Realtime collab (CRDT) design

Core idea

Use a sequence CRDT (RGA or YATA) where each character carries a unique Lamport timestamp + site ID. Inserts reference left/right neighbours. Deletes are tombstones. Merges are commutative — no central server needed for correctness.

Data model

• Atom — { id: [clock, siteId], value: char, tombstone: bool }
• Doc — ordered list of atoms, causal graph for partial ordering
• Version vector — per-site clock for anti-entropy sync

Sync protocol

Peers exchange version vectors on connect. Missing atoms are pulled via a range query over the causal graph. WebSocket transport with msgpack binary encoding keeps overhead under 2 ms per op. Tombstone GC runs every 500 edits with a 30-second retention window.

Conflict resolution

Concurrent inserts at the same position are ordered by site ID (deterministic tiebreak). No OT transform needed. The CRDT guarantees strong eventual consistency — all peers converge to identical document state without a coordinator.