[Windows][26.901.5280/6511] Closing the last in-app Browser Use tab crashes the desktop app

Summary

On Windows, closing or finalizing the last active in-app Browser Use tab can terminate the entire Codex desktop application.

This was reproduced twice on the same machine across two Codex Desktop builds, including after a Microsoft Store update:

• 26.901.5280.0
• 26.901.6511.0

The app restarted normally after each crash, but all active tasks were interrupted.

Environment

• Windows 11 x64
• OS build: 26200
• Microsoft Store / MSIX installation

No user names, project names, local paths, conversation identifiers, task content, or raw session logs are included in this public report.

Reproduction pattern

1. Start a Codex task that invokes the in-app Browser.
2. Allow the Browser Use tab to open and operate normally.
3. Close or finalize the last Browser Use tab while the browser session is active or has just completed.
4. The browser WebView teardown sequence begins.
5. The entire Codex desktop application exits.
6. Restarting the app succeeds.

The close may be initiated by the Browser Use workflow rather than by a manual click.

Sanitized log sequence

The following sequence appeared immediately before both crashes. Identifiers and local details have been removed:

warning [browser-use-pip] Failed to upsert Browser Use PiP content
info [browser-use-iab-api] IAB_LIFECYCLE unregistered debugger listener reason=target-close
info [browser-sidebar-manager] IAB_LIFECYCLE syncing browser use active state isActive=false
info [electron-message-handler] IAB_LIFECYCLE renderer disposed browser sidebar webview
warning [browser-session-registry] IAB_LIFECYCLE browser sidebar guest torn down
info [electron-message-handler] IAB_LIFECYCLE renderer removed browser sidebar webview
info [browser-session-registry] IAB_LIFECYCLE closed browser sidebar page

In one reproduction, this also appeared shortly before teardown:

warning [browser-use-iab-api] IAB backend request failed:
Cannot find context with specified id
request=executeCdp:Runtime.evaluate

The desktop log ends immediately after the teardown sequence.

Crashpad evidence

Both crashes produced the same generic Crashpad sidecar:

{"capture_kind":"crash","osarch":"x86_64","ptype":"browser"}

A Crashpad record was created within approximately one second of the Browser Use WebView teardown. No local minidump was retained, so a native stack trace is not available.

Crash report identifiers are intentionally omitted from this public issue but can be supplied through a private support channel if useful.

System checks

• No matching Windows Application or System error was recorded in the one-minute window around either crash.
• No resource-exhaustion event was recorded at either crash time.
• No display-driver reset or GPU error was recorded at either crash time.
• The same failure occurred before and after the Store update.

Expected behavior

Closing or finalizing a Browser Use tab should cleanly dispose of the WebView. A stale CDP context or Browser/PiP state should fail the individual browser operation without terminating the desktop application.

Actual behavior

The Electron browser/main process crashes, terminating the complete Codex desktop app and interrupting active tasks.

Related issues

• #42006 — Windows desktop app crashes when in-app Browser route is torn down
• #41854 — Built-in Browser crashes the entire app on Windows

This report adds a reproduction on two later 26.901 builds and shows the same crash surviving an app update.

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Submitted by Codex at the user's explicit request after local log review. All public evidence was manually minimized and sanitized; full raw logs are not attached because they contain private project and session information.

Start by tracing the Browser Use workflow through the WebView teardown sequence and the Electron browser/main process, using the sanitized log order as the entry point. Compare this report with related issues #42006 and #41854. Done means closing or finalizing the last Browser Use tab disposes of the WebView without terminating the desktop app, while stale CDP or Browser/PiP state remains isolated to that operation.