diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
new file mode 100644
index 0000000000..40c5739e6f
--- /dev/null
+++ b/.github/workflows/coverage.yml
@@ -0,0 +1,33 @@
+name: Coverage
+
+# Measures coverage for every package on main. The numbers themselves are not
+# asserted here — the point is to populate the Nx Cloud cache, so that when a
+# PR re-measures its merge-base the `test:coverage` task hashes already exist
+# remotely and the summaries are restored instead of recomputed.
+on:
+  push:
+    branches: [main]
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+env:
+  NX_CLOUD_ACCESS_TOKEN: ${{ secrets.NX_CLOUD_ACCESS_TOKEN }}
+
+permissions:
+  contents: read
+
+jobs:
+  coverage:
+    name: Warm Coverage Cache
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
+      - name: Setup Tools
+        uses: TanStack/config/.github/setup@190f659075ff0845850e330883eb26d7ffd0671f # main
+      - name: Run Coverage
+        run: pnpm run test:coverage:all
diff --git a/.github/workflows/pr.yml b/.github/workflows/pr.yml
index a83eb33a81..2eb32ac37b 100644
--- a/.github/workflows/pr.yml
+++ b/.github/workflows/pr.yml
@@ -31,6 +31,82 @@ jobs:
           main-branch-name: main
       - name: Run Checks
         run: pnpm run test:pr
+  coverage:
+    name: Coverage
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          fetch-depth: 0
+          persist-credentials: false
+      - name: Setup Tools
+        uses: TanStack/config/.github/setup@190f659075ff0845850e330883eb26d7ffd0671f # main
+      - name: Get base and head commits for `nx affected`
+        uses: nrwl/nx-set-shas@3e9ad7370203c1e93d109be57f3b72eb0eb511b1 # v4.4.0
+        with:
+          main-branch-name: main
+      # Stashed outside the working tree because checking out the merge base
+      # would otherwise remove it — the script may be added or changed by the
+      # very PR under test. Both runs and the comparison use this copy, so all
+      # three agree on the version.
+      - name: Stage the coverage script
+        run: cp scripts/coverage-check.mjs "$RUNNER_TEMP/coverage-check.mjs"
+      # The set of packages to measure is decided once, here, so that the base
+      # run measures exactly what the head run does. `--with-target` keeps out
+      # projects that have no test:coverage script, so a docs-only PR resolves
+      # to an empty list rather than erroring in run-many.
+      - name: Resolve affected packages
+        id: affected
+        run: |
+          list=$(pnpm exec nx show projects --affected --with-target=test:coverage --exclude='examples/**,testing/**' --json | jq -r 'sort | join(",")')
+          echo "list=$list" >> "$GITHUB_OUTPUT"
+          echo "Measuring: ${list:-<none>}"
+      - name: Coverage for this PR
+        if: steps.affected.outputs.list != ''
+        # Via env, not `${{ }}` inside run: project names come from the PR's own
+        # files, so interpolating them into the shell would be injectable.
+        env:
+          PROJECTS: ${{ steps.affected.outputs.list }}
+        run: |
+          rm -rf packages/*/coverage
+          pnpm exec nx run-many --targets=test:coverage --projects="$PROJECTS" -- --coverage.reporter=json-summary --coverage.include='src/**'
+          node "$RUNNER_TEMP/coverage-check.mjs" --collect "$RUNNER_TEMP/cov-head" --expect "$PROJECTS"
+      # Re-measuring the merge-base is normally a set of Nx Cloud cache
+      # restores seeded by the Coverage workflow on main: the task hashes are
+      # identical, and `test:coverage` declares its coverage dir as an output,
+      # so the summaries come back without the tests re-running.
+      - name: Coverage for the merge base
+        if: steps.affected.outputs.list != ''
+        env:
+          PROJECTS: ${{ steps.affected.outputs.list }}
+        run: |
+          git checkout --force --detach "$NX_BASE"
+          # coverage/ is gitignored, so the checkout leaves this PR's results in
+          # place — without this the base collection silently re-reads head's
+          # numbers and every delta comes out as 0.00.
+          rm -rf packages/*/coverage
+          pnpm install --frozen-lockfile
+          # Intersect with projects that have test:coverage on the base commit
+          # (added packages, or packages that gained the script in this PR).
+          printf '%s\n' "$PROJECTS" | tr ',' '\n' | sort > /tmp/wanted
+          pnpm exec nx show projects --with-target=test:coverage --json | jq -r '.[]' | sort > /tmp/available
+          base_list=$(comm -12 /tmp/wanted /tmp/available | paste -sd, -)
+          if [ -z "$base_list" ]; then
+            echo "No affected package has test:coverage on the base commit; treating all as new."
+            mkdir -p "$RUNNER_TEMP/cov-base"
+            exit 0
+          fi
+          # Extra reporters/include so a merge-base whose scripts are still
+          # `vitest run --coverage` still writes coverage-summary.json.
+          pnpm exec nx run-many --targets=test:coverage --projects="$base_list" -- --coverage.reporter=json-summary --coverage.include='src/**'
+          node "$RUNNER_TEMP/coverage-check.mjs" --collect "$RUNNER_TEMP/cov-base" --expect "$base_list"
+      - name: Compare
+        if: steps.affected.outputs.list != ''
+        run: |
+          node "$RUNNER_TEMP/coverage-check.mjs" \
+            --base "$RUNNER_TEMP/cov-base" \
+            --head "$RUNNER_TEMP/cov-head"
   preview:
     name: Preview
     runs-on: ubuntu-latest
diff --git a/AGENTS.md b/AGENTS.md
index 4e8635c694..399cff6617 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -153,6 +153,13 @@ each of these and confirm they're green before pushing:
 
 Do **not** rely on CI as your first signal. Run locally, fix, then push.
 
+## Coverage
+
+Coverage is CI-only. Do not run it locally and do not add it to `test`,
+`test:pr`, `test:ci`, or git hooks. There is no baseline file. The PR
+`Coverage` job compares affected packages on the branch against their
+merge-base with `main`. See **Coverage** in `CONTRIBUTING.md`.
