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schemaui turns JSON Schema documents into fully interactive terminal UIs powered by ratatui, crossterm, and jsonschema.

The library parses rich schemas (nested sections, $ref, arrays, key/value maps, pattern properties…) into a navigable form tree, renders it as a keyboard-first editor, and validates the result after every edit so users always see the full list of issues before saving.

CLI available: schemaui-cli installs the schemaui binary. Prefer the CLI? Jump to CLI installation and usage.

Feature Highlights

• Schema fidelity – draft-07 compatible, including $ref, definitions, patternProperties, enums, numeric ranges, and nested objects/arrays.
• Sections & overlays – top-level properties become root tabs, nested objects are flattened into sections, and complex nodes (composites, key/value collections, array entries) open dedicated overlays with their own validators.
• Immediate validation – every keystroke can trigger jsonschema::Validator, and all errors (field-scoped + global) are collected and displayed together.
• Pluggable I/O – io::input ingests JSON/YAML/TOML (feature-gated) while io::output can emit to stdout and/or multiple files in any enabled format.
• Batteries-included CLI – schemaui-cli offers the same pipeline as the library, including multi-destination output, stdin/inline specs, and aggregated diagnostics.
• Embedded Web UI – enabling the web feature bundles a browser UI and exposes helpers under schemaui::web::session so host applications can serve the experience without reimplementing the stack.

Config Schema Auto-Detection

When you launch the CLI with --config and omit --schema, schemaui-cli now resolves the schema in this order:

1. Explicit --schema
2. A schema declaration embedded in the config document
3. Fallback inference via schema_from_data_value

Supported declarations:

• JSON: root $schema
• TOML: #:schema ./schema.json
• YAML: # yaml-language-server: $schema=...
• YAML fallback: # @schema ...

Both local and remote schema references are supported. Relative local paths are resolved against the config file directory, while inline/stdin configs fall back to the current working directory. JSON $schema metadata is stripped from the in-memory defaults before validation/output so editor hints do not leak into the final config payload.

Remote http(s) schema loading exists only in schemaui-cli, and the CLI enables the remote-schema feature by default. Disable it if you want a local-only binary surface; the schemaui library crate does not enable any remote schema loading by default.

Feature defaults are intentionally split by audience:

• schemaui-cli defaults to the convenient, batteries-included path: TUI + Web + remote schema loading.
• schemaui defaults to tui + json, so library consumers keep JSON support without pulling in Web or remote/network-related surface area by default.
• json, yaml, and toml are real code-level gates. Keep at least one of them enabled; disabling all three triggers a clear compile-time error.

References:

• JSON Schema $schema: https://json-schema.org/understanding-json-schema/reference/schema
• Taplo directives (#:schema): https://taplo.tamasfe.dev/configuration/directives.html
• YAML language server modeline: https://github.com/redhat-developer/yaml-language-server

Quick Start

[dependencies]
schemaui = "0.11.1"
serde_json = "1"

use schemaui::prelude::*;
use serde_json::json;

fn main() -> color_eyre::Result<()> {
    color_eyre::install()?;
    let schema = json!({
        "$schema": "http://json-schema.org/draft-07/schema#",
        "title": "Service Runtime",
        "type": "object",
        "properties": {
            "metadata": {
                "type": "object",
                "properties": {
                    "serviceName": {"type": "string"},
                    "environment": {
                        "type": "string",
                        "enum": ["dev", "staging", "prod"]
                    }
                },
                "required": ["serviceName"]
            },
            "runtime": {
                "type": "object",
                "properties": {
                    "http": {
                        "type": "object",
                        "properties": {
                            "host": {"type": "string", "default": "0.0.0.0"},
                            "port": {"type": "integer", "minimum": 1024, "maximum": 65535}
                        }
                    }
                }
            }
        },
        "required": ["metadata", "runtime"]
    });

    let config = serde_json::json!({
        "metadata": { "name": "demo-service" },
        "runtime": { "http": { "host": "127.0.0.1", "port": 8080 } }
    });

    let value = SchemaUI::new(config)
        .with_schema(schema)
        .with_title("SchemaUI Demo")
        .with_description("Edit an existing config against a validation schema")
        .run(FrontendOptions::Tui(UiOptions::default()))?;
    println!("{}", serde_json::to_string_pretty(&value)?);
    Ok(())
}

Public API surface

For library integrations, the main entry points are:

