- Rejected malformed atom diff lines (orphan '-' and unrecognized ops) with parse errors.
- Tracked mutating set/delete anchors during validation and errored when multiple stale anchors required auto-rebase.
- Added duplicate-line auto-fix in applyAtomEdits when bracket balance restores, emitting Auto-fixed warnings.
- Updated atom prompts/changelog and expanded tests for unknown ops, auto-rebase, and duplicate-line handling.