Codex Desktop macOS: “Look Up” context menu item does nothing for selected chat text

Summary

On Codex Desktop for macOS, selecting rendered chat text, right-clicking, and choosing the macOS-style Look Up ... context menu item does not open the Dictionary / Look Up panel.

This appears to be a Codex Desktop / Electron context-menu issue rather than a system Dictionary issue: the menu item is present and dispatches, but the lookup panel never appears.

Environment

• App: Codex Desktop macOS
• App version: 26.623.101652
• App build: 4674
• Bundle ID: com.openai.codex
• Chromium base version: 149.0.7827.197
• Codex CLI: codex-cli 0.142.5
• macOS: 26.5.2 (25F84)
• Hardware/arch: Apple Silicon (arm64)

Steps to Reproduce

1. Open Codex Desktop on macOS.
2. Select text in a rendered chat message.
3. Right-click the selected text.
4. Choose Look Up "<selected text>" from the context menu.

Expected Behavior

The macOS Dictionary / Look Up panel appears for the selected text, matching normal behavior in other macOS apps.

Actual Behavior

Nothing appears. The context menu closes, but the Dictionary / Look Up panel is not shown.

Evidence Collected

A short Record & Replay capture showed:

• Codex produced a context menu containing Look Up “Recording is running.”.
• The selected menu item was clicked.
• No Dictionary / Look Up UI appeared afterward.

Nearby system logs at the click time showed AppKit receiving the menu action:

Codex ... (AppKit) perform action for menu item
Codex ... (AppKit) sendAction:

I also inspected the installed app bundle. The bundled Electron context menu appears to wire the item to Electron's selection lookup API:

lookUpSelection: ... {
  label: 'Look Up “{selection}”',
  visible: platform === 'darwin' && hasSelection && !isLink,
  click() {
    webContents.showDefinitionForSelection()
  }
}

So the likely failure mode is that webContents.showDefinitionForSelection() is silently no-oping for this WebContents selection, or the retained selection is no longer usable by the time the menu item fires.

Notes

No raw Record & Replay event file or app logs are attached here, to avoid exposing local/private session data. Happy to provide a sanitized trace if useful.