⚡ Incremental Diffing Sync Engine: Implemented tree reconciliation (reconcileBookmarkSubtree) in bookmark_sync.js. Reuses existing folder IDs and bookmark nodes to eliminate sync churn and prevent duplicate root folders across Chrome Sync and Firefox Sync devices.
📂 Customizable Sync Target Location: Added a preference in Options (options.html) allowing users to choose where the FMHY directory is synced:
Bookmarks Bar: Mounts FMHY at position 0 directly on the main Bookmarks Bar.
Other Bookmarks / All Bookmarks: Places FMHY inside Other Bookmarks (populates Chrome "All Bookmarks" side panel).
Bookmarks Menu: Firefox-exclusive container that hides FMHY from toolbar/other bookmarks and keeps it in the Bookmark Manager / Library.

🔔 Dynamic Desktop Notification Target Labels: Updated service_worker.js to dynamically format notification location names (e.g., "Updated 26609 bookmarks in Other Bookmarks") matching the user's configured sync location.
⏳ Options Re-location Progress Feedback: Added live progress status ("Moving FMHY folder to destination...") and explicit await synchronization in options.js to disable controls until background folder re-location completes.

🚀 Parallel Subtree Reconciliation & Batch Processing: Concurrently processes subfolder trees per level and increased link creation batch sizes from 25 to 100 promises for faster initial setup and <1s routine re-syncs.