diff --git a/.changeset/ci-cache-tier1-optimizations.md b/.changeset/ci-cache-tier1-optimizations.md
new file mode 100644
index 0000000000..676cb470c6
--- /dev/null
+++ b/.changeset/ci-cache-tier1-optimizations.md
@@ -0,0 +1,4 @@
+---
+---
+
+CI-only: turbo cache for the Release job, console-dist cache keyed on the objectui pin, restore-only turbo caches on PRs (main seeds them), CodeQL off pull_request (main push + weekly schedule), spec coverage moved to a nightly workflow. Releases nothing.
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 67d71706a0..6019a739a6 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -111,8 +111,13 @@ jobs:
           restore-keys: |
             ${{ runner.os }}-pnpm-store-v3-
 
-      - name: Setup Turbo cache
-        uses: actions/cache@v6
+      # Restore-only on PRs: PR-side saves (~5 turbo entries per push) churned
+      # the repo's 10 GB Actions cache pool and evicted the main-branch seeds —
+      # observed as sudden cold-cache spikes (Build Core 51s → 4m30s). PRs fall
+      # back to main's entries via the prefix restore-keys; only main pushes
+      # save (the "Save Turbo cache" step at the end of the job).
+      - name: Restore Turbo cache
+        uses: actions/cache/restore@v6
         with:
           path: .turbo/cache
           key: ${{ runner.os }}-turbo-${{ github.job }}-${{ github.ref_name }}-${{ github.sha }}
@@ -142,25 +147,25 @@ jobs:
           TURBO_SCM_BASE: ${{ github.event.pull_request.base.sha }}
         run: pnpm turbo run test --affected --filter=!@objectstack/dogfood --concurrency=4
 
-      # Push to main: full run, but exclude spec's plain test task — the
-      # coverage step below executes the exact same 250-file spec suite once,
-      # with coverage. Previously the spec suite ran twice per push. Dogfood is
-      # excluded for the same reason as the PR step: the Dogfood job runs it.
+      # Push to main: full run. Spec's suite runs here plain (uninstrumented);
+      # the coverage-instrumented pass moved to the nightly Spec Coverage
+      # workflow (coverage-nightly.yml) — instrumentation added minutes to
+      # every main push for a trend artifact that is consulted occasionally at
+      # best. Dogfood is excluded for the same reason as the PR step: the
+      # Dogfood job runs it.
       - name: Run all tests (push)
         if: github.event_name == 'push'
-        run: pnpm turbo run test --filter=!@objectstack/spec --filter=!@objectstack/dogfood --concurrency=4
-
-      - name: Generate coverage report
-        if: github.event_name == 'push'
-        run: pnpm --filter @objectstack/spec test:coverage
-
-      - name: Upload coverage reports
-        if: github.event_name == 'push'
-        uses: actions/upload-artifact@v7
+        run: pnpm turbo run test --filter=!@objectstack/dogfood --concurrency=4
+
+      # Seed the shared Turbo cache from main only (see the restore step
+      # above). always(): keep the seed fresh even when a test fails, matching
+      # the old actions/cache post-step behavior.
+      - name: Save Turbo cache (main only)
+        if: always() && github.event_name == 'push'
+        uses: actions/cache/save@v6
         with:
-          name: coverage-report
-          path: packages/spec/coverage/
-          retention-days: 30
+          path: .turbo/cache
+          key: ${{ runner.os }}-turbo-${{ github.job }}-${{ github.ref_name }}-${{ github.sha }}
 
   dogfood:
     # Sharded 2-way: the suite is ~60 independent test files, each booting its
@@ -209,10 +214,11 @@ jobs:
             ${{ runner.os }}-pnpm-store-v3-
 
       # Shard-scoped key: the turbo test hash differs per shard (pass-through
-      # args are part of the task hash), and two same-named matrix jobs would
-      # otherwise race to save one cache entry per sha.
-      - name: Setup Turbo cache
-        uses: actions/cache@v6
+      # args are part of the task hash). Restore-only on PRs — see the Restore
+      # Turbo cache comment in the test job; the save step at the end of this
+      # job seeds from main only.
+      - name: Restore Turbo cache
+        uses: actions/cache/restore@v6
         with:
           path: .turbo/cache
           key: ${{ runner.os }}-turbo-${{ github.job }}-${{ matrix.shard }}-${{ github.ref_name }}-${{ github.sha }}
@@ -247,6 +253,15 @@ jobs:
             echo "::endgroup::"
           done
 
