Real-Time Collaboration Feature Spec Template

Operational Transform (OT) transforms operations against each other in sequence to maintain consistency. It requires a central server to order operations. CRDTs (Conflict-free Replicated Data Types) are data structures that merge automatically without coordination. OT is proven at scale (Google Docs uses it) but harder to implement. CRDTs are simpler to reason about and work better for offline-first apps, but can produce surprising merge results for complex data structures. For most SaaS products, using a library like Yjs (CRDT) or ShareDB (OT) is faster than building from scratch.

Start with a practical limit based on your use case. Document editors typically cap at 20-50 concurrent users. Whiteboards and dashboards may need 10-25. Set a hard limit, communicate it in the UI ("5 of 15 spots taken"), and increase it later based on demand. Supporting 100+ concurrent editors requires significant infrastructure investment that most products do not need on day one.

Probably not. Offline collaboration requires a CRDT-based architecture, local-first storage, and a reliable sync engine. These are significant engineering investments. For V1, show a clear "You're offline" state and queue edits for replay on reconnection. Add true offline editing in a later phase once the online collaboration is stable.

When a user's access is downgraded (e.g., from Editor to Viewer) during an active session, immediately disable editing controls and show a notification. Any unsaved edits should be preserved locally and surfaced as "Your unsaved changes" that the user can copy. Do not silently discard in-progress work.

Track three tiers. Adoption: what percentage of sessions involve 2+ active users. Engagement: average session duration and edits per user in collaborative sessions. Quality: sync error rate, "lost edit" support tickets, and P99 edit propagation latency. The adoption metric is the leading indicator. If users are not collaborating, the feature is not solving the right problem. ---