ci: balance test shards and reuse package download caches

.github/workflows/ci.yml

@@ -118,6 +118,8 @@ jobs:
           name: rea-test-runtime
           path: .
       - run: npm run test:ci:shard:run -- --shard=${{ matrix.shard }}
+        env:
+          REA_CI_TEST_HISTORY: .cache/ci-test-history/test-results.json
       - uses: actions/upload-artifact@v4
         if: ${{ !cancelled() }}
         with:
@@ -133,6 +135,9 @@ jobs:
     needs: changes
     if: needs.changes.outputs.code == 'true'
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      actions: read
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
@@ -141,6 +146,28 @@ jobs:
           cache: npm
       - run: npm ci
       - run: npm run test:prepare
+      - name: Find successful default-branch timing history
+        id: history
+        continue-on-error: true
+        env:
+          GH_TOKEN: ${{ github.token }}
+          CI_REPOSITORY: ${{ github.repository }}
+          CI_DEFAULT_BRANCH: ${{ github.event.repository.default_branch }}
+        run: |
+          run_id="$(gh api --method GET \
+            "repos/${CI_REPOSITORY}/actions/workflows/ci.yml/runs" \
+            -f branch="${CI_DEFAULT_BRANCH}" -f event=push -f status=success -f per_page=1 \
+            --jq '.workflow_runs[0].id // empty')"
+          echo "run-id=${run_id}" >> "${GITHUB_OUTPUT}"
+      - name: Download previous timing report
+        if: steps.history.outputs.run-id != ''
+        continue-on-error: true
+        uses: actions/download-artifact@v4
+        with:
+          name: test-results
+          run-id: ${{ steps.history.outputs.run-id }}
+          github-token: ${{ github.token }}
+          path: .cache/ci-test-history
       - uses: actions/upload-artifact@v4
         with:
           name: rea-test-runtime
@@ -148,6 +175,7 @@ jobs:
             dist/
             skills/
             .cache/mcp-tool-catalog.json
+            .cache/ci-test-history/test-results.json
             docs/public/product-catalog.json
             docs/verification/managed-conformance-*.json
           include-hidden-files: true
@@ -305,7 +333,14 @@ jobs:
           name: windows-native-controls
           path: native/windows/build/
       - run: npm run verify:windows-native:artifact
+      - name: Resolve npm cache before verifier HOME isolation
+        id: npm-cache
+        run: |
+          cache_path="$(npm config get cache)"
+          echo "path=${cache_path}" >> "${GITHUB_OUTPUT}"
       - run: npm run verify:package
+        env:
+          npm_config_cache: ${{ steps.npm-cache.outputs.path }}
       - name: Verify real Node Inspector discovery and observation
         timeout-minutes: 10
         run: npm run verify:inspector