fix: stale closure causing wrong cell to flash on edit mode entry

- Add position to useEffect dependency array in useCursor
- Fixes issue where old position was captured in handleKeyDown closure
- Edit mode entry now correctly validates current cell position

IMPLEMENTATION.md

@@ -877,6 +877,19 @@ User sees '5' in the cell
 
 **Result**: ✅ Golden glow persists when typing digits in edit mode
 
+### Issue 2: Wrong Cell Flashing Red on Edit Mode Entry
+
+**Problem**: After attempting to enter edit mode on a given cell (red flash), moving to an empty cell and pressing `i` would flash the *previous* given cell red instead of entering edit mode on the current cell.
+
+**Root Cause**: Stale closure in `useEffect`. The `handleKeyDown` function captured `position` from when the effect was created. The dependency array was `[gameStatus, mode]` but didn't include `position`. When position changed, the event handler wasn't recreated, so it still used the old position coordinates.
+
+**Solution**: Add `position` to the `useEffect` dependency array.
+
+**Changes**:
+- `useCursor.ts`: Changed dependency array from `[gameStatus, mode]` to `[gameStatus, mode, position]`
+
+**Result**: ✅ Edit mode entry now correctly checks and flashes the current cell position
+
 ### Next Steps
 - Phase 40.3.4: Add erase functionality (x, Backspace, Delete)
 - Phase 40.3.5: Add replace mode (r)

src/useCursor/useCursor.ts

@@ -165,7 +165,7 @@ export function useCursor(gameStatusManager: GameStatusManager, containerRef: Re
 
     window.addEventListener('keydown', handleKeyDown);
     return () => window.removeEventListener('keydown', handleKeyDown);
-  }, [gameStatus, mode]);
+  }, [gameStatus, mode, position]);
 
   const cursor: CursorManager = {
     position: () => position,