ci(e2e): split browser tests into four parallel shards (#7241)

* ci(e2e): split browser tests into four parallel shards

* docs: keep E2E guidance within the module size budget

.github/workflows/e2e-tests.yml

@@ -42,6 +42,10 @@ jobs:
     if: ${{ github.event_name != 'pull_request' || github.event.pull_request.draft == false }}
     runs-on: ubuntu-latest
     timeout-minutes: 25
+    strategy:
+      fail-fast: false
+      matrix:
+        shard: [1, 2, 3, 4]
 
     steps:
       - name: Checkout
@@ -84,20 +88,32 @@ jobs:
 
       - name: Run E2E tests
         working-directory: frontend
-        run: pnpm exec playwright test
+        run: >-
+          pnpm exec playwright test
+          --shard=${{ matrix.shard }}/4
+          --workers=1
+          --reporter=github,html
+          --output=test-results/e2e
         env:
           SKIP_ENV_VALIDATION: '1'
+          PLAYWRIGHT_HTML_OUTPUT_DIR: playwright-report/e2e
 
       - name: Run auth recovery E2E tests
+        # Keep auth coverage unsharded and run it even if the first shard fails.
+        if: ${{ !cancelled() && matrix.shard == 1 }}
         working-directory: frontend
-        run: pnpm exec playwright test -c playwright.auth.config.ts
+        run: >-
+          pnpm exec playwright test -c playwright.auth.config.ts
+          --reporter=github,html
+          --output=test-results/auth
         env:
           SKIP_ENV_VALIDATION: '1'
+          PLAYWRIGHT_HTML_OUTPUT_DIR: playwright-report/auth
 
       - name: Upload Playwright report
         uses: actions/upload-artifact@v4
         if: ${{ !cancelled() }}
         with:
-          name: playwright-report
+          name: playwright-report-${{ matrix.shard }}
           path: frontend/playwright-report/
           retention-days: 7

frontend/AGENTS.md

@@ -51,6 +51,8 @@ in node tests to cover those behaviors.
 
 E2E tests live under `tests/e2e/` and use Playwright with Chromium. They mock all backend APIs via `page.route()` network interception and test real page interactions (navigation, chat input, streaming responses). Config: `playwright.config.ts`. The real-backend auth contract in `tests/e2e-real-backend/auth-disabled-contract.spec.ts` and `backend/tests/test_auth_me_permissions.py` pin the complete route-permission list; update both when adding registered permissions (including `projects:read/write/delete`).
 
+CI runs four E2E shards; only shard 1 runs auth recovery. Suite reports stay separate.
+
 The dedicated `run-history.ts` hook replaces the unpaged runs hook. Show counts
 only after a successful history read, never during initial loading or errors.
 Scheduled run history uses task/page query keys and the existing live offset API.