• High-level runtime: SchemaUI, DocumentInput, FrontendOptions, ServeOptions, and UiOptions
• TUI runtime: crate::tui::session::TuiFrontend for custom frontend injection via SchemaUI::run_with_frontend
• TUI state: crate::tui::state::* (for example FormState, FormCommand, FormEngine, SectionState)
• Schema backend: crate::ui_ast::build_ui_ast together with crate::tui::model::form_schema_from_ui_ast (builds FormSchema from the canonical UI AST)

Architecture Snapshot

┌─────────────┐   parse/merge    ┌───────────────┐   layout + typing      ┌───────────────┐
│ io::input   ├─────────────────▶│ schema        ├───────────────────────▶│ tui::state    │
└─────────────┘                  │ (loader /     │                        │ (FormState,   │
                                 │ resolver /    │                        │ sections,     │
┌─────────────┐   emit Value     │ build_form_   │   FormSchema           │ reducers)     │
│ io::output  ◀──────────────────┴────pipeline───┘                        └────────┬──────┘
└─────────────┘                                                      focus/edits│
                                                                                │
                                                                     ┌──────────▼──────────┐
                                                                     │ tui::app::runtime   │
                                                                     │ (InputRouter,       │
                                                                     │ overlays, status)   │
                                                                     └──────────┬──────────┘
                                                                                │ draw
                                                                     ┌──────────▼──────────┐
                                                                     │ tui::view::*        │
                                                                     │ (ratatui view)      │
                                                                     └─────────────────────┘

This layout mirrors the actual modules under src/, making it easy to map any code change to its architectural responsibility.

Input & Output Design

• io::input::parse_document_str converts JSON/YAML/TOML (via serde_json, serde_yaml, toml) into serde_json::Value. Feature flags (json, yaml, toml) keep dependencies lean, and the same gates also drive DocumentFormat parsing/probing at compile time.
• schema_from_data_value/str infers schemas from live configs, injecting draft-07 metadata and defaults so UIs load pre-existing values.
• schema_with_defaults merges canonical schemas with user data, propagating defaults through properties, patternProperties, additionalProperties, dependencies, dependentSchemas, arrays, and $ref targets without mutating the original tree.
• io::output::OutputOptions encapsulates serialization format, pretty/compact toggle, and a vector of OutputDestination::{Stdout, File}. Multiple destinations are supported; conflicts are caught before emission.
• OutputOptions::render turns the final serde_json::Value into JSON/YAML/TOML text, and OutputOptions::write sends that payload to stdout/files explicitly after SchemaUI::run* returns.

Web UI Mode

The optional web feature bundles the files under web/dist/ directly into the crate and exposes high-level helpers for hosting the browser UI. Basic usage:

use schemaui::web::session::{
    ServeOptions,
    WebSessionBuilder,
    bind_session,
};

async fn run() -> anyhow::Result<()> {
  let schema = serde_json::json!({
      "$schema": "http://json-schema.org/draft-07/schema#",
      "type": "object",
      "properties": {
          "host": {"type": "string", "default": "127.0.0.1"},
          "port": {"type": "integer", "default": 8080}
      },
      "required": ["host", "port"]
  });

  let config = WebSessionBuilder::new(schema)
      .with_title("Service Config")
      .build()?;
  let session = bind_session(config, ServeOptions::default()).await?;
  println!("visit http://{}/", session.local_addr());
  let value = session.run().await?;
  println!("final JSON: {}", serde_json::to_string_pretty(&value)?);
  Ok(())
}

The helper spawns an Axum router that exposes /api/session, /api/save, and /api/exit alongside the embedded static assets. Library users can either call bind_session/serve_session for a turnkey flow or reuse session_router/WebSessionBuilder to integrate the UI into an existing HTTP stack. The official CLI (schemaui-cli web …) is merely a thin wrapper around these APIs.

JSON Schema → TUI Mapping

build_ui_ast resolves the schema into the canonical UI AST, and form_schema_from_ui_ast maps that tree into FormSection/FieldSchema for the TUI runtime:

Schema feature	Resulting control
type: string, integer, number	Inline text editors with numeric guards
type: boolean	Toggle/checkbox
enum	Popup selector (single or multi-select for array enums)
Arrays	Inline list summary + overlay editor per item
patternProperties, propertyNames, additionalProperties	Key/Value editor with schema-backed validation
$ref, definitions	Resolved before layout; treated like inline schemas
oneOf / anyOf	Variant chooser + overlay form, keeps inactive variants out of the final payload

Root objects spawn tabs; nested objects become sections with breadcrumb titles. Every field records its JSON pointer (for example /runtime/http/port) so focus management and validation can map errors back precisely.

