test: roll stable-test-runner to 1.64.0-alpha-2026-09-14

[microsoft-playwright-automation]

No description provided.

[github-actions]

Test results for "tests 1"

4 flaky

⚠️ [chromium-library] › library/popup.spec.ts:260 › should not throw when click closes popup `@chromium-ubuntu-22.04-node24`
⚠️ [chromium-library] › library/video.spec.ts:495 › screencast › should capture static page in persistent context Radoslav Kirilov (@smoke) `@chromium-ubuntu-22.04-node22`
⚠️ [firefox-library] › library/browsercontext-cookies-third-party.spec.ts:257 › third party 'Partitioned;' cookies `@firefox-ubuntu-22.04-node20`
⚠️ [firefox-library] › library/browsercontext-cookies-third-party.spec.ts:470 › top level 'Partitioned;' cookie and same origin iframe `@firefox-ubuntu-22.04-node20`

51692 passed, 1247 skipped

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Merge workflow run.

[github-actions]

Test results for "MCP"

1 failed
❌ [firefox] › mcp/cli-session.spec.ts:54 › idle timeout shuts the session down @mcp-windows-latest-firefox

8508 passed, 1436 skipped

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Merge workflow run.

[github-actions]

🟢 Nothing here points at this PR

The one failure — mcp/cli-session.spec.ts:54 on Firefox/Windows — is a pre-existing flake that also fails on a plain push SHA with no PR attached.

Details

This PR only bumps tests/playwright-test/stable-test-runner (package.json + lockfile), which is the pinned released runner used by the playwright-test suite. It doesn't reach the MCP CLI session code at all.

Pre-existing flake / infra

• [firefox] › mcp/cli-session.spec.ts:54 › idle timeout shuts the session down @mcp-windows-latest-firefox — fails with expect(received).toContain("(no browsers)") while the report still shows ### Browsers - default: status: o…, i.e. the idle shutdown hadn't landed yet when the assertion ran. The identical failure appears on push sha d1ead3ec (no PR) and on feat(coverage): experimental istanbul coverage collection via tracing #42684, so this PR can't be responsible. Across the results DB it's 3 failed of 9 runs on mcp-windows-latest-firefox and 0 failed of 118 runs on every other MCP bot — a Windows/Firefox timing flake.

  🟩🟩🟩🟩🟩🟥🟩🟥🟥

The four flaky tests in the "tests 1" report (library/popup.spec.ts:260, library/video.spec.ts:495, two browsercontext-cookies-third-party.spec.ts cases) all passed on retry and aren't in the playwright-test suite either.

_{Triaged by the Playwright bot - agent run}