fix: resolve lost updates in multi-user collaboration sync

Concurrent edits to shared notes (e.g., one user checks a shopping list
item while another adds an item) were lost because the sync system used
whole-document Last-Write-Wins. This replaces it with a 3-way line-level
content merge using node-diff3, so changes to different lines are
preserved from both users.

Key changes:
- Add node-diff3 for 3-way line-level content merging
- Remove the timestamp gate in processSyncPush that rejected entire
  offline sync pushes when another user had updated the note
- Add content merge to both the sync push path and the PATCH endpoint,
  using version snapshots as the merge base
- Send baseVersion from the client so the server can find the correct
  common ancestor for 3-way merge
- Protect pending local fields during client pull merge by reading
  the sync queue and preserving queued-but-unpushed changes
- Add comprehensive tests for content merge, server sync, and CRDT merge

https://claude.ai/code/session_01FNpVBBjM6vKzfR8y9NM9Ci

This commit is contained in:

Claude

2026-03-12 20:19:10 +01:00

committed by

Fred Cabassut

parent 3e7f5188d1

commit 9ed5c52fb6

13 changed files with 520 additions and 72 deletions

									
										package.json
									
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				@@ -54,6 +54,7 @@

				    "idb": "^8.0.3",

				    "lucide-svelte": "^0.577.0",

				    "markdown-it": "^14.1.1",

				    "node-diff3": "^3.2.0",

				    "nodemailer": "^8.0.2",

				    "svelte-dnd-action": "^0.9.69",

				    "tiptap-markdown": "^0.9.0",