+
 ## Documentation
 
 Load the `docs` skill first (see **Docs skill** above). Then also obey
diff --git a/CLAUDE.md b/CLAUDE.md
index 6dee2e3d76..a86dbbdb00 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -55,7 +55,7 @@ pnpm test:lib:dev          # Watch mode for unit tests
 pnpm test:oxlint           # Lint affected packages (oxlint, incl. type-aware)
 pnpm test:types            # Type check affected packages
 pnpm test:build            # Verify build artifacts with publint
-pnpm test:coverage         # Generate coverage reports
+# Coverage is CI-only. See CONTRIBUTING.md. Don't run it locally.
 pnpm test:knip             # Check for unused dependencies
 pnpm test:sherif           # Check pnpm workspace consistency
 pnpm test:docs             # Verify documentation links
@@ -319,7 +319,16 @@ Each package uses `exports` field in package.json for subpath exports (e.g., `@t
 
 - Unit tests in `*.test.ts` files alongside source
 - Uses Vitest with happy-dom for DOM testing
-- Test coverage via `pnpm test:coverage`
+- **Coverage is CI-only.** Don't run it locally and don't add it to local
+  gates — it is deliberately absent from `test`, `test:pr`, `test:ci` and the
+  git hooks. The `Coverage` job on each PR measures every affected package
+  twice, on the PR head and on its merge-base with `main`, and fails when a
+  metric drops more than 0.5pp between them. There is **no baseline file** —
+  don't reintroduce one, it was removed precisely because it needed manual
+  syncing and was platform-sensitive. The only remedy for a drop is tests.
+  `.github/workflows/coverage.yml` runs coverage on pushes to `main` purely to
+  warm the Nx Cloud cache so the base-side run is mostly cache restores. See
+  CONTRIBUTING.md.
 - **E2E tests are mandatory** — see E2E Testing section below
 
 ### E2E Testing (REQUIRED)
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index ee03bd6b15..67fee1c0f5 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -77,7 +77,7 @@ All commands are run from the repo root. Nx handles affected detection and cachi
 | Run unit tests (affected)     | `pnpm test:lib`     |
 | Watch unit tests              | `pnpm test:lib:dev` |
 | Type-check (affected)         | `pnpm test:types`   |
-| Lint (affected)               | `pnpm test:eslint`  |
+| Lint (affected)               | `pnpm test:oxlint`  |
 | Verify build artifacts        | `pnpm test:build`   |
 | Format the repo               | `pnpm format`       |
 | Build (affected)              | `pnpm build`        |
@@ -89,6 +89,31 @@ All commands are run from the repo root. Nx handles affected detection and cachi
 
 Working on a single package? `cd packages/<pkg>` and use its scripts directly (`pnpm test:lib`, `pnpm test:types`, etc.).
 
+## Coverage
+
+**Coverage runs in CI only. It is not part of `pnpm test`, `pnpm test:pr`, or any git hook, and you are not expected to run it locally.**
+
+The `Coverage` job on every PR measures each affected package that has a `test:coverage` target twice: once on your branch and once on its merge-base with `main`. A drop of more than 0.5 percentage points in any metric (statements, branches, functions, lines) fails the job. Packages your PR didn't affect, and packages without that target, are never measured.
+
+There is no baseline file to keep in sync, and nothing to update when a package is added or removed: both numbers come from the same job on the same runner. There are also no target percentages to hit — the gate only catches coverage getting _worse_ in what you touched, and never blocks a PR for being below some repo-wide bar.
+
+Read the numbers from the PR's Checks tab: open the `Coverage` job. When at least one package with `test:coverage` is affected, the job summary has a per-package table with deltas, pass or fail. It is not posted as a PR comment.
+
+Re-measuring the merge-base is usually close to free. A separate `Coverage` workflow runs `test:coverage:all` on every push to `main`, which populates the Nx Cloud cache; because `test:coverage` declares its `coverage/` directory as a task output, the base-side run generally restores cached summaries rather than re-running any tests.
+
+### If the job says coverage dropped
+
+Add tests covering the code you changed. That's the whole remedy — there is no number to override. If you genuinely deleted well-tested code and the drop is expected, say so in the PR and a maintainer can merge past the failing check.
+
+Two known limitations:
+
+- Uncovered `.tsx` files can't be remapped by the coverage provider and are dropped from the report with a `Failed to parse ... Excluding it from coverage` warning. `.tsx` files that tests _do_ load are measured normally, so the UI packages read higher than their real coverage.
+- `preact-ai-devtools`, `react-ai-devtools`, and `solid-ai-devtools` have no tests. They may be omitted (0 statements after `.tsx` remap failure) or show ~0% of remaining `.ts`; they do not gate the job.
+
+A **new package that defines `test:coverage`** shows as `new` and cannot fail the comparison. Packages without that script are not measured.
+
+If a package was measured on the base commit and has no summary on this PR, the job fails. A crashing `test:coverage` suite on either side also fails the job. It is not treated as `new`.
+
 ## TypeScript configuration
 
 There is a single `tsconfig.base.json` at the repo root with the shared `compilerOptions`. Every package extends it and overrides only what's unique to that package (e.g. `outDir`, JSX runtime, framework lib).
@@ -113,7 +138,7 @@ Tests are included in typecheck. `vite.config.ts` / `vitest.config.ts` are not 
 
 - Place tests under `packages/<pkg>/tests/` with the suffix `.test.ts` (or `.test.tsx` for JSX).
 - Vitest's defaults discover anything matching `**/*.{test,spec}.?(c|m)[jt]s?(x)` — no per-package config is needed.
-- Tests are typechecked by `tsc` and linted by ESLint.
+- Tests are typechecked by `tsc` and linted by oxlint.
 
 ## Adding E2E test coverage (required)
 
@@ -173,10 +198,12 @@ The defensive `ignore` list in `.changeset/config.json` blocks accidental public
 
 1. Push your branch and open a PR against `main`.
 2. Fill the PR template. Tick **docs** and **changeset** honestly, or say why you skipped them.
-3. CI runs: `pnpm test:pr` (sherif workspace check, knip dead-code, docs link verification, ESLint, unit tests, typecheck, build artifacts, build) + the full E2E suite.
+3. CI runs: `pnpm test:pr` (sherif workspace check, knip dead-code, docs link verification, oxlint, unit tests, typecheck, build artifacts, build), the `Coverage` regression gate, and the full E2E suite.
 4. Address review comments.
 5. A maintainer merges. Releases are cut via Changesets. Your changeset entry lands in the next release.
 
+The PR template lists the steps. The `Test plan` section is required — describe how a reviewer can verify your change.
