Excalidraw sync drops legitimate updates due to fragile checksum heuristic
Nobody has claimed this yet.
Assessment
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Newbie friendliness
- 48/100
- Issue type
- Bug
- Clarity
- Mostly clear
- Activity status
- Stale
- Tech stack
- typescript
- Domain
- distributed-systems, frontend
Research direction
Start with examples/excalidraw-example/src/hooks/useLoroSync.ts at lines 210-218 and inspect how the checksum guard decides whether to return early. Exercise scene changes such as reordered elements, app-state changes, and attribute tweaks, then remove the false-negative path or replace it with the stated ID/version and app-state comparison. Done means legitimate updates reach the CRDT while identical imports remain safely deduplicated.
Written by the indexing model from the issue text.
Description
examples/excalidraw-example/src/hooks/useLoroSync.ts:210-218
- The hook sums element version fields and treats equal sums as “no change,” returning early. Any scene
change that keeps the sum constant (e.g. swapping shapes with same version, many app-state changes, or
attribute tweaks that don’t bump version) gets skipped and never written into the CRDT. - Collaborators then miss color/theme toggles or reordered elements, even though CRDT state actually
changed. - Fix: Remove the checksum guard or replace it with a real diff keyed by element ID + version/app-state
hash. Let Loro’s own dedup handle identical imports instead of this false-negative-prone shortcut.
- Dominant language
- TypeScript
- Stars
- 38
- Forks
- 11
- PR merge metrics
- No merged PRs in 30d
Getting set up
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First steps
- Read the whole issue, then the project's contributing guide.
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- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
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