AI API Latency Metrics: TTFT, First Response, and Output Speed
Separate upstream headers, first SSE event, first effective response, first visible text, total latency, and output speed when diagnosing AI APIs.

Separate upstream headers, first SSE event, first effective response, first visible text, total latency, and output speed when diagnosing AI APIs.

Decide when to retry, use a same-contract fallback, stop, or investigate based on status, timeout phase, streaming state, and idempotency.

Compare tool definitions, call identifiers, result messages, streaming events, and migration risks across Responses and Chat Completions.
