All editors now work on a server document at the same time instead of
taking turns behind an edit lock.
- The document's content is a sequence of Yjs updates (document_updates);
DocumentChannel stores and relays them immediately, checks access on
subscribe and again whenever links or memberships change.
- app/frontend/collab/: the store stays position-based; a binding maps it
to a Yjs form with stable row/column ids, so a row inserted by one
person doesn't misplace what another is typing. Remote changes are
applied only after pending local ones went into Yjs.
- Per-person undo (Y.UndoManager), presence via awareness: the others'
selections as coloured boxes with names, avatars in the toolbar.
- Existing JSON documents convert on first open, deterministically, so
two people opening one at once end up with the same Yjs state.
- Editors compact the stored updates after 200 and keep a JSON snapshot
current for export and duplicating. Edit lock and polling are gone.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
wkhandClaude Opus 5.5
7fce972fdc