+
 ### Automated Grok review
 
 A Grok agent comments on open, non-draft PRs. The first lines of that comment say it is automated. It is not a maintainer review.
diff --git a/package.json b/package.json
index 77d9e58bd0..d5b8a0ecec 100644
--- a/package.json
+++ b/package.json
@@ -21,12 +21,13 @@
     "test:lib": "nx affected --targets=test:lib --exclude=examples/**,testing/**",
     "test:lib:dev": "pnpm test:lib && nx watch --all -- pnpm test:lib",
     "test:coverage": "nx affected --targets=test:coverage --exclude=examples/**,testing/**",
+    "test:coverage:all": "nx run-many --targets=test:coverage --exclude=examples/**,testing/**",
     "test:build": "nx affected --target=test:build --exclude=examples/**,testing/**",
     "test:types": "nx affected --targets=test:types --exclude=examples/**,testing/**",
     "test:knip": "knip",
     "test:docs": "tsx scripts/verify-links.ts",
     "test:dts": "node scripts/scan-dangling-dts.mjs",
-    "test:maintainer": "vitest run --root scripts/maintainer && vitest run scripts/model-sync scripts/publish-staged-docs.test.ts",
+    "test:maintainer": "vitest run --root scripts/maintainer && vitest run scripts/model-sync scripts/publish-staged-docs.test.ts && vitest run scripts/coverage-check.test.ts",
     "test:ai-review": "vitest run --root agent-scripts/ai-review",
     "ai-review": "tsx agent-scripts/ai-review/run.ts",
     "maintainer:sweep": "tsx scripts/maintainer/sweep.ts",
diff --git a/packages/ai-acp/package.json b/packages/ai-acp/package.json
index 1219138c54..93944c1c4d 100644
--- a/packages/ai-acp/package.json
+++ b/packages/ai-acp/package.json
@@ -38,6 +38,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run --testTimeout=30000",
     "test:lib:dev": "vitest --watch",
     "test:types": "tsc"
diff --git a/packages/ai-angular/package.json b/packages/ai-angular/package.json
index 2935c73a99..da9eadb2e3 100644
--- a/packages/ai-angular/package.json
+++ b/packages/ai-angular/package.json
@@ -46,6 +46,7 @@
   "scripts": {
     "clean": "premove ./build ./dist",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "vitest",
     "test:types": "tsc",
diff --git a/packages/ai-anthropic/package.json b/packages/ai-anthropic/package.json
index 8a8d86bd9d..1643e9b96d 100644
--- a/packages/ai-anthropic/package.json
+++ b/packages/ai-anthropic/package.json
@@ -61,6 +61,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-bedrock/package.json b/packages/ai-bedrock/package.json
index 3f6a81892e..c9cf22e8e3 100644
--- a/packages/ai-bedrock/package.json
+++ b/packages/ai-bedrock/package.json
@@ -32,6 +32,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-byteplus/package.json b/packages/ai-byteplus/package.json
index aecf32e4e8..75534a4f1d 100644
--- a/packages/ai-byteplus/package.json
+++ b/packages/ai-byteplus/package.json
@@ -40,6 +40,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-claude-code/package.json b/packages/ai-claude-code/package.json
index ad75e4eb05..f762cf96b4 100644
--- a/packages/ai-claude-code/package.json
+++ b/packages/ai-claude-code/package.json
@@ -46,6 +46,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-client/package.json b/packages/ai-client/package.json
index 0831d0e7a0..b0ce64d42e 100644
--- a/packages/ai-client/package.json
+++ b/packages/ai-client/package.json
@@ -57,9 +57,9 @@
     "clean": "premove ./build ./dist",
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
-    "test:coverage": "vitest run --coverage",
-    "test:coverage:watch": "vitest --coverage --watch",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
+    "test:coverage:watch": "vitest --coverage --watch",
     "test:lib": "vitest",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-code-mode-snippets/package.json b/packages/ai-code-mode-snippets/package.json
index 830c7803b7..4467073318 100644
--- a/packages/ai-code-mode-snippets/package.json
+++ b/packages/ai-code-mode-snippets/package.json
@@ -44,6 +44,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --passWithNoTests --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest --passWithNoTests",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc",
diff --git a/packages/ai-code-mode/package.json b/packages/ai-code-mode/package.json
index 29267ef032..6eaf35efbd 100644
--- a/packages/ai-code-mode/package.json
+++ b/packages/ai-code-mode/package.json
@@ -41,6 +41,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-codex/package.json b/packages/ai-codex/package.json
index 0c474d5e0b..7a10683593 100644
--- a/packages/ai-codex/package.json
+++ b/packages/ai-codex/package.json
@@ -45,6 +45,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-cohere/package.json b/packages/ai-cohere/package.json
index 43f4a048ad..a791970d49 100644
--- a/packages/ai-cohere/package.json
+++ b/packages/ai-cohere/package.json
@@ -44,6 +44,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-devtools/package.json b/packages/ai-devtools/package.json
index b55453b46f..f06174e22b 100644
--- a/packages/ai-devtools/package.json
+++ b/packages/ai-devtools/package.json
@@ -73,6 +73,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --passWithNoTests --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest --passWithNoTests",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-durable-stream/package.json b/packages/ai-durable-stream/package.json
index 5784c05bc3..ef964de8d8 100644
--- a/packages/ai-durable-stream/package.json
+++ b/packages/ai-durable-stream/package.json
@@ -36,6 +36,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-elevenlabs/package.json b/packages/ai-elevenlabs/package.json
index 3e7088a91e..fb1df1f3c2 100644
--- a/packages/ai-elevenlabs/package.json
+++ b/packages/ai-elevenlabs/package.json
@@ -57,6 +57,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --passWithNoTests --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest --passWithNoTests",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-event-client/package.json b/packages/ai-event-client/package.json
index 411dd0433b..d95ce2bd2d 100644
--- a/packages/ai-event-client/package.json
+++ b/packages/ai-event-client/package.json
@@ -37,6 +37,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --passWithNoTests --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest --passWithNoTests",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-fal/package.json b/packages/ai-fal/package.json
index 4dc62e1e45..54ebb9e778 100644
--- a/packages/ai-fal/package.json
+++ b/packages/ai-fal/package.json
@@ -40,6 +40,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-gemini/package.json b/packages/ai-gemini/package.json
index 98309ec7af..cb16a3e610 100644
--- a/packages/ai-gemini/package.json
+++ b/packages/ai-gemini/package.json
@@ -48,6 +48,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-grok-build/package.json b/packages/ai-grok-build/package.json
index f64c576395..60be1c785f 100644
--- a/packages/ai-grok-build/package.json
+++ b/packages/ai-grok-build/package.json
@@ -46,6 +46,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-grok/package.json b/packages/ai-grok/package.json
index 4e138a2481..a84aec9642 100644
--- a/packages/ai-grok/package.json
+++ b/packages/ai-grok/package.json
