[gateway]

Summary

A delayed History Restore could replace the active canvas and persisted draft after switching tabs or editing while it loaded. Keep completion owned by the initiating tab, workspace version and workflow snapshot using existing state.

 restore historical run
   load run detail
+  ignore completion if its workspace changed
   hydrate historical canvas and run

Evidence

• Before: production-built base in Codex Browser: hold a real HTTP200 historical detail response, switch to an unsaved note draft, release unchanged; the draft's canvas and stored snapshot are overwritten. Seven new regression cases fail on base.
  After: built candidate0d2b2ad in the same installation passes the identical delayed-response trigger; active draft and all persisted snapshots remain intact. Same-tab intervening edit stays intact, normal Restore applies the historical nodes/edge/text/run, and undo works. Real response bodies never mocked. Graph is desktop-only; phone guard unchanged.
• All24 focused restore cases, safe full1,427 web tests, types, full lint/static analysis, file-size and production build pass. No baseline changes. Routine independent Standards/Spec and additional fresh Standards/Spec all pass with zero findings at exact head0d2b2ad.
• All11 exact-head PR checks pass, including1,062 backend/1,427 web tests, production build and hosted Studio browser smoke. Original browser storage,14 protected/config tables, environment/safeguards and unrelated work verified preserved. No local pytest/collection, Save/Run/Assistant, generation or saved-record writes.

Merge Danger

Door: two-way

Frontend guard and tests are reversible; no schema, dependency or API contract changes.

Blast Radius: Graph

Only History Restore completion ownership and existing error feedback.