/v1/chat/completions and /v1/responses, Anthropic shape on /v1/messages.
OpenAI shape
Anthropic shape
Anthropic streaming error frame
When a stream fails mid-flight, the server emits anevent: error SSE frame:
Status codes
Policy-blocked requests
On/policy/* endpoints, a policy decision rides alongside the normal response. When enforcement_action: block fires in enforced mode, the status is 4xx and the body includes the upstream-shape error plus a policy object describing the decision. When the action is rewrite or summarize (decision rewrite / summary), the status stays 200 but the content is modified. See policy endpoints and streaming policy metadata.