Computer Use fails when per-user runtime app is missing

Computer Use failed to start in Codex Desktop with:

Computer Use could not start because its runtime app is missing.

Setup:

• macOS, Codex Desktop app build 26.616.81150
• computer-use@openai-bundled enabled, version 1.0.829
• Browser backends enabled: chrome,iab
• ~/.codex/config.toml had notify pointing at ~/.codex/computer-use/Codex Computer Use.app/.../SkyComputerUseClient

What I found:

• ~/.codex/computer-use/ contained config.json, but Codex Computer Use.app was missing.
• The bundled app still existed under the Codex app resources and plugin cache.
• Existing SkyComputerUseClient helper processes were stale, and Computer Use calls failed before any desktop task could start.

Workaround:

• Restored ~/.codex/computer-use/Codex Computer Use.app as a symlink to the bundled Computer Use app.
• Killed stale SkyComputerUseClient helpers.
• Restarted Codex so the Computer Use MCP transport could reconnect.

Expected behavior:

• Codex should repair or reinstall the missing per-user Computer Use runtime automatically, or surface a one-click repair path.
• The MCP transport should recover cleanly after the runtime path is repaired.

Possibly related to #28485, but this failure mode was a missing per-user runtime app path, not a macOS damaged-app dialog.

cc @tibo-openai @jif-oai