@@ -48,6 +48,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-groq/package.json b/packages/ai-groq/package.json
index 000cd5b95e..61834c1cbd 100644
--- a/packages/ai-groq/package.json
+++ b/packages/ai-groq/package.json
@@ -44,6 +44,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-isolate-cloudflare/package.json b/packages/ai-isolate-cloudflare/package.json
index dbc798ac08..fc05f4ec02 100644
--- a/packages/ai-isolate-cloudflare/package.json
+++ b/packages/ai-isolate-cloudflare/package.json
@@ -48,6 +48,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --passWithNoTests --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest --passWithNoTests",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-isolate-daytona/package.json b/packages/ai-isolate-daytona/package.json
index 9463108e9e..38fe215f75 100644
--- a/packages/ai-isolate-daytona/package.json
+++ b/packages/ai-isolate-daytona/package.json
@@ -32,6 +32,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --passWithNoTests --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:live": "vitest --run tests/live.test.ts",
     "test:lib": "vitest --passWithNoTests",
     "test:lib:dev": "pnpm test:lib --watch",
diff --git a/packages/ai-isolate-node/package.json b/packages/ai-isolate-node/package.json
index 5a3d6103ff..0ba6661848 100644
--- a/packages/ai-isolate-node/package.json
+++ b/packages/ai-isolate-node/package.json
@@ -40,6 +40,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --passWithNoTests --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest --passWithNoTests",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-isolate-quickjs-bun/package.json b/packages/ai-isolate-quickjs-bun/package.json
index 21a4b8abeb..28ca0779b4 100644
--- a/packages/ai-isolate-quickjs-bun/package.json
+++ b/packages/ai-isolate-quickjs-bun/package.json
@@ -41,6 +41,7 @@
     "test:build": "publint --strict",
     "test:bun": "bun test ./tests",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --passWithNoTests --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest --passWithNoTests",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-isolate-quickjs/package.json b/packages/ai-isolate-quickjs/package.json
index 6c1acdb344..55b1e2e8bd 100644
--- a/packages/ai-isolate-quickjs/package.json
+++ b/packages/ai-isolate-quickjs/package.json
@@ -37,6 +37,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --passWithNoTests --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest --passWithNoTests",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-llmgateway/package.json b/packages/ai-llmgateway/package.json
index d4626e0b0d..5797a5341d 100644
--- a/packages/ai-llmgateway/package.json
+++ b/packages/ai-llmgateway/package.json
@@ -36,6 +36,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-mcp/package.json b/packages/ai-mcp/package.json
index af2b215910..503db2f533 100644
--- a/packages/ai-mcp/package.json
+++ b/packages/ai-mcp/package.json
@@ -56,8 +56,8 @@
     "clean": "premove ./build ./dist",
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
-    "test:coverage": "vitest run --coverage",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-memory/package.json b/packages/ai-memory/package.json
index e1bccda116..69d1e6b107 100644
--- a/packages/ai-memory/package.json
+++ b/packages/ai-memory/package.json
@@ -50,6 +50,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --passWithNoTests --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest --passWithNoTests",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-mistral/package.json b/packages/ai-mistral/package.json
index 6f2981348e..28f85c9589 100644
--- a/packages/ai-mistral/package.json
+++ b/packages/ai-mistral/package.json
@@ -44,6 +44,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-octane/package.json b/packages/ai-octane/package.json
index 8c9b7d57dc..8bc48febe8 100644
--- a/packages/ai-octane/package.json
+++ b/packages/ai-octane/package.json
@@ -48,6 +48,7 @@
   "scripts": {
     "lint:fix": "oxlint src --type-aware --ignore-pattern '**/*.tsrx.d.ts' --fix",
     "test:oxlint": "oxlint src --type-aware --ignore-pattern '**/*.tsrx.d.ts'",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc && tsc -p typetests/tsconfig.json"
diff --git a/packages/ai-ollama/package.json b/packages/ai-ollama/package.json
index aa30d0904c..b78c2ef636 100644
--- a/packages/ai-ollama/package.json
+++ b/packages/ai-ollama/package.json
@@ -40,6 +40,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --passWithNoTests --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest --passWithNoTests",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-openai/package.json b/packages/ai-openai/package.json
index f11498e5d7..abf009c518 100644
--- a/packages/ai-openai/package.json
+++ b/packages/ai-openai/package.json
@@ -48,6 +48,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-opencode/package.json b/packages/ai-opencode/package.json
index 2fb2cfe307..c52f71aa11 100644
--- a/packages/ai-opencode/package.json
+++ b/packages/ai-opencode/package.json
@@ -44,6 +44,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-openrouter/package.json b/packages/ai-openrouter/package.json
index 13ca18ab9c..0c27f1b329 100644
--- a/packages/ai-openrouter/package.json
+++ b/packages/ai-openrouter/package.json
@@ -52,6 +52,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-perplexity/package.json b/packages/ai-perplexity/package.json
index 72551b64c7..c7b9a7c3a8 100644
--- a/packages/ai-perplexity/package.json
+++ b/packages/ai-perplexity/package.json
@@ -44,6 +44,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-persistence/package.json b/packages/ai-persistence/package.json
index bb720c29c1..2903bc2e20 100644
--- a/packages/ai-persistence/package.json
+++ b/packages/ai-persistence/package.json
@@ -43,6 +43,7 @@
     "clean": "premove ./build ./dist",
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc",
diff --git a/packages/ai-preact/package.json b/packages/ai-preact/package.json
index 1053d61907..60c1b7f89c 100644
--- a/packages/ai-preact/package.json
+++ b/packages/ai-preact/package.json
@@ -38,6 +38,7 @@
     "clean": "premove ./build ./dist",
     "lint:fix": "oxlint src --type-aware --fix",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc",
diff --git a/packages/ai-react-ui/package.json b/packages/ai-react-ui/package.json
index a49b3d1525..451821a44d 100644
--- a/packages/ai-react-ui/package.json
+++ b/packages/ai-react-ui/package.json
@@ -34,6 +34,7 @@
     "clean": "premove ./build ./dist",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --passWithNoTests --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest --passWithNoTests",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-react/package.json b/packages/ai-react/package.json
index abe8955b9b..49114f6b57 100644
--- a/packages/ai-react/package.json
+++ b/packages/ai-react/package.json
@@ -38,6 +38,7 @@
     "clean": "premove ./build ./dist",
     "lint:fix": "oxlint src --type-aware --fix",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc",
diff --git a/packages/ai-sandbox-cloudflare/package.json b/packages/ai-sandbox-cloudflare/package.json
index cb1c9377d4..adb03bacf2 100644
