Read running apps' bundle IDs off the main thread

[r3dbars]

🤖 Generated with Claude Code

https://claude.ai/code/session_0126tPTsXGHmWx6EmsR32sjX

Why

The freeze reporting that shipped in 1.1.66 (#1864) caught its first real freeze. Sentry APPLE-MACOS-2Q, "App hanging for at least 5000 ms": 5 events in 30 minutes from one user on published 1.1.66, with the app idle. Stack: the main thread was inside a Swift async job, in -[NSRunningApplication bundleIdentifier], blocked 5+ s on a synchronous LaunchServices XPC call (_LSCopyApplicationInformation).

Two main-actor async paths scan every running app's bundle ID:

• MeetingPromptDetector.evaluate(), which runs every 120 s plus on mic, camera and app events. Given the idle context, this is the likely source (inferred; Sentry 9.10 gives no app frame names).
• BrowserWindowTitleReader.titles, which is @MainActor and filters runningApplications before its AX work.

Product Impact

• Affects: meetings (call detection, all users)
• Lane: meeting reliability / app health
• Why this matters: a slow LaunchServices reply now just delays one detection pass instead of freezing the app.

What changed

• New RunningApplicationsReader: reads NSWorkspace.shared.runningApplications (pid, bundle ID, regular-app flag) on one serial .utility queue behind a checked continuation. It uses a serial queue, not a detached task, so a stuck reply can't tie up the Swift thread pool (same lesson as Settings reads the login-item status once, off the main thread #1867).
• MeetingPromptDetector.evaluate() takes bundle IDs from a new injectable runningBundleIDsProvider (default: the reader). now is taken after that await.
• BrowserWindowTitleReader.titles builds its pid list from the reader.
• Added the new file to run-tests.sh APP_SOURCES and to Sources/Meeting/CLAUDE.md.

Left alone:

• frontmostApplication?.bundleIdentifier: the active app's info is already loaded, and tests inject it synchronously.
• The workspace-notification app's bundle ID.
• CallAppMicrophoneSharingMonitor.refresh: synchronous and only on app launch/quit; it isn't the async job in the stack.

How I checked it

• bash scripts/dev/linux-checks.sh: 48 passed
• python3 scripts/dev/check-source-pins.py --changed-only: PASS
• bash build-deps.sh --force / bash build.sh --no-open / bash run-tests.sh / bash run-integration-smoke.sh: CI

Checks I could not run, and why:

• Build, fast tests and integration smoke: cloud session, no Swift toolchain. CI runs them.
• The freeze itself can't be reproduced on demand (it needs a slow LaunchServices).

Mac or hardware test still needed? If yes:

• None to merge. After the next release ships, APPLE-MACOS-2Q should stop getting new events from the new version.

Risk Review

• Privacy / local-first behavior reviewed (bundle IDs stay in memory, as before)
• Checked the text-pin tests for every file I edited
• Agent PRs got an independent deep review of the full diff (requested)
• No private transcripts, audio, tokens, personal paths, or customer data are included

Notes

Found by the 1.1.66 release watch (/mnt/project-files/release-watch/1.1.66-watch-log.md).

Agent handoff

COORD_DONE: BRIEF | this PR | running-apps scan off main (Sentry 2Q) | none | none | linux-checks, source pins | CI + deep review

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