fix(cli): stop daemon when socket disappears

[Devin Rousso (dcrousso)]

detached browser daemons stay alive after losing their control socket

monitor the socket identity and exit gracefully when it disappears or is replaced

fixes #42428

[github-actions]

Test results for "MCP"

3 failed
❌ [firefox] › mcp/annotate.spec.ts:291 › should enter annotate mode on fresh dashboard.tsx mount with -s --annotate @mcp-windows-latest-firefox
❌ [firefox] › mcp/annotate.spec.ts:316 › should annotate via direct browser_annotate MCP call @mcp-windows-latest-firefox
❌ [firefox] › mcp/cli-core.spec.ts:140 › uncheck @mcp-windows-latest-firefox

8264 passed, 1366 skipped

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Merge workflow run.

[github-actions]

🟢 CI is clear — all three failures are pre-existing Firefox flakes

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

The three failures are all Firefox-only MCP tests that have nothing to do with this change. This PR only touches the CLI daemon's socket monitor (daemon.ts) and its test — it doesn't go near the MCP annotate flow or the uncheck interaction. Each of the three has a long green history and has failed on other PRs and push runs the PR can't be responsible for, so these are flakes, not regressions.

Details

Overall: none of the failures are caused by this PR. The diff adds monitorSocketPath() in packages/playwright-core/src/tools/cli-daemon/daemon.ts plus a cli-session.spec.ts test — a Unix-socket-identity poll for the browser daemon. That code path is unrelated to the annotate MCP tool and to browser_uncheck, and all three failures reproduce elsewhere.

Pre-existing flake / infra

• [firefox] › mcp/annotate.spec.ts:291 › should enter annotate mode on fresh dashboard.tsx mount with -s --annotate — flaky on firefox: failed 5 of 726 runs, passed 721. Failures land on unrelated work, e.g. PR docs(browsercontext): undeprecate setHTTPCredentials #42419 (278cd4d3), PR fix(trace-viewer): store snapshot style text in an attribute #42405 (2c37eeb3), PR chore(net): use native happy eyeballs instead of the manual implementation #42240 (a3640c77), and push runs 484274c4 / 1720c55c / b856094e. Passes on every other browser (chromium/webkit 0 failures).

• [firefox] › mcp/annotate.spec.ts:316 › should annotate via direct browser_annotate MCP call — flaky on firefox: failed 4 of 726 runs, passed 722. Prior failures on PR Revert "chore(deps-dev): bump fast-uri from 3.1.3 to 3.1.4" #41978 (bb336448) and PR chore: mark v1.62.1 #42020 (026226a8). Green on chromium and webkit throughout.

• [firefox] › mcp/cli-core.spec.ts:140 › uncheck — flaky on firefox: failed 5 of 726 runs, passed 721. Prior failures on PR fix(mcp): drop the backend after browser_close with a shared browser #42365 (72b57098), PR feat(tracing): allow configuring the screenshots size #42283 (ce184078), PR feat(mcp): default codegen language from PW_LANG_NAME #42150 (ab0ab1e4), and push run 30d5b2ec. Green on chromium/webkit. The daemon socket poll this PR adds doesn't touch the browser_uncheck code path.

_{Triaged by the Playwright bot - agent run}