--- a/packages/ai-sandbox-cloudflare/package.json
+++ b/packages/ai-sandbox-cloudflare/package.json
@@ -46,6 +46,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-sandbox-daytona/package.json b/packages/ai-sandbox-daytona/package.json
index da599519f1..51f0454654 100644
--- a/packages/ai-sandbox-daytona/package.json
+++ b/packages/ai-sandbox-daytona/package.json
@@ -37,6 +37,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-sandbox-docker/package.json b/packages/ai-sandbox-docker/package.json
index 29f2575ea7..f93578aa61 100644
--- a/packages/ai-sandbox-docker/package.json
+++ b/packages/ai-sandbox-docker/package.json
@@ -38,6 +38,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-sandbox-local-process/package.json b/packages/ai-sandbox-local-process/package.json
index a0336621c6..78f100bdec 100644
--- a/packages/ai-sandbox-local-process/package.json
+++ b/packages/ai-sandbox-local-process/package.json
@@ -36,6 +36,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-sandbox-sprites/package.json b/packages/ai-sandbox-sprites/package.json
index a33ffcc967..918df8db48 100644
--- a/packages/ai-sandbox-sprites/package.json
+++ b/packages/ai-sandbox-sprites/package.json
@@ -38,6 +38,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-sandbox-vercel/package.json b/packages/ai-sandbox-vercel/package.json
index 0751d96072..20ce9a226b 100644
--- a/packages/ai-sandbox-vercel/package.json
+++ b/packages/ai-sandbox-vercel/package.json
@@ -37,6 +37,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-sandbox/package.json b/packages/ai-sandbox/package.json
index 922a4cbcd3..9fa6f9299a 100644
--- a/packages/ai-sandbox/package.json
+++ b/packages/ai-sandbox/package.json
@@ -50,6 +50,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-solid-ui/package.json b/packages/ai-solid-ui/package.json
index 81d69c7582..50aae37c59 100644
--- a/packages/ai-solid-ui/package.json
+++ b/packages/ai-solid-ui/package.json
@@ -36,6 +36,7 @@
     "clean": "premove ./build ./dist",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --passWithNoTests --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest --passWithNoTests",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-solid/package.json b/packages/ai-solid/package.json
index 59099d3a8e..7343aef22d 100644
--- a/packages/ai-solid/package.json
+++ b/packages/ai-solid/package.json
@@ -33,6 +33,7 @@
   "scripts": {
     "clean": "premove ./build ./dist",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc",
diff --git a/packages/ai-svelte/package.json b/packages/ai-svelte/package.json
index 1c9f6a4b88..3ea86a43d2 100644
--- a/packages/ai-svelte/package.json
+++ b/packages/ai-svelte/package.json
@@ -36,6 +36,7 @@
     "clean": "rm -rf ./dist",
     "lint:fix": "oxlint src --type-aware --fix",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "svelte-check",
diff --git a/packages/ai-utils/package.json b/packages/ai-utils/package.json
index f3c738318d..46c4384e96 100644
--- a/packages/ai-utils/package.json
+++ b/packages/ai-utils/package.json
@@ -36,6 +36,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-vercel-gateway/package.json b/packages/ai-vercel-gateway/package.json
index 9783088bdb..3d77a83da0 100644
--- a/packages/ai-vercel-gateway/package.json
+++ b/packages/ai-vercel-gateway/package.json
@@ -44,6 +44,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-vertex/package.json b/packages/ai-vertex/package.json
index 11eee71a7e..80d6d6e665 100644
--- a/packages/ai-vertex/package.json
+++ b/packages/ai-vertex/package.json
@@ -36,6 +36,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/ai-vue-ui/package.json b/packages/ai-vue-ui/package.json
index 64ea5e45d7..ec29b072f2 100644
--- a/packages/ai-vue-ui/package.json
+++ b/packages/ai-vue-ui/package.json
@@ -35,6 +35,7 @@
     "clean": "premove ./build ./dist",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --passWithNoTests --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest --passWithNoTests",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "vue-tsc --noEmit"
diff --git a/packages/ai-vue/package.json b/packages/ai-vue/package.json
index ad8231d710..138058ea4b 100644
--- a/packages/ai-vue/package.json
+++ b/packages/ai-vue/package.json
@@ -33,6 +33,7 @@
   "scripts": {
     "clean": "premove ./build ./dist",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc",
diff --git a/packages/ai/package.json b/packages/ai/package.json
index 998dd3c84f..686c748b87 100644
--- a/packages/ai/package.json
+++ b/packages/ai/package.json
@@ -72,9 +72,9 @@
     "clean": "premove ./build ./dist",
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
-    "test:coverage": "vitest run --coverage",
-    "test:coverage:watch": "vitest --coverage --watch",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
+    "test:coverage:watch": "vitest --coverage --watch",
     "test:lib": "vitest",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/openai-base/package.json b/packages/openai-base/package.json
index 21b0ce38c0..ebe2392178 100644
--- a/packages/openai-base/package.json
+++ b/packages/openai-base/package.json
@@ -36,6 +36,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest run",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/packages/preact-ai-devtools/package.json b/packages/preact-ai-devtools/package.json
index 5d0bc3ee25..39e567fc18 100644
--- a/packages/preact-ai-devtools/package.json
+++ b/packages/preact-ai-devtools/package.json
@@ -21,6 +21,7 @@
     "clean": "premove ./build ./dist",
     "lint:fix": "oxlint src --type-aware --fix",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --passWithNoTests --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest --passWithNoTests",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc",
diff --git a/packages/react-ai-devtools/package.json b/packages/react-ai-devtools/package.json
index a2951c2ad0..56a70f48f8 100644
--- a/packages/react-ai-devtools/package.json
+++ b/packages/react-ai-devtools/package.json
@@ -21,6 +21,7 @@
     "clean": "premove ./build ./dist",
     "lint:fix": "oxlint src --type-aware --fix",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --passWithNoTests --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest --passWithNoTests",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc",
diff --git a/packages/solid-ai-devtools/package.json b/packages/solid-ai-devtools/package.json
index 70ce24ca58..35f2205e6f 100644
--- a/packages/solid-ai-devtools/package.json
+++ b/packages/solid-ai-devtools/package.json
@@ -42,6 +42,7 @@
     "lint:fix": "oxlint src --type-aware --fix",
     "test:build": "publint --strict",
     "test:oxlint": "oxlint src --type-aware",
+    "test:coverage": "vitest run --passWithNoTests --coverage --coverage.include='src/**' --coverage.reporter=text-summary --coverage.reporter=json-summary",
     "test:lib": "vitest --passWithNoTests",
     "test:lib:dev": "pnpm test:lib --watch",
     "test:types": "tsc"
diff --git a/scripts/coverage-check.mjs b/scripts/coverage-check.mjs
new file mode 100644
index 0000000000..b0e01278be
--- /dev/null
+++ b/scripts/coverage-check.mjs
@@ -0,0 +1,286 @@
+// Compares coverage between two runs and fails when a package regressed.
