One person can open two tabs, lose connectivity in one, and edit the same case from a second device. Local messages help tabs react quickly, but they do not establish durable order or authorization. This track uses scoped invalidation, a bounded offline outbox, snapshot-and-delta recovery, and explicit conflict decisions. Each operation carries a stable identity and a server-checked version. The UI distinguishes queued work, accepted writes, conflicts, and data that still needs a fresh read.
Topics in this track
- Cross-Tab Invalidation and Version Checks — Use same-origin tab messages to prompt a server read rather than as a durable source of truth.
- Offline Outbox, Idempotency, and Replay — Queue bounded mutations with stable keys and explicit accepted, conflicted, and rejected outcomes.
- Snapshot, Delta Cursor, and Gap Recovery — Combine a consistent snapshot with ordered changes and restart when a replay window is lost.
- Collaborative Conflicts and Presence Expiry — Separate editing presence from durable ownership and resolve concurrent changes at field scope.
Prerequisite paths
Offline Sync and Conflict Policy; Live Update Reconnect and Event Ordering; Conditional Writes and Lost-Update Prevention.
Neighbor track
Production Signals and Incident Decisions.
Practice path
Build Project: multi-tab offline case review and check decisions in Web Development: operations and sync decisions quiz.