Undo stack is cleared unexpectedly on focus changes

Phenomenon

When the contenteditable element loses and regains focus, the undo stack may be cleared unexpectedly. Users cannot undo operations that were performed before the focus change.

Reproduction example

1. Make several edits in contenteditable
2. Click outside to blur the element
3. Click back to focus the element
4. Press Ctrl+Z to undo

Observed behavior

• Undo stack is cleared
• Previous operations cannot be undone
• Undo history is lost
• User loses ability to undo

Expected behavior

• Undo stack should be preserved across focus changes
• Or behavior should be predictable
• Users should be able to undo previous operations
• History should be maintained

Browser Comparison

• Chrome/Edge: Stack may be cleared (this case)
• Firefox: Similar stack clearing behavior
• Safari: Stack clearing most unpredictable

Notes and possible direction for workarounds

• Implement custom undo/redo that persists across focus
• Save undo stack in memory
• Restore stack when element regains focus
• Document undo stack behavior for users