+      # Seed the shared Turbo cache from main only (see the restore step
+      # above); shard-scoped key so the two matrix jobs don't collide.
+      - name: Save Turbo cache (main only)
+        if: always() && github.event_name == 'push'
+        uses: actions/cache/save@v6
+        with:
+          path: .turbo/cache
+          key: ${{ runner.os }}-turbo-${{ github.job }}-${{ matrix.shard }}-${{ github.ref_name }}-${{ github.sha }}
+
   dogfood-gate:
     # Stable required-check name for a SHARDED job (#3622 follow-up).
     #
@@ -312,8 +327,13 @@ jobs:
           restore-keys: |
             ${{ runner.os }}-pnpm-store-v3-
 
-      - name: Setup Turbo cache
-        uses: actions/cache@v6
+      # Restore-only on PRs: PR-side saves (~5 turbo entries per push) churned
+      # the repo's 10 GB Actions cache pool and evicted the main-branch seeds —
+      # observed as sudden cold-cache spikes (Build Core 51s → 4m30s). PRs fall
+      # back to main's entries via the prefix restore-keys; only main pushes
+      # save (the "Save Turbo cache" step at the end of the job).
+      - name: Restore Turbo cache
+        uses: actions/cache/restore@v6
         with:
           path: .turbo/cache
           key: ${{ runner.os }}-turbo-${{ github.job }}-${{ github.ref_name }}-${{ github.sha }}
@@ -377,6 +397,14 @@ jobs:
             packages/spec/json-schema/
           retention-days: 30
 
+      # Seed the shared Turbo cache from main only (see the restore step above).
+      - name: Save Turbo cache (main only)
+        if: always() && github.event_name == 'push'
+        uses: actions/cache/save@v6
+        with:
+          path: .turbo/cache
+          key: ${{ runner.os }}-turbo-${{ github.job }}-${{ github.ref_name }}-${{ github.sha }}
+
   build-docs:
     name: Build Docs
     needs: filter
diff --git a/.github/workflows/codeql.yml b/.github/workflows/codeql.yml
index f962e0453c..b96600be01 100644
--- a/.github/workflows/codeql.yml
+++ b/.github/workflows/codeql.yml
@@ -1,21 +1,24 @@
 name: CodeQL Security Analysis
 
+# Deliberately NOT on pull_request: the analysis took ~4½ runner-minutes per
+# PR sync, and everything a PR introduces is analyzed on main within minutes
+# of the merge anyway (multi-agent merge cadence). Alerts surface on main's
+# runs + the weekly deep pass instead of blocking/occupying PR runners.
+# If branch protection ever required the "Analyze (javascript)" check, that
+# requirement must be dropped along with this trigger.
 on:
   push:
     branches:
       - main
-  pull_request:
-    branches:
-      - main
   schedule:
     # Run at 02:00 UTC every Monday
     - cron: '0 2 * * 1'
 
-# A superseded analysis of an outdated commit has no value — cancel it. PR runs
-# group by PR number; push/schedule runs group by ref, so a newer main push
-# cancels only an in-flight main analysis (the newer commit gets analyzed).
+# A superseded analysis of an outdated commit has no value — cancel it. A newer
+# main push cancels only an in-flight main analysis (the newer commit still
+# gets analyzed).
 concurrency:
-  group: codeql-${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  group: codeql-${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true
 
