (FR26-FR30) | `main.rs` | `logging/` |
+| Error Handling & Observability (FR31-FR34) | `logging/` | all modules |
+| Packaging & Distribution (FR35-FR38) | `Dockerfile`, `Makefile`, `.github/` | — |
+
+### Data Flow
+
+```
+spec.yaml → config/ (parse) → graph/ (sort) → reconcile/ (orchestrate)
+                                                    │
+                                    ┌───────────────┼───────────────┐
+                                    ▼               ▼               ▼
+                               state.rs         diff.rs        execute.rs
+                            (GET actual)    (compare)      (POST/PUT/DELETE)
+                                    │               │               │
+                                    └───────┬───────┘               │
+                                            ▼                       ▼
+                                    reference/ (resolve refs)   http/ (send request)
+                                                                    │
+                                                                auth/ (apply credentials)
+```
+
+### Development Workflow
+
+**Local development:**
+```bash
+make fmt        # cargo fmt
+make lint       # cargo clippy -- -D warnings
+make test       # cargo test (runs tests/ directory)
+make build      # cargo build --release
+make cross      # cargo zigbuild for musl targets
+make docker     # docker build multi-arch
+```
+
+**CI pipeline (on PR):**
+`fmt check` → `clippy` → `unit tests` → `e2e tests` → pass/fail
+
+**Release pipeline (on tag):**
+`cross-compile` → `docker build` → `push GHCR` → `publish crates.io`
+
+## Architecture Validation Results
+
+### Coherence Validation ✅
+
+**Decision Compatibility:** All technology choices (clap, ureq, rustls, serde, petgraph) are compatible, support static musl linking, and have no version conflicts. Synchronous runtime eliminates async complexity.
+
+**Pattern Consistency:** snake_case naming throughout, directory-style modules, Result<T, String> error handling, and Logger dependency injection are consistent across all components.
+
+**Structure Alignment:** Module dependency graph is acyclic. Every module maps to one FR category. Test structure mirrors source structure.
+
+### Requirements Coverage ✅
+
+**Functional Requirements:** All 38 FRs mapped to specific modules with no gaps.
+
+**Non-Functional Requirements:** All 14 NFRs addressed by architectural decisions (scratch container, secret redaction, CI pipelines, release automation, deterministic reconciliation).
+
+### Implementation Readiness ✅
+
+**Decision Completeness:** All critical decisions documented with specific crate versions. Initium source code reviewed for error handling and logging patterns.
+
+**Structure Completeness:** Full project tree defined with every file and directory. Module boundaries and dependency graph documented.
+
+**Pattern Completeness:** Naming, structure, error, logging, and process patterns all specified with concrete examples and anti-patterns.
+
+### Gap Analysis Results
+
+**Investigation Items (non-blocking):**
+- Verify `ureq` v2 + `rustls` supports mTLS client certificate presentation. Fallback: configure `rustls::ClientConfig` directly with client cert/key and pass to `ureq::AgentBuilder`.
+
+**No critical or important gaps found.**
+
+### Architecture Completeness Checklist
+
+**✅ Requirements Analysis**
+- [x] Project context thoroughly analyzed
+- [x] Scale and complexity assessed
+- [x] Technical constraints identified
+- [x] Cross-cutting concerns mapped
+
+**✅ Architectural Decisions**
+- [x] Critical decisions documented with versions
+- [x] Technology stack fully specified
+- [x] Integration patterns defined
+- [x] Error handling and logging patterns established
+
+**✅ Implementation Patterns**
+- [x] Naming conventions established
+- [x] Structure patterns defined
+- [x] Error message format specified
+- [x] Process patterns documented
+- [x] Anti-patterns listed
+
+**✅ Project Structure**
+- [x] Complete directory structure defined
+- [x] Component boundaries established
+- [x] FR-to-module mapping complete
+- [x] Data flow documented
+
+### Architecture Readiness Assessment
+
+**Overall Status:** READY FOR IMPLEMENTATION
+
+**Confidence Level:** High
+
+**Key Strengths:**
+- Tight alignment with proven Initium patterns — reduces risk and setup decisions
+- Minimal dependency footprint — fewer things to break
+- Clear module boundaries with acyclic dependency graph
+- Every FR traceable to a specific module
+
+**Areas for Future Enhancement:**
+- Plugin architecture (Phase 3) — not needed yet, but module boundaries support future extraction
+- State persistence (Phase 2) — will likely add a `state/` module when needed
+- mTLS implementation details — needs investigation during auth module development
+
+### Implementation Handoff
+
+**AI Agent Guidelines:**
+- Follow all architectural decisions exactly as documented
+- Use implementation patterns consistently across all components
+- Respect project structure and module boundaries
+- Refer to this document for all architectural questions
+- Port Initium's `logging.rs` as the first module after project scaffold
+
+**First Implementation Priority:**
+1. `cargo init restium` — scaffold with Initium-aligned Cargo.toml
+2. Port `logging/mod.rs` from Initium
+3. Define `config/` types with serde
+4. Build outward from there following the implementation sequence in Core Architectural Decisions
diff --git a/_bmad-output/planning-artifacts/epics.md b/_bmad-output/planning-artifacts/epics.md
index cb9cf67..67eb573 100644
--- a/_bmad-output/planning-artifacts/epics.md
+++ b/_bmad-output/planning-artifacts/epics.md
@@ -1,42 +1,92 @@
 ---
-stepsCompleted: []
-inputDocuments: []
+stepsCompleted:
+  - step-01-validate-prerequisites
+  - step-02-design-epics
+  - step-03-create-stories
+  - step-04-final-validation
+inputDocuments:
+  - _bmad-output/planning-artifacts/prd.md
+  - _bmad-output/planning-artifacts/architecture.md
 ---
 
 # Restium - Epic Breakdown
 
 ## Overview
 
-This document provides the complete epic and story breakdown for Restium, a declarative reconciling REST client implemented in Rust. Restium manages CRUD objects against REST APIs using YAML-based declarative configuration, supporting dependency graphs, parameterized references, and configurable output format extraction.
+This document provides the complete epic and story breakdown for Restium, decomposing the requirements from the PRD and Architecture into implementable stories.
 
 ## Requirements Inventory
 
 ### Functional Requirements
 
-- FR-1: Declarative YAML configuration for REST resources
-- FR-2: CRUD operations (Create, Read, Update, Delete) against REST APIs
-- FR-3: Reconciliation engine that converges actual state to desired state
-- FR-4: Dependency graph between resources (implicit via references, explicit via depends_on)
-- FR-5: Parameterized references allowing resource A to refer to outputs of resource B
-- FR-6: Structured YAML payloads for REST request bodies
-- FR-7: Configurable output format snippets to extract IDs/primary keys from responses
-- FR-8: JSON/YAML payload support only (no XML, form-data, etc.)
-- FR-9: Authentication support for REST APIs (bearer token, basic auth, API key)
-- FR-10: Ordered execution based on dependency resolution (topological sort)
+- FR1: User can define REST resources declaratively in a single YAML spec file
+- FR2: User can specify resource endpoints, HTTP methods, and structured YAML payloads per resource
+- FR3: User can define global settings (base URL, default headers) that apply to all resources unless overridden
+- FR4: User can define parameterized references between resources using `${resource_name.output.field}` syntax
+- FR5: User can define explicit ordering constraints between resources via `depends_on`
+- FR6: System validates spec file schema, references, and dependency graph on load and reports all errors with context
+- FR7: User can configure bearer token authentication for API endpoints
+- FR8: User can configure basic auth (username/password) for API endpoints
+- FR9: User can configure API key authentication for API endpoints
+- FR10: User can supply authentication credentials via environment variables, never in spec files
+- FR11: User can configure OIDC/OAuth2 client credentials authentication for API endpoints
+- FR12: User can configure mutual TLS (mTLS) authentication with client certificates for API endpoints
+- FR13: System verifies TLS certificates by default and requires explicit `--insecure-tls` opt-in to skip verification
+- FR14: User can specify a custom CA bundle for connecting to APIs with internal/self-signed certificates
+- FR15: System can discover current state of resources via GET requests to configured read endpoints
+- FR16: System can compute diff between desired state (spec) and actual state (API) per resource
+- FR17: System can create resources that exist in spec but not in the API
+- FR18: System can update resources where desired state differs from actual state
+- FR19: User can mark specific resources for explicit deletion to clean up previously auto-created objects
+- FR20: System executes operations in topological order based on the dependency graph
+- FR21: System skips resources where desired state already matches actual state (idempotent)
+- FR22: System detects circular dependencies and reports the cycle path
+- FR23: User can configure output extraction rules to capture fields (IDs, keys) from API responses
+- FR24: System resolves parameterized references to actual values at execution time using extracted outputs
+- FR25: System reports clear errors when a referenced resource or output field cannot be resolved
+- FR26: User can run `restium reconcile --spec <path>` to converge API state to match the spec
+- FR27: User can run `restium validate --spec <path>` to check spec validity without making API calls
+- FR28: User can enable structured JSON log output via `--json` flag
+- FR29: User can run in sidecar mode via `--sidecar` flag to keep the process alive after completion
+- FR30: User can configure all flags via `RESTIUM_*` environment variables
+- FR31: System provides actionable error messages that include: resource name, HTTP method, endpoint, status code, and a hint at the cause
+- FR32: System logs all operations (create, update, delete, skip) with resource identifiers in structured JSON format
+- FR33: System exits with meaningful exit codes to signal success or failure to K8s Job controllers
+- FR34: System never logs or echoes secret values (tokens, passwords, API keys)
+- FR35: System ships as a static binary with no runtime dependencies
+- FR36: System is distributed as a distroless/scratch Docker image for linux/amd64 and linux/arm64
+- FR37: System is published to crates.io for installation via `cargo install`
+- FR38: System is published to GHCR as a container image
 
 ### NonFunctional Requirements
 
-- NFR-1: Super tiny Docker container (FROM scratch or distroless)
-- NFR-2: Cross-platform Docker image builds (linux/amd64, linux/arm64)
-- NFR-3: Publish to crates.io
-- NFR-4: CI/CD pipeline with lint, test, build, release
-- NFR-5: Deterministic reconciliation (same input always produces same plan)
-- NFR-6: Clear error messages with context on failures
-- NFR-7: Idempotent operations where possible
+- NFR1: Container image has zero CVEs — no OS packages, no shell, no package manager
+- NFR2: Secrets (tokens, passwords, API keys) never appear in log output under any verbosity level
+- NFR3: All security-sensitive features require explicit opt-in via flags or configuration
+- NFR4: All PRs must pass: unit tests, e2e tests, `cargo fmt` check, `cargo clippy` lints — merge is blocked on failure
+- NFR5: Release process is fully automated — tagging a version triggers build, container image push to GHCR, and crates.io publish
+- NFR6: CI pipeline runs on every PR and every push to main
+- NFR7: Cross-platform container images (linux/amd64, linux/arm64) built automatically on release
+- NFR8: Documentation has clearly defined audience segments: platform engineers, SecOps, contributors
+- NFR9: README enables time-to-first-use under 5 minutes with a copy-paste real-world example
+- NFR10: All spec file options are documented with examples and failure modes
+- NFR11: Documentation is visually appealing — clear structure, code examples, and diagrams where they add value
+- NFR12: Reconciliation is deterministic — same spec + same API state always produces same operations
+- NFR13: Operations are idempotent — running reconciliation twice with unchanged spec produces no unnecessary API calls
+- NFR14: Container image size under 10MB
 
 ### Additional Requirements
 
-- None at this stage
+- Starter template: Use Initium as structural template — same Cargo.toml patterns, build profile, CI/CD pipeline, container strategy. First implementation story.
+- Synchronous runtime only (no async) — ureq v2 for HTTP, rustls v0.23 for TLS
+- petgraph crate for directed dependency graph and topological sort
+- Custom Logger struct ported from Initium's logging.rs with built-in secret redaction and JSON/text modes
+- Plain `Result<(), String>` error handling with `.map_err()` context chaining (Initium pattern)
+- All tests in `tests/` directory — no inline `#[cfg(test)]` modules
+- Directory-style modules (`mod.rs`) for all new modules
+- Helm chart for K8s Job deployment (charts/restium/)
+- Release profile: opt-level="z", LTO, single codegen unit, stripped, panic=abort
+- Cross-compilation via cargo-zigbuild for x86_64-unknown-linux-musl and aarch64-unknown-linux-musl
 
 ### UX Design Requirements
 
@@ -44,388 +94,607 @@ This document provides the complete epic and story breakdown for Restium, a decl
 
 ### FR Coverage Map
 
-| Requirement | Epic |
-|---|---|
-| FR-1 | Epic 1: YAML Configuration & Parsing |
-| FR-2 | Epic 2: REST Client Engine |
-| FR-3 | Epic 4: Reconciliation Engine |
-| FR-4, FR-5 | Epic 3: Dependency Graph & References |
-| FR-6 | Epic 1: YAML Configuration & Parsing |
-| FR-7 | Epic 2: REST Client Engine |
-| FR-8 | Epic 2: REST Client Engine |
-| FR-9 | Epic 2: REST Client Engine |
-| FR-10 | Epic 3: Dependency Graph & References |
-| NFR-1, NFR-2, NFR-3, NFR-4 | Epic 5: Packaging & CI/CD |
+| FR | Epic | Description |
+|---|---|---|
+| FR1 | Epic 1 | Declarative YAML spec file |
+| FR2 | Epic 1 | Resource endpoints, methods, payloads |
+| FR3 | Epic 1 | Global settings inheritance |
+| FR4 | Epic 3 | Parameterized references (`${resource.output.field}`) |
+| FR5 | Epic 1 | Explicit `depends_on` ordering |
+| FR6 | Epic 1 | Schema/reference/graph validation on load |
+| FR7 | Epic 2 | Bearer token auth |
+| FR8 | Epic 2 | Basic auth |
+| FR9 | Epic 2 | API key auth |
+| FR10 | Epic 2 | Credentials via env vars |
+| FR11 | Epic 2 | OIDC client credentials |
+| FR12 | Epic 2 | mTLS with client certificates |
+| FR13 | Epic 2 | TLS verification default + `--insecure-tls` |
+| FR14 | Epic 2 | Custom CA bundle |
+| FR15 | Epic 3 | State discovery via GET |
+| FR16 | Epic 3 | Diff computation |
+| FR17 | Epic 3 | Create missing resources |
+| FR18 | Epic 3 | Update changed resources |
+| FR19 | Epic 3 | Explicit deletion |
+| FR20 | Epic 3 | Topological execution order |
+| FR21 | Epic 3 | Idempotent skip |
+| FR22 | Epic 3 | Cycle detection |
+| FR23 | Epic 3 | Output extraction rules |
+| FR24 | Epic 3 | Reference resolution at execution |
+| FR25 | Epic 3 | Clear errors on unresolvable refs |
+| FR26 | Epic 3 | `reconcile` subcommand |
+| FR27 | Epic 1 | `validate` subcommand |
+| FR28 | Epic 1 | `--json` structured logging |
+| FR29 | Epic 4 | `--sidecar` mode |
+| FR30 | Epic 1 | `RESTIUM_*` env var support |
+| FR31 | Epic 3 | Actionable error messages |
+| FR32 | Epic 3 | Structured operation logging |
+| FR33 | Epic 1 | Meaningful exit codes |
+| FR34 | Epic 3 | Secret value redaction |
+| FR35 | Epic 1 | Static binary |
+| FR36 | Epic 4 | Distroless Docker image |
+| FR37 | Epic 4 | crates.io publish |
+| FR38 | Epic 4 | GHCR publish |
 
 ## Epic List
 
-1. Epic 1: YAML Configuration & Parsing
-2. Epic 2: REST Client Engine
-3. Epic 3: Dependency Graph & References
-4. Epic 4: Reconciliation Engine
-5. Epic 5: CLI & User Experience
-6. Epic 6: Packaging, CI/CD & Release
+### Epic 1: Declarative Spec & CLI Foundation
+Users can write declarative YAML resource specs and validate them offline with `restium validate --spec <path>`. A working binary with structured JSON logging and environment variable configuration.
+**FRs covered:** FR1, FR2, FR3, FR5, FR6, FR27, FR28, FR30, FR33, FR35
 
-## Epic 1: YAML Configuration & Parsing
+### Epic 2: Secure API Connectivity
+Users can configure authentication (bearer, basic, API key, OIDC, mTLS) and TLS settings to connect to any REST API securely. Credentials come from environment variables, never spec files.
+**FRs covered:** FR7, FR8, FR9, FR10, FR11, FR12, FR13, FR14
 
-Define and implement the declarative YAML configuration schema that describes REST resources, their endpoints, payloads, and relationships.
+### Epic 3: Resource Reconciliation
+Users can run `restium reconcile --spec <path>` to converge API state to match their spec. Resources are created, updated, or explicitly deleted in dependency order. Outputs from one resource feed into dependent resources. Unchanged resources are skipped. Errors are actionable and secrets never leak.
+**FRs covered:** FR4, FR15, FR16, FR17, FR18, FR19, FR20, FR21, FR22, FR23, FR24, FR25, FR26, FR31, FR32, FR34
 
-### Story 1.1: Define YAML Configuration Schema
+### Epic 4: Production Deployment & Distribution
+Users can deploy Restium as K8s Jobs or sidecars via distroless containers from GHCR, or install via `cargo install` from crates.io. CI/CD automates the full release pipeline.
+**FRs covered:** FR29, FR36, FR37, FR38
 
-As a user,
-I want a well-defined YAML schema for declaring REST resources,
-So that I can declaratively describe the desired state of my REST API objects.
+## Epic 1: Declarative Spec & CLI Foundation
+
+Users can write declarative YAML resource specs and validate them offline with `restium validate --spec <path>`. A working binary with structured JSON logging and environment variable configuration.
+
+### Story 1.1: Project Scaffold & CLI Skeleton
+
+As a platform engineer,
+I want a working `restium` binary with `reconcile` and `validate` subcommands,
+So that I have a functional CLI entry point with proper flags and exit codes.
 
 **Acceptance Criteria:**
 
-**Given** a YAML configuration file
-**When** it contains resource definitions with name, endpoint, method, and payload
-**Then** the parser validates and loads the configuration into typed Rust structs
+**Given** the Restium binary is built
+**When** the user runs `restium --help`
+**Then** it displays available subcommands (`reconcile`, `validate`) and global flags (`--json`, `--spec`, `--sidecar`, `--insecure-tls`)
+
+**Given** the user runs `restium reconcile --spec <path>` or `restium validate --spec <path>`
+**When** the spec file does not exist
+**Then** the process exits with code 2 and an error message indicating the file was not found
+
+**Given** any global flag (e.g. `--json`)
+**When** the equivalent `RESTIUM_*` environment variable is set (e.g. `RESTIUM_JSON=true`)
+**Then** the flag value is picked up from the environment variable
 
-**Given** a YAML configuration file with syntax errors
-**When** it is parsed
-**Then** a clear error message with line number and context is returned
+**Given** the project scaffold
+**When** built with `cargo build --release`
+**Then** it produces a statically-linkable binary following the Initium Cargo.toml patterns (opt-level="z", LTO, panic=abort)
 
-### Story 1.2: Structured YAML Payloads
+**Covers:** FR28, FR30, FR33, FR35, Additional (Initium template, clap CLI)
 
-As a user,
-I want to specify REST payloads as structured YAML within the configuration,
-So that I can define request bodies declaratively without writing raw JSON.
+### Story 1.2: Structured Logging with Secret Redaction
+
+As a platform engineer,
+I want structured JSON logging with automatic secret redaction,
+So that I can safely aggregate logs in K8s without leaking credentials.
 
 **Acceptance Criteria:**
 
-**Given** a resource with a YAML-structured payload
-**When** the resource is processed
-**Then** the payload is serialized to JSON for the REST request
+**Given** the `--json` flag is set
+**When** any log message is emitted
+**Then** it is written to stderr as a structured JSON object with level, message, and key-value pairs
+
+**Given** the `--json` flag is not set
+**When** any log message is emitted
+**Then** it is written to stderr in human-readable text format
+
+**Given** a log message that includes a key-value pair where the key matches a sensitive pattern (e.g., `authorization`, `token`, `password`, `api_key`, `client_secret`)
+**When** the message is rendered
+**Then** the value is replaced with `[REDACTED]`
 
-**Given** a payload with nested objects and arrays
-**When** serialized
-**Then** the JSON output preserves the structure faithfully
+**Given** an error containing a URL with a query parameter that includes a secret
+**When** logged
+**Then** the secret portion is redacted
 
-### Story 1.3: Global Configuration
+**Covers:** FR28, FR34, NFR2
 
-As a user,
-I want to define global settings (base URL, authentication, headers),
-So that I don't repeat common configuration across resources.
+### Story 1.3: YAML Spec Parsing & Global Settings
+
+As a platform engineer,
+I want to define REST resources and global settings in a YAML spec file,
+So that my infrastructure configuration is declarative and readable.
 
 **Acceptance Criteria:**
 
-**Given** a YAML file with a global section defining base_url and headers
-**When** resources are processed
-**Then** they inherit global settings unless overridden per-resource
+**Given** a YAML spec file with a `global` section defining `base_url` and `default_headers`
+**When** parsed
+**Then** global settings are loaded and available for resource processing
+
+**Given** a YAML spec file with resource definitions containing `name`, `endpoint`, `method`, and `payload`
+**When** parsed
+**Then** each resource is loaded into typed Rust structs with all fields accessible
 
-### Story 1.4: Multi-file Configuration
+**Given** a resource that does not specify `base_url` or headers
+**When** processed
+**Then** it inherits the global settings
 
-As a user,
-I want to split configuration across multiple YAML files,
-So that I can organize large configurations by domain or team.
+**Given** a resource that specifies its own `base_url` or headers
+**When** processed
+**Then** the per-resource values override the global settings
+
+**Given** a YAML spec file with `depends_on` fields on resources
+**When** parsed
+**Then** the explicit dependency relationships are captured in the resource definitions
+
+**Given** a YAML spec file with a structured payload containing nested objects and arrays
+**When** parsed and serialized to JSON
+**Then** the structure is preserved faithfully
+
+**Given** a YAML file with syntax errors or unknown fields
+**When** parsed
+**Then** a clear error message with context (line number or field name) is returned and the process exits with code 2
+
+**Covers:** FR1, FR2, FR3, FR5, FR6 (partially)
+
+### Story 1.4: Spec Validation & Validate Command
+
+As a platform engineer,
+I want to run `restium validate --spec <path>` to check my spec file without making API calls,
+So that I can catch errors in CI or locally before deploying.
 
 **Acceptance Criteria:**
 
-**Given** a directory of YAML files or a glob pattern
-**When** restium loads configuration
-**Then** all files are merged into a unified resource set
+**Given** a valid spec file with correct schema, valid references, and no circular dependencies
+**When** the user runs `restium validate --spec <path>`
+**Then** the process exits with code 0 and logs a success message
+
+**Given** a spec file with a reference `${resource_b.output.id}` where `resource_b` does not exist
+**When** validated
+**Then** the error message identifies the broken reference and the resource containing it, and exits with code 2
+
+**Given** a spec file where resources form a circular dependency (A → B → C → A)
+**When** validated
+**Then** the error message lists the cycle path and exits with code 2
+
+**Given** a spec file with multiple validation errors (broken references and invalid fields)
+**When** validated
+**Then** all errors are reported (not just the first one)
+
+**Given** the `--json` flag is set
+**When** validation errors are reported
+**Then** errors are output in structured JSON format
 
-## Epic 2: REST Client Engine
+**Covers:** FR6, FR27
 
-Implement the HTTP client layer that performs CRUD operations against REST APIs with JSON/YAML payloads.
+## Epic 2: Secure API Connectivity
 
-### Story 2.1: HTTP Client with JSON Payloads
+Users can configure authentication (bearer, basic, API key, OIDC, mTLS) and TLS settings to connect to any REST API securely. Credentials come from environment variables, never spec files.
 
-As a user,
-I want restium to make HTTP requests with JSON payloads,
-So that it can interact with standard REST APIs.
+### Story 2.1: HTTP Client & TLS Configuration
+
+As a platform engineer,
+I want Restium to make HTTPS requests with TLS verification by default and support custom CA bundles,
+So that I can connect securely to APIs with internal or self-signed certificates.
 
 **Acceptance Criteria:**
 
-**Given** a resource with a POST/PUT/PATCH method and payload
-**When** the operation is executed
-**Then** the payload is sent as application/json with correct HTTP method
+**Given** no TLS flags are set
+**When** Restium makes an HTTPS request
+**Then** TLS certificates are verified against the system CA bundle
 
-**Given** a resource with a GET method
-**When** the operation is executed
-**Then** the response body is parsed as JSON
+**Given** the `--insecure-tls` flag is set
+**When** Restium makes an HTTPS request
+**Then** TLS certificate verification is skipped
+
+**Given** a custom CA bundle path is configured in the spec file
+**When** Restium makes an HTTPS request
+**Then** the custom CA bundle is used for certificate verification
+
+**Given** a custom CA bundle path that does not exist
+**When** Restium attempts to load it
+**Then** an actionable error message is returned and the process exits with code 2
 
-### Story 2.2: Authentication Support
+**Given** the HTTP client wrapper
+**When** an `AuthProvider` is configured for the request
+**Then** the provider's `apply()` method is called to attach credentials before sending
 
-As a user,
-I want to configure authentication for API endpoints,
-So that restium can manage resources on protected APIs.
+**Covers:** FR13, FR14, NFR3
+
+### Story 2.2: Bearer Token & Basic Auth Providers
+
+As a platform engineer,
+I want to configure bearer token or basic auth for API endpoints via environment variables,
+So that I can authenticate against protected APIs without putting credentials in spec files.
 
 **Acceptance Criteria:**
 
-**Given** global or per-resource auth configuration (bearer, basic, api-key)
+**Given** a resource or global auth config specifying `type: bearer` with `token_env: NETBIRD_TOKEN`
 **When** a request is made
-**Then** the correct authentication header is included
+**Then** the `Authorization: Bearer <value>` header is set using the value from the `NETBIRD_TOKEN` environment variable
+
+**Given** a resource or global auth config specifying `type: basic` with `username_env` and `password_env`
+**When** a request is made
+**Then** the `Authorization: Basic <base64>` header is set using credentials from the specified environment variables
+
+**Given** an auth config referencing an environment variable that is not set
+**When** the auth provider is initialized
+**Then** an actionable error message identifies the missing variable and the process exits with code 2
 
-### Story 2.3: Output Format Extraction
+**Given** any auth credential value
+**When** logged (via error messages or debug output)
+**Then** the value is redacted by the Logger
 
-As a user,
-I want to configure output snippets that extract IDs and primary keys from API responses,
-So that dependent resources can reference them.
+**Covers:** FR7, FR8, FR10
+
+### Story 2.3: API Key Authentication
+
+As a platform engineer,
+I want to configure API key authentication sent as a header or query parameter,
+So that I can connect to APIs that use API key schemes.
 
 **Acceptance Criteria:**
 
-**Given** an output configuration with a JSONPath or field-path expression
-**When** a resource is created/read
-**Then** the specified fields are extracted and stored as outputs
+**Given** an auth config specifying `type: api_key` with `header_name` and `key_env`
+**When** a request is made
+**Then** the specified header is set with the key value from the environment variable
+
+**Given** an auth config specifying `type: api_key` with `query_param` and `key_env`
+**When** a request is made
+**Then** the key is appended as a query parameter
+
+**Given** an API key value
+**When** it appears in any log output
+**Then** it is redacted
 
-**Given** an output extraction that fails (field missing)
-**When** the operation completes
-**Then** a clear error indicates which output field could not be extracted
+**Covers:** FR9, FR10
 
-### Story 2.4: Error Handling & Retries
+### Story 2.4: OIDC Client Credentials Authentication
 
-As a user,
-I want sensible error handling and optional retries,
-So that transient failures don't break the reconciliation.
+As a platform engineer,
+I want to configure OIDC/OAuth2 client credentials authentication,
+So that I can connect to APIs protected by OAuth2 token endpoints.
 
 **Acceptance Criteria:**
 
-**Given** a request that returns a 5xx error
-**When** retries are configured
-**Then** the request is retried with backoff up to the configured limit
+**Given** an auth config specifying `type: oidc` with `token_url`, `client_id_env`, and `client_secret_env`
+**When** a request is made
+**Then** Restium performs a POST to the token endpoint with `grant_type=client_credentials`, extracts the `access_token` from the JSON response, and sets `Authorization: Bearer <access_token>`
+
+**Given** the token endpoint returns an error (e.g., 401 invalid credentials)
+**When** the token request fails
+**Then** an actionable error message includes the token URL and status code
 
-## Epic 3: Dependency Graph & References
+**Given** the client secret environment variable
+**When** the token request is logged
+**Then** the client secret is redacted in all log output
 
-Implement the dependency resolution system that ensures resources are created/updated/deleted in the correct order, with parameterized references between resources.
+**Given** a valid OIDC config with optional `scope` field
+**When** scope is specified
+**Then** it is included in the token request body
 
-### Story 3.1: Implicit Dependencies via References
+**Covers:** FR11, FR10
 
-As a user,
-I want to use references like `${resource_b.output.id}` in resource A's payload,
-So that resource A automatically depends on resource B.
+### Story 2.5: mTLS Client Certificate Authentication
+
+As a platform engineer,
+I want to configure mutual TLS with client certificates,
+So that I can connect to APIs that require certificate-based authentication.
 
 **Acceptance Criteria:**
 
-**Given** a resource A with a reference to resource B's output
-**When** the dependency graph is built
-**Then** A depends on B and B is processed before A
+**Given** an auth config specifying `type: mtls` with `client_cert_path` and `client_key_path`
+**When** a TLS connection is established
+**Then** the client certificate and key are presented to the server during the TLS handshake
+
+**Given** a client certificate or key file that does not exist or is malformed
+**When** Restium attempts to load it
+**Then** an actionable error message identifies the problematic file and the process exits with code 2
+
+**Given** mTLS combined with a custom CA bundle
+**When** a connection is established
+**Then** both the client certificate and the custom CA are used
+
+**Covers:** FR12
+
+## Epic 3: Resource Reconciliation
 
-**Given** a reference to a non-existent resource
-**When** the configuration is loaded
-**Then** a clear error identifies the broken reference
+Users can run `restium reconcile --spec <path>` to converge API state to match their spec. Resources are created, updated, or explicitly deleted in dependency order. Outputs from one resource feed into dependent resources. Unchanged resources are skipped. Errors are actionable and secrets never leak.
 
