perf: reduce e2e test suite time by ~20%

.github/workflows/lintBuildTest.yml

@@ -55,14 +55,15 @@ jobs:
       - name: Build
         run: npm run build
   playwright:
-    name: Playwright (${{ matrix.browser }})
+    name: Playwright (${{ matrix.browser }}, shard ${{ matrix.shard }}/3)
     timeout-minutes: 20
     runs-on: macos-15-xlarge
     needs: install
     strategy:
       fail-fast: false
       matrix:
         browser: ['chrome', 'firefox', 'safari']
+        shard: [1, 2, 3]
     steps:
       - uses: actions/checkout@v6
       - uses: actions/setup-node@v6
@@ -96,10 +97,53 @@ jobs:
         if: steps.playwright-cache.outputs.cache-hit == 'true'
         run: npx playwright install-deps
       - name: Run Playwright browser tests
-        run: npx playwright test --project=${{matrix.browser}}
+        run: npx playwright test --project=${{matrix.browser}} --shard=${{matrix.shard}}/3
       - uses: actions/upload-artifact@v7
         if: always()
         with:
-          name: test-results-${{ matrix.browser }}
+          name: test-results-${{ matrix.browser }}-shard-${{ matrix.shard }}
           path: test-results/
           retention-days: 7
+      # blob reports get merged into a single HTML report in playwright-result
+      - name: Upload blob report
+        uses: actions/upload-artifact@v7
+        if: ${{ !cancelled() }}
+        with:
+          name: blob-report-${{ matrix.browser }}-${{ matrix.shard }}
+          path: blob-report/
+          retention-days: 1
+  # Merges shard reports and serves as the single status check for branch protection
+  playwright-result:
+    name: Playwright
+    if: always()
+    needs: playwright
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: actions/setup-node@v6
+        with:
+          node-version: 22
+          cache: 'npm'
+      - run: npm ci
+      - name: Download blob reports
+        uses: actions/download-artifact@v8
+        with:
+          path: all-blob-reports
+          pattern: blob-report-*
+          merge-multiple: true
+      - name: Merge into HTML report
+        run: npx playwright merge-reports --reporter html ./all-blob-reports
+      - name: Upload merged HTML report
+        uses: actions/upload-artifact@v7
+        with:
+          name: playwright-report
+          path: playwright-report/
+          retention-days: 7
+      - name: Check shard results
+        run: |
+          if [ "${{ needs.playwright.result }}" = "success" ]; then
+            echo "All Playwright shards passed"
+          else
+            echo "Some Playwright shards failed: ${{ needs.playwright.result }}"
+            exit 1
+          fi

playwright.config.ts

@@ -27,7 +27,10 @@ export default {
   // Local runs also emit a compact plain-text failure report to .e2e-logs/
   // (timestamped per run, last 10 kept) via test/e2e/compact-reporter.ts, so
   // an LLM agent can read the failures.
-  reporter: process.env.CI ? 'list' : [['list'], ['./test/e2e/compact-reporter.ts']],
+  // blob reports from sharded CI runs get merged into one HTML report in CI
+  reporter: process.env.CI
+    ? [['list'], ['blob']]
+    : [['list'], ['./test/e2e/compact-reporter.ts']],
   use: {
     trace: process.env.CI ? 'on-first-retry' : 'retain-on-failure',
     baseURL: 'http://localhost:4009',