fix(quit): enforce Warn Before Quit when Cmd+Q arrives via app switcher - #2186

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Greptile Summary

This PR fixes a gap in the "Warn Before Quit" feature: when Cmd+Q arrives via the Cmd+Tab app-switcher, macOS calls applicationShouldTerminate directly, completely bypassing handleCustomShortcut / handleQuitShortcutWarning. The fix correctly gates applicationShouldTerminate on QuitWarningSettings.isEnabled(), shows the same confirmation alert asynchronously, and uses NSApp.reply(toApplicationShouldTerminate:) to answer the pending termination request. A new isQuitWarningConfirmed flag prevents a double-dialog on the normal Cmd+Q path.\n\nKey observations:\n- Logic is correct for all described scenarios (warning on/off, both Cmd+Q paths, "Don't warn again" suppression).\n- isQuitWarningConfirmed consume-and-reset: the flag is read in applicationShouldTerminate but never reset to false after serving its purpose. In the extremely unlikely event that the app survives after returning .terminateNow, the flag stays true and would silently bypass the dialog on every subsequent quit via app switcher.\n- Duplicated alert construction: the full NSAlert setup block is copy-pasted verbatim between applicationShouldTerminate (lines 2723–2730) and handleQuitShortcutWarning (lines 9013–9020). A private showQuitConfirmationAlert() helper would eliminate the drift risk.

Confidence Score: 4/5

Safe to merge; the core fix is correct and all described test scenarios are handled properly, with two non-blocking P2 items remaining.

The fix correctly addresses the root cause (app-switcher bypassing handleCustomShortcut), the isQuitWarningConfirmed double-dialog guard works for both quit paths, and suppression-button persistence is handled consistently. The two remaining issues — not resetting isQuitWarningConfirmed after consumption, and duplicated alert-construction code — are style/defensive-coding concerns that don't affect normal user flows.

Sources/AppDelegate.swift — the duplicated alert block and the unconsumed isQuitWarningConfirmed flag after .terminateNow.

Important Files Changed

Sequence Diagram

sequenceDiagram
    participant User
    participant macOS
    participant AppDelegate

    Note over User,AppDelegate: Normal Cmd+Q path (handleCustomShortcut)
    User->>AppDelegate: Cmd+Q key event
    AppDelegate->>AppDelegate: handleQuitShortcutWarning()
    AppDelegate->>AppDelegate: QuitWarningSettings.isEnabled()?
    alt warning disabled
        AppDelegate->>macOS: NSApp.terminate(nil)
    else warning enabled
        AppDelegate->>User: Show "Quit cmux?" alert (runModal)
        User-->>AppDelegate: Confirms quit
        AppDelegate->>AppDelegate: isQuitWarningConfirmed = true
        AppDelegate->>macOS: NSApp.terminate(nil)
        macOS->>AppDelegate: applicationShouldTerminate(_:)
        AppDelegate->>AppDelegate: isQuitWarningConfirmed == true → .terminateNow
        macOS->>AppDelegate: applicationWillTerminate(_:)
    end

    Note over User,AppDelegate: Cmd+Tab app-switcher path (NEW)
    User->>macOS: Cmd+Q in app switcher
    macOS->>AppDelegate: applicationShouldTerminate(_:)
    AppDelegate->>AppDelegate: isTerminatingApp = true, saveSessionSnapshot
    AppDelegate->>AppDelegate: isQuitWarningConfirmed? → false
    AppDelegate->>AppDelegate: QuitWarningSettings.isEnabled()?
    alt warning disabled
        AppDelegate-->>macOS: .terminateNow
    else warning enabled
        AppDelegate->>AppDelegate: DispatchQueue.main.async { show alert }
        AppDelegate-->>macOS: .terminateLater
        AppDelegate->>User: Show "Quit cmux?" alert (runModal)
        alt User confirms
            AppDelegate->>AppDelegate: isQuitWarningConfirmed = true
            AppDelegate->>macOS: NSApp.reply(toApplicationShouldTerminate: true)
            macOS->>AppDelegate: applicationWillTerminate(_:)
        else User cancels
            AppDelegate->>AppDelegate: isTerminatingApp = false
            AppDelegate->>macOS: NSApp.reply(toApplicationShouldTerminate: false)
        end
    end

_{Reviews (1): Last reviewed commit: "fix(quit): enforce Warn Before Quit when..." | Re-trigger Greptile}

Thank you for the contribution!