test: roll stable-test-runner to 1.64.0-alpha-2026-09-21

[microsoft-playwright-automation]

No description provided.

[github-actions]

Test results for "tests 1"

3 flaky

⚠️ [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`
⚠️ [firefox-page] › page/page-event-request.spec.ts:181 › should return response body when Cross-Origin-Opener-Policy is set `@firefox-ubuntu-22.04-node20`

52022 passed, 1250 skipped

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Merge workflow run.

[github-actions]

Test results for "MCP"

1 failed
❌ [firefox] › mcp/annotate.spec.ts:269 › should start dashboard and annotate when no dashboard is running @mcp-windows-latest-firefox

8691 passed, 1474 skipped

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Merge workflow run.

[github-actions]

Hi, I'm the Playwright bot and I took a look at the CI failures here.

🟢 The one failure is a known pre-existing flake — this PR is clear

mcp/annotate.spec.ts:269 on mcp-windows-latest-firefox fails the same way on unrelated PRs and on main pushes. This PR only bumps the stable-test-runner dev dependency, which MCP tests don't use.

Details

Pre-existing flake / infra

• [firefox] › mcp/annotate.spec.ts:269 › should start dashboard and annotate when no dashboard is running @mcp-windows-latest-firefox — flaky on Windows only, with the identical error every time: expect(getByRole('main', { name: 'Dashboard: annotate' })).toBeVisible() times out after 15s. Across the test-results DB it flips verdict on every Windows bot on SHAs this PR can't touch:

  bot	runs	failed	passed
  mcp-windows-latest-firefox	701	8	693
  mcp-windows-latest-msedge	713	7	706
  mcp-windows-latest-chromium	716	6	710
  mcp-windows-latest-webkit	721	4	717
  mcp-windows-latest-chrome	714	3	711

  All six macOS/Ubuntu MCP bots: 0 failures in ~4300 runs. Recent examples elsewhere — run 34989724789 and 34518279279 (pushes to main, sha a0241629 / efb0761d), and PRs fix(mcp): keep upload modal, skip short secrets and bad headers #42713, Fix spelling of restoring in credentials docs #42718, feat(coverage): experimental istanbul coverage collection via tracing #42684, feat(mcp): offer page-registered WebMCP tools as MCP tools #42671. Looks like the dashboard server is just slow to come up on the Windows runners.

Not a failure

• The three firefox-ubuntu-22.04-node20 entries in "tests 1" (browsercontext-cookies-third-party.spec.ts:257/:470, page-event-request.spec.ts:181) are flaky, not failed — they passed on retry, so there's nothing to triage there.

The diff

Only tests/playwright-test/stable-test-runner/package.json and its lockfile change (roll to 1.64.0-alpha-2026-09-21). That package is used exclusively by the tests/playwright-test/ suite; nothing in it reaches the MCP dashboard code path or the Firefox cookie/request tests.

_{Triaged by the Playwright bot - agent run}