-2 <= value <= 2-2 <= value <= 2-1 <= valuevalue <= 1value <= 2falseStable identifier for a sequence of requests that share a long prefix (a chat session, an agent loop). Requests with the same key are routed to the same worker while it stays warm, so the shared prefix is served from its prompt cache. Without it, placement is inferred from the message text.
Processing tier for the request. "flex" selects flex processing (beta) on flex-enabled accounts: discounted tokens in exchange for lower scheduling priority and best-effort completion — the request may queue significantly longer than default-tier requests, so raise your client timeout accordingly. A flex request that cannot complete in time fails with 408 (OpenAI SDKs retry it automatically). All other accepted values (auto, default, scale, priority) are served at the default tier. Responses echo the tier actually served in service_tier.