The September 2026 pattern sweep exposed two test-harness failures that initially looked like navigation and CORS problems.

insertPatternBySlug() used one asynchronous page.evaluate() for both fetching the pattern registry and parsing/inserting the chosen pattern. The browser could report Protocol error (Runtime.callFunctionOn): Promise was collected even though the blocks had already appeared in the editor. Playwright rewrote that protocol error as Execution context was destroyed, most likely because of a navigation. Browser lifecycle instrumentation confirmed that no document or execution context was destroyed at that point.

Tracing changed the timing and concealed the failure. Repeating the same checks with tracing disabled reproduced it. The helper now resolves the pattern content first, then parses and inserts it in a separate, synchronous evaluation. It does not retry insertion: repeating an operation that already inserted content could duplicate blocks.

tests/e2e/pattern-insertion.spec.js covers initial and cached lookups, the exact number of inserted blocks, unique client IDs, validation, and missing-pattern errors without content changes.

The Mobile Safari failure involved the editor's /wp/v2/pages?context=edit request. A trace showed that request returning HTTP 200, followed by later requests to the same endpoint being canceled when the test navigated the editor tab to the published frontend. The original failure surfaced an access-control error during this transition.

The pattern sweep now uses openFrontendPage() to review the published frontend in a separate page in the same browser context. Editor requests can finish. Errors from both pages remain assertions, with editor/frontend labels for triage. The frontend listener is attached before navigation so startup errors are captured.

tests/e2e/editor-lifecycle.spec.js holds a real browser request pending while opening the frontend. Same-tab navigation failed the check because the request was canceled; separate-page navigation lets it complete with HTTP 200. A second check verifies that frontend JavaScript exceptions remain observable.

With wp-env running:

npx playwright test tests/e2e/pattern-insertion.spec.js tests/e2e/editor-lifecycle.spec.js --workers=2 --trace=off

Use --trace=off when reproducing the collected-promise failure. Traces remain useful for examining request URLs, status codes, and navigation timing, but a passing traced run alone does not rule out that race.

Auto-generated from docs/testing/E2E-LIFECYCLE.md. To update, edit the source file and changes will sync on next push to main.