feat: Implement Ctrl+C double-press delay for exit

[medic-code]

TLDR

This PR introduces a configurable delay to the Ctrl+C exit mechanism. This prevents the application from accidentally terminating due to rapid, unintended double-presses or lag that interprets a single Ctrl + c as a double press, making the exit behaviour more robust and improving the user experience.

Dive Deeper

The root cause of the issue is that rapid, successive Ctrl+C presses can be registered as a valid double-press, causing an immediate and sometimes unintentional shutdown. This can be frustrating for users who did not intend to exit the application.

This change modifies the core process exit hook to check the time interval between two Ctrl+C signals. A new constant is introduced to define this minimum delay, ensuring that only deliberate double-presses trigger an exit. The implementation also includes updated tests to verify the new timing logic.

Specific code changes

• Adds MIN_CTRL_C_INTERVAL_MS to define the minimum time (400ms) between two Ctrl+C presses for a deliberate exit.
• Modifies the useEffect hook in AppContainer.tsx to check this interval before triggering a quit.
• Updates AppContainer.test.tsx with new tests to verify the delay logic and removes an obsolete test case.

Reviewer Test Plan

1. Verify all checks pass:

   npm run preflight

2. Test the delay logic:

   • Run the CLI application.
   • Press Ctrl+C once. The "press again to exit" message should appear.
   • Immediately press Ctrl+C again (faster than the configured delay). The application should not exit.
   • Press Ctrl+C once, wait a moment (longer than the delay), and press Ctrl+C again. The application should exit as expected.

Testing Matrix

	🍏	🪟	🐧
npm run	✅	❓	❓
npx	✅	❓	❓

Related Issues

Fixes #12421

Pre-Merge Checklist

• ran npm run preflight without errors
• Added/updated tests (if needed)
• Noted breaking changes (if any)
• Updated relevant documentation and README (if needed)

[gemini-code-assist]

Summary of Changes

Hello @medic-code, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the application's exit mechanism by introducing a configurable delay for the Ctrl+C double-press action. The change aims to improve user experience and prevent unintentional application shutdowns that could occur due to rapid or accidental key presses. By requiring a minimum time interval between successive Ctrl+C signals, the system ensures that only deliberate attempts to quit the application are successful, making the overall behavior more robust and predictable.

Highlights

• Configurable Ctrl+C Exit Delay: Introduces a configurable delay to the Ctrl+C double-press exit mechanism, preventing accidental application termination from rapid or unintended key presses.
• New Constant for Delay: Adds a new constant, MIN_CTRL_C_INTERVAL_MS, set to 400ms, to define the minimum time required between two Ctrl+C presses for a deliberate exit.
• Logic Update in AppContainer: Modifies the useEffect hook in AppContainer.tsx to incorporate the new delay logic, ensuring that the application only quits if the time between two Ctrl+C presses exceeds the defined interval.
• Updated Test Suite: Updates AppContainer.test.tsx by removing an obsolete test case and adding new tests to specifically verify the functionality of the Ctrl+C delay logic under different timing conditions.

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[gemini-code-assist]

Code Review

This pull request introduces a delay to the Ctrl+C exit mechanism to prevent accidental termination, which is a great improvement for the user experience. The implementation is logical and the accompanying tests correctly verify the new timing behavior. I have one suggestion to enhance the robustness of the timing logic by using a monotonic clock, which will make the feature more resilient to system time changes.

[gemini-code-assist]

Date.now() is not guaranteed to be monotonic, meaning it can go backwards or jump if the system clock is adjusted. This could lead to unpredictable behavior in the double-press logic, such as preventing an exit even with a correct delay or causing an exit unexpectedly. For time interval measurements, it's safer to use a monotonic clock like performance.now() from Node's perf_hooks module. This ensures that time measurements always move forward, making the exit logic more robust.

You will need to add import { performance } from 'node:perf_hooks'; at the top of the file.

Suggested change

	const now = Date.now();
	const now = performance.now();