-### Story 3.2: Explicit Dependencies
+### Story 3.1: Dependency Graph & Topological Sort
 
-As a user,
-I want to declare explicit `depends_on` relationships,
-So that I can express ordering constraints not captured by references.
+As a platform engineer,
+I want resources to be processed in dependency order with cycle detection,
+So that dependent resources always have their prerequisites satisfied before execution.
 
 **Acceptance Criteria:**
 
-**Given** a resource with `depends_on: [resource_c]`
+**Given** a spec with resources A, B, C where B `depends_on: [A]` and C `depends_on: [B]`
+**When** the dependency graph is built and sorted
+**Then** the execution order is A → B → C
+
+**Given** a spec with implicit dependencies via references (e.g., resource A's payload contains `${resource_b.output.id}`)
 **When** the dependency graph is built
-**Then** resource_c is processed before this resource
+**Then** A depends on B and B is processed before A
 
-### Story 3.3: Dependency Graph Validation
+**Given** a spec where resources form a cycle (A → B → C → A)
+**When** the graph is sorted
+**Then** an error message lists the cycle path and the process exits with code 2
 
-As a user,
-I want the tool to detect circular dependencies,
-So that I get a clear error instead of an infinite loop.
+**Given** a spec with both explicit `depends_on` and implicit reference dependencies
+**When** the graph is built
+**Then** both dependency types are merged into a single DAG
 
-**Acceptance Criteria:**
+**Given** a spec with independent resources (no dependencies between them)
+**When** the graph is sorted
+**Then** a valid topological order is produced (any order is acceptable)
 
-**Given** resources A -> B -> C -> A (circular)
-**When** the graph is validated
-**Then** an error lists the cycle path
+**Covers:** FR5, FR20, FR22
 
-### Story 3.4: Topological Execution Order
+### Story 3.2: State Discovery & Diff Computation
 
-As a user,
-I want resources to be processed in topological order,
-So that dependencies are always satisfied before dependent resources.
+As a platform engineer,
+I want Restium to discover the current API state and compute what needs to change,
+So that only necessary operations are performed.
 
 **Acceptance Criteria:**
 
-**Given** a valid DAG of resources
-**When** reconciliation runs
-**Then** resources are processed in a valid topological order
+**Given** a resource with a configured read endpoint (GET URL)
+**When** reconciliation starts for that resource
+**Then** the current state is fetched via GET and stored for comparison
 
-### Story 3.5: Reference Resolution
+**Given** a resource where the GET returns 404
+**When** the state is discovered
+**Then** the resource is marked as not existing (needs creation)
 
-As a user,
-I want references in payloads to be resolved to actual values at execution time,
-So that dynamically assigned IDs can be used in dependent resources.
+**Given** a desired state that matches the actual state (key-order-independent JSON comparison)
+**When** the diff is computed
+**Then** the resource is marked as "skip" and no mutation is performed
 
-**Acceptance Criteria:**
+**Given** a desired state that differs from the actual state
+**When** the diff is computed
+**Then** the resource is marked as "update"
 
-**Given** resource B was created and produced output `id: 42`
-**When** resource A's payload contains `${resource_b.output.id}`
-**Then** the reference is resolved to `42` in the actual request payload
+**Given** JSON objects with keys in different order but same values
+**When** compared
+**Then** they are considered equal
 
-## Epic 4: Reconciliation Engine
+**Given** JSON arrays with the same elements in different order
+**When** compared
+**Then** they are considered different (array order is significant)
 
-Implement the core reconciliation loop that compares desired state to actual state and performs the minimum set of operations to converge.
+**Covers:** FR15, FR16, FR21, NFR12, NFR13
 
-### Story 4.1: State Discovery (Read Current State)
+### Story 3.3: Resource Create & Update Operations
 
-As a user,
-I want restium to discover the current state of resources via GET requests,
-So that it can determine what needs to change.
+As a platform engineer,
+I want Restium to create missing resources and update changed ones,
+So that the API state converges to my declared spec.
 
 **Acceptance Criteria:**
 
-**Given** a resource with a configured read endpoint
-**When** reconciliation starts
-**Then** the current state is fetched and stored for comparison
+**Given** a resource marked as "create" (does not exist in API)
+**When** the operation is executed
+**Then** a POST (or configured method) is sent with the resource payload as JSON and the response is logged with resource name, method, endpoint, and status code
 
-### Story 4.2: Diff Calculation
+**Given** a resource marked as "update" (exists but differs)
+**When** the operation is executed
+**Then** a PUT (or configured method) is sent with the updated payload
 
-As a user,
-I want restium to compute the diff between desired and actual state,
-So that only necessary changes are made.
+**Given** a resource marked as "skip" (already matches)
+**When** the operation is executed
+**Then** no HTTP request is made and the skip is logged
 
-**Acceptance Criteria:**
+**Given** a create or update operation that returns an error (e.g., 403, 500)
+**When** the error occurs
+**Then** the error message includes: resource name, HTTP method, endpoint, status code, and an actionable hint
 
-**Given** a desired state that matches the actual state
-**When** reconciliation runs
-**Then** no mutation operations are performed for that resource
+**Given** an error response body that may contain secrets
+**When** the error is logged
+**Then** raw response bodies are not included in the error message
 
-**Given** a desired state that differs from actual state
-**When** reconciliation runs
-**Then** an update operation is planned
+**Covers:** FR17, FR18, FR21, FR31, FR32
 
-### Story 4.3: Plan & Apply Model
+### Story 3.4: Output Extraction & Reference Resolution
 
-As a user,
-I want a plan/apply workflow (like terraform),
-So that I can review changes before they are executed.
+As a platform engineer,
+I want to extract fields from API responses and use them in dependent resource payloads,
+So that dynamically assigned IDs flow automatically between resources.
 
 **Acceptance Criteria:**
 
-**Given** a `restium plan` command
-**When** executed
-**Then** it shows what would be created, updated, or deleted without making changes
+**Given** a resource with output extraction rules (e.g., `outputs: { id: "id", key: "api_key" }`)
+**When** the resource is created or its state is read
+**Then** the specified fields are extracted from the JSON response and stored as outputs
 
-**Given** a `restium apply` command
-**When** executed
-**Then** the planned changes are applied
+**Given** a resource B that was processed and produced output `id: "abc123"`
+**When** resource A's payload contains `${resource_b.output.id}`
+**Then** the reference is resolved to `"abc123"` in the actual request payload
 
-### Story 4.4: Resource Deletion
+**Given** a reference `${resource_b.output.id}` where resource B has not been processed yet
+**When** reference resolution is attempted
+**Then** an error message identifies the unresolved reference (this should not happen due to topological ordering, but is a safety check)
 
-As a user,
-I want resources removed from configuration to be deleted from the API,
-So that the actual state converges to the desired state.
+**Given** a reference `${resource_b.output.missing_field}` where the field was not extracted
+**When** reference resolution is attempted
+**Then** an actionable error identifies the missing output field and the resource it belongs to
 
-**Acceptance Criteria:**
+**Given** a payload with multiple references to different resources
+**When** resolved
+**Then** all references are substituted with their actual values
 
-**Given** a resource that exists in the API but not in configuration
-**When** reconciliation runs
-**Then** a DELETE operation is planned/executed (with reverse dependency order)
+**Covers:** FR4, FR23, FR24, FR25
 
-### Story 4.5: State Persistence
+### Story 3.5: Explicit Resource Deletion
 
-As a user,
-I want restium to persist known state locally,
-So that it can detect drift and deletions efficiently.
+As a platform engineer,
+I want to mark resources for explicit deletion in my spec,
+So that I can clean up previously created objects as part of reconciliation.
 
 **Acceptance Criteria:**
 
-**Given** a successful reconciliation
-**When** it completes
-**Then** the current state and outputs are persisted to a state file
+**Given** a resource in the spec marked for deletion (e.g., `action: delete`)
+**When** reconciliation processes that resource
+**Then** a DELETE request is sent to the configured endpoint
 
-## Epic 5: CLI & User Experience
+**Given** a resource marked for deletion that does not exist in the API (GET returns 404)
+**When** reconciliation processes it
+**Then** the delete is skipped and logged as "already absent"
 
-Implement the command-line interface and user-facing features.
+**Given** multiple resources marked for deletion with dependencies between them
+**When** reconciliation processes them
+**Then** dependent resources are deleted before their dependencies (reverse topological order for deletes)
 
-### Story 5.1: CLI Structure
+**Given** a delete operation that returns an error
+**When** the error occurs
+**Then** the error message follows the standard format: resource name, HTTP method, endpoint, status code, and hint
 
-As a user,
-I want a clear CLI with subcommands (plan, apply, validate, destroy),
-So that I can easily interact with restium.
+**Covers:** FR19
+
+### Story 3.6: Reconcile Command Orchestration
+
+As a platform engineer,
+I want to run `restium reconcile --spec <path>` to converge all resources in one command,
+So that my infrastructure bootstrapping is a single declarative operation.
 
 **Acceptance Criteria:**
 
-**Given** the `restium` binary
-**When** run with `--help`
-**Then** it shows available subcommands and global options
+**Given** a valid spec file with multiple resources
+**When** `restium reconcile --spec <path>` is executed
+**Then** the system: parses the spec, builds the dependency graph, sorts topologically, and for each resource in order: discovers state → computes diff → executes action → extracts outputs
 
-### Story 5.2: Validate Command
+**Given** all resources reconcile successfully
+**When** the process completes
+**Then** it exits with code 0 and logs a summary of actions taken (created: N, updated: N, deleted: N, skipped: N)
 
-As a user,
-I want a `validate` subcommand,
-So that I can check my configuration without making any API calls.
+**Given** one or more resources fail during reconciliation
+**When** the process completes
+**Then** it exits with code 1 and logs which resources failed with actionable errors
 
-**Acceptance Criteria:**
+**Given** the `--json` flag is set
+**When** reconciliation runs
+**Then** all operation logs (create, update, delete, skip) are output as structured JSON with consistent key-value pairs (resource, action, method, endpoint, status)
+
+**Given** any authentication credential in the reconciliation flow
+**When** it passes through logging
+**Then** it is redacted by the Logger
 
-**Given** `restium validate -f config.yaml`
-**When** executed
-**Then** it validates schema, references, and dependency graph, reporting all errors
+**Covers:** FR26, FR32, FR33, FR34
 
-### Story 5.3: Dry-run / Plan Output
+## Epic 4: Production Deployment & Distribution
 
-As a user,
-I want clear, readable plan output showing intended changes,
-So that I can review before applying.
+Users can deploy Restium as K8s Jobs or sidecars via distroless containers from GHCR, or install via `cargo install` from crates.io. CI/CD automates the full release pipeline.
+
+### Story 4.1: Sidecar Mode
+
+As a platform engineer,
+I want to run Restium with `--sidecar` to keep the process alive after reconciliation,
+So that I can deploy it as a K8s sidecar container for continuous reconciliation use cases.
 
 **Acceptance Criteria:**
 
-**Given** `restium plan`
-**When** changes are needed
-**Then** output shows each resource with action (create/update/delete) and a diff of payload changes
+**Given** the `--sidecar` flag is set
+**When** reconciliation completes successfully
+**Then** the process stays alive (blocks indefinitely) instead of exiting
+
+**Given** the `--sidecar` flag is set
+**When** reconciliation fails
+**Then** the process stays alive (blocks indefinitely) — it does not exit with an error code
+
+**Given** the `--sidecar` flag is not set
+**When** reconciliation completes
+**Then** the process exits normally with the appropriate exit code (0 or 1)
+
+**Given** the `RESTIUM_SIDECAR=true` environment variable is set
+**When** the binary starts
+**Then** sidecar mode is enabled (same as `--sidecar` flag)
 
-### Story 5.4: Destroy Command
+**Covers:** FR29
 
-As a user,
-I want a `destroy` subcommand,
-So that I can tear down all managed resources in reverse dependency order.
+### Story 4.2: Distroless Docker Image & Cross-Compilation
+
+As a platform engineer,
+I want a tiny, zero-CVE Docker image for linux/amd64 and linux/arm64,
+So that I can deploy Restium in security-hardened K8s environments.
 
 **Acceptance Criteria:**
 
-**Given** `restium destroy`
-**When** confirmed
-**Then** all managed resources are deleted in reverse topological order
+**Given** the Dockerfile
+**When** built
+**Then** it uses a multi-stage build with `FROM scratch` for the production image containing only the static binary
+
+**Given** the production image
+**When** scanned for vulnerabilities
+**Then** zero CVEs are reported (no OS packages, no shell, no package manager)
+
+**Given** the release build
+**When** cross-compiled via cargo-zigbuild
+**Then** static binaries are produced for both `x86_64-unknown-linux-musl` and `aarch64-unknown-linux-musl`
 
-## Epic 6: Packaging, CI/CD & Release
+**Given** the production Docker image
+**When** its size is measured
+**Then** it is under 10MB
 
-Set up the build pipeline, Docker packaging, and release automation.
+**Covers:** FR35, FR36, NFR1, NFR7, NFR14
 
-### Story 6.1: CI Pipeline
+### Story 4.3: CI/CD Pipeline
 
 As a developer,
-I want automated CI that runs lint, test, and build on every PR,
-So that code quality is maintained.
+I want automated CI on every PR and automated releases on version tags,
+So that code quality is enforced and releases are frictionless.
 
 **Acceptance Criteria:**
 
-**Given** a PR is opened
+**Given** a PR is opened or updated
 **When** CI runs
-**Then** clippy, fmt check, and tests all pass before merge is allowed
+**Then** `cargo fmt --check`, `cargo clippy -- -D warnings`, and `cargo test` all pass before merge is allowed
 
-### Story 6.2: Cross-platform Docker Image
+**Given** CI includes e2e tests
+**When** the e2e test suite runs
+**Then** tests execute against a mock HTTP server and pass
 
-As a user,
-I want a tiny Docker image for linux/amd64 and linux/arm64,
-So that I can run restium in any container environment.
+**Given** a version tag is pushed (e.g., `v0.1.0`)
+**When** the release pipeline runs
+**Then** it cross-compiles for both musl targets, builds multi-arch Docker images, pushes to GHCR, and publishes to crates.io
 
-**Acceptance Criteria:**
+**Given** CI runs on every push to main
+**When** main is updated
+**Then** the same checks (fmt, clippy, test) run as on PR
 
-**Given** a release tag
-**When** the release pipeline runs
-**Then** a multi-arch Docker image is pushed to GHCR
+**Covers:** FR37, FR38, NFR4, NFR5, NFR6, NFR7
 
-### Story 6.3: Crates.io Publishing
+### Story 4.4: Documentation & Examples
 
-As a developer,
-I want automatic crates.io publishing on release,
-So that users can install restium via `cargo install`.
+As a platform engineer,
+I want a README with a real-world example and spec reference documentation,
+So that I can go from zero to a working reconciliation in under 5 minutes.
 
 **Acceptance Criteria:**
 
-**Given** a release tag
-**When** the release pipeline runs
-**Then** the crate is published to crates.io
+**Given** the README
+**When** a new user reads it
+**Then** it includes: value proposition, quick start with copy-paste commands, a real-world Netbird bootstrapping example, security posture summary, and links to detailed docs
 
-### Story 6.4: Auto-tagging
+**Given** the examples directory
+**When** a user browses it
+**Then** it contains at least: `simple.yaml` (minimal getting-started), `netbird.yaml` (real-world Netbird bootstrapping)
 
-As a developer,
-I want automatic git tag creation when Cargo.toml version is bumped,
-So that the release process is frictionless.
+**Given** the spec reference documentation
+**When** a user looks up a spec option
+**Then** every field is documented with description, type, default, example, and failure modes
 
-**Acceptance Criteria:**
+**Given** a Helm chart in `charts/restium/`
+**When** a user deploys via Helm
+**Then** it creates a K8s Job with the Restium image and a ConfigMap-mounted spec file
 