Validation Lifecycle

• jsonschema::validator_for compiles the complete schema once when SchemaUI::run begins.
• Each edit dispatches FormCommand::FieldEdited. FormEngine rebuilds the current document via FormState::try_build_value, runs the validator, and feeds errors back into FieldState or the global status line.
• Overlays (composite variants, key/value maps, list entries) spin up their own validators built from the sub-schema currently being edited. Nested overlays live on a stack, so each level validates in place before changes flow back to the parent form.

┌─────────────┐ parse schema ┌─────────────────┐ inflate state  ┌────────────┐
│ SchemaUI::run├────────────▶│ domain::parse   ├───────────────▶│ FormState  │
└─────┬───────┘              │ (schema::layout)│                └─────┬──────┘
      │ validator_for()      └─────────────────┘                edits │
      │                                                        ┌──────▼─────────┐
      └────────────────────────────────────────────────────── ▶│ app::runtime   │
                                                               │ (status, input)│
                                                               └──────┬─────────┘
                                                                      │ FormCommand
                                                               ┌──────▼──────────┐
                                                               │ FormEngine      │
                                                               │ + jsonschema    │
                                                               └─────────────────┘

App is the sole owner of FormState; even overlay edits flow through FormEngine so validation rules stay centralized.

TUI Building Blocks & Shortcuts

• Single source for shortcuts – keymap/default.keymap.json lists every shortcut (context, combos, action). The app::keymap::keymap_source!() macro pulls this file into the binary, InputRouter uses it to classify KeyEvents, and the runtime footer renders help text from the same data—keeping docs and behavior DRY.
• Root tabs & sections – focus cycles with Ctrl+J / Ctrl+L (roots) and Ctrl+Tab / Ctrl+Shift+Tab (sections). Ordinary Tab/Shift+Tab walk individual fields.
• Fields – render labels, descriptions, and inline error messages. Enum/composite fields show the current selection; arrays summarize length and selected entry.
• Popups & overlays – pressing Enter opens a popup for enums/oneOf selectors; Ctrl+E pushes a full-screen overlay editor for composites, key/value pairs, and array items. Overlays expose collection shortcuts (Ctrl+N, Ctrl+D, Ctrl+←/→, Ctrl+↑/↓), Ctrl+S saves the active level without closing, and Esc / Ctrl+Q pops a single overlay.
• Status & help – the footer highlights dirty state, outstanding validation errors, and context-aware help text. When auto-validate is enabled, each edit updates these counters immediately.

Generated shortcut reference

Default context

Shortcut	Action	Kind
Tab / Down	Next field	command
BackTab / Up	Previous field	command
Ctrl+Tab	Next section	command
Ctrl+Shift+Tab	Previous section	command
Ctrl+L	Next root tab	command
Ctrl+J	Previous root tab	command
Enter	Open popup / apply selection	command
Ctrl+E	Open composite editor	command
Ctrl+S	Save & validate (overlays stay open)	command
Ctrl+Q / Ctrl+C	Quit (confirm if dirty)	command
Esc	Cancel / clear status (overlays: pop current level)	command
Ctrl+? / Ctrl+H	Show help and error summary	command

Collection context

Shortcut	Action	Kind
Ctrl+E	Open composite editor	command
Ctrl+N	Add entry	command
Ctrl+D	Remove entry	command
Ctrl+Left	Select previous entry	command
Ctrl+Right	Select next entry	command
Ctrl+Up	Move entry up	command
Ctrl+Down	Move entry down	command
Ctrl+? / Ctrl+H	Show help and error summary	command

Overlay context

Shortcut	Action	Kind
Tab / Down	Next field	command
BackTab / Up	Previous field	command
Ctrl+N	Add entry	command
Ctrl+D	Remove entry	command
Ctrl+Left	Select previous entry	command
Ctrl+Right	Select next entry	command
Ctrl+Up	Move entry up	command
Ctrl+Down	Move entry down	command
Ctrl+S	Save & validate (overlays stay open)	command
Esc	Cancel / clear status (overlays: pop current level)	command
Ctrl+? / Ctrl+H	Show help and error summary	command

