The mock handler now appends -2, -3, etc. when the target path already exists, matching the Rust unique_dest_path logic. Previously it would silently overwrite the existing note's content in MOCK_CONTENT. Also adds a Rust test that verifies both the moved note and the pre-existing note retain their respective content after a collision. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>