-**Given** a merge to main that changes the version in Cargo.toml
-**When** the auto-tag workflow runs
-**Then** a git tag matching the version is created and pushed
+**Covers:** NFR8, NFR9, NFR10, NFR11
diff --git a/_bmad-output/planning-artifacts/implementation-readiness-report-2026-03-14.md b/_bmad-output/planning-artifacts/implementation-readiness-report-2026-03-14.md
new file mode 100644
index 0000000..212cdc1
--- /dev/null
+++ b/_bmad-output/planning-artifacts/implementation-readiness-report-2026-03-14.md
@@ -0,0 +1,279 @@
+# Implementation Readiness Assessment Report
+
+**Date:** 2026-03-14
+**Project:** restium
+
+---
+
+## Step 1: Document Discovery
+
+**stepsCompleted:** [step-01-document-discovery, step-02-prd-analysis, step-03-epic-coverage-validation, step-04-ux-alignment, step-05-epic-quality-review, step-06-final-assessment]
+
+### Documents Included in Assessment
+
+| Document Type | File | Format |
+|---|---|---|
+| PRD | `_bmad-output/planning-artifacts/prd.md` | Whole |
+| Architecture | `_bmad-output/planning-artifacts/architecture.md` | Whole |
+| Epics & Stories | `_bmad-output/planning-artifacts/epics.md` | Whole |
+| UX Design | *Not found* | N/A |
+
+### Issues
+- No duplicates found
+- UX Design document missing (may not be applicable for CLI/library project)
+
+---
+
+## Step 2: PRD Analysis
+
+### Functional Requirements (38 total)
+
+| ID | Requirement |
+|---|---|
+| FR1 | User can define REST resources declaratively in a single YAML spec file |
+| FR2 | User can specify resource endpoints, HTTP methods, and structured YAML payloads per resource |
+| FR3 | User can define global settings (base URL, default headers) that apply to all resources unless overridden |
+| FR4 | User can define parameterized references between resources using `${resource_name.output.field}` syntax |
+| FR5 | User can define explicit ordering constraints between resources via `depends_on` |
+| FR6 | System validates spec file schema, references, and dependency graph on load and reports all errors with context |
+| FR7 | User can configure bearer token authentication for API endpoints |
+| FR8 | User can configure basic auth (username/password) for API endpoints |
+| FR9 | User can configure API key authentication for API endpoints |
+| FR10 | User can supply authentication credentials via environment variables, never in spec files |
+| FR11 | User can configure OIDC/OAuth2 client credentials authentication for API endpoints |
+| FR12 | User can configure mutual TLS (mTLS) authentication with client certificates for API endpoints |
+| FR13 | System verifies TLS certificates by default and requires explicit `--insecure-tls` opt-in to skip verification |
+| FR14 | User can specify a custom CA bundle for connecting to APIs with internal/self-signed certificates |
+| FR15 | System can discover current state of resources via GET requests to configured read endpoints |
+| FR16 | System can compute diff between desired state (spec) and actual state (API) per resource |
+| FR17 | System can create resources that exist in spec but not in the API |
+| FR18 | System can update resources where desired state differs from actual state |
+| FR19 | User can mark specific resources for explicit deletion to clean up previously auto-created objects |
+| FR20 | System executes operations in topological order based on the dependency graph |
+| FR21 | System skips resources where desired state already matches actual state (idempotent) |
+| FR22 | System detects circular dependencies and reports the cycle path |
+| FR23 | User can configure output extraction rules to capture fields (IDs, keys) from API responses |
+| FR24 | System resolves parameterized references to actual values at execution time using extracted outputs |
+| FR25 | System reports clear errors when a referenced resource or output field cannot be resolved |
+| FR26 | User can run `restium reconcile --spec <path>` to converge API state to match the spec |
+| FR27 | User can run `restium validate --spec <path>` to check spec validity without making API calls |
+| FR28 | User can enable structured JSON log output via `--json` flag |
+| FR29 | User can run in sidecar mode via `--sidecar` flag to keep the process alive after completion |
+| FR30 | User can configure all flags via `RESTIUM_*` environment variables |
+| FR31 | System provides actionable error messages that include: resource name, HTTP method, endpoint, status code, and a hint at the cause |
+| FR32 | System logs all operations (create, update, delete, skip) with resource identifiers in structured JSON format |
+| FR33 | System exits with meaningful exit codes to signal success or failure to K8s Job controllers |
+| FR34 | System never logs or echoes secret values (tokens, passwords, API keys) |
+| FR35 | System ships as a static binary with no runtime dependencies |
+| FR36 | System is distributed as a distroless/scratch Docker image for linux/amd64 and linux/arm64 |
+| FR37 | System is published to crates.io for installation via `cargo install` |
+| FR38 | System is published to GHCR as a container image |
+
+### Non-Functional Requirements (14 total)
+
+| ID | Requirement |
+|---|---|
+| NFR1 | Container image has zero CVEs — no OS packages, no shell, no package manager |
+| NFR2 | Secrets (tokens, passwords, API keys) never appear in log output under any verbosity level |
+| NFR3 | All security-sensitive features require explicit opt-in via flags or configuration |
+| NFR4 | All PRs must pass: unit tests, e2e tests, cargo fmt check, cargo clippy lints — merge is blocked on failure |
+| NFR5 | Release process is fully automated — tagging triggers build, GHCR push, crates.io publish |
+| NFR6 | CI pipeline runs on every PR and every push to main |
+| NFR7 | Cross-platform container images (linux/amd64, linux/arm64) built automatically on release |
+| NFR8 | Documentation has clearly defined audience segments |
+| NFR9 | README enables time-to-first-use under 5 minutes with copy-paste real-world example |
+| NFR10 | All spec file options are documented with examples and failure modes |
+| NFR11 | Documentation is visually appealing with clear structure, code examples, and diagrams |
+| NFR12 | Reconciliation is deterministic |
+| NFR13 | Operations are idempotent |
+| NFR14 | Container image size under 10MB |
+
+### Additional Requirements (from PRD sections outside FR/NFR)
+
+- **Success Criteria:** 1,000 GitHub stars in 3 months, measurable GHCR downloads, zero security findings
+- **Phasing:** MVP includes reconcile/validate commands; plan/apply/destroy deferred to Phase 2-3
+- **Risk Mitigations:** Comprehensive e2e tests against mock APIs; invest in compelling README
+- **Constraints:** Rust codebase, single crate, no external service dependencies
+
+### PRD Completeness Assessment
+
+The PRD is well-structured and thorough. Requirements are clearly numbered and specific. The phased approach is well-defined with clear MVP boundaries. User journeys effectively ground the requirements in real scenarios. No ambiguous or contradictory requirements detected.
+
+---
+
+## Step 3: Epic Coverage Validation
+
+### Coverage Matrix
+
+| FR | Epic Coverage | Story | Status |
+|---|---|---|---|
+| FR1 | Epic 1 | Story 1.3 | ✓ Covered |
+| FR2 | Epic 1 | Story 1.3 | ✓ Covered |
+| FR3 | Epic 1 | Story 1.3 | ✓ Covered |
+| FR4 | Epic 3 | Story 3.4 | ✓ Covered |
+| FR5 | Epic 1/3 | Story 1.3, 3.1 | ✓ Covered |
+| FR6 | Epic 1 | Story 1.3, 1.4 | ✓ Covered |
+| FR7 | Epic 2 | Story 2.2 | ✓ Covered |
+| FR8 | Epic 2 | Story 2.2 | ✓ Covered |
+| FR9 | Epic 2 | Story 2.3 | ✓ Covered |
+| FR10 | Epic 2 | Story 2.2, 2.3, 2.4 | ✓ Covered |
+| FR11 | Epic 2 | Story 2.4 | ✓ Covered |
+| FR12 | Epic 2 | Story 2.5 | ✓ Covered |
+| FR13 | Epic 2 | Story 2.1 | ✓ Covered |
+| FR14 | Epic 2 | Story 2.1 | ✓ Covered |
+| FR15 | Epic 3 | Story 3.2 | ✓ Covered |
+| FR16 | Epic 3 | Story 3.2 | ✓ Covered |
+| FR17 | Epic 3 | Story 3.3 | ✓ Covered |
+| FR18 | Epic 3 | Story 3.3 | ✓ Covered |
+| FR19 | Epic 3 | Story 3.5 | ✓ Covered |
+| FR20 | Epic 3 | Story 3.1 | ✓ Covered |
+| FR21 | Epic 3 | Story 3.2, 3.3 | ✓ Covered |
+| FR22 | Epic 3 | Story 3.1 | ✓ Covered |
+| FR23 | Epic 3 | Story 3.4 | ✓ Covered |
+| FR24 | Epic 3 | Story 3.4 | ✓ Covered |
+| FR25 | Epic 3 | Story 3.4 | ✓ Covered |
+| FR26 | Epic 3 | Story 3.6 | ✓ Covered |
+| FR27 | Epic 1 | Story 1.4 | ✓ Covered |
+| FR28 | Epic 1 | Story 1.1, 1.2 | ✓ Covered |
+| FR29 | Epic 4 | Story 4.1 | ✓ Covered |
+| FR30 | Epic 1 | Story 1.1 | ✓ Covered |
+| FR31 | Epic 3 | Story 3.3 | ✓ Covered |
+| FR32 | Epic 3 | Story 3.6 | ✓ Covered |
+| FR33 | Epic 1 | Story 1.1 | ✓ Covered |
+| FR34 | Epic 1/3 | Story 1.2, 3.6 | ✓ Covered |
+| FR35 | Epic 1/4 | Story 1.1, 4.2 | ✓ Covered |
+| FR36 | Epic 4 | Story 4.2 | ✓ Covered |
+| FR37 | Epic 4 | Story 4.3 | ✓ Covered |
+| FR38 | Epic 4 | Story 4.3 | ✓ Covered |
+
+### Missing Requirements
+
+None — all 38 FRs are covered.
+
+### Coverage Statistics
+
+- Total PRD FRs: 38
+- FRs covered in epics: 38
+- Coverage percentage: 100%
+
+---
+
+## Step 4: UX Alignment Assessment
+
+### UX Document Status
+
+Not Found — no UX design document in planning artifacts.
+
+### Assessment
+
+- PRD classifies this as a CLI tool with no GUI
+- Epics document explicitly states: "CLI-only interface, no GUI required"
+- No web or mobile components implied
+- CLI interface fully defined by FR specifications (commands, flags, output format, error messages)
+
+### Alignment Issues
+
+None — UX documentation is not applicable for this CLI-only project.
+
+### Warnings
+
+None — no UX gap exists.
+
+---
+
+## Step 5: Epic Quality Review
+
+### Epic User Value Assessment
+
+| Epic | Title | User-Centric | Independent | Assessment |
+|---|---|---|---|---|
+| Epic 1 | Declarative Spec & CLI Foundation | ✓ | ✓ Standalone | Users can write and validate YAML specs |
+| Epic 2 | Secure API Connectivity | ✓ | ✓ Uses Epic 1 | Users can configure auth and TLS |
+| Epic 3 | Resource Reconciliation | ✓ | ✓ Uses Epic 1-2 | Users can converge API state |
+| Epic 4 | Production Deployment & Distribution | ✓ | ✓ Uses Epic 1-3 | Users can deploy via K8s/GHCR/crates.io |
+
+### Story Quality Summary
+
+- All 19 stories follow Given/When/Then BDD format
+- All stories have clear, testable acceptance criteria
+- Error conditions covered in all stories
+- No forward dependencies detected
+- Stories are appropriately sized
+
+### Dependency Analysis
+
+- No circular dependencies between epics
+- No forward references within epics
+- Each story builds on prior stories naturally
+- Epic ordering is valid: 1 → 2 → 3 → 4
+
+### Best Practices Compliance
+
+All 4 epics pass all compliance checks:
+- ✓ Delivers user value
+- ✓ Functions independently
+- ✓ Stories appropriately sized
+- ✓ No forward dependencies
+- ✓ Clear acceptance criteria
+- ✓ FR traceability maintained
+
+### Findings
+
+**Critical Violations:** None
+**Major Issues:** None
+
+**Minor Concerns:**
+1. Story 3.6 (Reconcile Command Orchestration) is an integration story tying together Stories 3.1-3.5. Larger than ideal but pragmatic — not blocking.
+2. NFR coverage is implicit in stories but lacks a formal NFR coverage map in the epics document. Story 4.3 covers NFR4-7, Story 3.2 covers NFR12-13, Story 4.2 covers NFR1/NFR14, Story 1.2 covers NFR2, Story 2.1 covers NFR3, Story 4.4 covers NFR8-11. All NFRs are addressed but the mapping is not explicit.
+
+---
+
+## Step 6: Final Assessment
+
+### Architecture ↔ PRD Alignment
+
+The architecture document directly addresses all 38 FRs with a module-to-FR mapping table. All 14 NFRs are supported by architectural decisions (scratch container, Logger redaction, CI pipelines, release automation, deterministic reconciliation). The architecture's own validation section confirms readiness with no critical gaps.
+
+**Technology stack alignment:**
+- clap v4 → FR26, FR27, FR28, FR29, FR30 (CLI)
+- ureq v2 + rustls → FR7-FR14 (auth/TLS)
+- petgraph → FR20, FR22 (dependency graph)
+- serde + serde_yaml + serde_json → FR1-FR6 (config parsing)
+- Custom Logger → FR31-FR34, NFR2 (logging/redaction)
+
+**No contradictions detected** between PRD requirements, architecture decisions, and epic stories.
+
+### Overall Readiness Status
+
+**READY**
+
+### Critical Issues Requiring Immediate Action
+
+None. All artifacts are aligned, complete, and implementation-ready.
+
+### Recommended Next Steps
+
+1. **Optional:** Add a formal NFR Coverage Map to the epics document (similar to the FR Coverage Map) to make NFR traceability explicit. All NFRs are covered but the mapping is implicit.
+2. **Optional:** Consider splitting Story 3.6 (Reconcile Command Orchestration) if implementation reveals it is too large. The current scoping is acceptable but it's the largest story.
+3. **Proceed with implementation** starting from Epic 1, Story 1.1 (Project Scaffold & CLI Skeleton).
+
+### Assessment Summary
+
+| Area | Status | Issues |
+|---|---|---|
+| PRD Completeness | ✓ Complete | 38 FRs, 14 NFRs, clearly numbered and specific |
+| Architecture Alignment | ✓ Aligned | All FRs mapped to modules, all decisions documented |
+| FR Coverage in Epics | ✓ 100% | All 38 FRs traceable to specific stories |
+| NFR Coverage | ✓ Covered (implicit) | All 14 NFRs addressed, mapping not formalized |
+| UX Requirements | ✓ N/A | CLI-only project, no GUI needed |
+| Epic Quality | ✓ Strong | User-centric, independent, no forward dependencies |
+| Story Quality | ✓ Strong | BDD acceptance criteria, error cases covered |
+| Dependency Structure | ✓ Valid | Epic 1 → 2 → 3 → 4, no circular or forward deps |
+
+### Final Note
+
+This assessment identified **0 critical issues** and **2 minor concerns** across 6 validation categories. The project planning artifacts are exceptionally well-aligned — PRD, architecture, and epics tell a consistent story with complete requirements traceability. The team can proceed directly to implementation with confidence.
+
+**Assessed by:** Implementation Readiness Workflow
+**Date:** 2026-03-14
+
diff --git a/_bmad-output/planning-artifacts/prd.md b/_bmad-output/planning-artifacts/prd.md
new file mode 100644
index 0000000..07e830f
--- /dev/null
+++ b/_bmad-output/planning-artifacts/prd.md
@@ -0,0 +1,330 @@
+---
+stepsCompleted:
+  - step-01-init
+  - step-02-discovery
+  - step-02b-vision
+  - step-02c-executive-summary
+  - step-03-success
+  - step-04-journeys
+  - step-05-domain
+  - step-06-innovation
+  - step-07-project-type
+  - step-08-scoping
+  - step-09-functional
+  - step-10-nonfunctional
+  - step-11-polish
+inputDocuments:
+  - _bmad-output/planning-artifacts/epics.md
+documentCounts:
+  briefs: 0
+  research: 0
+  projectDocs: 0
+  planningArtifacts: 1
+classification:
+  projectType: cli_tool
+  domain: general
+  complexity: low-medium
+  projectContext: greenfield
+workflowType: 'prd'
+---
+
+# Product Requirements Document - Restium
+
+**Author:** Mikkel Damsgaard
+**Date:** 2026-03-14
+
+## Executive Summary
+
+Restium is a declarative REST resource reconciler written in Rust. It fills a recurring gap in infrastructure automation: REST APIs that lack a dedicated Kubernetes operator or IaC provider. Users declare desired REST resources in YAML, and Restium converges the actual API state to match — creating, updating, or cleaning up resources as needed.
+
+The primary deployment model is as a Kubernetes Job or sidecar container, running unattended during infrastructure bootstrapping. Target users are platform engineers and cloud infrastructure developers who need to provision resources (e.g., Keycloak realms, API gateway routes, Netbird networks) against REST APIs as part of automated deployment pipelines.
+
+### What Makes This Special
+
+- **Readable over writable.** YAML declarations that any team member can review, vs. curl-in-bash scripts that are effectively write-only code. Configuration is the documentation.
+- **Minimal attack surface.** Ships as a distroless/scratch container — no shell, no package manager, nothing to exploit. Security through absence.
+- **Tiny footprint.** Designed to run as a lightweight job alongside actual workloads without resource contention.
+- **Solves a universal gap.** The distance between "this API exists" and "this API has an operator" is surprisingly common. Restium is the generic, lightweight bridge that eliminates bespoke curl scripts every time this gap appears.
+
+## Project Classification
+
+- **Type:** CLI tool (runs as K8s Jobs/sidecars, invoked from command line)
+- **Domain:** DevOps / Infrastructure tooling
+- **Complexity:** Low-medium — straightforward domain, technical depth in reconciliation logic and dependency resolution
+- **Context:** Greenfield — no existing codebase
+
+## Success Criteria
+
+### User Success
+
+- Platform engineers replace existing bash/curl bootstrapping scripts with declarative YAML configs readable by any team member without explanation.
+- New team members understand infrastructure bootstrapping by reading the YAML — no tribal knowledge required.
+- Modifications to bootstrapping configuration are reviewable in PRs with clear, visible blast radius.
+- Init jobs run unattended and converge correctly on first execution.
+
+### Business Success
+
+- 1,000 GitHub stars within 3 months of public release.
+- Measurable GHCR image downloads indicating real-world adoption beyond the originating team.
+- Zero security review findings related to bootstrapping containers in deployments using Restium.
+
+### Measurable Outcomes
+
+- Time-to-first-use under 5 minutes (clone, write YAML, run against a test API).
+- Container image size under 10MB.
+- Bootstrapping config readability: a new team member can understand what resources are provisioned by reading YAML alone.
+
+## User Journeys
+
+### Journey 1: Platform Engineer — "Marcus" (Primary User, Success Path)
+
+Marcus is a platform engineer at a mid-size company. He's setting up Netbird for the team's infrastructure. There's no K8s operator, and the existing bash script with curl calls is 200 lines of fragile spaghetti that nobody wants to touch. Last time someone modified it, it silently double-created resources because the error handling was wrong.
+
+**Opening Scene:** Marcus finds Restium, reads the README, and within 5 minutes understands the value proposition — replace curl scripts with declarative YAML.
+
+**Rising Action:** He writes a 30-line YAML file declaring the Netbird resources — networks, routes, access policies. He adds it as a Job in his Helm chart, referencing the distroless Restium image from GHCR. Dependencies between resources are expressed as references (`${netbird-network.output.id}`), and Restium resolves the execution order automatically.
+
+**Climax:** He deploys to staging. Restium converges correctly on first run — resources created in dependency order, outputs extracted, references resolved. The 200-line bash script is replaced.
+
+**Resolution:** A week later, he needs to add a new network route. He adds 5 lines of YAML, opens a PR. The change is obvious, reviewable, and safe. He reruns the job — Restium detects the existing resources are already correct and only creates the new route.
+
+### Journey 2: Platform Engineer — "Marcus" (Edge Case, Error Recovery)
+
+**Opening Scene:** Marcus deploys a config update to production. The Netbird API returns 403 on one resource creation because the service account token is missing a required scope.
+
+**Rising Action:** The K8s job fails. Marcus checks the logs.
+
+**Climax:** Restium's error message is clear and actionable: "Failed to create resource 'netbird-route-internal': 403 Forbidden on POST /api/routes — check authentication token permissions." No stack traces, no cryptic codes — just what failed, where, and a hint at why.
+
+**Resolution:** Marcus fixes the token scope in the K8s secret, reruns the job. Restium picks up where it matters — resources that already exist are left alone (idempotent), and the previously failed resource is created successfully.
+
+### Journey 3: Team Member / PR Reviewer — "Sofia"
+
+Sofia is a backend developer on Marcus's team. She doesn't write infrastructure config, but she reviews PRs that affect deployment.
+
+**Opening Scene:** Marcus opens a PR adding a new Netbird access control policy. Sofia sees a diff in `restium.yaml` — 8 lines added under a new resource block.
+
+**Rising Action:** She reads the resource name, the endpoint, the payload fields. It's immediately clear: this creates an access policy granting the monitoring team access to the internal network.
+
+**Climax:** She doesn't need to understand curl flags, jq pipelines, or bash conditionals. The YAML is self-documenting. Compare this to the old world: a 40-line bash diff with `curl -X POST ... | jq '.id'` piped into a variable used 30 lines later — she'd have to trace the logic to understand what it does.
+
+**Resolution:** Sofia approves the PR with confidence because the intent is obvious from the config. She understood a bootstrapping change without asking Marcus to explain it.
+
+### Journey 4: SecOps Engineer — "Kai" (Security Evaluation)
+
+Kai is on the security team. A platform engineer wants to introduce a new container into the deployment pipeline. Kai's job is to evaluate the risk.
+
+**Opening Scene:** Kai pulls the Restium container image and runs a vulnerability scan — zero CVEs because there's nothing in the image except a static binary. No shell, no package manager, no libc.
+
+**Rising Action:** He checks the network profile: outbound HTTPS to the target API, no inbound. He reviews the YAML config — secrets aren't in the YAML, they come from K8s secrets mounted as environment variables. The binary doesn't log or echo secret values.
+
+**Climax:** He compares this to the current approach: a bash image with curl, jq, and a shell. That's a much larger attack surface with known CVE exposure in the base image and a shell that could be exploited if the container is compromised.
+
+**Resolution:** Kai blue-stamps Restium. The security posture actually improved by adopting it. Evaluation took under 30 minutes.
+
+### Journey Requirements Summary
+
+| Capability | Revealed By |
+|---|---|
+| YAML config parsing with clear schema | Marcus (success path), Sofia |
+| HTTP client with auth (bearer, basic, API key, OIDC) | Marcus (success path) |
+| Dependency graph with parameterized references | Marcus (success path) |
+| Idempotent reconciliation (skip unchanged resources) | Marcus (success path, error recovery) |
+| Clear, actionable error messages with context | Marcus (error recovery) |
+| Output extraction from API responses | Marcus (success path) |
+| Distroless/scratch container image | Kai |
+| Secrets via environment variables, never logged | Kai |
+| mTLS and custom CA support | Kai |
+| Self-documenting YAML readable by non-authors | Sofia |
+
+## CLI Tool Specific Requirements
+
+### Project-Type Overview
+
+Restium is a CLI tool designed for both automated (K8s Job/sidecar) and interactive (developer terminal) use. It follows the same interface conventions as the Initium project — subcommand-based architecture, environment variable configuration, and structured JSON logging.
+
+### Command Structure
+
+```
+restium [GLOBAL FLAGS] <subcommand> [SUBCOMMAND FLAGS]
+```
+
+**Global Flags (MVP):**
+- `--json` — Structured JSON log output (default in automated mode)
+- `--sidecar` — Keep process alive after completion (for sidecar deployment)
+- All flags configurable via `RESTIUM_*` environment variables
+
+**Subcommands (MVP):**
+
+| Command | Purpose |
+|---------|---------|
+| `reconcile` | Converge actual API state to match desired state from spec |
+| `validate` | Validate spec file (schema, references, dependency graph) without making API calls |
+
+**Subcommands (Future/Interactive Mode):**
+
+| Command | Purpose |
+|---------|---------|
+| `plan` | Show what changes would be made without executing |
+| `apply` | Execute planned changes |
+| `destroy` | Tear down all managed resources |
+
+### Technical Architecture Considerations
+
+- **Config input:** `--spec <path>` flag pointing to YAML spec file, consistent with Initium's `--spec` pattern
+- **Output:** Structured JSON logs for K8s log aggregation; human-readable output not required for MVP
+- **Security:** Explicit opt-in for security-sensitive features (e.g., `--insecure-tls`), consistent with Initium's PSA restricted compatible posture
+- **Secrets:** Via environment variables (`RESTIUM_*`) or K8s-mounted secrets, never in spec files
+
+### Implementation Considerations
+
+- Static binary, no runtime dependencies — enables distroless/scratch container
+- Shell completion deferred to future interactive mode
+- Sidecar mode keeps process alive for continuous reconciliation use cases
+- Exit codes must be meaningful for K8s Job success/failure detection
+
+## Project Scoping & Phased Development
+
+### MVP Strategy & Philosophy
+
+**MVP Approach:** Problem-solving MVP — the smallest tool that solves a real, recurring pain (replacing bash/curl bootstrapping scripts with declarative YAML).
+
+**Resource Requirements:** Team project, Rust expertise required. Single crate, no external service dependencies.
+
+### MVP Feature Set (Phase 1)
+
+**Core User Journeys Supported:**
+- Marcus: full success path (write YAML, deploy as Job, converge resources)
+- Marcus: error recovery (clear errors, idempotent rerun)
+- Sofia: PR review (readable YAML diffs)
+- Kai: security evaluation (distroless image, no secrets in config)
+
+**Must-Have Capabilities:**
+- YAML spec parsing with schema validation (`--spec <path>`)
+- HTTP client with JSON payloads
+- Authentication: bearer token, basic auth, API key, OIDC client credentials (via env vars)
+- mTLS with client certificates, custom CA bundles, TLS verification by default
+- Dependency graph with parameterized references (`${resource.output.field}`)
+- Reconciliation: create, update, and explicit delete to converge to desired state
+- Output extraction from API responses for cross-resource references
+- Cycle detection in dependency graph
+- `reconcile` and `validate` subcommands
+- `--json` structured logging, `--sidecar` mode
+- `RESTIUM_*` environment variable support for all flags
+- Distroless/scratch Docker image (linux/amd64, linux/arm64)
+- CI pipeline (clippy, fmt, tests, e2e tests)
+- Publish to crates.io and GHCR
+- README with compelling example (Netbird bootstrapping use case)
+
+### Post-MVP Features
+
+**Phase 2 (Growth):**
+- Multi-file configuration support
+- Retry with configurable backoff for transient failures
+- State persistence for drift detection
+- Shell completion
+- `destroy` subcommand for teardown
+- Human-readable output mode for interactive terminal use
+
+**Phase 3 (Expansion — "Terraform for REST"):**
+- `plan` / `apply` workflow for interactive use cases
+- Plugin system for common REST APIs (Keycloak, Netbird, API gateways)
+- Community-contributed plugin registry
+- Advanced diffing and drift reporting
+
+### Risk Mitigation Strategy
+
+**Technical Risks:** Reconciliation logic (diffing, idempotency, dependency ordering) is non-trivial but well-understood by the team. No novel technology risks. Mitigation: comprehensive e2e tests against mock APIs.
+
+**Market Risks:** Primary risk is discoverability — the tool solves a real problem but the audience doesn't know it exists. Mitigation: invest in a compelling README with a real-world example (Netbird), shareable demo output, and positioning that makes the value obvious in 30 seconds. Target dev communities where the pain is felt (K8s, platform engineering).
+
+**Resource Risks:** Team project with Rust expertise. No external dependencies or third-party service risks. If resources constrain, Phase 2/3 features defer cleanly without affecting MVP value.
+
+## Functional Requirements
+
+### Configuration & Parsing
+
+- **FR1:** User can define REST resources declaratively in a single YAML spec file
+- **FR2:** User can specify resource endpoints, HTTP methods, and structured YAML payloads per resource
+- **FR3:** User can define global settings (base URL, default headers) that apply to all resources unless overridden
+- **FR4:** User can define parameterized references between resources using `${resource_name.output.field}` syntax
+- **FR5:** User can define explicit ordering constraints between resources via `depends_on`
+- **FR6:** System validates spec file schema, references, and dependency graph on load and reports all errors with context
+
+### Authentication & TLS
+
+- **FR7:** User can configure bearer token authentication for API endpoints
+- **FR8:** User can configure basic auth (username/password) for API endpoints
+- **FR9:** User can configure API key authentication for API endpoints
+- **FR10:** User can supply authentication credentials via environment variables, never in spec files
+- **FR11:** User can configure OIDC/OAuth2 client credentials authentication for API endpoints
+- **FR12:** User can configure mutual TLS (mTLS) authentication with client certificates for API endpoints
+- **FR13:** System verifies TLS certificates by default and requires explicit `--insecure-tls` opt-in to skip verification
+- **FR14:** User can specify a custom CA bundle for connecting to APIs with internal/self-signed certificates
+
+### Reconciliation
+
+- **FR15:** System can discover current state of resources via GET requests to configured read endpoints
+- **FR16:** System can compute diff between desired state (spec) and actual state (API) per resource
+- **FR17:** System can create resources that exist in spec but not in the API
+- **FR18:** System can update resources where desired state differs from actual state
+- **FR19:** User can mark specific resources for explicit deletion to clean up previously auto-created objects
+- **FR20:** System executes operations in topological order based on the dependency graph
+- **FR21:** System skips resources where desired state already matches actual state (idempotent)
+- **FR22:** System detects circular dependencies and reports the cycle path
+
+### Output Extraction & References
+
+- **FR23:** User can configure output extraction rules to capture fields (IDs, keys) from API responses
+- **FR24:** System resolves parameterized references to actual values at execution time using extracted outputs
+- **FR25:** System reports clear errors when a referenced resource or output field cannot be resolved
+
+### CLI Interface
+
+- **FR26:** User can run `restium reconcile --spec <path>` to converge API state to match the spec
+- **FR27:** User can run `restium validate --spec <path>` to check spec validity without making API calls
+- **FR28:** User can enable structured JSON log output via `--json` flag
+- **FR29:** User can run in sidecar mode via `--sidecar` flag to keep the process alive after completion
+- **FR30:** User can configure all flags via `RESTIUM_*` environment variables
+
+### Error Handling & Observability
+
+- **FR31:** System provides actionable error messages that include: resource name, HTTP method, endpoint, status code, and a hint at the cause
+- **FR32:** System logs all operations (create, update, delete, skip) with resource identifiers in structured JSON format
+- **FR33:** System exits with meaningful exit codes to signal success or failure to K8s Job controllers
+- **FR34:** System never logs or echoes secret values (tokens, passwords, API keys)
+
+### Packaging & Distribution
+
+- **FR35:** System ships as a static binary with no runtime dependencies
+- **FR36:** System is distributed as a distroless/scratch Docker image for linux/amd64 and linux/arm64
+- **FR37:** System is published to crates.io for installation via `cargo install`
+- **FR38:** System is published to GHCR as a container image
+
+## Non-Functional Requirements
+
+### Security
+
+- **NFR1:** Container image has zero CVEs — no OS packages, no shell, no package manager
+- **NFR2:** Secrets (tokens, passwords, API keys) never appear in log output under any verbosity level
+- **NFR3:** All security-sensitive features require explicit opt-in via flags or configuration
+
+### CI/CD & Code Quality
+
+- **NFR4:** All PRs must pass: unit tests, e2e tests, `cargo fmt` check, `cargo clippy` lints — merge is blocked on failure
+- **NFR5:** Release process is fully automated — tagging a version triggers build, container image push to GHCR, and crates.io publish (following the Initium release model)
+- **NFR6:** CI pipeline runs on every PR and every push to main
+- **NFR7:** Cross-platform container images (linux/amd64, linux/arm64) built automatically on release
+
+### Documentation
+
+- **NFR8:** Documentation has clearly defined audience segments: platform engineers (getting started, spec reference), SecOps (security posture, container scanning), contributors (architecture, development setup)
+- **NFR9:** README enables time-to-first-use under 5 minutes with a copy-paste real-world example
+- **NFR10:** All spec file options are documented with examples and failure modes
+- **NFR11:** Documentation is visually appealing — not a wall of text, uses clear structure, code examples, and diagrams where they add value
+
+### Reliability
+
+- **NFR12:** Reconciliation is deterministic — same spec + same API state always produces same operations
+- **NFR13:** Operations are idempotent — running reconciliation twice with unchanged spec produces no unnecessary API calls
+- **NFR14:** Container image size under 10MB
diff --git a/_bmad/bmm/config.yaml b/_bmad/bmm/config.yaml
index 1e66f5b..5a2310c 100644
--- a/_bmad/bmm/config.yaml
+++ b/_bmad/bmm/config.yaml
@@ -10,7 +10,7 @@ implementation_artifacts: "{project-root}/_bmad-output/implementation-artifacts"
 project_knowledge: "{project-root}/docs"
 
