AI SDK UI Message Stream chat (streaming-only)
Vercel AI SDK–native chat endpoint, parallel to `/v1/chat/completions`. Accepts a `UIMessage[]` body and streams the AI SDK **UI Message Stream** protocol (typed `data: {"type":…}` chunks under `x-vercel-ai-ui-message-stream: v1`, terminated by `data: [DONE]`). Point `useChat` / `DefaultChatTransport` at it. Streaming-only: `stream: false` returns 400. Top-level fields (`model`, `reasoning_effort`, `tools`, `tool_choice`, `stop`, `temperature`, `top_p`, `max_tokens`, `stream_options`) are identical to `/v1/chat/completions`; only `messages` takes the AI SDK shape. **Client-side tools only** in v1 — the gateway emits `tool-input-*` (the model's call); clients execute tools and replay results as `tool-<name>` parts with `state: "output-available"`. Reasoning replays via `reasoning` parts; `providerMetadata` round-trips the replay payload. See `docs/llm-gateway/AISDK.md` for the chunk union and multi-turn replay contract.
/v1/chatVercel AI SDK–native chat endpoint, parallel to /v1/chat/completions. Accepts a UIMessage[] body and streams the AI SDK UI Message Stream protocol (typed data: {"type":…} chunks under x-vercel-ai-ui-message-stream: v1, terminated by data: [DONE]). Point useChat / DefaultChatTransport at it.
Streaming-only: stream: false returns 400. Top-level fields (model, reasoning_effort, tools, tool_choice, stop, temperature, top_p, max_tokens, stream_options) are identical to /v1/chat/completions; only messages takes the AI SDK shape.
Client-side tools only in v1 — the gateway emits tool-input-* (the model's call); clients execute tools and replay results as tool-<name> parts with state: "output-available". Reasoning replays via reasoning parts; providerMetadata round-trips the replay payload. See docs/llm-gateway/AISDK.md for the chunk union and multi-turn replay contract.
Authorization
bearerAuth In: header
Request Body
application/json
TypeScript Definitions
Use the request body type in TypeScript.
Request body for POST /v1/chat.
Top-level fields mirror ChatRequest (and translate identically); only
messages takes the AI SDK UIMessage[] shape instead of OpenAI messages.
Response Body
text/event-stream
application/json
application/json
application/json
curl -X POST "https://example.com/v1/chat" \ -H "Content-Type: application/json" \ -d '{ "messages": [ { "role": "user" } ], "model": "claude-opus-4-7" }'{ "messageId": "string", "type": "start"}{ "error": { "message": "model not supported: foo", "type": "invalid_request_error" }}{ "error": { "message": "model not supported: foo", "type": "invalid_request_error" }}{ "error": { "message": "model not supported: foo", "type": "invalid_request_error" }}Chat completions (streaming + non-streaming, with reasoning) POST
OpenAI-compatible chat completions over an upstream provider chosen by `model`. Set `"stream": true` for SSE; otherwise the response is a single JSON body. ### Reasoning Opt into model thinking with top-level `reasoning_effort` (`minimal | low | medium | high | xhigh | max`). Allowed values are per-model — query `/v1/models` for `reasoning_levels`. Reasoning is **streaming-only**: non-streaming responses drop it entirely. Streaming reasoning surfaces two channels per `delta`: - `reasoning_content` — display text for live UI (DeepSeek-style extension; concatenate across chunks like `content`). - `reasoning_meta` — structured snapshot at block close, carrying the `signature` (Anthropic) or `encrypted_content` (OpenAI) clients need to replay reasoning on subsequent turns. ### Multi-turn replay Persist `reasoning_meta` between turns and send it back as a `{"type": "reasoning", ...}` block on the assistant message — before text and tool calls (Anthropic enforces this order). Required on Anthropic for tool-using turns (the API 400s without the matching thinking block); recommended on OpenAI so the model doesn't re-derive its plan and re-bill reasoning tokens. OpenAI's Responses API requires `id` on every replayed reasoning block — the gateway 400s pre-flight if missing. Anthropic ignores `id` (signatures live per-block instead). Signatures and encrypted blobs are **model-bound**: persist `model` alongside the reasoning meta and refuse to replay across models. See `docs/llm-gateway/REASONING.md` for the full contract, JSONL persistence shape, and end-to-end curl examples.
List_models GET
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