StreamSubmitOptions

Fork the run from an explicit checkpoint instead of the thread's latest. Ergonomic alias the SDK folds into config.configurable.checkpoint_id before dispatching the run, so the server receives the fork target via the single legacy-compliant field (never a top-level forkFrom).

Behaviour when a run is already in-flight on the thread.

• "interrupt" (default) — cancel the active run on the server, keeping the steps it completed, and start the new one.
• "rollback" — like "interrupt", but the server also deletes the active run and its checkpoints, as if it never ran.
• "enqueue" — do NOT abort the active run; the new submission lands in StreamController.queueStore and is forwarded once the current run terminates.
• "reject" — error out client-side when a run is already in flight.

When the thread shows no run in flight, only a strategy passed here is sent, so by default the server queues the new run behind a run this client has not seen.

Per-submit error callback. Invoked when the run errors out — either before the first event lands (network/dispatch failure) or mid-stream. Does NOT suppress the error from being written to RootSnapshot.error; the callback is a local hook for showing toasts or routing the submission error to a component state slot, letting the rest of the UI keep using stream.error for render-level error display.

Per-submit thread-id override. When provided, the controller rebinds to this thread before dispatching the run; subsequent submits stick with the new id unless the hook's threadId prop changes. Useful when you want to start a new thread without unmounting the component (e.g. "New Chat" buttons).