 # Core Configuration Values
-user_name: Mikkeldamsgaard
+user_name: Mikkel Damsgaard
 communication_language: English
 document_output_language: English
 output_folder: _bmad-output
diff --git a/charts/restium/Chart.yaml b/charts/restium/Chart.yaml
new file mode 100644
index 0000000..3178499
--- /dev/null
+++ b/charts/restium/Chart.yaml
@@ -0,0 +1,12 @@
+apiVersion: v2
+name: restium
+description: A declarative reconciling REST client for Kubernetes
+type: application
+version: 0.1.0
+appVersion: "0.1.0"
+home: https://github.com/KitStream/restium
+sources:
+  - https://github.com/KitStream/restium
+maintainers:
+  - name: Kitstream
+    url: https://github.com/KitStream
diff --git a/charts/restium/templates/configmap.yaml b/charts/restium/templates/configmap.yaml
new file mode 100644
index 0000000..46c077b
--- /dev/null
+++ b/charts/restium/templates/configmap.yaml
@@ -0,0 +1,10 @@
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: {{ .Release.Name }}-spec
+  labels:
+    app.kubernetes.io/name: restium
+    app.kubernetes.io/instance: {{ .Release.Name }}
+data:
+  spec.yaml: |
+    {{- .Values.spec | nindent 4 }}
diff --git a/charts/restium/templates/job.yaml b/charts/restium/templates/job.yaml
new file mode 100644
index 0000000..842eb44
--- /dev/null
+++ b/charts/restium/templates/job.yaml
@@ -0,0 +1,46 @@
+apiVersion: batch/v1
+kind: Job
+metadata:
+  name: {{ .Release.Name }}
+  labels:
+    app.kubernetes.io/name: restium
+    app.kubernetes.io/instance: {{ .Release.Name }}
+spec:
+  backoffLimit: {{ .Values.backoffLimit }}
+  template:
+    metadata:
+      labels:
+        app.kubernetes.io/name: restium
+        app.kubernetes.io/instance: {{ .Release.Name }}
+    spec:
+      containers:
+        - name: restium
+          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
+          imagePullPolicy: {{ .Values.image.pullPolicy }}
+          args:
+            {{- if .Values.flags.json }}
+            - "--json"
+            {{- end }}
+            {{- if .Values.flags.insecureTls }}
+            - "--insecure-tls"
+            {{- end }}
+            {{- if .Values.flags.sidecar }}
+            - "--sidecar"
+            {{- end }}
+            - "reconcile"
+            - "--spec"
+            - "/config/spec.yaml"
+          volumeMounts:
+            - name: spec
+              mountPath: /config
+              readOnly: true
+          {{- if .Values.secretName }}
+          envFrom:
+            - secretRef:
+                name: {{ .Values.secretName }}
+          {{- end }}
+      volumes:
+        - name: spec
+          configMap:
+            name: {{ .Release.Name }}-spec
+      restartPolicy: {{ .Values.restartPolicy }}
diff --git a/charts/restium/values.yaml b/charts/restium/values.yaml
new file mode 100644
index 0000000..8c0bc43
--- /dev/null
+++ b/charts/restium/values.yaml
@@ -0,0 +1,24 @@
+image:
+  repository: ghcr.io/kitstream/restium
+  tag: latest
+  pullPolicy: IfNotPresent
+
+# Name of the K8s Secret containing auth credentials (env vars).
+# Set to "" to disable envFrom. The Secret must exist if specified.
+secretName: ""
+
+# Inline spec file content — mounted as /config/spec.yaml
+spec: |
+  global:
+    base_url: https://api.example.com
+  resources: []
+
+# Additional flags passed to restium
+flags:
+  json: false
+  insecureTls: false
+  sidecar: false
+
+# Job configuration
+backoffLimit: 1
+restartPolicy: Never
diff --git a/examples/netbird.yaml b/examples/netbird.yaml
new file mode 100644
index 0000000..68c7e12
--- /dev/null
+++ b/examples/netbird.yaml
@@ -0,0 +1,71 @@
+# Netbird bootstrapping — create networks, routes, and access policies
+# Run: NETBIRD_TOKEN="your-token" restium reconcile --spec examples/netbird.yaml
+
+global:
+  base_url: https://api.netbird.io/api
+  auth:
+    type: bearer
+    token_env: NETBIRD_TOKEN
+
+resources:
+  - name: internal_network
+    endpoint: /networks
+    read_endpoint: /networks/internal
+    payload:
+      name: internal
+      description: Internal service network
+    outputs:
+      id: id
+
+  - name: monitoring_network
+    endpoint: /networks
+    read_endpoint: /networks/monitoring
+    payload:
+      name: monitoring
+      description: Monitoring and observability network
+    outputs:
+      id: id
+
+  - name: internal_route
+    endpoint: /routes
+    payload:
+      network_id: "${internal_network.output.id}"
+      peer: gateway-peer
+      network: 10.100.0.0/24
+      metric: 9999
+      masquerade: true
+      enabled: true
+      description: Route to internal services
+    depends_on:
+      - internal_network
+
+  - name: monitoring_route
+    endpoint: /routes
+    payload:
+      network_id: "${monitoring_network.output.id}"
+      peer: monitoring-peer
+      network: 10.200.0.0/24
+      metric: 9999
+      masquerade: true
+      enabled: true
+      description: Route to monitoring subnet
+    depends_on:
+      - monitoring_network
+
+  - name: monitoring_access_policy
+    endpoint: /policies
+    payload:
+      name: monitoring-access
+      description: Allow monitoring group to reach internal network
+      enabled: true
+      rules:
+        - name: allow-monitoring
+          sources:
+            - monitoring-group
+          destinations:
+            - "${internal_network.output.id}"
+          bidirectional: false
+          protocol: all
+          action: accept
+    depends_on:
+      - internal_network
diff --git a/examples/simple.yaml b/examples/simple.yaml
new file mode 100644
index 0000000..1b5c7de
--- /dev/null
+++ b/examples/simple.yaml
@@ -0,0 +1,23 @@
+# Simple example — create two resources against a local API
+# Run: restium reconcile --spec examples/simple.yaml
+
+global:
+  base_url: http://localhost:8080/api
+
+resources:
+  - name: project
+    endpoint: /projects
+    read_endpoint: /projects/my-project
+    payload:
+      name: my-project
+      description: Example project created by Restium
+    outputs:
+      id: id
+
+  - name: environment
+    endpoint: /environments
+    payload:
+      name: staging
+      project_id: "${project.output.id}"
+    depends_on:
+      - project
diff --git a/src/auth/api_key.rs b/src/auth/api_key.rs
new file mode 100644
index 0000000..4a3c90c
--- /dev/null
+++ b/src/auth/api_key.rs
@@ -0,0 +1,70 @@
+use std::fmt;
+
+use super::{AuthProvider, read_env_credential};
+
+enum ApiKeyMode {
+    Header(String),
+    QueryParam(String),
+}
+
+pub struct ApiKeyAuthProvider {
+    key: String,
+    mode: ApiKeyMode,
+}
+
+impl fmt::Debug for ApiKeyAuthProvider {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let mode_str = match &self.mode {
+            ApiKeyMode::Header(h) => format!("Header({h})"),
+            ApiKeyMode::QueryParam(q) => format!("QueryParam({q})"),
+        };
+        f.debug_struct("ApiKeyAuthProvider")
+            .field("key", &"[REDACTED]")
+            .field("mode", &mode_str)
+            .finish()
+    }
+}
+
+impl ApiKeyAuthProvider {
+    pub fn new(
+        key_env: &str,
+        header_name: Option<&str>,
+        query_param: Option<&str>,
+    ) -> Result<Self, String> {
+        let key = read_env_credential(key_env, "API key authentication")?;
+
+        let mode = match (header_name, query_param) {
+            (Some(""), None) => {
+                return Err("API key auth: 'header_name' must not be empty".to_string());
+            }
+            (Some(h), None) => ApiKeyMode::Header(h.to_string()),
+            (None, Some("")) => {
+                return Err("API key auth: 'query_param' must not be empty".to_string());
+            }
+            (None, Some(q)) => ApiKeyMode::QueryParam(q.to_string()),
+            (Some(_), Some(_)) => {
+                return Err(
+                    "API key auth: specify either 'header_name' or 'query_param', not both"
+                        .to_string(),
+                );
+            }
+            (None, None) => {
+                return Err(
+                    "API key auth: one of 'header_name' or 'query_param' must be specified"
+                        .to_string(),
+                );
+            }
+        };
+
+        Ok(Self { key, mode })
+    }
+}
+
+impl AuthProvider for ApiKeyAuthProvider {
+    fn apply(&self, request: ureq::Request) -> Result<ureq::Request, String> {
+        match &self.mode {
+            ApiKeyMode::Header(name) => Ok(request.set(name, &self.key)),
+            ApiKeyMode::QueryParam(param) => Ok(request.query(param, &self.key)),
+        }
+    }
+}
diff --git a/src/auth/basic.rs b/src/auth/basic.rs
new file mode 100644
index 0000000..5473ebb
--- /dev/null
+++ b/src/auth/basic.rs
@@ -0,0 +1,33 @@
+use std::fmt;
+
+use base64::Engine;
+
+use super::{AuthProvider, read_env_credential};
+
+pub struct BasicAuthProvider {
+    encoded: String,
+}
+
+impl fmt::Debug for BasicAuthProvider {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("BasicAuthProvider")
+            .field("encoded", &"[REDACTED]")
+            .finish()
+    }
+}
+
+impl BasicAuthProvider {
+    pub fn new(username_env: &str, password_env: &str) -> Result<Self, String> {
+        let username = read_env_credential(username_env, "basic authentication")?;
+        let password = read_env_credential(password_env, "basic authentication")?;
+        let encoded =
+            base64::engine::general_purpose::STANDARD.encode(format!("{username}:{password}"));
+        Ok(Self { encoded })
+    }
+}
+
+impl AuthProvider for BasicAuthProvider {
+    fn apply(&self, request: ureq::Request) -> Result<ureq::Request, String> {
+        Ok(request.set("Authorization", &format!("Basic {}", self.encoded)))
+    }
+}
diff --git a/src/auth/bearer.rs b/src/auth/bearer.rs
new file mode 100644
index 0000000..ec1a206
--- /dev/null
+++ b/src/auth/bearer.rs
@@ -0,0 +1,28 @@
+use std::fmt;
+
+use super::{AuthProvider, read_env_credential};
+
+pub struct BearerAuthProvider {
+    token: String,
+}
+
+impl fmt::Debug for BearerAuthProvider {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("BearerAuthProvider")
+            .field("token", &"[REDACTED]")
+            .finish()
+    }
+}
+
+impl BearerAuthProvider {
+    pub fn new(token_env: &str) -> Result<Self, String> {
+        let token = read_env_credential(token_env, "bearer token authentication")?;
+        Ok(Self { token })
+    }
+}
+
+impl AuthProvider for BearerAuthProvider {
+    fn apply(&self, request: ureq::Request) -> Result<ureq::Request, String> {
+        Ok(request.set("Authorization", &format!("Bearer {}", self.token)))
+    }
+}
diff --git a/src/auth/mod.rs b/src/auth/mod.rs
new file mode 100644
index 0000000..146e069
--- /dev/null
+++ b/src/auth/mod.rs
@@ -0,0 +1,87 @@
+mod api_key;
+mod basic;
+mod bearer;
+mod mtls;
+mod oidc;
+
+use crate::config::AuthConfig;
+
+pub use api_key::ApiKeyAuthProvider;
+pub use basic::BasicAuthProvider;
+pub use bearer::BearerAuthProvider;
+pub use mtls::MtlsAuthProvider;
+pub use oidc::OidcAuthProvider;
+
+/// Trait for authentication providers that attach credentials to HTTP requests.
+pub trait AuthProvider {
+    fn apply(&self, request: ureq::Request) -> Result<ureq::Request, String>;
+}
+
+/// Read a required, non-empty environment variable for auth configuration.
+fn read_env_credential(env_var: &str, purpose: &str) -> Result<String, String> {
+    match std::env::var(env_var) {
+        Ok(value) if value.is_empty() => Err(format!(
+            "Environment variable '{env_var}' is set but empty — required for {purpose}"
+        )),
+        Ok(value) => Ok(value),
+        Err(std::env::VarError::NotPresent) => Err(format!(
+            "Environment variable '{env_var}' is not set — required for {purpose}"
+        )),
+        Err(std::env::VarError::NotUnicode(_)) => Err(format!(
+            "Environment variable '{env_var}' contains non-UTF-8 data — must be a valid string"
+        )),
+    }
+}
+
+/// Create an auth provider from an AuthConfig.
+///
+/// `agent` is required for OIDC auth (token endpoint uses the same TLS configuration
+/// as the rest of the application). Pass `HttpClient::agent()` when available.
+pub fn create_auth_provider(
+    config: &AuthConfig,
+    agent: Option<&ureq::Agent>,
+) -> Result<Box<dyn AuthProvider>, String> {
+    match config {
+        AuthConfig::Bearer { token_env } => Ok(Box::new(BearerAuthProvider::new(token_env)?)),
+        AuthConfig::Basic {
+            username_env,
+            password_env,
+        } => Ok(Box::new(BasicAuthProvider::new(
+            username_env,
+            password_env,
+        )?)),
+        AuthConfig::ApiKey {
+            key_env,
+            header_name,
+            query_param,
+        } => Ok(Box::new(ApiKeyAuthProvider::new(
+            key_env,
+            header_name.as_deref(),
+            query_param.as_deref(),
+        )?)),
+        AuthConfig::Oidc {
+            token_url,
+            client_id_env,
+            client_secret_env,
+            scope,
+        } => {
+            let oidc_agent = agent.ok_or_else(|| {
+                "OIDC authentication requires an HTTP client for token requests".to_string()
+            })?;
+            Ok(Box::new(OidcAuthProvider::new(
+                oidc_agent,
+                token_url,
+                client_id_env,
+                client_secret_env,
+                scope.as_deref(),
+            )?))
+        }
+        AuthConfig::Mtls {
+            client_cert_path,
+            client_key_path,
+        } => Ok(Box::new(MtlsAuthProvider::new(
+            client_cert_path,
+            client_key_path,
+        )?)),
+    }
+}
diff --git a/src/auth/mtls.rs b/src/auth/mtls.rs
new file mode 100644
index 0000000..7e71be3
--- /dev/null
+++ b/src/auth/mtls.rs
@@ -0,0 +1,24 @@
+use super::AuthProvider;
+
+/// mTLS authentication provider.
+/// The `apply()` method is a no-op because mTLS operates at the TLS layer,
+/// not as per-request headers. The cert/key paths are configured on the
+/// `HttpClient` (ureq Agent) at construction time via `extract_mtls_paths()`.
+#[derive(Debug)]
+pub struct MtlsAuthProvider;
+
+impl MtlsAuthProvider {
+    pub fn new(_client_cert_path: &str, _client_key_path: &str) -> Result<Self, String> {
+        // File validation is deferred to HttpClient::new() which reads and parses
+        // the cert/key files. mTLS paths are extracted from AuthConfig directly
+        // by extract_mtls_paths() in main.rs.
+        Ok(Self)
+    }
+}
+
+impl AuthProvider for MtlsAuthProvider {
+    fn apply(&self, request: ureq::Request) -> Result<ureq::Request, String> {
+        // mTLS is configured at the TLS layer (on the ureq Agent), not per-request
+        Ok(request)
+    }
+}
diff --git a/src/auth/oidc.rs b/src/auth/oidc.rs
new file mode 100644
index 0000000..e265ba3
--- /dev/null
+++ b/src/auth/oidc.rs
@@ -0,0 +1,129 @@
+use std::fmt::Write;
+
+use super::{AuthProvider, read_env_credential};
+
+/// OIDC/OAuth2 client credentials authentication provider.
+///
+/// Known limitation: the access token is fetched once at construction and never refreshed.
+/// Long-running reconciliation runs may encounter 401 errors if the token expires.
+pub struct OidcAuthProvider {
+    access_token: String,
+}
+
+impl std::fmt::Debug for OidcAuthProvider {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("OidcAuthProvider")
+            .field("access_token", &"[REDACTED]")
+            .finish()
+    }
+}
+
+impl OidcAuthProvider {
+    /// Create a new OIDC auth provider by performing a client_credentials token request.
+    ///
+    /// Uses the provided `agent` so the token endpoint request inherits the same TLS
+    /// configuration (custom CA bundle, insecure_tls) as the rest of the application.
+    pub fn new(
+        agent: &ureq::Agent,
+        token_url: &str,
+        client_id_env: &str,
+        client_secret_env: &str,
+        scope: Option<&str>,
+    ) -> Result<Self, String> {
+        if token_url.is_empty() {
+            return Err("OIDC token_url must not be empty".to_string());
+        }
+
+        let client_id = read_env_credential(client_id_env, "OIDC authentication")?;
+        let client_secret = read_env_credential(client_secret_env, "OIDC authentication")?;
+
+        let mut form_body = format!(
+            "grant_type=client_credentials&client_id={}&client_secret={}",
+            form_url_encode(&client_id),
+            form_url_encode(&client_secret)
+        );
+        if let Some(s) = scope {
+            let _ = write!(form_body, "&scope={}", form_url_encode(s));
+        }
+
+        let response = agent
+            .post(token_url)
+            .set("Content-Type", "application/x-www-form-urlencoded")
+            .send_string(&form_body)
+            .map_err(|e| {
+                // Format a controlled error message that never includes the request body
+                // (which contains client_secret). Only expose status code and OAuth error fields.
+                match e {
+                    ureq::Error::Status(code, resp) => {
+                        let oauth_hint = resp
+                            .into_string()
+                            .ok()
+                            .and_then(|body| {
+                                let json: serde_json::Value = serde_json::from_str(&body).ok()?;
+                                let error = json["error"].as_str()?;
+                                let desc = json["error_description"].as_str().unwrap_or("");
+                                if desc.is_empty() {
+                                    Some(format!(" ({error})"))
+                                } else {
+                                    Some(format!(" ({error}: {desc})"))
+                                }
+                            })
+                            .unwrap_or_default();
+                        format!(
+                            "OIDC token request to '{token_url}' failed: HTTP {code}{oauth_hint}"
+                        )
+                    }
+                    ureq::Error::Transport(t) => {
+                        format!("OIDC token request to '{token_url}' failed: {}", t.kind())
+                    }
+                }
+            })?;
+
+        let json: serde_json::Value = response
+            .into_json()
+            .map_err(|e| format!("Failed to parse OIDC token response from '{token_url}': {e}"))?;
+
+        let access_token = json["access_token"]
+            .as_str()
+            .ok_or_else(|| {
+                format!("OIDC token response from '{token_url}' missing 'access_token' field")
+            })?
+            .to_string();
+
+        Ok(Self { access_token })
+    }
+
+    /// Create an OidcAuthProvider with a pre-fetched token (testing only).
+    #[doc(hidden)]
+    pub fn with_token(token: &str) -> Self {
+        Self {
+            access_token: token.to_string(),
+        }
+    }
+}
+
+impl AuthProvider for OidcAuthProvider {
+    fn apply(&self, request: ureq::Request) -> Result<ureq::Request, String> {
+        Ok(request.set("Authorization", &format!("Bearer {}", self.access_token)))
+    }
+}
+
+/// application/x-www-form-urlencoded encoding (RFC 1866).
+/// Uses `+` for spaces (not `%20`) per the HTML form encoding standard.
+fn form_url_encode(s: &str) -> String {
+    let mut encoded = String::with_capacity(s.len());
+    for byte in s.bytes() {
+        match byte {
+            b'A'..=b'Z' | b'a'..=b'z' | b'0'..=b'9' | b'-' | b'_' | b'.' | b'~' => {
+                encoded.push(byte as char);
+            }
+            b' ' => {
+                encoded.push('+');
+            }
+            _ => {
+                let _ = write!(encoded, "%{byte:02X}");
+            }
+        }
+    }
+    encoded
+}
diff --git a/src/config/mod.rs b/src/config/mod.rs
new file mode 100644
index 0000000..3775729
--- /dev/null
+++ b/src/config/mod.rs
@@ -0,0 +1,105 @@
+pub mod validation;
+
+use std::collections::HashMap;
+
+use serde::{Deserialize, Serialize};
+
+pub use validation::validate_spec;
+
+/// Top-level spec file structure.
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(deny_unknown_fields)]
+pub struct SpecFile {
+    #[serde(default)]
+    pub global: GlobalConfig,
+    #[serde(default)]
+    pub resources: Vec<ResourceSpec>,
+}
+
+/// Global configuration that applies to all resources unless overridden.
+#[derive(Debug, Default, Deserialize, Serialize)]
+#[serde(deny_unknown_fields)]
+pub struct GlobalConfig {
+    pub base_url: Option<String>,
+    pub default_headers: Option<HashMap<String, String>>,
+    pub auth: Option<AuthConfig>,
+    pub ca_bundle: Option<String>,
+}
+
+/// A single resource definition within the spec.
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(deny_unknown_fields)]
+pub struct ResourceSpec {
+    pub name: String,
+    pub endpoint: String,
+    pub method: Option<String>,
+    pub payload: Option<serde_json::Value>,
+    pub headers: Option<HashMap<String, String>>,
+    pub base_url: Option<String>,
+    pub depends_on: Option<Vec<String>>,
+    pub read_endpoint: Option<String>,
+    pub outputs: Option<HashMap<String, String>>,
+    pub action: Option<String>,
+    pub auth: Option<AuthConfig>,
+}
+
+/// Authentication configuration. Type definitions only — implementation in Epic 2.
+#[derive(Debug, Deserialize, Serialize, Clone)]
+#[serde(tag = "type", rename_all = "snake_case")]
+pub enum AuthConfig {
+    Bearer {
+        token_env: String,
+    },
+    Basic {
+        username_env: String,
+        password_env: String,
+    },
+    ApiKey {
+        key_env: String,
+        header_name: Option<String>,
+        query_param: Option<String>,
+    },
+    Oidc {
+        token_url: String,
+        client_id_env: String,
+        client_secret_env: String,
+        scope: Option<String>,
+    },
+    Mtls {
+        client_cert_path: String,
+        client_key_path: String,
+    },
+}
+
+impl SpecFile {
+    /// Load and parse a YAML spec file from disk.
+    pub fn load(path: &str) -> Result<Self, String> {
+        let content = std::fs::read_to_string(path)
+            .map_err(|e| format!("Failed to read spec file '{path}': {e}"))?;
+        serde_yaml::from_str(&content)
+            .map_err(|e| format!("Failed to parse spec file '{path}': {e}"))
+    }
+}
+
+impl ResourceSpec {
+    /// Returns the effective base URL: resource-level if set, otherwise global.
+    pub fn effective_base_url<'a>(&'a self, global: &'a GlobalConfig) -> Option<&'a str> {
+        self.base_url.as_deref().or(global.base_url.as_deref())
+    }
+
+    /// Returns the effective headers: global defaults merged with resource overrides.
+    pub fn effective_headers(&self, global: &GlobalConfig) -> HashMap<String, String> {
+        let mut headers = global.default_headers.clone().unwrap_or_default();
+        if let Some(ref resource_headers) = self.headers {
+            for (key, value) in resource_headers {
+                headers.insert(key.clone(), value.clone());
+            }
+        }
+        headers
+    }
+
+    /// Returns the effective HTTP method, defaulting to POST.
+    pub fn effective_method(&self) -> &str {
+        self.method.as_deref().unwrap_or("POST")
+    }
+}
diff --git a/src/config/validation.rs b/src/config/validation.rs
new file mode 100644
index 0000000..e3433a0
--- /dev/null
+++ b/src/config/validation.rs
@@ -0,0 +1,138 @@
+use std::collections::HashSet;
+
+use super::SpecFile;
+use crate::graph::DependencyGraph;
+
+/// Validate a spec file and return all errors found.
+/// Returns an empty vec if the spec is valid.
+pub fn validate_spec(spec: &SpecFile) -> Vec<String> {
+    let mut errors = Vec::new();
+
+    let resource_names: HashSet<&str> = spec.resources.iter().map(|r| r.name.as_str()).collect();
+
+    check_duplicate_names(spec, &mut errors);
+    check_action_values(spec, &mut errors);
+    check_depends_on(spec, &resource_names, &mut errors);
+    check_references(spec, &resource_names, &mut errors);
+    check_cycles_via_graph(spec, &mut errors);
+
+    errors
+}
+
+fn check_duplicate_names(spec: &SpecFile, errors: &mut Vec<String>) {
+    let mut seen = HashSet::new();
+    for resource in &spec.resources {
+        if !seen.insert(&resource.name) {
+            errors.push(format!("Duplicate resource name: '{}'", resource.name));
+        }
+    }
+}
+
+fn check_action_values(spec: &SpecFile, errors: &mut Vec<String>) {
+    for resource in &spec.resources {
+        if let Some(ref action) = resource.action
+            && action != "delete"
+        {
+            errors.push(format!(
+                "Resource '{}' has invalid action '{action}' — only 'delete' is supported",
+                resource.name
+            ));
+        }
+    }
+}
+
+fn check_depends_on(spec: &SpecFile, known: &HashSet<&str>, errors: &mut Vec<String>) {
+    for resource in &spec.resources {
+        if let Some(ref deps) = resource.depends_on {
+            for dep in deps {
+                if !known.contains(dep.as_str()) {
+                    errors.push(format!(
+                        "Resource '{}' depends on unknown resource '{dep}'",
+                        resource.name
+                    ));
+                }
+            }
+        }
+    }
+}
+
+fn check_references(spec: &SpecFile, known: &HashSet<&str>, errors: &mut Vec<String>) {
+    for resource in &spec.resources {
+        let mut refs = Vec::new();
+
+        extract_refs_from_string(&resource.endpoint, &mut refs);
+
+        if let Some(ref payload) = resource.payload {
+            extract_references_from_value(payload, &mut refs);
+        }
+
+        if let Some(ref read_ep) = resource.read_endpoint {
+            extract_refs_from_string(read_ep, &mut refs);
+        }
+
+        for (ref_name, ref_expr) in &refs {
+            if !known.contains(ref_name.as_str()) {
+                errors.push(format!(
+                    "Resource '{}' references unknown resource '{ref_name}' via '{ref_expr}'",
+                    resource.name
+                ));
+            }
+        }
+    }
+}
+
+/// Extract `${resource_name.output.field}` references from a JSON value recursively.
+pub fn extract_references_from_value(value: &serde_json::Value, out: &mut Vec<(String, String)>) {
+    match value {
+        serde_json::Value::String(s) => extract_refs_from_string(s, out),
+        serde_json::Value::Object(map) => {
+            for v in map.values() {
+                extract_references_from_value(v, out);
+            }
+        }
+        serde_json::Value::Array(arr) => {
+            for v in arr {
+                extract_references_from_value(v, out);
+            }
+        }
+        _ => {}
+    }
+}
+
+/// Extract reference patterns `${name.output.field}` from a string.
+/// Returns (resource_name, full_expression) pairs.
+pub fn extract_refs_from_string(s: &str, out: &mut Vec<(String, String)>) {
+    let mut search_from = 0;
+    while let Some(start) = s[search_from..].find("${") {
+        let abs_start = search_from + start;
+        if let Some(end) = s[abs_start..].find('}') {
+            let abs_end = abs_start + end;
+            let inner = &s[abs_start + 2..abs_end];
+            let full_expr = format!("${{{inner}}}");
+
+            if let Some(resource_name) = inner.split(".output.").next()
+                && inner.contains(".output.")
+                && !resource_name.is_empty()
+            {
+                out.push((resource_name.to_string(), full_expr));
+            }
+
+            search_from = abs_end + 1;
+        } else {
+            break;
+        }
+    }
+}
+
+fn check_cycles_via_graph(spec: &SpecFile, errors: &mut Vec<String>) {
+    match DependencyGraph::build(&spec.resources) {
+        Ok(graph) => {
+            if let Err(cycle_err) = graph.topological_sort() {
+                errors.push(cycle_err);
+            }
+        }
+        Err(_) => {
+            // build() errors (unknown deps) are already reported by check_depends_on
+        }
+    }
+}
diff --git a/src/graph/mod.rs b/src/graph/mod.rs
new file mode 100644
index 0000000..0f39859
--- /dev/null
+++ b/src/graph/mod.rs
@@ -0,0 +1,135 @@
+use std::collections::HashMap;
+
+use petgraph::graph::DiGraph;
+use petgraph::graph::NodeIndex;
+use petgraph::visit::{EdgeRef, NodeIndexable};
+
+use crate::config::ResourceSpec;
+use crate::config::validation::{extract_references_from_value, extract_refs_from_string};
+
+/// Directed acyclic graph of resource dependencies used for topological ordering.
+#[derive(Debug)]
+pub struct DependencyGraph {
+    graph: DiGraph<String, ()>,
+}
+
+impl DependencyGraph {
+    /// Build a dependency graph from resource specs.
+    ///
+    /// Edges are derived from both explicit `depends_on` declarations
+    /// and implicit `${resource.output.field}` template references found
+    /// in endpoint, payload, and read_endpoint fields.
+    ///
+    /// Returns an error if any dependency target does not exist.
+    pub fn build(resources: &[ResourceSpec]) -> Result<Self, String> {
+        let mut graph = DiGraph::new();
+        let mut node_indices = HashMap::new();
+
+        for r in resources {
+            let idx = graph.add_node(r.name.clone());
+            node_indices.insert(r.name.clone(), idx);
+        }
+
+        for r in resources {
+            let from = node_indices[&r.name];
+
+            // Explicit depends_on
+            if let Some(ref deps) = r.depends_on {
+                for dep in deps {
+                    let to = *node_indices.get(dep.as_str()).ok_or_else(|| {
+                        format!("Resource '{}' depends on unknown resource '{dep}'", r.name)
+                    })?;
+                    // Edge direction: dependency -> dependent (dep is processed before r)
+                    graph.update_edge(to, from, ());
+                }
+            }
+
+            // Implicit dependencies from template references
+            let mut refs: Vec<(String, String)> = Vec::new();
+            extract_refs_from_string(&r.endpoint, &mut refs);
+            if let Some(ref payload) = r.payload {
+                extract_references_from_value(payload, &mut refs);
+            }
+            if let Some(ref read_ep) = r.read_endpoint {
+                extract_refs_from_string(read_ep, &mut refs);
+            }
+
+            for (ref_name, _) in &refs {
+                if let Some(&to) = node_indices.get(ref_name.as_str()) {
+                    // Edge direction: referenced resource -> this resource
+                    graph.update_edge(to, from, ());
+                }
+                // Unknown references are NOT an error here — validation.rs handles that
+            }
+        }
+
+        Ok(Self { graph })
+    }
+
+    /// Return resource names in topological order (dependencies first).
+    ///
+    /// Returns an error with the cycle path if the graph contains a cycle.
+    pub fn topological_sort(&self) -> Result<Vec<String>, String> {
+        match petgraph::algo::toposort(&self.graph, None) {
+            Ok(indices) => Ok(indices.iter().map(|i| self.graph[*i].clone()).collect()),
+            Err(cycle) => {
+                let cycle_path = self.find_cycle_path(cycle.node_id());
+                Err(format!("Circular dependency detected: {cycle_path}"))
+            }
+        }
+    }
+
+    /// Walk the graph from `start` to reconstruct a human-readable cycle path.
+    fn find_cycle_path(&self, start: NodeIndex) -> String {
+        let mut visited = vec![false; self.graph.node_bound()];
+        let mut stack = vec![false; self.graph.node_bound()];
+        let mut path = Vec::new();
+
+        if let Some(cycle) = self.dfs_cycle(start, &mut visited, &mut stack, &mut path) {
+            return cycle;
+        }
+
+        // Fallback: just name the node involved
+        self.graph[start].clone()
+    }
+
+    fn dfs_cycle(
+        &self,
+        node: NodeIndex,
+        visited: &mut [bool],
