[Windows Desktop 26.917] 5/5 browser-session end events followed by 90–150s app hang #48201

Environment

• Windows 11 Pro, build 26200, x64
• Microsoft Store package OpenAI.Codex 26.917.8451.0 (ChatGPT.exe)
• Bundled Codex runtime 0.155.0-alpha.16.3
• Git 2.55.0.windows.3
• A newer desktop package, 26.917.9434.0, is available but has not yet been installed. The user reports intermittent freezes have persisted through earlier updates.

Symptom

The entire desktop window intermittently becomes unresponsive for about 90–150 seconds, then recovers without a restart. This happens while tasks progress, around task completion, and sometimes while no task appears active. Windows Error Reporting recorded AppHangTransient for ChatGPT.exe at 2026-09-25 22:27:42 Australia/Sydney, and an earlier event at 2026-09-24 22:10:02.

90-minute monitored capture

A local monitor sampled the main window's Windows Responding flag, process private memory, and Git process count every five seconds from 2026-09-25 21:30:31 to 23:00:28 AEST (UTC+10). It recorded five continuous unresponsive episodes:

In that same monitoring interval, the desktop log recorded exactly five IAB_LIFECYCLE ended browser use session activity events. Each preceded one of the five hangs by 1.6–5.1 seconds. No additional unresponsive samples appeared through the end of monitoring. This is a strong timing association, but the available data do not prove the blocking call or root cause.

Selected desktop log lines (UTC; conversation IDs removed):

2026-09-25T11:34:23.611Z info [browser-session-registry] IAB_LIFECYCLE ended browser use session activity disposeAfterSessionActivity=false windowId=1
2026-09-25T11:40:22.529Z info [browser-session-registry] IAB_LIFECYCLE ended browser use session activity disposeAfterSessionActivity=false windowId=1
2026-09-25T12:13:53.161Z info [browser-session-registry] IAB_LIFECYCLE ended browser use session activity disposeAfterSessionActivity=true windowId=1
2026-09-25T12:25:34.287Z info [browser-session-registry] IAB_LIFECYCLE ended browser use session activity disposeAfterSessionActivity=true windowId=1
2026-09-25T12:35:31.203Z info [browser-session-registry] IAB_LIFECYCLE ended browser use session activity disposeAfterSessionActivity=false windowId=1
2026-09-25T12:38:01.260Z info [sampler-manager] main_thread_jank_snapshot mainThreadJankCountSinceLastSnapshot=2 processRole=browser_main snapshotReason=heartbeat windowAttention=visible_unfocused

The main desktop log was largely quiet during each hang and resumed with main_thread_jank_snapshot around recovery. The primary renderer also logged repeated ResizeObserver loop completed with undelivered notifications, including outside hang intervals, so that message is not treated as causal evidence.

Checks and attempted isolation

• Hiding the floating pet, restarting the app, switching to a smaller task, and upgrading Git did not stop the freezes.
• Temporarily disabling Windows notifications did not stop three subsequent hangs; the notification setting was restored.
• Direct git status outside the desktop app took about 72 ms. Git worker timeouts do appear elsewhere in the logs, but no Git process was present during any sampled hang.
• codex doctor reported healthy local databases and a consistent desktop installation.
• User configuration and agent routing were preserved. The bundled browser plugin has not been disabled for this test.

Related but distinct reports: #22655 describes turn-complete/browser-route hangs and exits; #25094 describes short freezes around browser-sidebar startup. This capture points specifically to browser-use session-end events followed by two-minute recoverable hangs.

Question for maintainers

Is this a known desktop/browser-session cleanup defect in 26.917, and is there a verified fix or safe workaround that preserves the user's browser and agent configuration? If a hang-time stack or trace is needed, please advise the preferred private diagnostic collection and submission path. Raw desktop logs, session transcripts, local paths, and task content are intentionally omitted from this public report because they may contain private information.

Private feedback reference

The user also submitted diagnostics through Codex /feedback. Feedback/session reference: 01a0cdf5-05bb-7a83-8a74-3403580e12a6. Please correlate that private submission with this issue; the raw diagnostics are not posted publicly.