Interactive Sync Conflict Resolution for Joplin Desktop and Mobile

Joplin's offline-first design is one of its best features, but it comes with a real cost when the same note is edited on two devices before either syncs, Joplin has no way to merge the changes. It saves one version as a conflict note and leaves the user to manually figure out what to keep. For long notes on mobile, most people just give up and pick whichever version looks more complete, which means changes get silently lost. This project adds an interactive conflict resolution UI to Joplin desktop and mobile. When a conflict note is opened, instead of seeing a raw copy with no context, the user gets a clear section-by-section view of exactly what each side changed. Non-conflicting changes like additions and deletions can be resolved in one click. Genuine conflicts where both sides changed the same part give the user full context to pick one side or edit manually. A Keep both option preserves both versions for users who want that. The same shared diff module powers both platforms so the behaviour is always identical. The core deliverables are a platform-independent diff module using node-diff3, a minimal addition to the sync pipeline to store a base snapshot for three-way merging, and a conflict resolution React component for desktop and React Native component for mobile. The implementation also handles edge cases including notes synced before the feature was deployed falling back to two-way diff, stale remote data being detected and reset on open, and second conflicts on the same note being handled gracefully. No existing conflict behaviour changes and sync is never blocked at any point.