macOS: Computer Use Accessibility permission crashes NVIDIA Nsight Systems during Timeline interaction #42666

Summary

Enabling the macOS Accessibility permission for Codex Computer Use causes NVIDIA Nsight Systems to crash when interacting with its Qt Timeline. Disabling only that Accessibility entry makes the crash disappear.

Environment

• macOS 26.6.2 (25G83), Apple Silicon M5 Pro
• ChatGPT/Codex desktop app 26.901.20858 (build 7658)
• Bundled CLI: codex-cli 0.153.0-alpha.5
• NVIDIA Nsight Systems 2026.2.1 (bundled Qt 6.8.1)
• Same .nsys-rep and same Nsight version in all tests

Reproduction

1. Enable System Settings > Privacy & Security > Accessibility > Codex Computer Use.
2. Open an .nsys-rep in Nsight Systems.
3. Expand or collapse the Python process row in Timeline.
4. Nsight exits/crashes, often immediately.
5. Disable only Codex Computer Use in Accessibility and repeat: Nsight remains stable.

Controls

• The same report/version works in another macOS user account.
• It works in the affected account as soon as Codex Computer Use Accessibility access is disabled.
• Reinstalling/alignment of Nsight and changing display configuration do not affect the result.

Debugger evidence

The crash is EXC_BAD_ACCESS in Qt's macOS accessibility bridge (libqcocoa.dylib). One captured stack includes:

objc_retain -> NSMutableArray insertObject:atIndex: -> libqcocoa.dylib -> -[QMacAccessibilityElement accessibilitySelectedChildren]

A second captured path reaches -[QMacAccessibilityElement isAccessibilityFocused] through NSWindow accessibilityFocusedUIElement.

This suggests that background accessibility traversal encounters stale Qt QAccessible elements after Timeline rows are collapsed.

Workaround

Disable Codex Computer Use in macOS Accessibility settings.

Requested mitigation

Please consider limiting background AX traversal to the active automation target/window, or excluding/guarding unstable Qt accessibility trees so unrelated applications are not queried while Computer Use is idle.