+        stack: &mut [bool],
+        path: &mut Vec<NodeIndex>,
+    ) -> Option<String> {
+        let idx = self.graph.to_index(node);
+        visited[idx] = true;
+        stack[idx] = true;
+        path.push(node);
+
+        let mut neighbors: Vec<NodeIndex> = self.graph.edges(node).map(|e| e.target()).collect();
+        neighbors.sort_by_key(|n| &self.graph[*n]);
+
+        for neighbor in neighbors {
+            let nidx = self.graph.to_index(neighbor);
+            if stack[nidx] {
+                // Found cycle — extract path from where the cycle starts
+                if let Some(pos) = path.iter().position(|&n| n == neighbor) {
+                    let cycle_names: Vec<&str> = path[pos..]
+                        .iter()
+                        .map(|&n| self.graph[n].as_str())
+                        .collect();
+                    let start_name = self.graph[neighbor].as_str();
+                    return Some(format!("{} -> {start_name}", cycle_names.join(" -> ")));
+                }
+            }
+            if !visited[nidx]
+                && let Some(cycle) = self.dfs_cycle(neighbor, visited, stack, path)
+            {
+                return Some(cycle);
+            }
+        }
+
+        path.pop();
+        stack[idx] = false;
+        None
+    }
+}
diff --git a/src/http/mod.rs b/src/http/mod.rs
new file mode 100644
index 0000000..49362e7
--- /dev/null
+++ b/src/http/mod.rs
@@ -0,0 +1,229 @@
+use std::sync::Arc;
+
+use crate::auth::AuthProvider;
+
+/// HTTP client wrapper around ureq with configurable TLS.
+#[derive(Debug)]
+pub struct HttpClient {
+    agent: ureq::Agent,
+}
+
+impl HttpClient {
+    /// Create a new HTTP client.
+    ///
+    /// - `insecure_tls`: if true, skip TLS certificate verification
+    /// - `ca_bundle`: optional path to a PEM CA bundle file
+    /// - `client_cert`: optional path to a PEM client certificate (for mTLS)
+    /// - `client_key`: optional path to a PEM client private key (for mTLS)
+    pub fn new(
+        insecure_tls: bool,
+        ca_bundle: Option<&str>,
+        client_cert: Option<&str>,
+        client_key: Option<&str>,
+    ) -> Result<Self, String> {
+        let builder = if insecure_tls {
+            if client_cert.is_some() || client_key.is_some() {
+                return Err(
+                    "insecure_tls and mTLS client certificates are mutually exclusive: \
+                     insecure_tls disables certificate verification, which is incompatible with mTLS"
+                        .to_string(),
+                );
+            }
+            let config = rustls::ClientConfig::builder()
+                .dangerous()
+                .with_custom_certificate_verifier(Arc::new(NoVerifier))
+                .with_no_client_auth();
+            ureq::AgentBuilder::new().tls_config(Arc::new(config))
+        } else {
+            let root_store = build_root_store(ca_bundle)?;
+            let config = match (client_cert, client_key) {
+                (Some(cert_path), Some(key_path)) => {
+                    let (certs, key) = load_client_identity(cert_path, key_path)?;
+                    rustls::ClientConfig::builder()
+                        .with_root_certificates(root_store)
+                        .with_client_auth_cert(certs, key)
+                        .map_err(|e| format!("Failed to configure mTLS client auth: {e}"))?
+                }
+                (None, None) => rustls::ClientConfig::builder()
+                    .with_root_certificates(root_store)
+                    .with_no_client_auth(),
+                _ => {
+                    return Err(
+                        "mTLS requires both client_cert_path and client_key_path".to_string()
+                    );
+                }
+            };
+            ureq::AgentBuilder::new().tls_config(Arc::new(config))
+        };
+
+        Ok(Self {
+            agent: builder.build(),
+        })
+    }
+
+    /// Access the underlying ureq Agent (e.g. for auth providers that need to make
+    /// their own HTTP calls with the same TLS configuration).
+    pub fn agent(&self) -> &ureq::Agent {
+        &self.agent
+    }
+
+    /// Send a GET request.
+    pub fn get(
+        &self,
+        url: &str,
+        auth: Option<&dyn AuthProvider>,
+    ) -> Result<ureq::Response, String> {
+        let mut request = self.agent.get(url);
+        if let Some(auth_provider) = auth {
+            request = auth_provider.apply(request)?;
+        }
+        request.call().map_err(|e| format!("GET {url} failed: {e}"))
+    }
+
+    /// Send a request with a JSON body.
+    pub fn send_json(
+        &self,
+        method: &str,
+        url: &str,
+        body: &serde_json::Value,
+        auth: Option<&dyn AuthProvider>,
+    ) -> Result<ureq::Response, String> {
+        let mut request = self.agent.request(method, url);
+        if let Some(auth_provider) = auth {
+            request = auth_provider.apply(request)?;
+        }
+        request
+            .send_json(body)
+            .map_err(|e| format!("{method} {url} failed: {e}"))
+    }
+
+    /// Build a request without sending it.
+    pub fn request(
+        &self,
+        method: &str,
+        url: &str,
+        auth: Option<&dyn AuthProvider>,
+    ) -> Result<ureq::Request, String> {
+        let mut request = self.agent.request(method, url);
+        if let Some(auth_provider) = auth {
+            request = auth_provider.apply(request)?;
+        }
+        Ok(request)
+    }
+}
+
+/// Build a root certificate store, using either a custom CA bundle or webpki defaults.
+fn build_root_store(ca_bundle: Option<&str>) -> Result<rustls::RootCertStore, String> {
+    if let Some(ca_path) = ca_bundle {
+        let pem_data = std::fs::read(ca_path)
+            .map_err(|e| format!("Failed to read CA bundle '{ca_path}': {e}"))?;
+
+        let mut root_store = rustls::RootCertStore::empty();
+        for cert in rustls_pemfile::certs(&mut &pem_data[..]) {
+            let cert = cert.map_err(|e| {
+                format!("Failed to parse certificate in CA bundle '{ca_path}': {e}")
+            })?;
+            root_store.add(cert).map_err(|e| {
+                format!("Failed to add certificate from CA bundle '{ca_path}': {e}")
+            })?;
+        }
+
+        if root_store.is_empty() {
+            return Err(format!(
+                "CA bundle '{ca_path}' contains no valid certificates"
+            ));
+        }
+
+        Ok(root_store)
+    } else {
+        // Default: use webpki-roots
+        let mut root_store = rustls::RootCertStore::empty();
+        root_store.extend(webpki_roots::TLS_SERVER_ROOTS.iter().cloned());
+        Ok(root_store)
+    }
+}
+
+/// Load client certificate chain and private key from PEM files.
+fn load_client_identity(
+    cert_path: &str,
+    key_path: &str,
+) -> Result<
+    (
+        Vec<rustls::pki_types::CertificateDer<'static>>,
+        rustls::pki_types::PrivateKeyDer<'static>,
+    ),
+    String,
+> {
+    let cert_data = std::fs::read(cert_path)
+        .map_err(|e| format!("Failed to read client certificate '{cert_path}': {e}"))?;
+    let certs: Vec<rustls::pki_types::CertificateDer<'static>> =
+        rustls_pemfile::certs(&mut &cert_data[..])
+            .collect::<Result<Vec<_>, _>>()
+            .map_err(|e| format!("Failed to parse client certificate '{cert_path}': {e}"))?;
+
+    if certs.is_empty() {
+        return Err(format!(
+            "Client certificate file '{cert_path}' contains no certificates"
+        ));
+    }
+
+    let key_data = std::fs::read(key_path)
+        .map_err(|e| format!("Failed to read client key '{key_path}': {e}"))?;
+    let key = rustls_pemfile::private_key(&mut &key_data[..])
+        .map_err(|e| format!("Failed to parse client key '{key_path}': {e}"))?
+        .ok_or_else(|| format!("Client key file '{key_path}' contains no private key"))?;
+
+    Ok((certs, key))
+}
+
+/// A TLS certificate verifier that accepts any certificate.
+/// Used only when `--insecure-tls` is explicitly set.
+///
+/// SECURITY: This completely disables TLS server certificate verification.
+/// All methods unconditionally return success, accepting any certificate chain.
+/// This is intentionally dangerous and only enabled via explicit user opt-in.
+#[derive(Debug)]
+struct NoVerifier;
+
+impl rustls::client::danger::ServerCertVerifier for NoVerifier {
+    fn verify_server_cert(
+        &self,
+        _end_entity: &rustls::pki_types::CertificateDer<'_>,
+        _intermediates: &[rustls::pki_types::CertificateDer<'_>],
+        _server_name: &rustls::pki_types::ServerName<'_>,
+        _ocsp_response: &[u8],
+        _now: rustls::pki_types::UnixTime,
+    ) -> Result<rustls::client::danger::ServerCertVerified, rustls::Error> {
+        Ok(rustls::client::danger::ServerCertVerified::assertion())
+    }
+
+    fn verify_tls12_signature(
+        &self,
+        _message: &[u8],
+        _cert: &rustls::pki_types::CertificateDer<'_>,
+        _dss: &rustls::DigitallySignedStruct,
+    ) -> Result<rustls::client::danger::HandshakeSignatureValid, rustls::Error> {
+        Ok(rustls::client::danger::HandshakeSignatureValid::assertion())
+    }
+
+    fn verify_tls13_signature(
+        &self,
+        _message: &[u8],
+        _cert: &rustls::pki_types::CertificateDer<'_>,
+        _dss: &rustls::DigitallySignedStruct,
+    ) -> Result<rustls::client::danger::HandshakeSignatureValid, rustls::Error> {
+        Ok(rustls::client::danger::HandshakeSignatureValid::assertion())
+    }
+
+    fn supported_verify_schemes(&self) -> Vec<rustls::SignatureScheme> {
+        // Cache-friendly: ring's default_provider() is cheap but we avoid
+        // re-computing on every TLS handshake by using a static list.
+        use std::sync::LazyLock;
+        static SCHEMES: LazyLock<Vec<rustls::SignatureScheme>> = LazyLock::new(|| {
+            rustls::crypto::ring::default_provider()
+                .signature_verification_algorithms
+                .supported_schemes()
+        });
+        SCHEMES.clone()
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..205f05c
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,7 @@
+pub mod auth;
+pub mod config;
+pub mod graph;
+pub mod http;
+pub mod logging;
+pub mod reconcile;
+pub mod reference;
diff --git a/src/logging/mod.rs b/src/logging/mod.rs
new file mode 100644
index 0000000..ce396c6
--- /dev/null
+++ b/src/logging/mod.rs
@@ -0,0 +1,125 @@
+use std::collections::BTreeMap;
+use std::fmt::Write as _;
+use std::io::Write;
+
+const SENSITIVE_KEYS: &[&str] = &[
+    "authorization",
+    "token",
+    "password",
+    "api_key",
+    "client_secret",
+    "access_token",
+    "refresh_token",
+    "bearer",
+    "credential",
+    "secret",
+];
+
+const REDACTED: &str = "[REDACTED]";
+
+pub struct Logger {
+    json: bool,
+}
+
+impl Logger {
+    pub fn new(json: bool) -> Self {
+        Self { json }
+    }
+
+    pub fn info(&self, message: &str, kvs: &[(&str, &str)]) {
+        self.log("info", message, kvs);
+    }
+
+    pub fn warn(&self, message: &str, kvs: &[(&str, &str)]) {
+        self.log("warn", message, kvs);
+    }
+
+    pub fn error(&self, message: &str, kvs: &[(&str, &str)]) {
+        self.log("error", message, kvs);
+    }
+
+    /// Format a log line without writing it. Exposed for integration testing only.
+    #[doc(hidden)]
+    pub fn format_line(&self, level: &str, message: &str, kvs: &[(&str, &str)]) -> String {
+        if self.json {
+            self.format_json(level, message, kvs)
+        } else {
+            self.format_text(level, message, kvs)
+        }
+    }
+
+    fn log(&self, level: &str, message: &str, kvs: &[(&str, &str)]) {
+        let line = self.format_line(level, message, kvs);
+        let _ = writeln!(std::io::stderr(), "{line}");
+    }
+
+    fn format_text(&self, level: &str, message: &str, kvs: &[(&str, &str)]) -> String {
+        let level_upper = level.to_uppercase();
+        let mut out = format!("[{level_upper}] {message}");
+        for &(key, value) in kvs {
+            let redacted_value = redact_value(key, value);
+            let _ = write!(out, " {key}={redacted_value}");
+        }
+        out
+    }
+
+    fn format_json(&self, level: &str, message: &str, kvs: &[(&str, &str)]) -> String {
+        let mut map = BTreeMap::new();
+        map.insert(
+            "level".to_string(),
+            serde_json::Value::String(level.to_string()),
+        );
+        map.insert(
+            "message".to_string(),
+            serde_json::Value::String(message.to_string()),
+        );
+        for &(key, value) in kvs {
+            let redacted_value = redact_value(key, value);
+            map.insert(key.to_string(), serde_json::Value::String(redacted_value));
+        }
+        // Note: BTreeMap<String, serde_json::Value::String> serialization is infallible.
+        serde_json::to_string(&map)
+            .expect("BTreeMap<String, Value::String> serialization is infallible")
+    }
+}
+
+fn is_sensitive_key(key: &str) -> bool {
+    let lower = key.to_lowercase();
+    SENSITIVE_KEYS.iter().any(|s| lower.contains(s))
+}
+
+fn redact_value(key: &str, value: &str) -> String {
+    if is_sensitive_key(key) {
+        REDACTED.to_string()
+    } else {
+        value.to_string()
+    }
+}
+
+/// Redact sensitive query parameters from a URL.
+///
+/// Parameters whose keys contain a sensitive pattern have their values
+/// replaced with `[REDACTED]`. Non-sensitive parameters and URLs without
+/// query strings are returned unchanged.
+pub fn redact_url(url: &str) -> String {
+    let Some((base, query)) = url.split_once('?') else {
+        return url.to_string();
+    };
+
+    let redacted_params: Vec<String> = query
+        .split('&')
+        .map(|param| {
+            if let Some((key, _value)) = param.split_once('=') {
+                if is_sensitive_key(key) {
+                    format!("{key}={REDACTED}")
+                } else {
+                    param.to_string()
+                }
+            } else {
+                param.to_string()
+            }
+        })
+        .collect();
+
+    format!("{base}?{}", redacted_params.join("&"))
+}
diff --git a/src/main.rs b/src/main.rs
index 3fc0d1c..e2b16e9 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,3 +1,140 @@
-fn main() {
-    println!("restium — declarative reconciling REST client");
+use std::process::ExitCode;
+
+use clap::{Parser, Subcommand};
+
+use restium::auth;
+use restium::config::{AuthConfig, SpecFile, validate_spec};
+use restium::http::HttpClient;
+use restium::logging::Logger;
+use restium::reconcile;
+
+#[derive(Parser)]
+#[command(name = "restium", about = "A declarative reconciling REST client")]
+struct Cli {
+    #[arg(long, env = "RESTIUM_JSON", help = "Enable structured JSON log output")]
+    json: bool,
+
+    #[arg(
+        long,
+        env = "RESTIUM_INSECURE_TLS",
+        help = "Skip TLS certificate verification"
+    )]
+    insecure_tls: bool,
+
+    #[arg(
+        long,
+        env = "RESTIUM_SIDECAR",
+        help = "Keep process alive after completion"
+    )]
+    sidecar: bool,
+
+    #[command(subcommand)]
+    command: Commands,
+}
+
+#[derive(Subcommand)]
+enum Commands {
+    /// Converge API state to match the spec
+    Reconcile {
+        #[arg(long, env = "RESTIUM_SPEC", help = "Path to YAML spec file")]
+        spec: String,
+    },
+    /// Validate spec file without making API calls
+    Validate {
+        #[arg(long, env = "RESTIUM_SPEC", help = "Path to YAML spec file")]
+        spec: String,
+    },
+}
+
+fn load_and_validate(spec_path: &str, logger: &Logger) -> Result<SpecFile, (u8, String)> {
+    let spec_file = SpecFile::load(spec_path).map_err(|e| (2u8, e))?;
+    let errors = validate_spec(&spec_file);
+    if !errors.is_empty() {
+        for err in &errors {
+            logger.error(err, &[]);
+        }
+        return Err((2, format!("{} validation error(s) found", errors.len())));
+    }
+    Ok(spec_file)
+}
+
+/// Extract mTLS cert/key paths from the global auth config, if mTLS is configured.
+fn extract_mtls_paths(spec: &SpecFile) -> (Option<&str>, Option<&str>) {
+    match &spec.global.auth {
+        Some(AuthConfig::Mtls {
+            client_cert_path,
+            client_key_path,
+        }) => (
+            Some(client_cert_path.as_str()),
+            Some(client_key_path.as_str()),
+        ),
+        _ => (None, None),
+    }
+}
+
+fn create_http_client(spec: &SpecFile, insecure_tls: bool) -> Result<HttpClient, (u8, String)> {
+    let (mtls_cert, mtls_key) = extract_mtls_paths(spec);
+    HttpClient::new(
+        insecure_tls,
+        spec.global.ca_bundle.as_deref(),
+        mtls_cert,
+        mtls_key,
+    )
+    .map_err(|e| (2u8, e))
+}
+
+fn execute(command: Commands, insecure_tls: bool, logger: &Logger) -> Result<(), (u8, String)> {
+    match command {
+        Commands::Reconcile { spec } => {
+            let spec_file = load_and_validate(&spec, logger)?;
+            let client = create_http_client(&spec_file, insecure_tls)?;
+
+            let auth_provider = match &spec_file.global.auth {
+                Some(config) => {
+                    let provider = auth::create_auth_provider(config, Some(client.agent()))
+                        .map_err(|e| (2u8, e))?;
+                    Some(provider)
+                }
+                None => None,
+            };
+
+            let auth_ref = auth_provider
+                .as_ref()
+                .map(|p| p.as_ref() as &dyn restium::auth::AuthProvider);
+
+            reconcile::reconcile(&spec_file, &client, auth_ref, logger).map_err(|e| (1u8, e))
+        }
+        Commands::Validate { spec } => {
+            let spec_file = load_and_validate(&spec, logger)?;
+            let count = spec_file.resources.len();
+            logger.info("Validation passed", &[("resources", &count.to_string())]);
+            Ok(())
+        }
+    }
+}
+
+fn main() -> ExitCode {
+    let cli = Cli::parse();
+    let logger = Logger::new(cli.json);
+
+    let result = execute(cli.command, cli.insecure_tls, &logger);
+
+    if cli.sidecar {
+        match &result {
+            Ok(()) => logger.info("Reconciliation complete", &[]),
+            Err((_, message)) => logger.error(message, &[]),
+        }
+        logger.info("Sidecar mode: process will stay alive", &[]);
+        loop {
+            std::thread::park();
+        }
+    } else {
+        match result {
+            Ok(()) => ExitCode::SUCCESS,
+            Err((code, message)) => {
+                logger.error(&message, &[]);
+                ExitCode::from(code)
+            }
+        }
+    }
 }
diff --git a/src/reconcile/diff.rs b/src/reconcile/diff.rs
new file mode 100644
index 0000000..79171c4
--- /dev/null
+++ b/src/reconcile/diff.rs
@@ -0,0 +1,23 @@
+use serde_json::Value;
+
+/// Compare two JSON values for equality with key-order-independent object comparison.
+///
+/// - Objects: keys are compared regardless of order (semantic equality).
+/// - Arrays: elements are compared in order (order IS significant).
+/// - Primitives: standard equality.
+pub fn json_equal(a: &Value, b: &Value) -> bool {
+    match (a, b) {
+        (Value::Object(a_map), Value::Object(b_map)) => {
+            if a_map.len() != b_map.len() {
+                return false;
+            }
+            a_map
+                .iter()
+                .all(|(k, v)| b_map.get(k).is_some_and(|bv| json_equal(v, bv)))
+        }
+        (Value::Array(a_arr), Value::Array(b_arr)) => {
+            a_arr.len() == b_arr.len() && a_arr.iter().zip(b_arr).all(|(av, bv)| json_equal(av, bv))
+        }
+        _ => a == b,
+    }
+}
diff --git a/src/reconcile/execute.rs b/src/reconcile/execute.rs
new file mode 100644
index 0000000..70d8fdf
--- /dev/null
+++ b/src/reconcile/execute.rs
@@ -0,0 +1,190 @@
+use crate::auth::AuthProvider;
+use crate::http::HttpClient;
+use crate::logging::Logger;
+use crate::reconcile::ResourceAction;
+
+/// Context for executing a resource action.
+pub struct ExecuteContext<'a> {
+    pub client: &'a HttpClient,
+    pub resource_name: &'a str,
+    pub endpoint: &'a str,
+    pub method: &'a str,
+    pub payload: Option<&'a serde_json::Value>,
+    pub auth: Option<&'a dyn AuthProvider>,
+    pub logger: &'a Logger,
+}
+
+/// Result of executing an action, distinguishing success outcomes.
+#[derive(Debug)]
+pub enum ExecuteResult {
+    /// Action performed, response body available for output extraction.
+    Performed(Option<serde_json::Value>),
+    /// Resource was already in desired state (skip or delete-404).
+    AlreadyOk,
+}
+
+/// Execute a reconciliation action for a resource.
+pub fn execute_action(
+    ctx: &ExecuteContext<'_>,
+    action: &ResourceAction,
+) -> Result<ExecuteResult, String> {
+    match action {
+        ResourceAction::Skip => {
+            ctx.logger.info(
+                "Resource already matches desired state",
+                &[("resource", ctx.resource_name), ("action", "skip")],
+            );
+            Ok(ExecuteResult::AlreadyOk)
+        }
+        ResourceAction::Create => {
+            let body = ctx.payload.ok_or_else(|| {
+                format!(
+                    "Resource '{}' has no payload for create operation",
+                    ctx.resource_name
+                )
+            })?;
+            execute_mutation(ctx, ctx.method, body, "create")
+        }
+        ResourceAction::Update { .. } => {
+            let body = ctx.payload.ok_or_else(|| {
+                format!(
+                    "Resource '{}' has no payload for update operation",
+                    ctx.resource_name
+                )
+            })?;
+            let update_method = if ctx.method.eq_ignore_ascii_case("POST") {
+                "PUT"
+            } else {
+                ctx.method
+            };
+            execute_mutation(ctx, update_method, body, "update")
+        }
+        ResourceAction::Delete => execute_delete(ctx),
+    }
+}
+
+fn execute_mutation(
+    ctx: &ExecuteContext<'_>,
+    method: &str,
+    body: &serde_json::Value,
+    action_name: &str,
+) -> Result<ExecuteResult, String> {
+    match ctx.client.send_json(method, ctx.endpoint, body, ctx.auth) {
+        Ok(response) => {
+            let status = response.status();
+            let status_str = status.to_string();
+            // Parse response body before logging success — a 2xx with non-JSON body
+            // is treated as success with no response body available for output extraction.
+            let response_body: Option<serde_json::Value> = response.into_json().ok();
+            ctx.logger.info(
+                &format!("Resource {action_name}d successfully"),
+                &[
+                    ("resource", ctx.resource_name),
+                    ("action", action_name),
+                    ("method", method),
+                    ("endpoint", ctx.endpoint),
+                    ("status", &status_str),
+                ],
+            );
+            Ok(ExecuteResult::Performed(response_body))
+        }
+        Err(err) => Err(format_action_error(
+            action_name,
+            ctx.resource_name,
+            method,
+            ctx.endpoint,
+            &err,
+        )),
+    }
+}
+
+fn execute_delete(ctx: &ExecuteContext<'_>) -> Result<ExecuteResult, String> {
+    let request = ctx.client.request("DELETE", ctx.endpoint, ctx.auth)?;
+    match request.call() {
+        Ok(response) => {
+            let status = response.status().to_string();
+            ctx.logger.info(
+                "Resource deleted successfully",
+                &[
+                    ("resource", ctx.resource_name),
+                    ("action", "delete"),
+                    ("method", "DELETE"),
+                    ("endpoint", ctx.endpoint),
+                    ("status", &status),
+                ],
+            );
+            Ok(ExecuteResult::Performed(None))
+        }
+        Err(ureq::Error::Status(404, _)) => {
+            ctx.logger.info(
+                "Resource already absent, skipping delete",
+                &[
+                    ("resource", ctx.resource_name),
+                    ("action", "delete"),
+                    ("reason", "already absent"),
+                ],
+            );
+            Ok(ExecuteResult::AlreadyOk)
+        }
+        Err(ureq::Error::Status(code, response)) => {
+            let status_text = response.status_text().to_string();
+            let error = format!("{code} {status_text}");
+            Err(format_action_error(
+                "delete",
+                ctx.resource_name,
+                "DELETE",
+                ctx.endpoint,
+                &error,
+            ))
+        }
+        Err(e) => Err(format_action_error(
+            "delete",
+            ctx.resource_name,
+            "DELETE",
+            ctx.endpoint,
+            &e.to_string(),
+        )),
+    }
+}
+
+/// Format an actionable error message following the architecture pattern.
+///
+/// Format: "Failed to {action} resource '{name}': {details} on {method} {endpoint} — {hint}"
+fn format_action_error(
+    action: &str,
+    resource_name: &str,
+    method: &str,
+    endpoint: &str,
+    error: &str,
+) -> String {
+    let hint = error_hint(error);
+    format!(
+        "Failed to {action} resource '{resource_name}': {error} on {method} {endpoint} — {hint}"
+    )
+}
+
+/// Map common error patterns to actionable hints.
+fn error_hint(error: &str) -> &'static str {
+    // Check transport errors first to avoid false matches on status-code digits in URLs
+    if error.contains("timeout") || error.contains("timed out") {
+        "request timed out, check network connectivity"
+    } else if error.contains("connection") {
+        "connection failed, check network and endpoint URL"
+    } else if error.contains("401") {
+        "check authentication credentials"
+    } else if error.contains("403") {
+        "check authentication token permissions"
+    } else if error.contains("404") {
+        "resource or endpoint may not exist"
+    } else if error.contains("409") {
+        "resource may already exist or conflict with existing state"
+    } else if error.contains("422") {
+        "check request payload format and required fields"
+    } else if error.contains("429") {
+        "rate limited, try again later"
+    } else if error.contains("500") || error.contains("502") || error.contains("503") {
+        "server error, check API health"
+    } else {
+        "check API documentation and endpoint configuration"
+    }
+}
diff --git a/src/reconcile/mod.rs b/src/reconcile/mod.rs
new file mode 100644
index 0000000..190c684
--- /dev/null
+++ b/src/reconcile/mod.rs
@@ -0,0 +1,308 @@
+pub mod diff;
+pub mod execute;
+pub mod state;
+
+use std::collections::HashMap;
+
+use crate::auth::{self, AuthProvider};
+use crate::config::{ResourceSpec, SpecFile};
+use crate::graph::DependencyGraph;
+use crate::http::HttpClient;
+use crate::logging::Logger;
+use crate::reference::{self, OutputStore};
+
+use execute::{ExecuteContext, ExecuteResult, execute_action};
+
+/// The action to take for a resource during reconciliation.
+#[derive(Debug, PartialEq)]
+pub enum ResourceAction {
+    /// Resource does not exist in the API — send a create request.
+    Create,
+    /// Resource exists but differs from desired state — send an update request.
+    Update { actual: serde_json::Value },
+    /// Resource matches desired state — no operation needed.
+    Skip,
+    /// Resource is marked for deletion.
+    Delete,
+}
+
+/// Determine the action for a resource by comparing desired state against actual state.
+///
+/// - `actual` is `None` when the resource does not exist (GET returned 404).
+/// - When `actual` matches `desired` (key-order-independent), the resource is skipped.
+/// - When `actual` differs from `desired`, the resource needs an update.
+pub fn compute_action(
+    desired: &serde_json::Value,
+    actual: Option<&serde_json::Value>,
+) -> ResourceAction {
+    match actual {
+        None => ResourceAction::Create,
+        Some(actual_val) => {
+            if diff::json_equal(desired, actual_val) {
+                ResourceAction::Skip
+            } else {
+                ResourceAction::Update {
+                    actual: actual_val.clone(),
+                }
+            }
+        }
+    }
+}
+
+/// Reconciliation summary counters.
+struct Summary {
+    created: u32,
+    updated: u32,
+    deleted: u32,
+    skipped: u32,
+    failed: u32,
+}
+
+/// Orchestrate reconciliation of all resources in a spec file.
+///
+/// Parses the dependency graph, sorts topologically, and for each resource:
+/// resolves references → discovers state → computes action → executes → extracts outputs.
+///
+/// Delete resources are processed in reverse topological order.
+/// Returns `Ok(())` if all resources succeed, `Err` if any fail.
+pub fn reconcile(
+    spec: &SpecFile,
+    client: &HttpClient,
+    auth: Option<&dyn AuthProvider>,
+    logger: &Logger,
+) -> Result<(), String> {
+    let graph = DependencyGraph::build(&spec.resources)?;
+    let topo_order = graph.topological_sort()?;
+
+    let resource_map: HashMap<&str, &ResourceSpec> = spec
+        .resources
+        .iter()
+        .map(|r| (r.name.as_str(), r))
+        .collect();
+
+    let mut output_store = OutputStore::new();
+    let mut summary = Summary {
+        created: 0,
+        updated: 0,
+        deleted: 0,
+        skipped: 0,
+        failed: 0,
+    };
+    let mut errors: Vec<String> = Vec::new();
+
+    // Separate delete and non-delete resources
+    let (non_delete_order, delete_order): (Vec<&str>, Vec<&str>) =
+        topo_order.iter().map(|s| s.as_str()).partition(|name| {
+            resource_map.get(name).and_then(|r| r.action.as_deref()) != Some("delete")
+        });
+
+    // Process non-delete resources in topological order
+    for name in &non_delete_order {
+        let resource = resource_map[name];
+        let resource_auth = resolve_resource_auth(resource, client, auth)?;
+        let effective_auth = resource_auth.as_deref().or(auth);
+        if let Err(e) = process_resource(
+            resource,
+            spec,
+            client,
+            effective_auth,
+            logger,
+            &mut output_store,
+            &mut summary,
+        ) {
+            summary.failed += 1;
+            logger.error(&e, &[("resource", name)]);
+            errors.push(e);
+        }
+    }
+
+    // Process delete resources in reverse topological order
+    for name in delete_order.iter().rev() {
+        let resource = resource_map[name];
+        let resource_auth = resolve_resource_auth(resource, client, auth)?;
+        let effective_auth = resource_auth.as_deref().or(auth);
+        if let Err(e) = process_delete_resource(
+            resource,
+            spec,
+            client,
+            effective_auth,
+            logger,
+            &output_store,
+            &mut summary,
+        ) {
+            summary.failed += 1;
+            logger.error(&e, &[("resource", name)]);
+            errors.push(e);
+        }
+    }
+
+    // Log summary
+    let created_s = summary.created.to_string();
+    let updated_s = summary.updated.to_string();
+    let deleted_s = summary.deleted.to_string();
+    let skipped_s = summary.skipped.to_string();
+    let failed_s = summary.failed.to_string();
+    logger.info(
+        "Reconciliation complete",
+        &[
+            ("created", &created_s),
+            ("updated", &updated_s),
+            ("deleted", &deleted_s),
+            ("skipped", &skipped_s),
+            ("failed", &failed_s),
+        ],
+    );
+
+    if errors.is_empty() {
+        Ok(())
+    } else {
+        Err(format!(
+            "{} resource(s) failed during reconciliation",
+            errors.len()