Help context

Shortcut	Action	Kind
Esc / Ctrl+H / Ctrl+?	Close help	command
Tab	Next error page	command
BackTab	Previous error page	command
Up / k	Scroll shortcuts up	command
Down / j	Scroll shortcuts down	command
PageUp	Page shortcuts up	command
PageDown	Page shortcuts down	command
Home	Jump shortcuts to top	command
End	Jump shortcuts to bottom	command
h	Scroll error text left	command
l	Scroll error text right	command

Text field context

Shortcut	Action	Kind
Left	Move cursor left	local edit
Right	Move cursor right	local edit
Home	Jump to line start	local edit
End	Jump to line end	local edit
Backspace	Delete previous character	local edit
Delete	Delete next character	local edit
Ctrl+W	Delete previous word	local edit
Ctrl+Z	Undo text edit	local edit
Ctrl+Y	Redo text edit	local edit

Numeric field context

Shortcut	Action	Kind
Left	Step value down	local edit
Right	Step value up	local edit
Shift+Left	Fast step value down	local edit
Shift+Right	Fast step value up	local edit
Backspace	Delete previous character	local edit
Delete	Delete next character	local edit
Ctrl+Z	Undo numeric edit	local edit
Ctrl+Y	Redo numeric edit	local edit

Keymap system

Put every shortcut into keymap/default.keymap.json, so runtime logic, help overlays, and generated README shortcut references all consume a single source of truth.

• Format – each JSON object declares an id, human-readable description, bilingual descriptionZh, contexts (any of "default", "collection", "overlay", "help", "text", "numeric"), an action discriminated union, and a list of textual combos. For example:

  {
    "id": "list.move.up",
    "description": "Move entry up",
    "descriptionZh": "条目上移",
    "contexts": ["collection", "overlay"],
    "action": { "kind": "ListMove", "delta": -1 },
    "combos": ["Ctrl+Up"]
  }

• Macro + parser – app::keymap::keymap_source!() include_str!s the JSON, once_cell::sync::Lazy parses it once at startup, and each combo is compiled into a KeyPattern (key code, required modifiers, pretty display string).

• Integration – InputRouter::classify delegates to keymap::classify_key, which returns the KeyAction embedded in the JSON. keymap::help_text filters bindings by KeymapContext, concatenating snippets used by StatusLine and overlay instructions.

• Generated docs – build.rs parses keymap/default.keymap.json and refreshes the shortcut blocks in README.md and README.ZH.md using explicit HTML markers, so normal Cargo builds keep the bilingual reference in sync with runtime behavior.

• Extending – to add a shortcut, edit the JSON, choose the contexts that should expose the help text, and wire the resulting KeyAction inside KeyBindingMap if a new semantic command is introduced.

Runtime Layers

Layer	Module(s)	Responsibilities
Ingestion	io::input, schema::loader, schema::resolver	Parse JSON/TOML/YAML, resolve $ref, and normalize metadata.
Layout typing	ui_ast::build_ui_ast, tui::model::form_schema_from_ui_ast	Produce FormSchema (roots/sections/fields) from the canonical UI AST.
Form state	tui::state::{form_state, section, field}	Track focus, pointers, dirty flags, coercions, and errors.
Commands & reducers	tui::state::{actions, reducers}, tui::app::validation	Define FormCommand, mutate state, and route validation results.
Runtime controller	tui::app::{runtime, overlay, popup, status, keymap}	Event loop, InputRouter dispatch, overlay lifecycle, help text, status updates.
Presentation	tui::view and tui::view::components::*	Render tabs, field lists, popups, overlays, and footer via ratatui.

Each module is kept under ~600 LOC (hard cap 800) to honor the KISS principle and make refactors manageable.

CLI (schemaui-cli)

Install

The installed binary is always named schemaui, so the normal entry point is schemaui -c ./config.json.