 jobs:
diff --git a/.github/workflows/coverage-nightly.yml b/.github/workflows/coverage-nightly.yml
new file mode 100644
index 0000000000..cc099feef2
--- /dev/null
+++ b/.github/workflows/coverage-nightly.yml
@@ -0,0 +1,63 @@
+# Spec coverage, nightly. Moved off the per-push path: the coverage-
+# instrumented spec suite added minutes of instrumentation overhead to every
+# main push (ci.yml previously excluded spec's plain test task and ran this
+# instead), for a trend artifact that is consulted occasionally at best. The
+# plain (uninstrumented) spec suite still runs on every main push in ci.yml's
+# Test Core; this workflow owns the coverage report.
+name: Spec Coverage
+
+on:
+  workflow_dispatch:
+  schedule:
+    - cron: '0 5 * * *' # 05:00 UTC nightly
+
+permissions:
+  contents: read
+
+jobs:
+  coverage:
+    name: Spec coverage report
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v7
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v7
+        with:
+          node-version: '20'
+
+      - name: Enable Corepack
+        run: corepack enable
+
+      - name: Get pnpm store directory
+        shell: bash
+        run: |
+          echo "STORE_PATH=$(pnpm store path --silent)" >> $GITHUB_ENV
+
+      # Restore-only: scheduled runs read main's store cache; the per-push
+      # workflows own saving it.
+      - name: Restore pnpm cache
+        uses: actions/cache/restore@v6
+        with:
+          path: ${{ env.STORE_PATH }}
+          key: ${{ runner.os }}-pnpm-store-v3-${{ hashFiles('**/pnpm-lock.yaml') }}
+          restore-keys: |
+            ${{ runner.os }}-pnpm-store-v3-
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+
+      # The spec package sits at the root of the workspace graph (no workspace
+      # deps) and its suite reads src/ directly, so no build step is needed —
+      # same reason lint.yml's typecheck gates run pre-build.
+      - name: Generate coverage report
+        run: pnpm --filter @objectstack/spec test:coverage
+
+      - name: Upload coverage report
+        uses: actions/upload-artifact@v7
+        with:
+          name: coverage-report
+          path: packages/spec/coverage/
+          retention-days: 30
diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index a32f094a18..cbaa07357b 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -145,8 +145,11 @@ jobs:
       # package from scratch on every run (~4½ min) while ci.yml's jobs — which
       # do carry this cache — finished the same build in under a minute. Same
       # key scheme as ci.yml so the fallback prefix can also hit main's caches.
-      - name: Setup Turbo cache
-        uses: actions/cache@v6
+      # Restore-only on PRs (same policy as ci.yml): PR-side saves churned the
+      # 10 GB Actions cache pool and evicted the main seeds; only main pushes
+      # save (the "Save Turbo cache" step at the end of the job).
+      - name: Restore Turbo cache
+        uses: actions/cache/restore@v6
         with:
           path: .turbo/cache
           key: ${{ runner.os }}-turbo-${{ github.job }}-${{ github.ref_name }}-${{ github.sha }}
@@ -243,3 +246,11 @@ jobs:
       # so it runs after the build step alongside the other consumer gates.
       - name: Check skills TypeScript examples compile
         run: pnpm --filter @objectstack/spec run check:skill-examples
+
+      # Seed the shared Turbo cache from main only (see the restore step above).
+      - name: Save Turbo cache (main only)
+        if: always() && github.event_name == 'push'
+        uses: actions/cache/save@v6
+        with:
+          path: .turbo/cache
+          key: ${{ runner.os }}-turbo-${{ github.job }}-${{ github.ref_name }}-${{ github.sha }}
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index b6699d6728..d5e3ae68c6 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -48,6 +48,19 @@ jobs:
           restore-keys: |
             ${{ runner.os }}-pnpm-store-v3-
 
+      # This job ran the full workspace build cold on every main push (~4½
+      # min) — the same omission lint.yml's typecheck job had. Same key scheme
+      # as ci.yml. Runs only on main pushes, so plain save+restore is right
+      # here (this job is one of the cache seeders).
+      - name: Setup Turbo cache
+        uses: actions/cache@v6
+        with:
+          path: .turbo/cache
+          key: ${{ runner.os }}-turbo-${{ github.job }}-${{ github.ref_name }}-${{ github.sha }}
+          restore-keys: |
+            ${{ runner.os }}-turbo-${{ github.job }}-${{ github.ref_name }}-
+            ${{ runner.os }}-turbo-${{ github.job }}-
+
       - name: Install dependencies
         run: pnpm install --frozen-lockfile
 
@@ -57,13 +70,34 @@ jobs:
       - name: Build
         run: pnpm run build
 
+      # The vendored Console dist is a pure function of the objectui pin (and
+      # of the build script itself) — yet it was cloned + vite-built from
+      # scratch on every main push (~3 min). Cache the finished dist keyed on
+      # exactly those inputs; the stamp check below still verifies whatever
+      # dist ends up in place, restored or fresh.
+      - name: Cache vendored Console dist (keyed on the objectui pin)
+        id: console-dist-cache
+        uses: actions/cache@v6
+        with:
+          path: packages/console/dist
+          key: ${{ runner.os }}-console-dist-${{ hashFiles('.objectui-sha', 'scripts/build-console.sh') }}
+
       - name: Build vendored @objectstack/console SPA
         # Clones objectstack-ai/objectui at the SHA pinned in .objectui-sha,
         # builds @object-ui/console, and copies dist/ into
         # packages/console/dist/. Must run before publish so the
-        # prepublishOnly guard in @objectstack/console passes.
+        # prepublishOnly guard in @objectstack/console passes. Skipped when the
+        # cache above restored a dist built from the same pin.
+        if: steps.console-dist-cache.outputs.cache-hit != 'true'
         run: bash scripts/build-console.sh
 
+      # Belt-and-suspenders for the cache path: build-console.sh stamps the
+      # objectui SHA it built from into dist/.objectui-sha; check:console-sha
+      # fails loudly if the dist in place (restored or fresh) drifts from the
+      # pin.
+      - name: Verify Console dist stamp matches pin
+        run: pnpm check:console-sha
+
       - name: Downstream backward-compat smoke (live hotcrm)
         # Pre-publish gate (#2035): the about-to-publish @objectstack/spec must
         # not break a real third-party consumer pinned to a published release.