+        ))
+    }
+}
+
+/// Resolve per-resource auth override. Returns `Some(provider)` if the resource
+/// has its own auth config, `None` to fall back to global auth.
+fn resolve_resource_auth(
+    resource: &ResourceSpec,
+    client: &HttpClient,
+    _global_auth: Option<&dyn AuthProvider>,
+) -> Result<Option<Box<dyn AuthProvider>>, String> {
+    match &resource.auth {
+        Some(config) => {
+            let provider =
+                auth::create_auth_provider(config, Some(client.agent())).map_err(|e| {
+                    format!(
+                        "Resource '{}' auth configuration failed: {e}",
+                        resource.name
+                    )
+                })?;
+            Ok(Some(provider))
+        }
+        None => Ok(None),
+    }
+}
+
+fn process_resource(
+    resource: &ResourceSpec,
+    spec: &SpecFile,
+    client: &HttpClient,
+    auth: Option<&dyn AuthProvider>,
+    logger: &Logger,
+    output_store: &mut OutputStore,
+    summary: &mut Summary,
+) -> Result<(), String> {
+    let base_url = resource
+        .effective_base_url(&spec.global)
+        .unwrap_or_default();
+
+    // Resolve references in endpoint
+    let resolved_endpoint =
+        reference::resolve_string(&format!("{base_url}{}", resource.endpoint), output_store)?;
+
+    // Resolve references in payload
+    let resolved_payload = match &resource.payload {
+        Some(p) => Some(reference::resolve_references(p, output_store)?),
+        None => None,
+    };
+
+    // Skip state discovery if there is no payload (nothing to compare or send)
+    let actual = if resolved_payload.is_some() {
+        if let Some(ref read_ep) = resource.read_endpoint {
+            let resolved_read_ep =
+                reference::resolve_string(&format!("{base_url}{read_ep}"), output_store)?;
+            state::discover_state(client, &resolved_read_ep, auth)?
+        } else {
+            None
+        }
+    } else {
+        None
+    };
+
+    // Compute action
+    let action = if let Some(ref payload) = resolved_payload {
+        compute_action(payload, actual.as_ref())
+    } else {
+        ResourceAction::Skip
+    };
+
+    // Execute action
+    let ctx = ExecuteContext {
+        client,
+        resource_name: &resource.name,
+        endpoint: &resolved_endpoint,
+        method: resource.effective_method(),
+        payload: resolved_payload.as_ref(),
+        auth,
+        logger,
+    };
+
+    let result = execute_action(&ctx, &action)?;
+
+    // Update summary and extract response body
+    let response_body = match result {
+        ExecuteResult::Performed(body) => {
+            match action {
+                ResourceAction::Create => summary.created += 1,
+                ResourceAction::Update { .. } => summary.updated += 1,
+                ResourceAction::Skip => summary.skipped += 1,
+                // Delete resources are handled by process_delete_resource
+                ResourceAction::Delete => {
+                    unreachable!("delete resources use process_delete_resource")
+                }
+            }
+            body
+        }
+        ExecuteResult::AlreadyOk => {
+            summary.skipped += 1;
+            None
+        }
+    };
+
+    // Extract outputs if configured
+    if let Some(ref output_rules) = resource.outputs {
+        if let Some(ref body) = response_body {
+            reference::extract_outputs(output_store, &resource.name, body, output_rules)?;
+        } else if let Some(ref actual_body) = actual {
+            // For skipped resources, extract from the actual state
+            reference::extract_outputs(output_store, &resource.name, actual_body, output_rules)?;
+        }
+    }
+
+    Ok(())
+}
+
+fn process_delete_resource(
+    resource: &ResourceSpec,
+    spec: &SpecFile,
+    client: &HttpClient,
+    auth: Option<&dyn AuthProvider>,
+    logger: &Logger,
+    output_store: &OutputStore,
+    summary: &mut Summary,
+) -> Result<(), String> {
+    let base_url = resource
+        .effective_base_url(&spec.global)
+        .unwrap_or_default();
+    let endpoint =
+        reference::resolve_string(&format!("{base_url}{}", resource.endpoint), output_store)?;
+
+    let ctx = ExecuteContext {
+        client,
+        resource_name: &resource.name,
+        endpoint: &endpoint,
+        method: "DELETE",
+        payload: None,
+        auth,
+        logger,
+    };
+
+    match execute_action(&ctx, &ResourceAction::Delete)? {
+        ExecuteResult::Performed(_) => summary.deleted += 1,
+        ExecuteResult::AlreadyOk => summary.skipped += 1,
+    }
+
+    Ok(())
+}
diff --git a/src/reconcile/state.rs b/src/reconcile/state.rs
new file mode 100644
index 0000000..2cdf2da
--- /dev/null
+++ b/src/reconcile/state.rs
@@ -0,0 +1,30 @@
+use crate::auth::AuthProvider;
+use crate::http::HttpClient;
+
+/// Discover the current state of a resource by sending a GET request.
+///
+/// - Returns `Ok(Some(value))` if the resource exists (HTTP 200).
+/// - Returns `Ok(None)` if the resource does not exist (HTTP 404).
+/// - Returns `Err` for unexpected status codes or network errors.
+pub fn discover_state(
+    client: &HttpClient,
+    url: &str,
+    auth: Option<&dyn AuthProvider>,
+) -> Result<Option<serde_json::Value>, String> {
+    let request = client.request("GET", url, auth)?;
+
+    match request.call() {
+        Ok(response) => {
+            let body: serde_json::Value = response
+                .into_json()
+                .map_err(|e| format!("Failed to parse JSON response from GET {url}: {e}"))?;
+            Ok(Some(body))
+        }
+        Err(ureq::Error::Status(404, _)) => Ok(None),
+        Err(ureq::Error::Status(code, response)) => {
+            let status = response.status_text().to_string();
+            Err(format!("Unexpected status {code} {status} on GET {url}"))
+        }
+        Err(e) => Err(format!("GET {url} failed: {e}")),
+    }
+}
diff --git a/src/reference/mod.rs b/src/reference/mod.rs
new file mode 100644
index 0000000..35a54ac
--- /dev/null
+++ b/src/reference/mod.rs
@@ -0,0 +1,117 @@
+use std::collections::HashMap;
+
+use serde_json::Value;
+
+/// Maps resource_name → (field_name → extracted_value).
+pub type OutputStore = HashMap<String, HashMap<String, String>>;
+
+/// Extract output fields from an API response body and store them.
+///
+/// `output_rules` maps output_key → json_field_path (currently top-level fields only).
+pub fn extract_outputs(
+    store: &mut OutputStore,
+    resource_name: &str,
+    response_body: &Value,
+    output_rules: &HashMap<String, String>,
+) -> Result<(), String> {
+    let mut outputs = HashMap::new();
+
+    for (output_key, json_field) in output_rules {
+        let value = response_body.get(json_field).ok_or_else(|| {
+            format!(
+                "Resource '{resource_name}': output field '{json_field}' not found in API response"
+            )
+        })?;
+
+        let string_value = match value {
+            Value::String(s) => s.clone(),
+            Value::Number(n) => n.to_string(),
+            Value::Bool(b) => b.to_string(),
+            Value::Null => "null".to_string(),
+            other => other.to_string(),
+        };
+
+        outputs.insert(output_key.clone(), string_value);
+    }
+
+    store.insert(resource_name.to_string(), outputs);
+    Ok(())
+}
+
+/// Resolve all `${resource.output.field}` references in a JSON value.
+///
+/// Recursively walks the value tree and substitutes references in strings.
+pub fn resolve_references(value: &Value, outputs: &OutputStore) -> Result<Value, String> {
+    match value {
+        Value::String(s) => {
+            let resolved = resolve_string(s, outputs)?;
+            Ok(Value::String(resolved))
+        }
+        Value::Object(map) => {
+            let mut result = serde_json::Map::new();
+            for (k, v) in map {
+                result.insert(k.clone(), resolve_references(v, outputs)?);
+            }
+            Ok(Value::Object(result))
+        }
+        Value::Array(arr) => {
+            let result: Result<Vec<Value>, String> =
+                arr.iter().map(|v| resolve_references(v, outputs)).collect();
+            Ok(Value::Array(result?))
+        }
+        other => Ok(other.clone()),
+    }
+}
+
+/// Resolve `${resource.output.field}` references in a string.
+pub fn resolve_string(s: &str, outputs: &OutputStore) -> Result<String, String> {
+    let mut result = String::with_capacity(s.len());
+    let mut search_from = 0;
+
+    while let Some(start) = s[search_from..].find("${") {
+        let abs_start = search_from + start;
+        result.push_str(&s[search_from..abs_start]);
+
+        if let Some(end) = s[abs_start..].find('}') {
+            let abs_end = abs_start + end;
+            let inner = &s[abs_start + 2..abs_end];
+
+            if let Some((resource_name, field_name)) = parse_reference(inner) {
+                let resource_outputs = outputs.get(resource_name).ok_or_else(|| {
+                    format!(
+                        "Cannot resolve reference '${{{inner}}}': resource '{resource_name}' has not been processed yet"
+                    )
+                })?;
+
+                let value = resource_outputs.get(field_name).ok_or_else(|| {
+                    format!(
+                        "Cannot resolve reference '${{{inner}}}': resource '{resource_name}' has no output field '{field_name}'"
+                    )
+                })?;
+
+                result.push_str(value);
+            } else {
+                // Not a valid reference pattern, keep as-is
+                result.push_str(&s[abs_start..=abs_end]);
+            }
+
+            search_from = abs_end + 1;
+        } else {
+            // No closing brace, keep remainder as-is
+            result.push_str(&s[abs_start..]);
+            return Ok(result);
+        }
+    }
+
+    result.push_str(&s[search_from..]);
+    Ok(result)
+}
+
+/// Parse `resource_name.output.field_name` from the inner part of `${...}`.
+fn parse_reference(inner: &str) -> Option<(&str, &str)> {
+    let (resource_name, rest) = inner.split_once(".output.")?;
+    if resource_name.is_empty() || rest.is_empty() {
+        return None;
+    }
+    Some((resource_name, rest))
+}
diff --git a/tests/auth_test.rs b/tests/auth_test.rs
new file mode 100644
index 0000000..6c44dc9
--- /dev/null
+++ b/tests/auth_test.rs
@@ -0,0 +1,289 @@
+use base64::Engine;
+
+use restium::auth::{
+    ApiKeyAuthProvider, AuthProvider, BasicAuthProvider, BearerAuthProvider, OidcAuthProvider,
+    create_auth_provider,
+};
+use restium::config::AuthConfig;
+
+#[test]
+fn bearer_provider_reads_env_var() {
+    unsafe { std::env::set_var("TEST_BEARER_1", "my-secret-token") };
+    let provider = BearerAuthProvider::new("TEST_BEARER_1").expect("should succeed");
+
+    let agent = ureq::agent();
+    let request = agent.get("https://example.com/api");
+    let request = provider.apply(request).expect("apply should succeed");
+
+    // Verify the Authorization header was set
+    assert_eq!(
+        request.header("Authorization"),
+        Some("Bearer my-secret-token")
+    );
+    unsafe { std::env::remove_var("TEST_BEARER_1") };
+}
+
+#[test]
+fn bearer_provider_fails_when_env_var_missing() {
+    unsafe { std::env::remove_var("TEST_BEARER_MISSING") };
+    let result = BearerAuthProvider::new("TEST_BEARER_MISSING");
+    assert!(result.is_err());
+    let err = result.unwrap_err();
+    assert!(
+        err.contains("TEST_BEARER_MISSING"),
+        "should mention the env var name, got: {err}"
+    );
+    assert!(err.contains("not set"), "should say not set, got: {err}");
+}
+
+#[test]
+fn basic_provider_reads_env_vars_and_encodes() {
+    unsafe {
+        std::env::set_var("TEST_BASIC_USER_1", "admin");
+        std::env::set_var("TEST_BASIC_PASS_1", "secret123");
+    }
+    let provider =
+        BasicAuthProvider::new("TEST_BASIC_USER_1", "TEST_BASIC_PASS_1").expect("should succeed");
+
+    let agent = ureq::agent();
+    let request = agent.get("https://example.com/api");
+    let request = provider.apply(request).expect("apply should succeed");
+
+    let expected = base64::engine::general_purpose::STANDARD.encode("admin:secret123");
+    assert_eq!(
+        request.header("Authorization"),
+        Some(format!("Basic {expected}").as_str())
+    );
+
+    unsafe {
+        std::env::remove_var("TEST_BASIC_USER_1");
+        std::env::remove_var("TEST_BASIC_PASS_1");
+    }
+}
+
+#[test]
+fn basic_provider_fails_when_username_env_missing() {
+    unsafe {
+        std::env::remove_var("TEST_BASIC_USER_MISSING");
+        std::env::set_var("TEST_BASIC_PASS_2", "pass");
+    }
+    let result = BasicAuthProvider::new("TEST_BASIC_USER_MISSING", "TEST_BASIC_PASS_2");
+    assert!(result.is_err());
+    let err = result.unwrap_err();
+    assert!(
+        err.contains("TEST_BASIC_USER_MISSING"),
+        "should mention the env var, got: {err}"
+    );
+    unsafe { std::env::remove_var("TEST_BASIC_PASS_2") };
+}
+
+#[test]
+fn basic_provider_fails_when_password_env_missing() {
+    unsafe {
+        std::env::set_var("TEST_BASIC_USER_3", "user");
+        std::env::remove_var("TEST_BASIC_PASS_MISSING");
+    }
+    let result = BasicAuthProvider::new("TEST_BASIC_USER_3", "TEST_BASIC_PASS_MISSING");
+    assert!(result.is_err());
+    let err = result.unwrap_err();
+    assert!(
+        err.contains("TEST_BASIC_PASS_MISSING"),
+        "should mention the env var, got: {err}"
+    );
+    unsafe { std::env::remove_var("TEST_BASIC_USER_3") };
+}
+
+#[test]
+fn basic_encoding_is_correct() {
+    unsafe {
+        std::env::set_var("TEST_BASIC_USER_4", "user");
+        std::env::set_var("TEST_BASIC_PASS_4", "pass");
+    }
+    let provider =
+        BasicAuthProvider::new("TEST_BASIC_USER_4", "TEST_BASIC_PASS_4").expect("should succeed");
+
+    let agent = ureq::agent();
+    let request = agent.get("https://example.com");
+    let request = provider.apply(request).expect("apply");
+
+    // "user:pass" base64 = "dXNlcjpwYXNz"
+    assert_eq!(request.header("Authorization"), Some("Basic dXNlcjpwYXNz"));
+
+    unsafe {
+        std::env::remove_var("TEST_BASIC_USER_4");
+        std::env::remove_var("TEST_BASIC_PASS_4");
+    }
+}
+
+#[test]
+fn create_auth_provider_bearer() {
+    unsafe { std::env::set_var("TEST_FACTORY_BEARER", "token123") };
+    let config = AuthConfig::Bearer {
+        token_env: "TEST_FACTORY_BEARER".to_string(),
+    };
+    let provider = create_auth_provider(&config, None);
+    assert!(provider.is_ok(), "should create bearer provider");
+    unsafe { std::env::remove_var("TEST_FACTORY_BEARER") };
+}
+
+#[test]
+fn create_auth_provider_basic() {
+    unsafe {
+        std::env::set_var("TEST_FACTORY_USER", "u");
+        std::env::set_var("TEST_FACTORY_PASS", "p");
+    }
+    let config = AuthConfig::Basic {
+        username_env: "TEST_FACTORY_USER".to_string(),
+        password_env: "TEST_FACTORY_PASS".to_string(),
+    };
+    let provider = create_auth_provider(&config, None);
+    assert!(provider.is_ok(), "should create basic provider");
+    unsafe {
+        std::env::remove_var("TEST_FACTORY_USER");
+        std::env::remove_var("TEST_FACTORY_PASS");
+    }
+}
+
+#[test]
+fn api_key_header_mode_sets_header() {
+    unsafe { std::env::set_var("TEST_APIKEY_1", "my-api-key-value") };
+    let provider =
+        ApiKeyAuthProvider::new("TEST_APIKEY_1", Some("X-API-Key"), None).expect("should succeed");
+
+    let agent = ureq::agent();
+    let request = agent.get("https://example.com/api");
+    let request = provider.apply(request).expect("apply");
+
+    assert_eq!(request.header("X-API-Key"), Some("my-api-key-value"));
+    unsafe { std::env::remove_var("TEST_APIKEY_1") };
+}
+
+#[test]
+fn api_key_query_param_mode() {
+    unsafe { std::env::set_var("TEST_APIKEY_2", "qp-key-value") };
+    let provider =
+        ApiKeyAuthProvider::new("TEST_APIKEY_2", None, Some("api_key")).expect("should succeed");
+
+    let agent = ureq::agent();
+    let request = agent.get("https://example.com/api");
+    let request = provider.apply(request).expect("apply");
+
+    // ureq's query() appends to the URL — verify via request URL
+    let url = request.url().to_string();
+    assert!(
+        url.contains("api_key=qp-key-value"),
+        "URL should contain query param, got: {url}"
+    );
+    unsafe { std::env::remove_var("TEST_APIKEY_2") };
+}
+
+#[test]
+fn api_key_missing_env_var_fails() {
+    unsafe { std::env::remove_var("TEST_APIKEY_MISSING") };
+    let result = ApiKeyAuthProvider::new("TEST_APIKEY_MISSING", Some("X-Key"), None);
+    assert!(result.is_err());
+    let err = result.unwrap_err();
+    assert!(
+        err.contains("TEST_APIKEY_MISSING"),
+        "should mention env var, got: {err}"
+    );
+}
+
+#[test]
+fn api_key_neither_header_nor_query_fails() {
+    unsafe { std::env::set_var("TEST_APIKEY_3", "val") };
+    let result = ApiKeyAuthProvider::new("TEST_APIKEY_3", None, None);
+    assert!(result.is_err());
+    let err = result.unwrap_err();
+    assert!(
+        err.contains("must be specified"),
+        "should say one must be specified, got: {err}"
+    );
+    unsafe { std::env::remove_var("TEST_APIKEY_3") };
+}
+
+#[test]
+fn api_key_both_header_and_query_fails() {
+    unsafe { std::env::set_var("TEST_APIKEY_4", "val") };
+    let result = ApiKeyAuthProvider::new("TEST_APIKEY_4", Some("H"), Some("q"));
+    assert!(result.is_err());
+    let err = result.unwrap_err();
+    assert!(err.contains("not both"), "should say not both, got: {err}");
+    unsafe { std::env::remove_var("TEST_APIKEY_4") };
+}
+
+#[test]
+fn create_auth_provider_api_key() {
+    unsafe { std::env::set_var("TEST_FACTORY_APIKEY", "k") };
+    let config = AuthConfig::ApiKey {
+        key_env: "TEST_FACTORY_APIKEY".to_string(),
+        header_name: Some("X-Key".to_string()),
+        query_param: None,
+    };
+    let provider = create_auth_provider(&config, None);
+    assert!(provider.is_ok(), "should create api key provider");
+    unsafe { std::env::remove_var("TEST_FACTORY_APIKEY") };
+}
+
+// --- OIDC Auth Provider Tests ---
+
+#[test]
+fn oidc_missing_client_id_env_fails() {
+    unsafe {
+        std::env::remove_var("TEST_OIDC_CID_MISSING");
+        std::env::set_var("TEST_OIDC_CS_1", "secret");
+    }
+    let agent = ureq::agent();
+    let result = OidcAuthProvider::new(
+        &agent,
+        "https://auth.example.com/token",
+        "TEST_OIDC_CID_MISSING",
+        "TEST_OIDC_CS_1",
+        None,
+    );
+    assert!(result.is_err());
+    let err = result.unwrap_err();
+    assert!(
+        err.contains("TEST_OIDC_CID_MISSING"),
+        "should mention env var, got: {err}"
+    );
+    assert!(err.contains("not set"), "should say not set, got: {err}");
+    unsafe { std::env::remove_var("TEST_OIDC_CS_1") };
+}
+
+#[test]
+fn oidc_missing_client_secret_env_fails() {
+    unsafe {
+        std::env::set_var("TEST_OIDC_CID_2", "client-id");
+        std::env::remove_var("TEST_OIDC_CS_MISSING");
+    }
+    let agent = ureq::agent();
+    let result = OidcAuthProvider::new(
+        &agent,
+        "https://auth.example.com/token",
+        "TEST_OIDC_CID_2",
+        "TEST_OIDC_CS_MISSING",
+        None,
+    );
+    assert!(result.is_err());
+    let err = result.unwrap_err();
+    assert!(
+        err.contains("TEST_OIDC_CS_MISSING"),
+        "should mention env var, got: {err}"
+    );
+    unsafe { std::env::remove_var("TEST_OIDC_CID_2") };
+}
+
+#[test]
+fn oidc_apply_sets_bearer_header() {
+    let provider = OidcAuthProvider::with_token("test-access-token");
+
+    let agent = ureq::agent();
+    let request = agent.get("https://api.example.com/resource");
+    let request = provider.apply(request).expect("apply");
+
+    assert_eq!(
+        request.header("Authorization"),
+        Some("Bearer test-access-token")
+    );
+}
diff --git a/tests/cli_tests.rs b/tests/cli_tests.rs
new file mode 100644
index 0000000..b6ae44f
--- /dev/null
+++ b/tests/cli_tests.rs
@@ -0,0 +1 @@
+mod e2e;
diff --git a/tests/config_test.rs b/tests/config_test.rs
new file mode 100644
index 0000000..d7be242
--- /dev/null
+++ b/tests/config_test.rs
@@ -0,0 +1,445 @@
+use restium::config::{GlobalConfig, SpecFile};
+
+fn parse_spec(yaml: &str) -> SpecFile {
+    serde_yaml::from_str(yaml).expect("valid YAML")
+}
+
+#[test]
+fn parse_valid_spec_with_global_and_resources() {
+    let spec = parse_spec(
+        r#"
+global:
+  base_url: "https://api.example.com"
+  default_headers:
+    Content-Type: "application/json"
+resources:
+  - name: my_resource
+    endpoint: /api/things
+"#,
+    );
+
+    assert_eq!(
+        spec.global.base_url.as_deref(),
+        Some("https://api.example.com")
+    );
+    assert_eq!(spec.resources.len(), 1);
+    assert_eq!(spec.resources[0].name, "my_resource");
+    assert_eq!(spec.resources[0].endpoint, "/api/things");
+}
+
+#[test]
+fn global_base_url_and_headers_loaded() {
+    let spec = parse_spec(
+        r#"
+global:
+  base_url: "https://api.netbird.io"
+  default_headers:
+    Accept: "application/json"
+    X-Custom: "value"
+"#,
+    );
+
+    assert_eq!(
+        spec.global.base_url.as_deref(),
+        Some("https://api.netbird.io")
+    );
+    let headers = spec.global.default_headers.as_ref().unwrap();
+    assert_eq!(headers.get("Accept").unwrap(), "application/json");
+    assert_eq!(headers.get("X-Custom").unwrap(), "value");
+}
+
+#[test]
+fn resource_with_all_fields() {
+    let spec = parse_spec(
+        r#"
+resources:
+  - name: test_resource
+    endpoint: /api/test
+    method: PUT
+    base_url: "https://custom.api.com"
+    headers:
+      Authorization: "Bearer test"
+    payload:
+      key: "value"
+    depends_on:
+      - other_resource
+    read_endpoint: /api/test/123
+    outputs:
+      id: "id"
+      name: "display_name"
+    action: delete
+"#,
+    );
+
+    let r = &spec.resources[0];
+    assert_eq!(r.name, "test_resource");
+    assert_eq!(r.endpoint, "/api/test");
+    assert_eq!(r.method.as_deref(), Some("PUT"));
+    assert_eq!(r.base_url.as_deref(), Some("https://custom.api.com"));
+    assert!(r.headers.is_some());
+    assert!(r.payload.is_some());
+    assert_eq!(r.depends_on.as_ref().unwrap(), &["other_resource"]);
+    assert_eq!(r.read_endpoint.as_deref(), Some("/api/test/123"));
+    assert_eq!(r.outputs.as_ref().unwrap().get("id").unwrap(), "id");
+    assert_eq!(r.action.as_deref(), Some("delete"));
+}
+
+#[test]
+fn resource_inherits_global_base_url() {
+    let spec = parse_spec(
+        r#"
+global:
+  base_url: "https://global.api.com"
+resources:
+  - name: inheriting
+    endpoint: /api/things
+"#,
+    );
+
+    let r = &spec.resources[0];
+    assert_eq!(
+        r.effective_base_url(&spec.global),
+        Some("https://global.api.com")
+    );
+}
+
+#[test]
+fn resource_overrides_global_base_url() {
+    let spec = parse_spec(
+        r#"
+global:
+  base_url: "https://global.api.com"
+resources:
+  - name: overriding
+    endpoint: /api/things
+    base_url: "https://custom.api.com"
+"#,
+    );
+
+    let r = &spec.resources[0];
+    assert_eq!(
+        r.effective_base_url(&spec.global),
+        Some("https://custom.api.com")
+    );
+}
+
+#[test]
+fn resource_inherits_global_headers_and_overrides() {
+    let spec = parse_spec(
+        r#"
+global:
+  default_headers:
+    Accept: "application/json"
+    X-Global: "global-value"
+resources:
+  - name: merging
+    endpoint: /api/things
+    headers:
+      Accept: "text/plain"
+      X-Custom: "custom-value"
+"#,
+    );
+
+    let headers = spec.resources[0].effective_headers(&spec.global);
+    assert_eq!(headers.get("Accept").unwrap(), "text/plain");
+    assert_eq!(headers.get("X-Global").unwrap(), "global-value");
+    assert_eq!(headers.get("X-Custom").unwrap(), "custom-value");
+}
+
+#[test]
+fn resource_inherits_all_global_headers_when_none_specified() {
+    let spec = parse_spec(
+        r#"
+global:
+  default_headers:
+    Content-Type: "application/json"
+resources:
+  - name: inheriting
+    endpoint: /api/things
+"#,
+    );
+
+    let headers = spec.resources[0].effective_headers(&spec.global);
+    assert_eq!(headers.get("Content-Type").unwrap(), "application/json");
+}
+
+#[test]
+fn depends_on_parsed_as_vec() {
+    let spec = parse_spec(
+        r#"
+resources:
+  - name: dependent
+    endpoint: /api/dep
+    depends_on:
+      - resource_a
+      - resource_b
+"#,
+    );
+
+    let deps = spec.resources[0].depends_on.as_ref().unwrap();
+    assert_eq!(deps, &["resource_a", "resource_b"]);
+}
+
+#[test]
+fn nested_payload_preserved_through_yaml_to_json() {
+    let spec = parse_spec(
+        r#"
+resources:
+  - name: nested
+    endpoint: /api/nested
+    payload:
+      name: "test"
+      count: 42
+      active: true
+      tags:
+        - alpha
+        - beta
+      config:
+        nested_key: "nested_value"
+        items:
+          - id: 1
+            label: "first"
+          - id: 2
+            label: "second"
+"#,
+    );
+
+    let payload = spec.resources[0].payload.as_ref().unwrap();
+
+    // Verify structure survives round-trip
+    assert_eq!(payload["name"], "test");
+    assert_eq!(payload["count"], 42);
+    assert_eq!(payload["active"], true);
+    assert_eq!(payload["tags"][0], "alpha");
+    assert_eq!(payload["tags"][1], "beta");
+    assert_eq!(payload["config"]["nested_key"], "nested_value");
+    assert_eq!(payload["config"]["items"][0]["id"], 1);
+    assert_eq!(payload["config"]["items"][1]["label"], "second");
+
+    // Verify JSON serialization preserves structure
+    let json = serde_json::to_string(payload).unwrap();
+    let reparsed: serde_json::Value = serde_json::from_str(&json).unwrap();
+    assert_eq!(*payload, reparsed);
+}
+
+#[test]
+fn invalid_yaml_syntax_returns_error() {
+    let result: Result<SpecFile, _> = serde_yaml::from_str("{{invalid yaml");
+    assert!(result.is_err());
+}
+
+#[test]
+fn unknown_field_returns_error() {
+    let result: Result<SpecFile, _> = serde_yaml::from_str(
+        r#"
+global:
+  base_url: "https://example.com"
+  unknown_field: "oops"
+"#,
+    );
+    assert!(result.is_err());
+    let err = result.unwrap_err().to_string();
+    assert!(
+        err.contains("unknown_field") || err.contains("unknown field"),
+        "error should mention the unknown field, got: {err}"
+    );
+}
+
+#[test]
+fn missing_required_resource_fields_returns_error() {
+    let result: Result<SpecFile, _> = serde_yaml::from_str(
+        r#"
+resources:
+  - endpoint: /api/things
+"#,
+    );
+    assert!(
+        result.is_err(),
+        "missing 'name' field should cause parse error"
+    );
+}
+
+#[test]
+fn empty_resources_list_is_valid() {
+    let spec = parse_spec(
+        r#"
+global:
+  base_url: "https://example.com"
+resources: []
+"#,
+    );
+    assert!(spec.resources.is_empty());
+}
+
+#[test]
+fn default_method_is_post() {
+    let spec = parse_spec(
+        r#"
+resources:
+  - name: no_method
+    endpoint: /api/things
+"#,
+    );
+
+    assert_eq!(spec.resources[0].effective_method(), "POST");
+}
+
+#[test]
+fn explicit_method_overrides_default() {
+    let spec = parse_spec(
+        r#"
+resources:
+  - name: with_method
+    endpoint: /api/things
+    method: DELETE
+"#,
+    );
+
+    assert_eq!(spec.resources[0].effective_method(), "DELETE");
+}
+
+#[test]
+fn no_base_url_anywhere_returns_none() {
+    let global = GlobalConfig::default();
+    let spec = parse_spec(
+        r#"
+resources:
+  - name: no_base
+    endpoint: /api/things
+"#,
+    );
+
+    assert_eq!(spec.resources[0].effective_base_url(&global), None);
+}
+
+#[test]
+fn spec_file_load_nonexistent_returns_error() {
+    let result = SpecFile::load("/tmp/nonexistent_restium_spec_12345.yaml");
+    assert!(result.is_err());
+    let err = result.unwrap_err();
+    assert!(
+        err.contains("Failed to read"),
+        "should have read error, got: {err}"
+    );
+}
+
+#[test]
+fn spec_file_load_invalid_yaml_returns_error() {
+    let dir = tempfile::tempdir().expect("temp dir");
+    let path = dir.path().join("bad.yaml");
+    std::fs::write(&path, "{{invalid").expect("write");
+
+    let result = SpecFile::load(path.to_str().unwrap());
+    assert!(result.is_err());
+    let err = result.unwrap_err();
+    assert!(
+        err.contains("Failed to parse"),
+        "should have parse error, got: {err}"
+    );
+}
+
+#[test]
+fn spec_file_load_valid_yaml() {
+    let dir = tempfile::tempdir().expect("temp dir");
+    let path = dir.path().join("good.yaml");
+    std::fs::write(
+        &path,
+        r#"
+global:
+  base_url: "https://test.com"
+resources:
+  - name: test
+    endpoint: /api/test
+"#,
+    )
+    .expect("write");
+
+    let spec = SpecFile::load(path.to_str().unwrap()).expect("should load");
+    assert_eq!(spec.resources.len(), 1);
+    assert_eq!(spec.global.base_url.as_deref(), Some("https://test.com"));
+}
+
+#[test]
+fn auth_config_bearer_parsed() {
+    let spec = parse_spec(
+        r#"
+global:
+  auth:
+    type: bearer
+    token_env: MY_TOKEN
+resources: []
+"#,
+    );
+
+    match spec.global.auth {
+        Some(restium::config::AuthConfig::Bearer { ref token_env }) => {
+            assert_eq!(token_env, "MY_TOKEN");
+        }
+        other => panic!("expected Bearer auth, got: {other:?}"),
+    }
+}
+
+#[test]
+fn auth_config_basic_parsed() {
+    let spec = parse_spec(
+        r#"
+global:
+  auth:
+    type: basic
+    username_env: USER
+    password_env: PASS
+resources: []
+"#,
+    );
+
+    match spec.global.auth {
+        Some(restium::config::AuthConfig::Basic {
+            ref username_env,
+            ref password_env,
+        }) => {
+            assert_eq!(username_env, "USER");
+            assert_eq!(password_env, "PASS");
+        }
+        other => panic!("expected Basic auth, got: {other:?}"),
+    }
+}
+
+#[test]
+fn resource_with_reference_in_payload() {
+    let spec = parse_spec(
+        r#"
+resources:
+  - name: with_ref
+    endpoint: /api/routes
+    payload:
+      network_id: "${netbird_network.output.id}"
+      name: "my-route"
+"#,
+    );
+
+    let payload = spec.resources[0].payload.as_ref().unwrap();
+    assert_eq!(payload["network_id"], "${netbird_network.output.id}");
+}
+
+#[test]
+fn empty_spec_file_is_valid() {
+    let spec: SpecFile = serde_yaml::from_str("{}").expect("empty spec");
+    assert!(spec.resources.is_empty());
+    assert!(spec.global.base_url.is_none());
+}
+
+#[test]
+fn unknown_field_on_resource_returns_error() {
+    let result: Result<SpecFile, _> = serde_yaml::from_str(
+        r#"
+resources:
+  - name: test
+    endpoint: /api/test
+    typo_field: "oops"
+"#,
+    );
+    assert!(
+        result.is_err(),
+        "unknown field on resource should cause parse error"
+    );
+}
diff --git a/tests/diff_test.rs b/tests/diff_test.rs
new file mode 100644
index 0000000..e54208e
--- /dev/null
+++ b/tests/diff_test.rs
@@ -0,0 +1,167 @@
+use restium::reconcile::diff::json_equal;
+use restium::reconcile::{ResourceAction, compute_action};
+use serde_json::json;
+
+// --- json_equal tests ---
+
+#[test]
+fn equal_objects_same_key_order() {
+    let a = json!({"name": "alice", "age": 30});
+    let b = json!({"name": "alice", "age": 30});
+    assert!(json_equal(&a, &b));
+}
+
+#[test]
+fn equal_objects_different_key_order() {
+    let a = json!({"age": 30, "name": "alice"});
+    let b = json!({"name": "alice", "age": 30});
+    assert!(json_equal(&a, &b));
+}
+
+#[test]
+fn different_objects_value_changed() {
+    let a = json!({"name": "alice", "age": 30});
+    let b = json!({"name": "alice", "age": 31});
+    assert!(!json_equal(&a, &b));
+}
+
+#[test]
+fn different_objects_key_missing() {
+    let a = json!({"name": "alice", "age": 30});
+    let b = json!({"name": "alice"});
+    assert!(!json_equal(&a, &b));