Choose one of the supported channels:

Cargo (cargo install)

Build from crates.io with Cargo.

cargo install schemaui-cli

Cargo binstall

Fetch prebuilt GitHub release binaries through cargo-binstall.

cargo binstall schemaui-cli

Homebrew

Install from the repository tap on macOS or Linux.

brew install YuniqueUnic/schemaui/schemaui

Scoop

Install on Windows from the repository-hosted Scoop manifest.

scoop install https://raw.githubusercontent.com/YuniqueUnic/schemaui/main/packaging/scoop/schemaui-cli.json

Direct download

Download the matching archive from https://github.com/YuniqueUnic/schemaui/releases/latest, extract schemaui / schemaui.exe, and place it on your PATH.

winget manifests

Use the versioned manifests in packaging/winget with winget install --manifest <dir>, or submit them upstream to the community repository.

schemaui \
  --schema ./schema.json \
  --config ./defaults.yaml \
  -o - \
  -o ./config.toml ./config.json

┌────────┐  argh args   ┌──────────────┐ read stdin/files ┌─────────────┐
│  CLI   ├─────────────▶│ InputSource  ├─────────────────▶│ io::input   │
└────┬───┘              └──────┬───────┘                  └────┬────────┘
     │ diagnostics             │ schema/default Value          │
┌────▼─────────┐        ┌──────▼──────┐                        |
│Diagnostic    │◀───────┤ FormatHint  │                        │
│Collector     │        └──────┬──────┘                        │
└────┬─────────┘               │ pass if clean                 │
     │                         │                               │
┌────▼────────┐  build options └────────────┐                  │
│Output logic ├────────────────────────────▶│ OutputOptions    │
└────┬────────┘                             └────────────┬─────┘
     │ SchemaUI::new / with_*                        ┌───▼────────┐
     └──────────────────────────────────────────────▶│ SchemaUI   │
                                                     │ (library)  │
                                                     └────────────┘

• Inputs – --schema / --config accept file paths, inline payloads, or - for stdin (but not both simultaneously). If only config is provided the CLI infers a schema via schema_from_data_value.
• Diagnostics – DiagnosticCollector accumulates format issues, feature flag mismatches, stdin conflicts, and existing output files before execution.
• Outputs – -o/--output is repeatable and may mix file paths with - for stdout. When no destination is set, the tool writes to stdout; pass --temp-file <PATH> if you explicitly want a fallback file. Extensions dictate formats; conflicting extensions are rejected.
• Flags – --no-pretty toggles compact output, --force/--yes allows overwriting files, and --title / --description wire through to SchemaUI::with_title / SchemaUI::with_description.
• Shell completion – schemaui completion <bash|zsh|fish|nushell> emits completion scripts from the same argh command graph. PowerShell is not exposed yet because upstream argh_complete does not currently ship a PowerShell generator.

Key Dependencies

Crate	Purpose
serde, serde_json, serde_yaml, toml	Parsing and serializing schema/config data.
schemars	Draft-07 schema representation used by the schema module.
jsonschema	Runtime validation for forms and overlays.
ratatui	Rendering widgets, layouts, overlays, and footer.
crossterm	Terminal events consumed by InputRouter.
indexmap	Order-preserving maps for schema traversal.
once_cell	Lazy parsing of the keymap JSON.
argh, argh_complete, color-eyre (CLI)	Argument parsing, shell completion, and ergonomic diagnostics.

Documentation Map

• README.md – overview + architecture snapshot (source of truth).
• README.ZH.md – Chinese overview kept in sync with this README.
• docs/en/structure_design.md – detailed schema/layout/runtime design with flow diagrams.
• docs/zh/structure_design.md – Chinese mirror of the architecture guide.
• docs/en/cli_usage.md – CLI-specific manual (inputs, outputs, piping, samples).
• docs/zh/cli_usage.zh.md – Chinese mirror of the CLI usage guide.

Development

• Run cargo fmt && cargo test regularly; most modules embed their tests by include!ing files from tests/ so private APIs stay covered.
• Keep modules below ~600 LOC (hard cap 800). Split helpers as soon as behavior grows to keep KISS intact.
• Prefer mature crates (serde_*, schemars, jsonschema, ratatui, crossterm) over bespoke code unless the change is trivial.
• Update docs/* whenever pipelines, shortcuts, or CLI semantics evolve so user-facing documentation stays truthful.

References

1. https://github.com/rjsf-team/react-jsonschema-form
2. https://ui-schema.bemit.codes/examples

Roadmap

• parse json schema at runtime and generate a TUI
• parse json schema at runtime and generate a Web UI
• parse json schema at compile time Then generate the code for TUI, expose necessary APIs for runtime.
• parse json schema at compile time Then generate the code for Web UI, expose necessary APIs for runtime.
• parse json schema at runtime and generate a Interactive CLI
• parse json schema at compile time Then generate the code for Interactive CLI, expose necessary APIs for runtime.

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Happy hacking!

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