Accept service_tier=ultrafast on the OpenAI/Codex gateway, advertise it
on GPT-5.6 Sol in the Codex model catalog, and include it in ChatGPT
OAuth routing hints so Codex clients can select Ultrafast.
- openai_ws_forwarder_ingress: resolve billing tier from the local
upstreamResponseModelObserver (upstream echo first) instead of the raw
request payload, matching the HTTP->WS bridge and WS v2 forwarder.
- openai_ws_http_bridge_test: add fast-alias + upstream default case
proving the local observer's echoed tier wins.
- handler tests: keep only invalid service_tier -> 400 (short-circuits at
validation); valid/omitted semantics covered by the pure service-level
validation tests, avoiding real account selection in tests.
- Accept fast|priority (canonical priority), flex|auto|default|scale on
/v1/responses and /v1/chat/completions; reject unknown/empty/non-string
with HTTP 400; omitted and null stay compatible.
- Propagate service_tier through JSON/SSE, Responses<->Chat conversions,
fallback paths and HTTP->upstream WebSocket bridge.
- Billing prefers the upstream terminal tier; the outbound (policy-
transformed) tier is used only when upstream omits the field.
Explicit upstream default bills Standard even when Fast was requested.
- Pricing: Fast premium 2x Standard for gpt-5.6-sol/terra/luna and
gpt-5.4; 2.5x for gpt-5.5; channel FastMultiplier stays authoritative.
- Live verification (official Codex 0.149.0 + gateway, HTTP & WS):
upstream ChatGPT backend may return terminal default even when the
account catalog advertises priority; billing follows the actual tier.
刘佳林