+//
+// Both sides are measured in the same CI job — the PR head and its merge-base
+// with main — so there is no baseline file to keep in sync, no per-platform
+// skew, and packages can be added or removed without anyone updating a
+// checked-in number.
+//
+// Usage:
+//   node scripts/coverage-check.mjs --collect <dir> [--expect pkg,pkg]
+//   node scripts/coverage-check.mjs --base <dir> --head <dir>
+import {
+  appendFileSync,
+  mkdirSync,
+  readFileSync,
+  readdirSync,
+  writeFileSync,
+} from 'node:fs'
+import { join } from 'node:path'
+
+const METRICS = ['statements', 'branches', 'functions', 'lines']
+
+// Coverage percentages wobble slightly between runs (v8 attributes some bytes
+// differently depending on JIT timing), so require a real drop.
+const TOLERANCE = 0.5
+
+function arg(name) {
+  const i = process.argv.indexOf(name)
+  return i === -1 ? undefined : process.argv[i + 1]
+}
+
+function totals(summary) {
+  // A package with no source loaded reports totals of 0/0 as 100%; that is not
+  // a number worth comparing.
+  if (summary.total.statements.total === 0) return undefined
+  return Object.fromEntries(
+    METRICS.map((metric) => [metric, summary.total[metric].pct]),
+  )
+}
+
+function packageDirs() {
+  const dirs = {}
+  for (const entry of readdirSync('packages', { withFileTypes: true })) {
+    if (!entry.isDirectory()) continue
+    dirs[entry.name] = entry.name
+    try {
+      const pkg = JSON.parse(
+        readFileSync(join('packages', entry.name, 'package.json'), 'utf8'),
+      )
+      if (pkg.name) dirs[pkg.name] = entry.name
+    } catch {
+      // Directory with no package.json is still collectable by folder name.
+    }
+  }
+  return dirs
+}
+
+function expectedDirs() {
+  const raw = arg('--expect')
+  if (raw === undefined) return undefined
+  const names = raw
+    .split(',')
+    .map((name) => name.trim())
+    .filter(Boolean)
+  const dirs = packageDirs()
+  const resolved = []
+  const unknown = []
+  for (const name of names) {
+    const dir = dirs[name]
+    if (!dir) unknown.push(name)
+    else resolved.push(dir)
+  }
+  if (unknown.length > 0) {
+    console.error(`Unknown package(s): ${unknown.join(', ')}`)
+    process.exit(1)
+  }
+  return resolved
+}
+
+function readSummary(dirName) {
+  try {
+    return JSON.parse(
+      readFileSync(
+        join('packages', dirName, 'coverage', 'coverage-summary.json'),
+        'utf8',
+      ),
+    )
+  } catch (error) {
+    if (error && error.code === 'ENOENT') return null
+    throw error
+  }
+}
+
+function collect(dir) {
+  mkdirSync(dir, { recursive: true })
+  const expected = expectedDirs()
+  const names =
+    expected ??
+    readdirSync('packages', { withFileTypes: true })
+      .filter((entry) => entry.isDirectory())
+      .map((entry) => entry.name)
+  const missing = []
+  let n = 0
+  for (const name of names) {
+    const summary = readSummary(name)
+    if (!summary) {
+      if (expected) missing.push(`${name} (no coverage-summary.json)`)
+      continue
+    }
+    const values = totals(summary)
+    if (!values) {
+      if (expected) missing.push(`${name} (0 statements)`)
+      continue
+    }
+    writeFileSync(join(dir, `${name}.json`), JSON.stringify(values))
+    n++
+  }
+  if (missing.length > 0) {
+    console.error(
+      `Coverage collect failed for ${missing.length} package(s):\n  ${missing.join('\n  ')}`,
+    )
+    process.exit(1)
+  }
+  console.log(`Collected ${n} coverage summary/summaries into ${dir}`)
+}
+
+function read(dir) {
+  let files
+  try {
+    files = readdirSync(dir)
+  } catch (error) {
+    if (error && error.code === 'ENOENT') return {}
+    throw error
+  }
+  return Object.fromEntries(
+    files
+      .filter((file) => file.endsWith('.json'))
+      .map((file) => [
+        file.replace(/\.json$/, ''),
+        JSON.parse(readFileSync(join(dir, file), 'utf8')),
+      ]),
+  )
+}
+
+const collectDir = arg('--collect')
+if (collectDir) {
+  collect(collectDir)
+  process.exit(0)
+}
+
+const baseDir = arg('--base')
+const headDir = arg('--head')
+if (!baseDir || !headDir) {
+  console.error(
+    'Usage: coverage-check.mjs --collect <dir> [--expect pkg,pkg] | --base <dir> --head <dir>',
+  )
+  process.exit(2)
+}
+
+const base = read(baseDir)
+const head = read(headDir)
+const names = Object.keys(head).sort()
+
+if (names.length === 0) {
+  console.error('No packages were measured — nothing to compare.')
