fix: tab and esc are properly reserved

[jpoly1219]

Description

Closes CON-3594.

Properly handle reservation and freeing of tab and esc. More user tests on different machines is needed once it's merged.

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• I've read the contributing guide
• The relevant docs, if any, have been updated or created
• The relevant tests, if any, have been updated or created

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Summary by cubic

Ensure Tab and Esc are correctly reserved and released for the Next Edit window to prevent conflicts and stuck keys across editors. Addresses CON-3594 by serializing key reservation and adding robust error handling and cleanup.

• Bug Fixes
  • Added internal state machine (free/reserved/transitioning) with promise gating to prevent race conditions.
  • Wrapped setContext in setKeyReservation; no-ops when already in desired state and waits for in-flight transitions.
  • On reserve failure, hides Next Edit windows; on hide/dispose, always frees keys with error logging.

[github-actions]

This PR adds state management for key reservation (Tab/Esc) in the NextEditWindowManager to prevent race conditions and ensure proper cleanup. The implementation uses a state machine approach with proper error handling and async coordination. Overall the changes are well-structured, but there's a typo in the equality check and some cleanup needed for commented code.

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[github-actions]

Code Review Summary

✅ Strengths

• State Management: Excellent introduction of proper state management for key reservation with states (free, reserved, transitioning) that prevent race conditions
• Error Handling: Comprehensive error handling added throughout the async operations with proper logging
• Async Safety: Implementation correctly handles inflight transitions and prevents concurrent operations
• Code Structure: Clean separation of concerns with setKeyReservation and performKeyReservation methods
• Defensive Programming: Multiple safety checks including early returns for redundant operations and proper cleanup in error cases

⚠️ Issues Found

Medium

• Dead Code: The commented-out code in reserveTabAndEsc() and freeTabAndEsc() methods should be removed rather than left as comments. This creates confusion about which implementation is active.

• Error Recovery: When key reservation fails in showNextEditWindow(), the method returns early but doesn't provide any user feedback. Consider adding a notification or status bar message to inform the user that the feature is temporarily unavailable.

• Dispose Method Inconsistency: The dispose() method uses a fire-and-forget pattern for freeing keys, which could lead to silent failures. While error handling is present, the approach differs from the more robust error handling used elsewhere.

Low

• Typo in Comparison: Line 181 uses == instead of === for the equality check. While functionally equivalent for strings, it's inconsistent with the strict equality used elsewhere in the code.

• Console Logging: The code uses console.error for error logging. Consider using VS Code's output channel or a proper logging service for better error tracking and debugging.

💡 Suggestions

• Testing: Add unit tests for the new state management logic, particularly for concurrent operation scenarios and error cases
• Documentation: Add JSDoc comments for the new private methods explaining their purpose and the state machine logic
• Timeout Configuration: Consider making the key reservation operation timeout configurable for better control in slow environments
• Telemetry: Consider adding telemetry for key reservation failures to track how often users encounter this issue

🚀 Overall Assessment

APPROVE

This is a well-implemented solution to prevent race conditions in key reservation. The state machine approach is robust and handles edge cases properly. The code maintains backward compatibility while significantly improving reliability. The minor issues identified don't impact functionality and can be addressed in follow-up PRs.

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