+}
+
+#[test]
+fn different_objects_extra_key() {
+    let a = json!({"name": "alice"});
+    let b = json!({"name": "alice", "age": 30});
+    assert!(!json_equal(&a, &b));
+}
+
+#[test]
+fn equal_arrays_same_order() {
+    let a = json!([1, 2, 3]);
+    let b = json!([1, 2, 3]);
+    assert!(json_equal(&a, &b));
+}
+
+#[test]
+fn different_arrays_different_order() {
+    let a = json!([1, 2, 3]);
+    let b = json!([3, 2, 1]);
+    assert!(!json_equal(&a, &b));
+}
+
+#[test]
+fn different_arrays_different_length() {
+    let a = json!([1, 2]);
+    let b = json!([1, 2, 3]);
+    assert!(!json_equal(&a, &b));
+}
+
+#[test]
+fn nested_objects_different_key_order() {
+    let a = json!({
+        "outer": {"b": 2, "a": 1},
+        "name": "test"
+    });
+    let b = json!({
+        "name": "test",
+        "outer": {"a": 1, "b": 2}
+    });
+    assert!(json_equal(&a, &b));
+}
+
+#[test]
+fn nested_different_values() {
+    let a = json!({"outer": {"inner": 1}});
+    let b = json!({"outer": {"inner": 2}});
+    assert!(!json_equal(&a, &b));
+}
+
+#[test]
+fn mixed_types_object_vs_array() {
+    let a = json!({"key": "value"});
+    let b = json!([1, 2, 3]);
+    assert!(!json_equal(&a, &b));
+}
+
+#[test]
+fn null_equality() {
+    assert!(json_equal(&json!(null), &json!(null)));
+}
+
+#[test]
+fn bool_equality() {
+    assert!(json_equal(&json!(true), &json!(true)));
+    assert!(!json_equal(&json!(true), &json!(false)));
+}
+
+#[test]
+fn number_equality() {
+    assert!(json_equal(&json!(42), &json!(42)));
+    assert!(!json_equal(&json!(42), &json!(43)));
+    assert!(json_equal(&json!(3.5), &json!(3.5)));
+}
+
+#[test]
+fn string_equality() {
+    assert!(json_equal(&json!("hello"), &json!("hello")));
+    assert!(!json_equal(&json!("hello"), &json!("world")));
+}
+
+#[test]
+fn null_vs_non_null() {
+    assert!(!json_equal(&json!(null), &json!(0)));
+    assert!(!json_equal(&json!(null), &json!("")));
+}
+
+#[test]
+fn deeply_nested_mixed_structures() {
+    let a = json!({
+        "level1": {
+            "level2": [
+                {"z": 3, "y": 2, "x": 1},
+                {"c": true}
+            ]
+        }
+    });
+    let b = json!({
+        "level1": {
+            "level2": [
+                {"x": 1, "y": 2, "z": 3},
+                {"c": true}
+            ]
+        }
+    });
+    assert!(json_equal(&a, &b));
+}
+
+// --- compute_action tests ---
+
+#[test]
+fn compute_action_create_when_actual_is_none() {
+    let desired = json!({"name": "test"});
+    let action = compute_action(&desired, None);
+    assert_eq!(action, ResourceAction::Create);
+}
+
+#[test]
+fn compute_action_skip_when_equal() {
+    let desired = json!({"name": "test", "value": 42});
+    let actual = json!({"value": 42, "name": "test"});
+    let action = compute_action(&desired, Some(&actual));
+    assert_eq!(action, ResourceAction::Skip);
+}
+
+#[test]
+fn compute_action_update_when_different() {
+    let desired = json!({"name": "test", "value": 42});
+    let actual = json!({"name": "test", "value": 99});
+    let action = compute_action(&desired, Some(&actual));
+    assert!(matches!(action, ResourceAction::Update { .. }));
+    if let ResourceAction::Update { actual: val } = action {
+        assert_eq!(val, json!({"name": "test", "value": 99}));
+    }
+}
diff --git a/tests/e2e/cli_test.rs b/tests/e2e/cli_test.rs
new file mode 100644
index 0000000..2bbc64f
--- /dev/null
+++ b/tests/e2e/cli_test.rs
@@ -0,0 +1,568 @@
+use std::process::Command;
+use std::time::Duration;
+
+fn restium_cmd() -> Command {
+    Command::new(env!("CARGO_BIN_EXE_restium"))
+}
+
+#[test]
+fn help_shows_subcommands() {
+    let output = restium_cmd()
+        .arg("--help")
+        .output()
+        .expect("failed to run restium");
+
+    let stdout = String::from_utf8_lossy(&output.stdout);
+    assert!(
+        stdout.contains("reconcile"),
+        "help should list reconcile subcommand"
+    );
+    assert!(
+        stdout.contains("validate"),
+        "help should list validate subcommand"
+    );
+}
+
+#[test]
+fn help_shows_global_flags() {
+    let output = restium_cmd()
+        .arg("--help")
+        .output()
+        .expect("failed to run restium");
+
+    let stdout = String::from_utf8_lossy(&output.stdout);
+    assert!(stdout.contains("--json"), "help should list --json flag");
+    assert!(
+        stdout.contains("--insecure-tls"),
+        "help should list --insecure-tls flag"
+    );
+}
+
+#[test]
+fn validate_missing_spec_exits_2() {
+    let output = restium_cmd()
+        .args(["validate", "--spec", "nonexistent.yaml"])
+        .output()
+        .expect("failed to run restium");
+
+    assert_eq!(
+        output.status.code(),
+        Some(2),
+        "missing spec should exit with code 2"
+    );
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    assert!(
+        stderr.contains("Failed to read spec file"),
+        "stderr should mention file read failure, got: {stderr}"
+    );
+}
+
+#[test]
+fn reconcile_missing_spec_exits_2() {
+    let output = restium_cmd()
+        .args(["reconcile", "--spec", "nonexistent.yaml"])
+        .output()
+        .expect("failed to run restium");
+
+    assert_eq!(
+        output.status.code(),
+        Some(2),
+        "missing spec should exit with code 2"
+    );
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    assert!(
+        stderr.contains("Failed to read spec file"),
+        "stderr should mention file read failure, got: {stderr}"
+    );
+}
+
+#[test]
+fn validate_valid_spec_exits_0() {
+    let dir = tempfile::tempdir().expect("failed to create temp dir");
+    let spec_path = dir.path().join("test.yaml");
+    std::fs::write(&spec_path, "global: {}").expect("failed to write temp spec");
+
+    let output = restium_cmd()
+        .args(["validate", "--spec", spec_path.to_str().unwrap()])
+        .output()
+        .expect("failed to run restium");
+
+    assert!(
+        output.status.success(),
+        "valid spec should exit with code 0"
+    );
+}
+
+#[test]
+fn reconcile_valid_spec_exits_0() {
+    let dir = tempfile::tempdir().expect("failed to create temp dir");
+    let spec_path = dir.path().join("test.yaml");
+    std::fs::write(&spec_path, "global: {}").expect("failed to write temp spec");
+
+    let output = restium_cmd()
+        .args(["reconcile", "--spec", spec_path.to_str().unwrap()])
+        .output()
+        .expect("failed to run restium");
+
+    assert!(
+        output.status.success(),
+        "valid spec should exit with code 0"
+    );
+}
+
+#[test]
+fn env_var_restium_spec_is_used() {
+    let dir = tempfile::tempdir().expect("failed to create temp dir");
+    let spec_path = dir.path().join("env-test.yaml");
+    std::fs::write(&spec_path, "global: {}").expect("failed to write temp spec");
+
+    let output = restium_cmd()
+        .arg("validate")
+        .env("RESTIUM_SPEC", spec_path.to_str().unwrap())
+        .output()
+        .expect("failed to run restium");
+
+    assert!(
+        output.status.success(),
+        "RESTIUM_SPEC env var should be picked up by validate subcommand"
+    );
+}
+
+#[test]
+fn env_var_restium_json_is_accepted() {
+    let dir = tempfile::tempdir().expect("failed to create temp dir");
+    let spec_path = dir.path().join("json-test.yaml");
+    std::fs::write(&spec_path, "global: {}").expect("failed to write temp spec");
+
+    let output = restium_cmd()
+        .args(["validate", "--spec", spec_path.to_str().unwrap()])
+        .env("RESTIUM_JSON", "true")
+        .output()
+        .expect("failed to run restium");
+
+    assert!(
+        output.status.success(),
+        "RESTIUM_JSON=true env var should be accepted without error"
+    );
+}
+
+#[test]
+fn help_shows_spec_flag_in_subcommand() {
+    let output = restium_cmd()
+        .args(["validate", "--help"])
+        .output()
+        .expect("failed to run restium");
+
+    let stdout = String::from_utf8_lossy(&output.stdout);
+    assert!(
+        stdout.contains("--spec"),
+        "validate --help should list --spec flag"
+    );
+}
+
+#[test]
+fn validate_proper_spec_logs_resource_count() {
+    let dir = tempfile::tempdir().expect("temp dir");
+    let spec_path = dir.path().join("multi.yaml");
+    std::fs::write(
+        &spec_path,
+        r#"
+resources:
+  - name: res_a
+    endpoint: /api/a
+  - name: res_b
+    endpoint: /api/b
+"#,
+    )
+    .expect("write spec");
+
+    let output = restium_cmd()
+        .args(["validate", "--spec", spec_path.to_str().unwrap()])
+        .output()
+        .expect("run");
+
+    assert!(output.status.success());
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    assert!(
+        stderr.contains("resources=2"),
+        "should log resource count, got: {stderr}"
+    );
+}
+
+#[test]
+fn validate_invalid_yaml_exits_2() {
+    let dir = tempfile::tempdir().expect("temp dir");
+    let spec_path = dir.path().join("bad.yaml");
+    std::fs::write(&spec_path, "{{invalid yaml").expect("write spec");
+
+    let output = restium_cmd()
+        .args(["validate", "--spec", spec_path.to_str().unwrap()])
+        .output()
+        .expect("run");
+
+    assert_eq!(output.status.code(), Some(2), "invalid YAML should exit 2");
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    assert!(
+        stderr.contains("Failed to parse"),
+        "should show parse error, got: {stderr}"
+    );
+}
+
+#[test]
+fn validate_json_mode_with_resources() {
+    let dir = tempfile::tempdir().expect("temp dir");
+    let spec_path = dir.path().join("json_test.yaml");
+    std::fs::write(
+        &spec_path,
+        r#"
+resources:
+  - name: r1
+    endpoint: /api/r1
+"#,
+    )
+    .expect("write spec");
+
+    let output = restium_cmd()
+        .args(["--json", "validate", "--spec", spec_path.to_str().unwrap()])
+        .output()
+        .expect("run");
+
+    assert!(output.status.success());
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    let line = stderr.lines().next().expect("output");
+    let parsed: serde_json::Value = serde_json::from_str(line).expect("valid JSON");
+    assert_eq!(parsed["resources"], "1");
+}
+
+#[test]
+fn validate_broken_reference_exits_2() {
+    let dir = tempfile::tempdir().expect("temp dir");
+    let spec_path = dir.path().join("broken_ref.yaml");
+    std::fs::write(
+        &spec_path,
+        r#"
+resources:
+  - name: my_resource
+    endpoint: /api/test
+    payload:
+      ref_id: "${nonexistent.output.id}"
+"#,
+    )
+    .expect("write spec");
+
+    let output = restium_cmd()
+        .args(["validate", "--spec", spec_path.to_str().unwrap()])
+        .output()
+        .expect("run");
+
+    assert_eq!(
+        output.status.code(),
+        Some(2),
+        "broken ref should exit with code 2"
+    );
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    assert!(
+        stderr.contains("nonexistent"),
+        "should mention the unknown resource, got: {stderr}"
+    );
+    assert!(
+        stderr.contains("my_resource"),
+        "should mention the resource containing the ref, got: {stderr}"
+    );
+}
+
+#[test]
+fn validate_circular_dependency_exits_2() {
+    let dir = tempfile::tempdir().expect("temp dir");
+    let spec_path = dir.path().join("cycle.yaml");
+    std::fs::write(
+        &spec_path,
+        r#"
+resources:
+  - name: a
+    endpoint: /api/a
+    depends_on: [b]
+  - name: b
+    endpoint: /api/b
+    depends_on: [a]
+"#,
+    )
+    .expect("write spec");
+
+    let output = restium_cmd()
+        .args(["validate", "--spec", spec_path.to_str().unwrap()])
+        .output()
+        .expect("run");
+
+    assert_eq!(
+        output.status.code(),
+        Some(2),
+        "cycle should exit with code 2"
+    );
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    assert!(
+        stderr.contains("Circular dependency"),
+        "should mention circular dependency, got: {stderr}"
+    );
+}
+
+#[test]
+fn validate_errors_in_json_mode() {
+    let dir = tempfile::tempdir().expect("temp dir");
+    let spec_path = dir.path().join("json_err.yaml");
+    std::fs::write(
+        &spec_path,
+        r#"
+resources:
+  - name: res
+    endpoint: /api/res
+    depends_on: [ghost]
+"#,
+    )
+    .expect("write spec");
+
+    let output = restium_cmd()
+        .args(["--json", "validate", "--spec", spec_path.to_str().unwrap()])
+        .output()
+        .expect("run");
+
+    assert_eq!(output.status.code(), Some(2));
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    // Each error line should be valid JSON
+    for line in stderr.lines() {
+        let parsed: serde_json::Value =
+            serde_json::from_str(line).unwrap_or_else(|e| panic!("invalid JSON: {e}: {line}"));
+        assert_eq!(
+            parsed["level"], "error",
+            "validation errors should be level error"
+        );
+    }
+}
+
+#[test]
+fn validate_empty_spec_exits_2() {
+    let output = restium_cmd()
+        .args(["validate", "--spec", ""])
+        .output()
+        .expect("failed to run restium");
+
+    assert_eq!(
+        output.status.code(),
+        Some(2),
+        "empty spec path should exit with code 2"
+    );
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    assert!(
+        stderr.contains("Failed to read spec file"),
+        "stderr should mention file read failure for empty path, got: {stderr}"
+    );
+}
+
+#[test]
+fn reconcile_bad_ca_bundle_exits_2() {
+    let dir = tempfile::tempdir().expect("temp dir");
+    let spec_path = dir.path().join("ca_test.yaml");
+    std::fs::write(
+        &spec_path,
+        r#"
+global:
+  ca_bundle: "/tmp/nonexistent_ca_bundle_restium.pem"
+resources: []
+"#,
+    )
+    .expect("write spec");
+
+    let output = restium_cmd()
+        .args(["reconcile", "--spec", spec_path.to_str().unwrap()])
+        .output()
+        .expect("run");
+
+    assert_eq!(
+        output.status.code(),
+        Some(2),
+        "bad CA bundle should exit with code 2"
+    );
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    assert!(
+        stderr.contains("CA bundle"),
+        "should mention CA bundle, got: {stderr}"
+    );
+}
+
+#[test]
+fn insecure_tls_flag_is_parsed() {
+    let dir = tempfile::tempdir().expect("temp dir");
+    let spec_path = dir.path().join("insecure_test.yaml");
+    std::fs::write(&spec_path, "resources: []").expect("write spec");
+
+    let output = restium_cmd()
+        .args([
+            "--insecure-tls",
+            "validate",
+            "--spec",
+            spec_path.to_str().unwrap(),
+        ])
+        .output()
+        .expect("run");
+
+    assert!(
+        output.status.success(),
+        "--insecure-tls should be accepted without error"
+    );
+}
+
+#[test]
+fn reconcile_broken_spec_exits_2() {
+    let dir = tempfile::tempdir().expect("temp dir");
+    let spec_path = dir.path().join("broken.yaml");
+    std::fs::write(
+        &spec_path,
+        r#"
+resources:
+  - name: a
+    endpoint: /api/a
+    depends_on: [b]
+  - name: b
+    endpoint: /api/b
+    depends_on: [a]
+"#,
+    )
+    .expect("write spec");
+
+    let output = restium_cmd()
+        .args(["reconcile", "--spec", spec_path.to_str().unwrap()])
+        .output()
+        .expect("run");
+
+    assert_eq!(
+        output.status.code(),
+        Some(2),
+        "reconcile with invalid spec should exit with code 2"
+    );
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    assert!(
+        stderr.contains("Circular dependency"),
+        "reconcile should validate spec, got: {stderr}"
+    );
+}
+
+// --- Sidecar Mode Tests ---
+
+#[test]
+fn help_shows_sidecar_flag() {
+    let output = restium_cmd()
+        .arg("--help")
+        .output()
+        .expect("failed to run restium");
+
+    let stdout = String::from_utf8_lossy(&output.stdout);
+    assert!(
+        stdout.contains("--sidecar"),
+        "help should list --sidecar flag, got: {stdout}"
+    );
+}
+
+#[test]
+fn sidecar_env_var_is_accepted() {
+    let dir = tempfile::tempdir().expect("temp dir");
+    let spec_path = dir.path().join("sidecar_env.yaml");
+    std::fs::write(&spec_path, "global: {}").expect("write spec");
+
+    let mut child = restium_cmd()
+        .args(["reconcile", "--spec", spec_path.to_str().unwrap()])
+        .env("RESTIUM_SIDECAR", "true")
+        .stderr(std::process::Stdio::piped())
+        .spawn()
+        .expect("spawn");
+
+    std::thread::sleep(Duration::from_millis(500));
+
+    match child.try_wait().expect("try_wait") {
+        None => { /* still running — sidecar via env var works */ }
+        Some(status) => panic!("RESTIUM_SIDECAR process exited unexpectedly with {status}"),
+    }
+
+    child.kill().expect("kill");
+}
+
+#[test]
+fn sidecar_mode_keeps_process_alive_on_success() {
+    let dir = tempfile::tempdir().expect("temp dir");
+    let spec_path = dir.path().join("sidecar_ok.yaml");
+    std::fs::write(&spec_path, "global: {}").expect("write spec");
+
+    let mut child = restium_cmd()
+        .args([
+            "--sidecar",
+            "reconcile",
+            "--spec",
+            spec_path.to_str().unwrap(),
+        ])
+        .stderr(std::process::Stdio::piped())
+        .spawn()
+        .expect("spawn");
+
+    std::thread::sleep(Duration::from_millis(500));
+
+    match child.try_wait().expect("try_wait") {
+        None => { /* still running — correct */ }
+        Some(status) => panic!("sidecar process exited unexpectedly with {status}"),
+    }
+
+    child.kill().expect("kill");
+}
+
+#[test]
+fn sidecar_mode_keeps_process_alive_on_failure() {
+    let dir = tempfile::tempdir().expect("temp dir");
+    let spec_path = dir.path().join("sidecar_fail.yaml");
+    // Invalid CA bundle will cause reconcile to fail with exit code 2
+    std::fs::write(
+        &spec_path,
+        r#"
+global:
+  ca_bundle: "/tmp/nonexistent_ca_restium_sidecar.pem"
+resources: []
+"#,
+    )
+    .expect("write spec");
+
+    let mut child = restium_cmd()
+        .args([
+            "--sidecar",
+            "reconcile",
+            "--spec",
+            spec_path.to_str().unwrap(),
+        ])
+        .stderr(std::process::Stdio::piped())
+        .spawn()
+        .expect("spawn");
+
+    std::thread::sleep(Duration::from_millis(500));
+
+    match child.try_wait().expect("try_wait") {
+        None => { /* still running despite failure — correct */ }
+        Some(status) => {
+            panic!("sidecar process should stay alive on failure, but exited with {status}")
+        }
+    }
+
+    child.kill().expect("kill");
+}
+
+#[test]
+fn without_sidecar_reconcile_exits_normally() {
+    let dir = tempfile::tempdir().expect("temp dir");
+    let spec_path = dir.path().join("no_sidecar.yaml");
+    std::fs::write(&spec_path, "global: {}").expect("write spec");
+
+    let output = restium_cmd()
+        .args(["reconcile", "--spec", spec_path.to_str().unwrap()])
+        .output()
+        .expect("run");
+
+    assert!(
+        output.status.success(),
+        "without --sidecar, reconcile should exit with code 0"
+    );
+}
diff --git a/tests/e2e/mod.rs b/tests/e2e/mod.rs
new file mode 100644
index 0000000..8dd01d6
--- /dev/null
+++ b/tests/e2e/mod.rs
@@ -0,0 +1 @@
+mod cli_test;
diff --git a/tests/execute_test.rs b/tests/execute_test.rs
new file mode 100644
index 0000000..5e11256
--- /dev/null
+++ b/tests/execute_test.rs
@@ -0,0 +1,240 @@
+use restium::logging::Logger;
+use restium::reconcile::ResourceAction;
+use restium::reconcile::execute::{ExecuteContext, ExecuteResult, execute_action};
+use serde_json::json;
+
+#[test]
+fn skip_action_returns_none_and_logs() {
+    let client = restium::http::HttpClient::new(false, None, None, None).unwrap();
+    let logger = Logger::new(false);
+    let payload = json!({"key": "value"});
+
+    let ctx = ExecuteContext {
+        client: &client,
+        resource_name: "test_resource",
+        endpoint: "https://example.com/api/test",
+        method: "POST",
+        payload: Some(&payload),
+        auth: None,
+        logger: &logger,
+    };
+
+    let result = execute_action(&ctx, &ResourceAction::Skip);
+    assert!(result.is_ok());
+    assert!(matches!(result.unwrap(), ExecuteResult::AlreadyOk));
+}
+
+#[test]
+fn skip_action_json_mode_returns_none() {
+    let client = restium::http::HttpClient::new(false, None, None, None).unwrap();
+    let logger = Logger::new(true);
+    let payload = json!({"key": "value"});
+
+    let ctx = ExecuteContext {
+        client: &client,
+        resource_name: "my_resource",
+        endpoint: "https://example.com/api/test",
+        method: "POST",
+        payload: Some(&payload),
+        auth: None,
+        logger: &logger,
+    };
+
+    let result = execute_action(&ctx, &ResourceAction::Skip);
+    assert!(result.is_ok());
+    assert!(matches!(result.unwrap(), ExecuteResult::AlreadyOk));
+}
+
+#[test]
+fn create_without_payload_returns_error() {
+    let client = restium::http::HttpClient::new(false, None, None, None).unwrap();
+    let logger = Logger::new(false);
+
+    let ctx = ExecuteContext {
+        client: &client,
+        resource_name: "no_payload",
+        endpoint: "https://example.com/api/test",
+        method: "POST",
+        payload: None,
+        auth: None,
+        logger: &logger,
+    };
+
+    let result = execute_action(&ctx, &ResourceAction::Create);
+    assert!(result.is_err());
+    assert!(result.unwrap_err().contains("no payload"));
+}
+
+#[test]
+fn update_without_payload_returns_error() {
+    let client = restium::http::HttpClient::new(false, None, None, None).unwrap();
+    let logger = Logger::new(false);
+
+    let ctx = ExecuteContext {
+        client: &client,
+        resource_name: "no_payload",
+        endpoint: "https://example.com/api/test",
+        method: "PUT",
+        payload: None,
+        auth: None,
+        logger: &logger,
+    };
+
+    let result = execute_action(
+        &ctx,
+        &ResourceAction::Update {
+            actual: json!({"old": "value"}),
+        },
+    );
+    assert!(result.is_err());
+    assert!(result.unwrap_err().contains("no payload"));
+}
+
+#[test]
+fn create_to_unreachable_host_returns_actionable_error() {
+    let client = restium::http::HttpClient::new(false, None, None, None).unwrap();
+    let logger = Logger::new(false);
+    let payload = json!({"key": "value"});
+
+    let ctx = ExecuteContext {
+        client: &client,
+        resource_name: "test_resource",
+        endpoint: "https://192.0.2.1:1/api/test",
+        method: "POST",
+        payload: Some(&payload),
+        auth: None,
+        logger: &logger,
+    };
+
+    let result = execute_action(&ctx, &ResourceAction::Create);
+    assert!(result.is_err());
+    let err = result.unwrap_err();
+    assert!(
+        err.contains("test_resource"),
+        "Error should name the resource: {err}"
+    );
+    assert!(
+        err.contains("Failed to create"),
+        "Error should identify action: {err}"
+    );
+    assert!(err.contains("POST"), "Error should include method: {err}");
+    assert!(
+        err.contains("192.0.2.1"),
+        "Error should include endpoint: {err}"
+    );
+}
+
+#[test]
+fn error_message_contains_hint_separator() {
+    let client = restium::http::HttpClient::new(true, None, None, None).unwrap();
+    let logger = Logger::new(false);
+    let payload = json!({"key": "value"});
+
+    let ctx = ExecuteContext {
+        client: &client,
+        resource_name: "auth_test",
+        endpoint: "https://192.0.2.1:1/api/test",
+        method: "POST",
+        payload: Some(&payload),
+        auth: None,
+        logger: &logger,
+    };
+
+    let result = execute_action(&ctx, &ResourceAction::Create);
+    assert!(result.is_err());
+    let err = result.unwrap_err();
+    assert!(err.contains("—"), "Error should have hint separator: {err}");
+}
+
+#[test]
+fn update_uses_put_when_method_is_post() {
+    let client = restium::http::HttpClient::new(false, None, None, None).unwrap();
+    let logger = Logger::new(false);
+    let payload = json!({"key": "value"});
+
+    let ctx = ExecuteContext {
+        client: &client,
+        resource_name: "update_test",
+        endpoint: "https://192.0.2.1:1/api/test",
+        method: "POST",
+        payload: Some(&payload),
+        auth: None,
+        logger: &logger,
+    };
+
+    let result = execute_action(
+        &ctx,
+        &ResourceAction::Update {
+            actual: json!({"key": "old"}),
+        },
+    );
+    assert!(result.is_err());
+    let err = result.unwrap_err();
+    assert!(
+        err.contains("PUT"),
+        "Update should use PUT when method is POST: {err}"
+    );
+}
+
+#[test]
+fn delete_to_unreachable_host_returns_actionable_error() {
+    let client = restium::http::HttpClient::new(false, None, None, None).unwrap();
+    let logger = Logger::new(false);
+
+    let ctx = ExecuteContext {
+        client: &client,
+        resource_name: "del_resource",
+        endpoint: "https://192.0.2.1:1/api/test/123",
+        method: "DELETE",
+        payload: None,
+        auth: None,
+        logger: &logger,
+    };
+
+    let result = execute_action(&ctx, &ResourceAction::Delete);
+    assert!(result.is_err());
+    let err = result.unwrap_err();
+    assert!(
+        err.contains("del_resource"),
+        "Error should name the resource: {err}"
+    );
+    assert!(
+        err.contains("Failed to delete"),
+        "Error should identify delete action: {err}"
+    );
+    assert!(err.contains("DELETE"), "Error should include method: {err}");
+    assert!(
+        err.contains("192.0.2.1"),
+        "Error should include endpoint: {err}"
+    );
+}
+
+#[test]
+fn update_keeps_custom_method() {
+    let client = restium::http::HttpClient::new(false, None, None, None).unwrap();
+    let logger = Logger::new(false);
+    let payload = json!({"key": "value"});
+
+    let ctx = ExecuteContext {
+        client: &client,
+        resource_name: "patch_test",
+        endpoint: "https://192.0.2.1:1/api/test",
+        method: "PATCH",
+        payload: Some(&payload),
+        auth: None,
+        logger: &logger,
+    };
+
+    let result = execute_action(
+        &ctx,
+        &ResourceAction::Update {
+            actual: json!({"key": "old"}),
+        },
+    );
+    assert!(result.is_err());
+    let err = result.unwrap_err();
+    assert!(
+        err.contains("PATCH"),
+        "Update should keep custom method: {err}"
+    );
+}
diff --git a/tests/fixtures/test-ca.pem b/tests/fixtures/test-ca.pem
new file mode 100644
index 0000000..810bcfc
--- /dev/null
+++ b/tests/fixtures/test-ca.pem
@@ -0,0 +1,19 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
diff --git a/tests/fixtures/test-client.key b/tests/fixtures/test-client.key
new file mode 100644
index 0000000..c1c14d9
--- /dev/null
+++ b/tests/fixtures/test-client.key
@@ -0,0 +1,28 @@
+-----BEGIN PRIVATE KEY-----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+-----END PRIVATE KEY-----
diff --git a/tests/fixtures/test-client.pem b/tests/fixtures/test-client.pem
new file mode 100644
index 0000000..d126f71
--- /dev/null
+++ b/tests/fixtures/test-client.pem
@@ -0,0 +1,19 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
diff --git a/tests/graph_test.rs b/tests/graph_test.rs
new file mode 100644
index 0000000..cdb76c2
--- /dev/null
+++ b/tests/graph_test.rs
@@ -0,0 +1,258 @@
+use restium::config::ResourceSpec;
+use restium::graph::DependencyGraph;
+
+fn resource(name: &str, endpoint: &str) -> ResourceSpec {
+    serde_json::from_value(serde_json::json!({
+        "name": name,
+        "endpoint": endpoint
+    }))
+    .unwrap()
+}
+
+fn resource_with_depends(name: &str, endpoint: &str, deps: Vec<&str>) -> ResourceSpec {
+    serde_json::from_value(serde_json::json!({
+        "name": name,
+        "endpoint": endpoint,
+        "depends_on": deps
+    }))
+    .unwrap()
+}
+
+fn resource_with_payload(name: &str, endpoint: &str, payload: serde_json::Value) -> ResourceSpec {
+    serde_json::from_value(serde_json::json!({
+        "name": name,
+        "endpoint": endpoint,
+        "payload": payload
+    }))
+    .unwrap()
+}
+
+#[test]
+fn linear_chain_produces_correct_order() {
+    let resources = vec![
+        resource_with_depends("c", "/c", vec!["b"]),
+        resource_with_depends("b", "/b", vec!["a"]),
+        resource("a", "/a"),
+    ];
+
+    let graph = DependencyGraph::build(&resources).unwrap();
+    let order = graph.topological_sort().unwrap();
+
+    let pos_a = order.iter().position(|n| n == "a").unwrap();
+    let pos_b = order.iter().position(|n| n == "b").unwrap();
+    let pos_c = order.iter().position(|n| n == "c").unwrap();
+
+    assert!(pos_a < pos_b, "a must come before b");
+    assert!(pos_b < pos_c, "b must come before c");
+}
+
+#[test]
+fn implicit_deps_from_payload_references() {
+    let resources = vec![
+        resource_with_payload(
+            "consumer",
+            "/consumer",
+            serde_json::json!({
+                "network_id": "${producer.output.id}"
+            }),
+        ),
+        resource("producer", "/producer"),
+    ];
+
+    let graph = DependencyGraph::build(&resources).unwrap();
+    let order = graph.topological_sort().unwrap();
+
+    let pos_producer = order.iter().position(|n| n == "producer").unwrap();
+    let pos_consumer = order.iter().position(|n| n == "consumer").unwrap();
+
+    assert!(
+        pos_producer < pos_consumer,
+        "producer must come before consumer"
+    );
+}
+
+#[test]
+fn implicit_deps_from_endpoint_references() {
+    let resources = vec![
+        resource("base_resource", "/base"),
+        resource("dependent", "/api/${base_resource.output.id}/items"),
+    ];
+
+    let graph = DependencyGraph::build(&resources).unwrap();
+    let order = graph.topological_sort().unwrap();
+
+    let pos_base = order.iter().position(|n| n == "base_resource").unwrap();
+    let pos_dep = order.iter().position(|n| n == "dependent").unwrap();
+
+    assert!(
+        pos_base < pos_dep,
+        "base_resource must come before dependent"
+    );
+}
+
+#[test]
+fn mixed_explicit_and_implicit_dependencies() {
+    let mut r = resource_with_payload("c", "/c", serde_json::json!({ "ref": "${a.output.id}" }));
+    r.depends_on = Some(vec!["b".to_string()]);
+
+    let resources = vec![resource("a", "/a"), resource("b", "/b"), r];
+
+    let graph = DependencyGraph::build(&resources).unwrap();
+    let order = graph.topological_sort().unwrap();
+
+    let pos_a = order.iter().position(|n| n == "a").unwrap();
+    let pos_b = order.iter().position(|n| n == "b").unwrap();
+    let pos_c = order.iter().position(|n| n == "c").unwrap();
+
+    assert!(pos_a < pos_c, "a must come before c (implicit ref)");
+    assert!(pos_b < pos_c, "b must come before c (explicit depends_on)");
+}
+
+#[test]
+fn cycle_detection_reports_cycle_path() {
+    let resources = vec![
+        resource_with_depends("a", "/a", vec!["c"]),
+        resource_with_depends("b", "/b", vec!["a"]),
+        resource_with_depends("c", "/c", vec!["b"]),
+    ];
+
+    let graph = DependencyGraph::build(&resources).unwrap();
+    let err = graph.topological_sort().unwrap_err();
+
+    assert!(
+        err.starts_with("Circular dependency detected:"),
+        "Error should start with cycle prefix, got: {err}"
+    );
+    assert!(err.contains("a"), "Cycle path should mention 'a': {err}");
+    assert!(err.contains("b"), "Cycle path should mention 'b': {err}");
+    assert!(err.contains("c"), "Cycle path should mention 'c': {err}");
+    assert!(
+        err.contains(" -> "),
+        "Cycle path should use arrow notation: {err}"
+    );
+}
+
+#[test]
+fn independent_resources_produce_valid_order() {
+    let resources = vec![
+        resource("x", "/x"),
+        resource("y", "/y"),
+        resource("z", "/z"),
+    ];
+
