You'll noticeTier: how much it should matter to you
2Useful: my rating, 1 to 5
0Signal: worth watching, 1 to 5
ElsewhereArea: what it touches
ImprovementsKind: in v2.1.219,
ImprovementsSection of the release
What
The documented model gate for mid-session system messages now covers more models, and two incorrect references were corrected.
Details
The gate list adds the previous Opus alongside the new one, Sonnet, Fable and Mythos; the rejection error name is unchanged.
The polling troubleshooting note now names GET /v1/sessions/{id}/events/stream as the endpoint you may have hit by mistake, where it previously named the paginated endpoint twice.
The overview's SDK advice corrects session.events.list() to sessions.events.list().
Evidence
model_does_not_support_mid_conversation_system
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
