What
A new system event is now emitted when the model ends a turn with stop reason "refusal" and no fallback model is configured, allowing SDK consumers to handle refusals programmatically.
Details
- Event fields:
type: "system",subtype: "model_refusal_no_fallback",original_model,request_id,api_refusal_category,api_refusal_explanation,content,uuid,session_id. - A new
refused_user_message_uuidfield (added to bothmodel_refusal_fallbackandmodel_refusal_no_fallback) contains the UUID of the human turn that triggered the refusal — the rewind target and composer prefill for edit-and-retry. refused_user_message_uuidisnullwhen the refused turn was not human-authored (e.g., a background task notification or auto-continuation).- Not emitted when a fallback model existed but was declined or gate-failed (that case uses the existing
model_refusal_fallbackevent).
Evidence
New event schema (search for "model_refusal_no_fallback" or "UUID of the user message the refused request was for")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.