ChatErrorCode

Sursa error codes:
- sources_inaccessible: a source card is not available to the user, so the whole answer is hidden.
- canceled: the answer was stopped with POST /v1/questions/{id}/cancel.
- server_restart: a Sursa or assistant instance stopped for an update, and the stream closed normally before the answer was complete. The event carries retry: true, the answer is marked as canceled and is not generated again, so you can send the same request again unchanged.
- out_of_scope: the answer relies only on documents from collections the user can read but that are outside the selected one, and the answer cannot be requested again without them (text has already been sent, or tools were used). The answer is hidden, and details.collections says where the answer exists (the interface offers to switch the collection).
- external_ai_disabled: the organization has turned off external AI providers (the external_ai feature flag), and this answer cannot be produced without them. Contact your admin.

A client that does not know a code handles it like any other stream error.