+    let graph = DependencyGraph::build(&resources).unwrap();
+    let order = graph.topological_sort().unwrap();
+
+    assert_eq!(order.len(), 3);
+    assert!(order.contains(&"x".to_string()));
+    assert!(order.contains(&"y".to_string()));
+    assert!(order.contains(&"z".to_string()));
+}
+
+#[test]
+fn single_resource_trivial_case() {
+    let resources = vec![resource("only", "/only")];
+
+    let graph = DependencyGraph::build(&resources).unwrap();
+    let order = graph.topological_sort().unwrap();
+
+    assert_eq!(order, vec!["only"]);
+}
+
+#[test]
+fn depends_on_nonexistent_resource_returns_error() {
+    let resources = vec![resource_with_depends("a", "/a", vec!["nonexistent"])];
+
+    let err = DependencyGraph::build(&resources).unwrap_err();
+    assert!(
+        err.contains("unknown resource 'nonexistent'"),
+        "Should report unknown dependency: {err}"
+    );
+}
+
+#[test]
+fn diamond_dependencies() {
+    // A depends on B and C; B and C both depend on D
+    let resources = vec![
+        resource_with_depends("a", "/a", vec!["b", "c"]),
+        resource_with_depends("b", "/b", vec!["d"]),
+        resource_with_depends("c", "/c", vec!["d"]),
+        resource("d", "/d"),
+    ];
+
+    let graph = DependencyGraph::build(&resources).unwrap();
+    let order = graph.topological_sort().unwrap();
+
+    let pos_a = order.iter().position(|n| n == "a").unwrap();
+    let pos_b = order.iter().position(|n| n == "b").unwrap();
+    let pos_c = order.iter().position(|n| n == "c").unwrap();
+    let pos_d = order.iter().position(|n| n == "d").unwrap();
+
+    assert!(pos_d < pos_b, "d must come before b");
+    assert!(pos_d < pos_c, "d must come before c");
+    assert!(pos_b < pos_a, "b must come before a");
+    assert!(pos_c < pos_a, "c must come before a");
+}
+
+#[test]
+fn implicit_deps_from_read_endpoint() {
+    let mut r = resource("reader", "/read");
+    r.read_endpoint = Some("/api/${source.output.id}".to_string());
+
+    let resources = vec![resource("source", "/source"), r];
+
+    let graph = DependencyGraph::build(&resources).unwrap();
+    let order = graph.topological_sort().unwrap();
+
+    let pos_source = order.iter().position(|n| n == "source").unwrap();
+    let pos_reader = order.iter().position(|n| n == "reader").unwrap();
+
+    assert!(
+        pos_source < pos_reader,
+        "source must come before reader (read_endpoint ref)"
+    );
+}
+
+#[test]
+fn self_cycle_detected() {
+    let resources = vec![resource_with_depends("a", "/a", vec!["a"])];
+
+    let graph = DependencyGraph::build(&resources).unwrap();
+    let err = graph.topological_sort().unwrap_err();
+
+    assert!(
+        err.starts_with("Circular dependency detected:"),
+        "Should detect self-cycle: {err}"
+    );
+    assert!(err.contains("a"), "Cycle should mention 'a': {err}");
+}
+
+#[test]
+fn nested_payload_references_extracted() {
+    let resources = vec![
+        resource_with_payload(
+            "consumer",
+            "/consumer",
+            serde_json::json!({
+                "level1": {
+                    "level2": {
+                        "id": "${deep_source.output.id}"
+                    }
+                },
+                "list": ["${array_source.output.key}"]
+            }),
+        ),
+        resource("deep_source", "/deep"),
+        resource("array_source", "/array"),
+    ];
+
+    let graph = DependencyGraph::build(&resources).unwrap();
+    let order = graph.topological_sort().unwrap();
+
+    let pos_deep = order.iter().position(|n| n == "deep_source").unwrap();
+    let pos_array = order.iter().position(|n| n == "array_source").unwrap();
+    let pos_consumer = order.iter().position(|n| n == "consumer").unwrap();
+
+    assert!(pos_deep < pos_consumer);
+    assert!(pos_array < pos_consumer);
+}
diff --git a/tests/http_test.rs b/tests/http_test.rs
new file mode 100644
index 0000000..e3d2ed9
--- /dev/null
+++ b/tests/http_test.rs
@@ -0,0 +1,171 @@
+use restium::auth::{AuthProvider, MtlsAuthProvider};
+use restium::http::HttpClient;
+
+const TEST_CLIENT_PEM: &str = concat!(
+    env!("CARGO_MANIFEST_DIR"),
+    "/tests/fixtures/test-client.pem"
+);
+const TEST_CLIENT_KEY: &str = concat!(
+    env!("CARGO_MANIFEST_DIR"),
+    "/tests/fixtures/test-client.key"
+);
+const TEST_CA_PEM: &str = concat!(env!("CARGO_MANIFEST_DIR"), "/tests/fixtures/test-ca.pem");
+
+#[test]
+fn default_tls_client_succeeds() {
+    let client = HttpClient::new(false, None, None, None);
+    assert!(client.is_ok(), "default TLS client should succeed");
+}
+
+#[test]
+fn insecure_tls_client_succeeds() {
+    let client = HttpClient::new(true, None, None, None);
+    assert!(client.is_ok(), "insecure TLS client should succeed");
+}
+
+#[test]
+fn nonexistent_ca_bundle_returns_error() {
+    let result = HttpClient::new(
+        false,
+        Some("/tmp/nonexistent_ca_bundle_restium.pem"),
+        None,
+        None,
+    );
+    assert!(result.is_err());
+    let err = result.unwrap_err();
+    assert!(
+        err.contains("Failed to read CA bundle"),
+        "should mention CA bundle read failure, got: {err}"
+    );
+}
+
+#[test]
+fn valid_ca_bundle_succeeds() {
+    let dir = tempfile::tempdir().expect("temp dir");
+    let ca_path = dir.path().join("ca.pem");
+    std::fs::write(&ca_path, include_str!("fixtures/test-ca.pem")).expect("write CA");
+
+    let result = HttpClient::new(false, Some(ca_path.to_str().unwrap()), None, None);
+    assert!(
+        result.is_ok(),
+        "valid CA bundle should succeed, got: {:?}",
+        result.err()
+    );
+}
+
+#[test]
+fn empty_ca_bundle_returns_error() {
+    let dir = tempfile::tempdir().expect("temp dir");
+    let ca_path = dir.path().join("empty.pem");
+    std::fs::write(&ca_path, "not a certificate").expect("write");
+
+    let result = HttpClient::new(false, Some(ca_path.to_str().unwrap()), None, None);
+    assert!(result.is_err());
+    let err = result.unwrap_err();
+    assert!(
+        err.contains("no valid certificates"),
+        "should mention no valid certs, got: {err}"
+    );
+}
+
+#[test]
+fn insecure_overrides_ca_bundle() {
+    let result = HttpClient::new(true, Some("/tmp/nonexistent.pem"), None, None);
+    assert!(result.is_ok(), "insecure mode should ignore CA bundle path");
+}
+
+// --- mTLS Tests ---
+
+#[test]
+fn mtls_with_valid_cert_and_key_succeeds() {
+    let result = HttpClient::new(false, None, Some(TEST_CLIENT_PEM), Some(TEST_CLIENT_KEY));
+    assert!(
+        result.is_ok(),
+        "mTLS with valid cert/key should succeed, got: {:?}",
+        result.err()
+    );
+}
+
+#[test]
+fn mtls_missing_cert_returns_error() {
+    let result = HttpClient::new(
+        false,
+        None,
+        Some("/tmp/nonexistent_cert.pem"),
+        Some(TEST_CLIENT_KEY),
+    );
+    assert!(result.is_err());
+    let err = result.unwrap_err();
+    assert!(
+        err.contains("client certificate"),
+        "should mention client certificate, got: {err}"
+    );
+}
+
+#[test]
+fn mtls_missing_key_returns_error() {
+    let result = HttpClient::new(
+        false,
+        None,
+        Some(TEST_CLIENT_PEM),
+        Some("/tmp/nonexistent_key.pem"),
+    );
+    assert!(result.is_err());
+    let err = result.unwrap_err();
+    assert!(
+        err.contains("client key"),
+        "should mention client key, got: {err}"
+    );
+}
+
+#[test]
+fn mtls_with_ca_bundle_succeeds() {
+    let result = HttpClient::new(
+        false,
+        Some(TEST_CA_PEM),
+        Some(TEST_CLIENT_PEM),
+        Some(TEST_CLIENT_KEY),
+    );
+    assert!(
+        result.is_ok(),
+        "mTLS + CA bundle should succeed, got: {:?}",
+        result.err()
+    );
+}
+
+#[test]
+fn mtls_provider_apply_is_noop() {
+    let provider = MtlsAuthProvider::new(TEST_CLIENT_PEM, TEST_CLIENT_KEY).expect("should succeed");
+
+    let agent = ureq::agent();
+    let request = agent.get("https://example.com");
+    let result = provider.apply(request);
+    assert!(result.is_ok(), "mTLS apply should be a no-op");
+}
+
+#[test]
+fn mtls_missing_cert_fails_at_http_client() {
+    let result = HttpClient::new(
+        false,
+        None,
+        Some("/tmp/nonexistent.pem"),
+        Some(TEST_CLIENT_KEY),
+    );
+    assert!(result.is_err());
+    let err = result.unwrap_err();
+    assert!(
+        err.contains("Failed to read client certificate"),
+        "should mention client certificate read failure, got: {err}"
+    );
+}
+
+#[test]
+fn insecure_tls_with_mtls_is_rejected() {
+    let result = HttpClient::new(true, None, Some(TEST_CLIENT_PEM), Some(TEST_CLIENT_KEY));
+    assert!(result.is_err());
+    let err = result.unwrap_err();
+    assert!(
+        err.contains("mutually exclusive"),
+        "should reject insecure_tls + mTLS, got: {err}"
+    );
+}
diff --git a/tests/logging_test.rs b/tests/logging_test.rs
new file mode 100644
index 0000000..ee204ba
--- /dev/null
+++ b/tests/logging_test.rs
@@ -0,0 +1,280 @@
+use std::process::Command;
+
+use restium::logging::{Logger, redact_url};
+
+fn restium_cmd() -> Command {
+    Command::new(env!("CARGO_BIN_EXE_restium"))
+}
+
+// --- Text mode tests ---
+
+#[test]
+fn text_mode_outputs_info_format() {
+    let dir = tempfile::tempdir().expect("temp dir");
+    let spec = dir.path().join("test.yaml");
+    std::fs::write(&spec, "global: {}").expect("write spec");
+
+    let output = restium_cmd()
+        .args(["validate", "--spec", spec.to_str().unwrap()])
+        .output()
+        .expect("run");
+
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    assert!(
+        stderr.contains("[INFO]"),
+        "text mode should include [INFO] prefix, got: {stderr}"
+    );
+    assert!(
+        stderr.contains("Validation passed"),
+        "text mode should include message, got: {stderr}"
+    );
+}
+
+#[test]
+fn text_mode_reconcile_info() {
+    let dir = tempfile::tempdir().expect("temp dir");
+    let spec = dir.path().join("test.yaml");
+    std::fs::write(&spec, "global: {}").expect("write spec");
+
+    let output = restium_cmd()
+        .args(["reconcile", "--spec", spec.to_str().unwrap()])
+        .output()
+        .expect("run");
+
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    assert!(
+        stderr.contains("[INFO]"),
+        "text mode should include [INFO], got: {stderr}"
+    );
+}
+
+// --- JSON mode tests ---
+
+#[test]
+fn json_mode_outputs_valid_json() {
+    let dir = tempfile::tempdir().expect("temp dir");
+    let spec = dir.path().join("test.yaml");
+    std::fs::write(&spec, "global: {}").expect("write spec");
+
+    let output = restium_cmd()
+        .args(["--json", "validate", "--spec", spec.to_str().unwrap()])
+        .output()
+        .expect("run");
+
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    for line in stderr.lines() {
+        let parsed: serde_json::Value =
+            serde_json::from_str(line).unwrap_or_else(|e| panic!("invalid JSON: {e}: {line}"));
+        assert_eq!(
+            parsed.get("level").and_then(|v| v.as_str()),
+            Some("info"),
+            "JSON should have level field"
+        );
+        assert!(
+            parsed.get("message").is_some(),
+            "JSON should have message field"
+        );
+    }
+}
+
+#[test]
+fn json_mode_has_level_and_message() {
+    let dir = tempfile::tempdir().expect("temp dir");
+    let spec = dir.path().join("test.yaml");
+    std::fs::write(&spec, "global: {}").expect("write spec");
+
+    let output = restium_cmd()
+        .args(["--json", "reconcile", "--spec", spec.to_str().unwrap()])
+        .output()
+        .expect("run");
+
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    let line = stderr.lines().next().expect("should have output");
+    let parsed: serde_json::Value = serde_json::from_str(line).expect("valid JSON");
+    assert_eq!(parsed["level"], "info");
+    assert!(
+        parsed["message"]
+            .as_str()
+            .unwrap()
+            .contains("Reconciliation")
+    );
+}
+
+// --- Error output tests ---
+
+#[test]
+fn error_output_uses_logger_text_format() {
+    let output = restium_cmd()
+        .args(["validate", "--spec", "nonexistent.yaml"])
+        .output()
+        .expect("run");
+
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    assert!(
+        stderr.contains("[ERROR]"),
+        "error should use [ERROR] prefix in text mode, got: {stderr}"
+    );
+}
+
+#[test]
+fn error_output_json_mode() {
+    let output = restium_cmd()
+        .args(["--json", "validate", "--spec", "nonexistent.yaml"])
+        .output()
+        .expect("run");
+
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    let line = stderr.lines().next().expect("should have output");
+    let parsed: serde_json::Value = serde_json::from_str(line).expect("valid JSON");
+    assert_eq!(parsed["level"], "error");
+    assert!(
+        parsed["message"]
+            .as_str()
+            .unwrap()
+            .contains("Failed to read spec file")
+    );
+}
+
+// --- Redaction unit tests (via lib crate) ---
+
+#[test]
+fn sensitive_key_authorization_is_redacted_text() {
+    let logger = Logger::new(false);
+    // We test via format_line helper — Logger writes to stderr.
+    // Use format_line directly by testing the output capture approach.
+    let line = logger.format_line("info", "test", &[("authorization", "Bearer secret123")]);
+    assert!(
+        line.contains("[REDACTED]"),
+        "authorization value should be redacted, got: {line}"
+    );
+    assert!(
+        !line.contains("secret123"),
+        "secret value should not appear, got: {line}"
+    );
+}
+
+#[test]
+fn sensitive_key_token_is_redacted_json() {
+    let logger = Logger::new(true);
+    let line = logger.format_line("info", "test", &[("token", "abc123")]);
+    assert!(
+        line.contains("[REDACTED]"),
+        "token value should be redacted in JSON, got: {line}"
+    );
+    assert!(
+        !line.contains("abc123"),
+        "token value should not appear, got: {line}"
+    );
+}
+
+#[test]
+fn non_sensitive_key_is_not_redacted() {
+    let logger = Logger::new(false);
+    let line = logger.format_line("info", "test", &[("resource", "my_resource")]);
+    assert!(
+        line.contains("my_resource"),
+        "non-sensitive value should appear, got: {line}"
+    );
+    assert!(
+        !line.contains("[REDACTED]"),
+        "non-sensitive key should not be redacted, got: {line}"
+    );
+}
+
+#[test]
+fn case_insensitive_redaction() {
+    let logger = Logger::new(false);
+    let line = logger.format_line("info", "test", &[("Authorization", "Bearer xyz")]);
+    assert!(
+        line.contains("[REDACTED]"),
+        "case-insensitive match should redact, got: {line}"
+    );
+}
+
+#[test]
+fn partial_key_match_redacts() {
+    let logger = Logger::new(false);
+    let line = logger.format_line("info", "test", &[("x_api_key", "mykey")]);
+    assert!(
+        line.contains("[REDACTED]"),
+        "partial key match (x_api_key contains api_key) should redact, got: {line}"
+    );
+}
+
+#[test]
+fn password_key_redacted() {
+    let logger = Logger::new(true);
+    let line = logger.format_line("info", "test", &[("password", "hunter2")]);
+    assert!(
+        line.contains("[REDACTED]"),
+        "password should be redacted, got: {line}"
+    );
+    assert!(
+        !line.contains("hunter2"),
+        "password value should not appear, got: {line}"
+    );
+}
+
+#[test]
+fn client_secret_key_redacted() {
+    let logger = Logger::new(false);
+    let line = logger.format_line("info", "test", &[("client_secret", "s3cr3t")]);
+    assert!(
+        line.contains("[REDACTED]"),
+        "client_secret should be redacted, got: {line}"
+    );
+}
+
+#[test]
+fn warn_level_outputs_correct_prefix() {
+    let logger = Logger::new(false);
+    let line = logger.format_line("warn", "something is off", &[]);
+    assert!(
+        line.contains("[WARN]"),
+        "warn level should produce [WARN] prefix, got: {line}"
+    );
+    assert!(
+        line.contains("something is off"),
+        "warn message should appear, got: {line}"
+    );
+}
+
+// --- URL redaction tests ---
+
+#[test]
+fn url_with_secret_query_param_is_redacted() {
+    let result = redact_url("https://api.example.com/oauth/token?client_secret=abc123&scope=read");
+    assert!(
+        result.contains("client_secret=[REDACTED]"),
+        "secret param should be redacted, got: {result}"
+    );
+    assert!(
+        result.contains("scope=read"),
+        "non-secret param should be preserved, got: {result}"
+    );
+}
+
+#[test]
+fn url_without_query_params_unchanged() {
+    let url = "https://api.example.com/api/networks";
+    assert_eq!(redact_url(url), url);
+}
+
+#[test]
+fn url_with_non_sensitive_query_params_unchanged() {
+    let url = "https://api.example.com/api?page=1&limit=50";
+    assert_eq!(redact_url(url), url);
+}
+
+#[test]
+fn url_with_token_query_param_redacted() {
+    let result = redact_url("https://api.example.com/api?access_token=xyz789&format=json");
+    assert!(
+        result.contains("access_token=[REDACTED]"),
+        "access_token param should be redacted, got: {result}"
+    );
+    assert!(
+        result.contains("format=json"),
+        "non-secret param should be preserved, got: {result}"
+    );
+}
diff --git a/tests/reference_test.rs b/tests/reference_test.rs
new file mode 100644
index 0000000..265551f
--- /dev/null
+++ b/tests/reference_test.rs
@@ -0,0 +1,230 @@
+use std::collections::HashMap;
+
+use restium::reference::{OutputStore, extract_outputs, resolve_references, resolve_string};
+use serde_json::json;
+
+fn empty_store() -> OutputStore {
+    OutputStore::new()
+}
+
+fn store_with(resource: &str, outputs: Vec<(&str, &str)>) -> OutputStore {
+    let mut store = OutputStore::new();
+    let mut map = HashMap::new();
+    for (k, v) in outputs {
+        map.insert(k.to_string(), v.to_string());
+    }
+    store.insert(resource.to_string(), map);
+    store
+}
+
+// --- extract_outputs tests ---
+
+#[test]
+fn extract_single_output_field() {
+    let mut store = empty_store();
+    let body = json!({"id": "abc123", "name": "test"});
+    let mut rules = HashMap::new();
+    rules.insert("id".to_string(), "id".to_string());
+
+    extract_outputs(&mut store, "my_resource", &body, &rules).unwrap();
+
+    assert_eq!(store["my_resource"]["id"], "abc123");
+}
+
+#[test]
+fn extract_multiple_output_fields() {
+    let mut store = empty_store();
+    let body = json!({"id": "abc123", "api_key": "key456", "status": "active"});
+    let mut rules = HashMap::new();
+    rules.insert("id".to_string(), "id".to_string());
+    rules.insert("key".to_string(), "api_key".to_string());
+
+    extract_outputs(&mut store, "my_resource", &body, &rules).unwrap();
+
+    assert_eq!(store["my_resource"]["id"], "abc123");
+    assert_eq!(store["my_resource"]["key"], "key456");
+}
+
+#[test]
+fn extract_numeric_field() {
+    let mut store = empty_store();
+    let body = json!({"id": 42});
+    let mut rules = HashMap::new();
+    rules.insert("id".to_string(), "id".to_string());
+
+    extract_outputs(&mut store, "res", &body, &rules).unwrap();
+
+    assert_eq!(store["res"]["id"], "42");
+}
+
+#[test]
+fn extract_missing_field_returns_error() {
+    let mut store = empty_store();
+    let body = json!({"name": "test"});
+    let mut rules = HashMap::new();
+    rules.insert("id".to_string(), "id".to_string());
+
+    let err = extract_outputs(&mut store, "my_resource", &body, &rules).unwrap_err();
+    assert!(
+        err.contains("my_resource"),
+        "Error should name resource: {err}"
+    );
+    assert!(
+        err.contains("'id' not found"),
+        "Error should name missing field: {err}"
+    );
+}
+
+// --- resolve_string tests ---
+
+#[test]
+fn resolve_single_reference_in_string() {
+    let store = store_with("resource_b", vec![("id", "abc123")]);
+    let result = resolve_string("prefix-${resource_b.output.id}-suffix", &store).unwrap();
+    assert_eq!(result, "prefix-abc123-suffix");
+}
+
+#[test]
+fn resolve_multiple_references_in_string() {
+    let mut store = store_with("res_a", vec![("id", "111")]);
+    store
+        .entry("res_b".to_string())
+        .or_default()
+        .insert("key".to_string(), "222".to_string());
+
+    let result = resolve_string("${res_a.output.id}/${res_b.output.key}", &store).unwrap();
+    assert_eq!(result, "111/222");
+}
+
+#[test]
+fn string_without_references_passes_through() {
+    let store = empty_store();
+    let result = resolve_string("no references here", &store).unwrap();
+    assert_eq!(result, "no references here");
+}
+
+#[test]
+fn unresolved_resource_returns_error() {
+    let store = empty_store();
+    let err = resolve_string("${unknown.output.id}", &store).unwrap_err();
+    assert!(
+        err.contains("unknown"),
+        "Error should name the resource: {err}"
+    );
+    assert!(
+        err.contains("not been processed"),
+        "Error should explain the issue: {err}"
+    );
+}
+
+#[test]
+fn missing_output_field_returns_error() {
+    let store = store_with("res_b", vec![("id", "abc")]);
+    let err = resolve_string("${res_b.output.missing_field}", &store).unwrap_err();
+    assert!(
+        err.contains("res_b"),
+        "Error should name the resource: {err}"
+    );
+    assert!(
+        err.contains("missing_field"),
+        "Error should name the field: {err}"
+    );
+}
+
+// --- resolve_references (JSON value) tests ---
+
+#[test]
+fn resolve_references_in_payload() {
+    let store = store_with("network", vec![("id", "net-123")]);
+    let payload = json!({
+        "network_id": "${network.output.id}",
+        "name": "my-route"
+    });
+
+    let resolved = resolve_references(&payload, &store).unwrap();
+    assert_eq!(
+        resolved,
+        json!({
+            "network_id": "net-123",
+            "name": "my-route"
+        })
+    );
+}
+
+#[test]
+fn resolve_nested_payload_references() {
+    let store = store_with("parent", vec![("id", "p-1")]);
+    let payload = json!({
+        "config": {
+            "parent_id": "${parent.output.id}",
+            "nested": {
+                "ref": "${parent.output.id}"
+            }
+        }
+    });
+
+    let resolved = resolve_references(&payload, &store).unwrap();
+    assert_eq!(
+        resolved,
+        json!({
+            "config": {
+                "parent_id": "p-1",
+                "nested": {
+                    "ref": "p-1"
+                }
+            }
+        })
+    );
+}
+
+#[test]
+fn resolve_array_payload_references() {
+    let store = store_with("src", vec![("id", "s-1")]);
+    let payload = json!({
+        "items": ["${src.output.id}", "static"]
+    });
+
+    let resolved = resolve_references(&payload, &store).unwrap();
+    assert_eq!(
+        resolved,
+        json!({
+            "items": ["s-1", "static"]
+        })
+    );
+}
+
+#[test]
+fn non_string_values_pass_through() {
+    let store = empty_store();
+    let payload = json!({
+        "count": 42,
+        "active": true,
+        "data": null
+    });
+
+    let resolved = resolve_references(&payload, &store).unwrap();
+    assert_eq!(resolved, payload);
+}
+
+#[test]
+fn multiple_resources_in_payload() {
+    let mut store = store_with("network", vec![("id", "net-1")]);
+    store
+        .entry("group".to_string())
+        .or_default()
+        .insert("id".to_string(), "grp-2".to_string());
+
+    let payload = json!({
+        "network_id": "${network.output.id}",
+        "group_id": "${group.output.id}"
+    });
+
+    let resolved = resolve_references(&payload, &store).unwrap();
+    assert_eq!(
+        resolved,
+        json!({
+            "network_id": "net-1",
+            "group_id": "grp-2"
+        })
+    );
+}
diff --git a/tests/validation_test.rs b/tests/validation_test.rs
new file mode 100644
index 0000000..85eca4d
--- /dev/null
+++ b/tests/validation_test.rs
@@ -0,0 +1,370 @@
+use restium::config::{SpecFile, validate_spec};
+
+fn parse_and_validate(yaml: &str) -> Vec<String> {
+    let spec: SpecFile = serde_yaml::from_str(yaml).expect("valid YAML");
+    validate_spec(&spec)
+}
+
+#[test]
+fn valid_spec_returns_no_errors() {
+    let errors = parse_and_validate(
+        r#"
+resources:
+  - name: resource_a
+    endpoint: /api/a
+  - name: resource_b
+    endpoint: /api/b
+    depends_on:
+      - resource_a
+"#,
+    );
+    assert!(
+        errors.is_empty(),
+        "valid spec should have no errors: {errors:?}"
+    );
+}
+
+#[test]
+fn duplicate_resource_names_detected() {
+    let errors = parse_and_validate(
+        r#"
+resources:
+  - name: my_resource
+    endpoint: /api/a
+  - name: my_resource
+    endpoint: /api/b
+"#,
+    );
+    assert_eq!(errors.len(), 1);
+    assert!(
+        errors[0].contains("Duplicate resource name: 'my_resource'"),
+        "got: {}",
+        errors[0]
+    );
+}
+
+#[test]
+fn reference_to_nonexistent_resource_detected() {
+    let errors = parse_and_validate(
+        r#"
+resources:
+  - name: resource_a
+    endpoint: /api/a
+    payload:
+      ref_id: "${nonexistent.output.id}"
+"#,
+    );
+    assert_eq!(errors.len(), 1);
+    assert!(
+        errors[0].contains("references unknown resource 'nonexistent'"),
+        "got: {}",
+        errors[0]
+    );
+    assert!(
+        errors[0].contains("resource_a"),
+        "should mention the resource containing the ref, got: {}",
+        errors[0]
+    );
+}
+
+#[test]
+fn depends_on_nonexistent_resource_detected() {
+    let errors = parse_and_validate(
+        r#"
+resources:
+  - name: resource_a
+    endpoint: /api/a
+    depends_on:
+      - does_not_exist
+"#,
+    );
+    assert_eq!(errors.len(), 1);
+    assert!(
+        errors[0].contains("depends on unknown resource 'does_not_exist'"),
+        "got: {}",
+        errors[0]
+    );
+}
+
+#[test]
+fn circular_dependency_two_nodes_detected() {
+    let errors = parse_and_validate(
+        r#"
+resources:
+  - name: a
+    endpoint: /api/a
+    depends_on:
+      - b
+  - name: b
+    endpoint: /api/b
+    depends_on:
+      - a
+"#,
+    );
+    let cycle_errors: Vec<&String> = errors
+        .iter()
+        .filter(|e| e.contains("Circular dependency"))
+        .collect();
+    assert!(
+        !cycle_errors.is_empty(),
+        "should detect cycle, got: {errors:?}"
+    );
+    let err = &cycle_errors[0];
+    assert!(err.contains("->"), "should show cycle path, got: {err}");
+}
+
+#[test]
+fn circular_dependency_three_nodes_detected() {
+    let errors = parse_and_validate(
+        r#"
+resources:
+  - name: a
+    endpoint: /api/a
+    depends_on:
+      - b
+  - name: b
+    endpoint: /api/b
+    depends_on:
+      - c
+  - name: c
+    endpoint: /api/c
+    depends_on:
+      - a
+"#,
+    );
+    let cycle_errors: Vec<&String> = errors
+        .iter()
+        .filter(|e| e.contains("Circular dependency"))
+        .collect();
+    assert!(
+        !cycle_errors.is_empty(),
+        "should detect cycle, got: {errors:?}"
+    );
+}
+
+#[test]
+fn self_dependency_detected() {
+    let errors = parse_and_validate(
+        r#"
+resources:
+  - name: self_ref
+    endpoint: /api/self
+    depends_on:
+      - self_ref
+"#,
+    );
+    let cycle_errors: Vec<&String> = errors
+        .iter()
+        .filter(|e| e.contains("Circular dependency"))
+        .collect();
+    assert!(
+        !cycle_errors.is_empty(),
+        "self-dependency should be detected as cycle, got: {errors:?}"
+    );
+}
+
+#[test]
+fn multiple_errors_collected() {
+    let errors = parse_and_validate(
+        r#"
+resources:
+  - name: dup
+    endpoint: /api/a
+  - name: dup
+    endpoint: /api/b
+  - name: broken_ref
+    endpoint: /api/c
+    payload:
+      id: "${ghost.output.id}"
+"#,
+    );
+    assert!(
+        errors.len() >= 2,
+        "should have at least 2 errors (dup + broken ref), got: {errors:?}"
+    );
+    assert!(errors.iter().any(|e| e.contains("Duplicate")));
+    assert!(
+        errors
+            .iter()
+            .any(|e| e.contains("unknown resource 'ghost'"))
+    );
+}
+
+#[test]
+fn payload_references_are_scanned() {
+    let errors = parse_and_validate(
+        r#"
+resources:
+  - name: a
+    endpoint: /api/a
+    payload:
+      nested:
+        deep:
+          ref: "${missing.output.value}"
+"#,
+    );
+    assert_eq!(errors.len(), 1);
+    assert!(errors[0].contains("missing"), "got: {}", errors[0]);
+}
+
+#[test]
+fn valid_references_pass() {
+    let errors = parse_and_validate(
+        r#"
+resources:
+  - name: network
+    endpoint: /api/networks
+    outputs:
+      id: "id"
+  - name: route
+    endpoint: /api/routes
+    payload:
+      network_id: "${network.output.id}"
+    depends_on:
+      - network
+"#,
+    );
+    assert!(errors.is_empty(), "valid refs should pass, got: {errors:?}");
+}
+
+#[test]
+fn complex_dependency_chain_without_cycles_passes() {
+    let errors = parse_and_validate(
+        r#"
+resources:
+  - name: a
+    endpoint: /api/a
+  - name: b
+    endpoint: /api/b
+    depends_on: [a]
+  - name: c
+    endpoint: /api/c
+    depends_on: [a, b]
+  - name: d
+    endpoint: /api/d
+    depends_on: [c]
+"#,
+    );
+    assert!(errors.is_empty(), "no cycles should be found: {errors:?}");
+}
+
+#[test]
+fn implicit_reference_creates_dependency_for_cycle_check() {
+    let errors = parse_and_validate(
+        r#"
+resources:
+  - name: a
+    endpoint: /api/a
+    payload:
+      b_id: "${b.output.id}"
+  - name: b
+    endpoint: /api/b
+    payload:
+      a_id: "${a.output.id}"
+"#,
+    );
+    let cycle_errors: Vec<&String> = errors
+        .iter()
+        .filter(|e| e.contains("Circular dependency"))
+        .collect();
+    assert!(
+        !cycle_errors.is_empty(),
+        "implicit ref cycle should be detected, got: {errors:?}"
+    );
+}
+
+#[test]
+fn read_endpoint_references_validated() {
+    let errors = parse_and_validate(
+        r#"
+resources:
+  - name: a
+    endpoint: /api/a
+    read_endpoint: "/api/a/${nonexistent.output.id}"
+"#,
+    );
+    assert_eq!(errors.len(), 1);
+    assert!(
+        errors[0].contains("nonexistent"),
+        "read_endpoint refs should be validated, got: {}",
+        errors[0]
+    );
+}
+
+#[test]
+fn empty_spec_is_valid() {
+    let errors = parse_and_validate("{}");
+    assert!(errors.is_empty());
+}
+
+#[test]
+fn endpoint_references_are_validated() {
+    let errors = parse_and_validate(
+        r#"
+resources:
+  - name: a
+    endpoint: "/api/${missing.output.id}/details"
+"#,
+    );
+    assert_eq!(errors.len(), 1);
+    assert!(
+        errors[0].contains("unknown resource 'missing'"),
+        "endpoint refs should be validated, got: {}",
+        errors[0]
+    );
+}
+
+#[test]
+fn invalid_action_value_detected() {
+    let errors = parse_and_validate(
+        r#"
+resources:
+  - name: bad_action
+    endpoint: /api/bad
+    action: upsert
+"#,
+    );
+    assert_eq!(errors.len(), 1);
+    assert!(
+        errors[0].contains("invalid action 'upsert'"),
+        "should detect invalid action, got: {}",
+        errors[0]
+    );
+}
+
+#[test]
+fn delete_action_is_valid() {
+    let errors = parse_and_validate(
+        r#"
+resources:
+  - name: cleanup
+    endpoint: /api/cleanup
+    action: delete
+"#,
+    );
+    assert!(
+        errors.is_empty(),
+        "action: delete should be valid, got: {errors:?}"
+    );
+}
+
+#[test]
+fn self_reference_in_payload_detected() {
+    let errors = parse_and_validate(
+        r#"
+resources:
+  - name: self_ref
+    endpoint: /api/self
+    payload:
+      id: "${self_ref.output.id}"
+"#,
+    );
+    let cycle_errors: Vec<&String> = errors
+        .iter()
+        .filter(|e| e.contains("Circular dependency"))
+        .collect();
+    assert!(
+        !cycle_errors.is_empty(),
+        "self-reference in payload should be detected as cycle, got: {errors:?}"
+    );
+}