[CI] Run focused checks for Mobile CI tool changes (#27532)

.github/workflows/pr.yml

@@ -39,6 +39,7 @@ jobs:
       mobile_web_app: ${{ steps.readiness.outputs.reused != 'true' && steps.filter.outputs.mobile_web_app }}
       static_analysis: ${{ steps.readiness.outputs.reused != 'true' && steps.filter.outputs.static_analysis }}
       typecheck: ${{ steps.readiness.outputs.reused != 'true' && steps.filter.outputs.typecheck }}
+      mobile_ci_tools: ${{ steps.readiness.outputs.reused != 'true' && steps.filter.outputs.mobile_ci_tools }}
       git_compatibility: ${{ steps.readiness.outputs.reused != 'true' && steps.filter.outputs.git_compatibility }}
       codex_index_heal_contract: ${{ steps.readiness.outputs.reused != 'true' && steps.filter.outputs.codex_index_heal_contract }}
       xterm_patch_sync: ${{ steps.readiness.outputs.reused != 'true' && steps.filter.outputs.xterm_patch_sync }}
@@ -115,7 +116,11 @@ jobs:
           CHANGED="$(git diff --name-only --no-renames --diff-filter=ACDMR "$DIFF_BASE" HEAD)"
           echo "Changed paths:"
           printf '%s\n' "$CHANGED"
-          printf '%s\n' "$CHANGED" | node config/scripts/pr-code-change-scope.mjs | tee -a "$GITHUB_OUTPUT"
+          MOBILE_CI_ARGS=()
+          if git diff --quiet --no-renames --diff-filter=ACDRTUXB "$DIFF_BASE" HEAD; then
+            MOBILE_CI_ARGS=(--mobile-ci-tools)
+          fi
+          printf '%s\n' "$CHANGED" | node config/scripts/pr-code-change-scope.mjs "${MOBILE_CI_ARGS[@]}" | tee -a "$GITHUB_OUTPUT"
 
       # Reuse the path-detector checkout instead of queuing another runner.
       - name: Filter changed E2E specs
@@ -461,6 +466,28 @@ jobs:
           path: ci-shards/unit-selection.json
           retention-days: 14
 
+      - name: Set up Bun for Mobile CI tool tests
+        if: needs.code_paths.outputs.mobile_ci_tools == 'true'
+        uses: oven-sh/setup-bun@0c5077e51419868618aeaa5fe8019c62421857d6 # v2.2.0
+        with:
+          bun-version-file: config/.bun-version
+
+      - name: Test Mobile CI tools and runtime routing
+        if: needs.code_paths.outputs.mobile_ci_tools == 'true'
+        env:
+          ORCA_BACKGROUND_LAUNCH: '1'
+          ORCA_BALANCE_UNIT_SHARDS: '1'
+        run: >-
+          node config/scripts/run-vitest.mjs run --config config/vitest.config.ts
+          --maxWorkers=4 --isolate --retry=0 --bail=0
+          config/scripts/mobile-release-check-scope.test.mjs
+          config/scripts/mobile-test-change-scope.test.mjs
+          config/scripts/pr-ready-check-reuse.test.mjs
+          config/scripts/ci-dependency-download-cache.test.mjs
+          config/scripts/win32-test-lane-registration.test.mjs
+          config/scripts/vitest-node-runtime-boundary.test.ts
+          config/scripts/vitest-sqlite-runtime-boundary.test.ts
+
   git_compatibility:
     name: Git compatibility
     needs: [code_paths, preflight]
@@ -811,6 +838,7 @@ jobs:
       node_versions: '["24"]'
       runner: ubuntu-24.04-arm
       shards: ${{ needs.preflight.outputs.shards }}
+      run_shards: ${{ needs.code_paths.outputs.mobile_ci_tools != 'true' }}
       browser_contract: ${{ needs.code_paths.outputs.orcad_browser == 'true' }}
 
   # Why a sibling and not part of the test workflow: it is advisory, so it must not delay the

.github/workflows/unit-tests.yml

@@ -20,6 +20,12 @@ on:
         default: false
         type: boolean
 
+      run_shards:
+        description: Run the planned root unit shards.
+        required: false
+        default: true
+        type: boolean
+
       shards:
         description: JSON array of shard assignments, produced by unit-plan.yml.
         required: true
@@ -30,6 +36,7 @@ permissions:
 
 jobs:
   test:
+    if: inputs.run_shards
     name: tests node ${{ matrix.node }} ${{ matrix.shard.index }}/${{ matrix.shard.count }}
     runs-on: ${{ inputs.runner }}
     timeout-minutes: 60