ThothII workflow UI contracts

Pi reasoning arrives as nested message_update.assistantMessageEvent.type = thinking_delta. The backend maps it to the named SSE event activity_delta; the frontend EventSource must explicitly subscribe to that name. Model activity is separate from final text_delta output.
Session create/resume must preserve the configured or persisted thinking level. Forcing thinking: off disables the upstream signal and makes the activity panel legitimately empty.
A join-only reviewer_decide proposal is one complete, atomic join set. The read-only join-review widget persists every proposed join on Continue; Other — specify persists none and requires the model to propose the complete corrected set again. Ledger read, sequence assignment, and atomic replacement share a per-session cross-process writer lock.
A v2 phase summary accepts open_questions?: string[]. Validate this at the gate boundary and normalize legacy malformed entries defensively in the viewer so one object cannot crash React.
SqlViewer's horizontal/vertical layout control is meaningful only with multiple SQL blocks; hide it for the single CTE result shown by CteResultViewer.
Deployment lifecycle details live in datamart-builder-deployment-gotchas: a rebuilt image does not update a running Compose service until the containers are recreated.