fix: clear pending edit operations when Start New Task is clicked (#7949)

[roomote]

Description

This PR fixes an issue where clicking "Start New Task" after completing a resumed task would reopen the previous task at the earlier cancel point instead of starting a fresh session.

Problem

When a user:

1. Creates a task with high reasoning
2. Cancels while reasoning is streaming
3. Resumes the task and completes it
4. Clicks "Start New Task" from the completion state

The UI would bring back the just-completed task and jump to where it was originally canceled, causing an inconsistent task history.

Solution

The fix ensures that pending edit operations are properly cleared when:

• The clearTask() method is called (when "Start New Task" is clicked)
• A new task is created with createTaskWithHistoryItem()

This prevents stale pending operations from being processed and causing the UI to jump back to previous states.

Changes

• Modified clearTask() in ClineProvider.ts to clear pending edit operations before removing the task
• Added safeguard in createTaskWithHistoryItem() to clear stale pending operations
• Added validation to only process pending edits for tasks being resumed, not cleared/replaced
• Added comprehensive test coverage in ClineProvider.clearTask.spec.ts

Testing

• ✅ All existing tests pass
• ✅ New test suite added with 4 test cases covering the fix
• ✅ Manual testing confirms the issue is resolved

Related Issue

Fixes #7949

---

Important

Fixes issue #7949 by clearing pending edit operations when starting a new task in ClineProvider.ts.

• Behavior:
  • Fixes issue where clicking "Start New Task" reopened the previous task at the cancel point instead of starting fresh.
  • Clears pending edit operations in clearTask() and createTaskWithHistoryItem() in ClineProvider.ts.
• Functions:
  • Modifies clearTask() to clear pending operations before removing the task.
  • Adds safeguard in createTaskWithHistoryItem() to clear stale pending operations.
• Testing:
  • Adds ClineProvider.clearTask.spec.ts with tests for clearing pending operations, handling no active tasks, and task removal failures.

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[roomote]

Reviewing my own code is like debugging in a mirror - everything looks backwards but the bugs are still mine.

Review Summary

This PR effectively fixes issue #7949 where "Start New Task" would reopen a completed task at an earlier cancel point. The solution is well-implemented with proper safeguards.

✅ Strengths

• Clear and focused fix that directly addresses the reported issue
• Comprehensive test coverage with 4 test cases covering edge cases
• Good defensive programming with multiple safeguards
• Proper logging for debugging
• Clean implementation that doesn't introduce unnecessary complexity

💭 Minor Suggestions for Future Improvements

1. Extract operation ID pattern: The task-${taskId} pattern appears in multiple places. Consider creating a helper method like getTaskOperationId(taskId) for consistency.

2. Additional validation: When checking if a task is still active (line ~917), we could also verify the task exists in this.clineStack for extra safety.

3. Test timeout behavior: The 30-second timeout for pending operations could benefit from a test case using vi.useFakeTimers() to verify automatic cleanup.

4. Document lifecycle: A comment block explaining the pending operations lifecycle (creation, processing, clearing) would help future maintainers.

Overall, this is a solid fix that addresses the issue effectively. The code is clean, well-tested, and ready to merge.

[daniel-lxs]

I’m not sure this is the root cause. It looks like when the model streams reasoning, the task ends up in an invalid state, which then causes issues like the one shown in the screenshot. It might be better to identify what state the task is entering during reasoning and fix that directly.

Closing for now.