When a steering prompt is refused by the enhancer (e.g. content-policy) or enhancement
fails for all providers, the backend enqueues nothing and won't re-emit prompt_sources_
blocked, leaving the UI stuck on the generating overlay. On prompt/fallback_used and
session/error in steering, return to the 'describe the next scene' state, drop the failed
scene from the history (steeringFailed), and surface a retry notice; clear the notice on
the next submit.
alexzms
b6eafbea50