+  process.exit(1)
+}
+
+const regressions = []
+const additions = []
+const rows = []
+
+for (const name of names) {
+  const before = base[name]
+  const after = head[name]
+  if (!before) {
+    additions.push(name)
+    rows.push([
+      name,
+      ...METRICS.map((metric) => `${after[metric].toFixed(2)}%`),
+      'new',
+    ])
+    continue
+  }
+  const deltas = METRICS.map((metric) => after[metric] - before[metric])
+  const dropped = METRICS.filter((metric, i) => deltas[i] < -TOLERANCE)
+  if (dropped.length > 0) regressions.push({ name, before, after, dropped })
+  rows.push([
+    name,
+    ...METRICS.map((metric, i) => {
+      const sign = deltas[i] > 0 ? '+' : ''
+      return `${after[metric].toFixed(2)}% (${sign}${deltas[i].toFixed(2)})`
+    }),
+    dropped.length > 0 ? 'DROP' : 'ok',
+  ])
+}
+
+for (const name of Object.keys(base)
+  .filter((name) => !head[name])
+  .sort()) {
+  const before = base[name]
+  regressions.push({ name, before, after: null, dropped: ['missing'] })
+  rows.push([
+    name,
+    ...METRICS.map((metric) => `missing (${before[metric].toFixed(2)}%)`),
+    'DROP',
+  ])
+}
+
+const compared = names.filter((name) => base[name]).length
+
+const header = ['package', ...METRICS, '']
+const widths = header.map((_, column) =>
+  Math.max(header[column].length, ...rows.map((row) => row[column].length)),
+)
+const line = (cells) =>
+  cells
+    .map((cell, i) => cell.padEnd(widths[i]))
+    .join('  ')
+    .trimEnd()
+
+console.log(line(header))
+console.log(widths.map((width) => '-'.repeat(width)).join('  '))
+for (const row of rows) console.log(line(row))
+
+if (additions.length > 0) {
+  console.log(
+    `\n${additions.length} package(s) had no coverage on the base commit` +
+      ` (new, or unmeasurable there): ${additions.join(', ')}`,
+  )
+}
+
+const headline =
+  regressions.length > 0
+    ? `❌ Coverage dropped in ${regressions.length} package(s).`
+    : compared > 0
+      ? `✅ Coverage held across ${compared} compared package(s).`
+      : `${additions.length} package(s) are new; nothing to compare against.`
+
+if (process.env.GITHUB_STEP_SUMMARY) {
+  const md = [
+    `## Coverage`,
+    ``,
+    headline,
+    ``,
+    `Each package is measured twice in this job — on this PR and on its merge-base` +
+      ` with \`main\` — and compared. A drop of more than ${TOLERANCE}pp in any metric fails.` +
+      ` Packages your PR doesn't affect are not measured and not listed.`,
+    ``,
+    `| package | ${METRICS.join(' | ')} | |`,
+    `| --- | ${METRICS.map(() => '---:').join(' | ')} | --- |`,
+    ...rows.map((row) => `| ${row.join(' | ')} |`),
+  ]
+  if (additions.length > 0) {
+    md.push(
+      ``,
+      `> No coverage on the base commit, so nothing to compare against:` +
+        ` ${additions.join(', ')}.`,
+    )
+  }
+  appendFileSync(process.env.GITHUB_STEP_SUMMARY, `${md.join('\n')}\n`)
+}
+
+if (regressions.length > 0) {
+  console.error(`\nCoverage dropped in ${regressions.length} package(s):`)
+  for (const { name, before, after, dropped } of regressions) {
+    if (!after) {
+      console.error(`  ${name}: measured on base, missing on this PR`)
+      continue
+    }
+    for (const metric of dropped) {
+      console.error(
+        `  ${name} ${metric}: ${before[metric].toFixed(2)}% -> ${after[metric].toFixed(2)}%`,
+      )
+    }
+  }
+  console.error(`\nAdd tests covering the code this PR changed.`)
+  process.exit(1)
+}
+
+if (compared === 0) {
+  console.log(
+    `\n${additions.length} package(s) are new; nothing to compare against.`,
+  )
+} else {
+  console.log(`\nCoverage held across ${compared} compared package(s).`)
+}
diff --git a/scripts/coverage-check.test.ts b/scripts/coverage-check.test.ts
new file mode 100644
index 0000000000..beeaa6662d
--- /dev/null
+++ b/scripts/coverage-check.test.ts
@@ -0,0 +1,236 @@
+import { spawnSync } from 'node:child_process'
+import { mkdtempSync, mkdirSync, rmSync, writeFileSync } from 'node:fs'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { fileURLToPath } from 'node:url'
+import { afterEach, describe, expect, it } from 'vitest'
+
+const SCRIPT = fileURLToPath(new URL('./coverage-check.mjs', import.meta.url))
+
+const temps: Array<string> = []
+
+afterEach(() => {
+  for (const dir of temps.splice(0))
+    rmSync(dir, { recursive: true, force: true })
+})
+
+function tmp() {
+  const dir = mkdtempSync(join(tmpdir(), 'cov-check-'))
+  temps.push(dir)
+  return dir
+}
+
+function run(
+  args: Array<string>,
+  opts: { cwd?: string; env?: NodeJS.ProcessEnv } = {},
+) {
+  const env: NodeJS.ProcessEnv = { ...process.env, ...opts.env }
+  if (!opts.env || !('GITHUB_STEP_SUMMARY' in opts.env)) {
+    delete env.GITHUB_STEP_SUMMARY
+  }
+  return spawnSync(process.execPath, [SCRIPT, ...args], {
+    encoding: 'utf8',
+    cwd: opts.cwd,
+    env,
+  })
+}
+
+function metrics(pct: number) {
+  return { statements: pct, branches: pct, functions: pct, lines: pct }
+}
+
+function writeSnapshot(dir: string, name: string, pct: number) {
+  mkdirSync(dir, { recursive: true })
+  writeFileSync(join(dir, `${name}.json`), JSON.stringify(metrics(pct)))
+}
+
+function vitestSummary(pct: number, total = 10) {
+  const cell = { total, covered: 1, pct }
+  return JSON.stringify({
+    total: {
+      statements: cell,
+      branches: cell,
+      functions: cell,
+      lines: cell,
+    },
+  })
+}
+
+function writePkg(
+  root: string,
+  dirName: string,
+  summary: string,
