Collaboration Model

ProCad.Collaboration shares CAD operation batches rather than opaque screen state.

Session Data

Collaboration contracts include:

operation kind, actor, session, Lamport/version metadata, and payload
presence state
selection, cursor, viewport, and tool-preview messages
conflict and reapply results
snapshot and oplog records

Transport Layer

The collaboration layer depends on transport abstractions. The repository includes ProEdit transport adapters and a server host for WebSocket-style sessions.

Snapshot Stores

Snapshot stores support:

in-memory sessions for tests and transient use
file-backed persistence for desktop
browser persistence for WebAssembly
legacy location migration
corrupt payload recovery
oplog compaction

Conflict Policy

Remote operation batches are versioned. Stale windows can be registered as conflicts, then reapplied or cleared when the local state catches up. The goal is deterministic recovery with clear diagnostics rather than silent state divergence.