+  pkgName = `@tanstack/${dirName}`,
+) {
+  mkdirSync(join(root, 'packages', dirName, 'coverage'), { recursive: true })
+  writeFileSync(
+    join(root, 'packages', dirName, 'package.json'),
+    JSON.stringify({ name: pkgName }),
+  )
+  writeFileSync(
+    join(root, 'packages', dirName, 'coverage', 'coverage-summary.json'),
+    summary,
+  )
+}
+
+describe('usage', () => {
+  it('exits 2 when --base or --head is missing', () => {
+    const r = run([])
+    expect(r.status).toBe(2)
+    expect(r.stderr).toMatch(/Usage:/)
+  })
+})
+
+describe('compare', () => {
+  it('passes a 0.4pp drop and a 0.5pp drop, fails 0.51pp', () => {
+    const base = tmp()
+    const head = tmp()
+    writeSnapshot(base, 'ok', 90)
+    writeSnapshot(head, 'ok', 89.5)
+    expect(run(['--base', base, '--head', head]).status).toBe(0)
+
+    writeSnapshot(head, 'ok', 89.6)
+    expect(run(['--base', base, '--head', head]).status).toBe(0)
+
+    writeSnapshot(head, 'ok', 89.49)
+    const r = run(['--base', base, '--head', head])
+    expect(r.status).toBe(1)
+    expect(r.stderr).toMatch(/ok statements: 90\.00% -> 89\.49%/)
+    expect(r.stdout).toMatch(/DROP/)
+  })
+
+  it('fails when only branches drop more than 0.5pp', () => {
+    const base = tmp()
+    const head = tmp()
+    mkdirSync(base, { recursive: true })
+    mkdirSync(head, { recursive: true })
+    writeFileSync(
+      join(base, 'pkg.json'),
+      JSON.stringify({
+        statements: 90,
+        branches: 80,
+        functions: 90,
+        lines: 90,
+      }),
+    )
+    writeFileSync(
+      join(head, 'pkg.json'),
+      JSON.stringify({
+        statements: 90,
+        branches: 79,
+        functions: 90,
+        lines: 90,
+      }),
+    )
+    const r = run(['--base', base, '--head', head])
+    expect(r.status).toBe(1)
+    expect(r.stderr).toMatch(/pkg branches: 80\.00% -> 79\.00%/)
+    expect(r.stderr).not.toMatch(/statements/)
+  })
+
+  it('treats a head-only package as new and exits 0', () => {
+    const base = tmp()
+    const head = tmp()
+    mkdirSync(base, { recursive: true })
+    writeSnapshot(head, 'ai-new', 12)
+    const r = run(['--base', base, '--head', head])
+    expect(r.status).toBe(0)
+    expect(r.stdout).toMatch(/\bnew\b/)
+    expect(r.stdout).toMatch(/nothing to compare against/)
+    expect(r.stdout).not.toMatch(/Coverage held/)
+  })
+
+  it('fails when a package was measured on base but not on head', () => {
+    const base = tmp()
+    const head = tmp()
+    writeSnapshot(base, 'ai-old', 90)
+    writeSnapshot(head, 'other', 90)
+    const r = run(['--base', base, '--head', head])
+    expect(r.status).toBe(1)
+    expect(r.stderr).toMatch(/ai-old: measured on base, missing on this PR/)
+  })
+
+  it('fails when head measured nothing', () => {
+    const base = tmp()
+    const head = tmp()
+    mkdirSync(base, { recursive: true })
+    mkdirSync(head, { recursive: true })
+    const r = run(['--base', base, '--head', head])
+    expect(r.status).toBe(1)
+    expect(r.stderr).toMatch(/nothing to compare/)
+  })
+
+  it('writes the step summary on a failing run', () => {
+    const base = tmp()
+    const head = tmp()
+    const summary = join(tmp(), 'summary.md')
+    writeSnapshot(base, 'pkg', 90)
+    writeSnapshot(head, 'pkg', 80)
+    const r = run(['--base', base, '--head', head], {
+      env: { ...process.env, GITHUB_STEP_SUMMARY: summary },
+    })
+    expect(r.status).toBe(1)
+    const md = require('node:fs').readFileSync(summary, 'utf8') as string
+    expect(md).toMatch(/Coverage dropped/)
+    expect(md).toMatch(/pkg/)
+  })
+})
+
+describe('collect', () => {
+  it('writes pct-only snapshots and skips packages with no summary', () => {
+    const root = tmp()
+    const out = join(root, 'out')
+    writePkg(root, 'ai', vitestSummary(90))
+    mkdirSync(join(root, 'packages', 'empty'), { recursive: true })
+    writeFileSync(
+      join(root, 'packages', 'empty', 'package.json'),
+      JSON.stringify({ name: '@tanstack/empty' }),
+    )
+    const r = run(['--collect', out], { cwd: root })
+    expect(r.status).toBe(0)
+    const written = JSON.parse(
+      require('node:fs').readFileSync(join(out, 'ai.json'), 'utf8'),
+    )
+    expect(written).toEqual(metrics(90))
+    expect(r.stdout).toMatch(/Collected 1 /)
+  })
+
+  it('fails --expect when a named package has no summary', () => {
+    const root = tmp()
+    const out = join(root, 'out')
+    writePkg(root, 'ai', vitestSummary(90))
+    const r = run(['--collect', out, '--expect', 'ai,missing-pkg'], {
+      cwd: root,
+    })
+    expect(r.status).toBe(1)
+    expect(r.stderr).toMatch(/missing-pkg/)
+  })
+
+  it('fails --expect when statements.total is 0', () => {
+    const root = tmp()
+    const out = join(root, 'out')
+    writePkg(root, 'empty', vitestSummary(100, 0))
+    const r = run(['--collect', out, '--expect', 'empty'], { cwd: root })
+    expect(r.status).toBe(1)
+    expect(r.stderr).toMatch(/0 statements/)
+  })
+
+  it('resolves @tanstack scoped names to the package directory', () => {
+    const root = tmp()
+    const out = join(root, 'out')
+    writePkg(
+      root,
+      'ai-devtools',
+      vitestSummary(81),
+      '@tanstack/ai-devtools-core',
+    )
+    const r = run(
+      ['--collect', out, '--expect', '@tanstack/ai-devtools-core'],
+      { cwd: root },
+    )
+    expect(r.status).toBe(0)
+    expect(require('node:fs').existsSync(join(out, 'ai-devtools.json'))).toBe(
+      true,
+    )
+  })
+})