> ## Documentation Index > Fetch the complete documentation index at: https://docs.plungeai.com/llms.txt > Use this file to discover all available pages before exploring further. # Create chat completion > Chat completion on the OpenRouter-compatible /api/v1 base. The same engine as POST /v1/chat/completions, with OpenRouter’s error envelope. ## OpenAPI ```yaml openapi.json post /api/v1/chat/completions openapi: 3.1.0 info: title: Ocean One API version: 2.3.1 servers: - url: https://api.plungeai.com paths: /api/v1/chat/completions: post: operationId: post-api-v1-chat-completions tags: - Compat summary: "Chat completion (proxied to inference-gateway). Phase 2: models[]/sort ordered fallback with retry + 30s outage exclusion, @preset/, guardrails, opt-in response cache." security: - ozkBearer: [] - skOcean: [] requestBody: required: true content: application/json: schema: $ref: "#/components/schemas/ChatCompletionRequest" responses: "200": description: Completion (model = the slug that actually served it, not necessarily the one requested). stream:true returns text/event-stream instead — see the developer guide for the streaming caveat. headers: x-cache: description: '"miss" or "hit" — present only when the org has response caching enabled and the request was cache-eligible (temperature:0, stream not true); absent otherwise.' schema: type: string enum: - miss - hit content: application/json: schema: $ref: "#/components/schemas/ChatCompletionResponse" text/event-stream: schema: type: string "400": description: invalid_json — body is not valid JSON; invalid_request_error — the gateway rejected the request (a missing or malformed field) content: application/json: schema: $ref: "#/components/schemas/CompatError" "401": description: Missing or invalid API key content: application/json: schema: $ref: "#/components/schemas/CompatError" "402": description: byok_required — this provider needs your own connected key on this plan content: application/json: schema: $ref: "#/components/schemas/CompatError" "403": description: model_not_allowed (routing candidates excluded by an allow-list) or content_blocked (prompt matched a guardrail regex) content: application/json: schema: $ref: "#/components/schemas/CompatError" "404": description: preset_not_found — @preset/ does not exist or is inactive; model_not_found — no such model in the catalog content: application/json: schema: $ref: "#/components/schemas/CompatError" "405": description: "method_not_allowed — the path serves one method: the Allow header names it, plus OPTIONS" content: application/json: schema: $ref: "#/components/schemas/CompatError" headers: Allow: description: The method this path serves, plus OPTIONS schema: type: string "429": description: rate_limit_exceeded (per-key/per-provider) or spend_cap_exceeded (guardrail cap reached) content: application/json: schema: $ref: "#/components/schemas/CompatError" components: schemas: ChatCompletionRequest: type: object description: Money plane, ozk_ auth. Transparent proxy to inference-gateway — any OpenAI-compatible field is passed through untouched; the fields below are the ones Phase 2 routing adds on top. properties: model: type: string example: openai/gpt-4o-mini description: A single model slug ("provider/model", e.g. "anthropic/claude-sonnet-5"), or "@preset/" to expand a stored model+routing+params bundle (request-explicit fields below still override the preset). Required unless models[] is set, which replaces it. models: type: array items: type: string description: Ordered fallback candidates — alternative to model. One retry per candidate on 429/5xx/network, then failover to the next; a candidate whose provider just failed out is excluded for 30s. sort: type: string enum: - price - latency - throughput description: Reorders models[] before the first attempt. latency/throughput sort by rolling provider stats; a provider with no history yet sorts last. messages: type: array items: $ref: "#/components/schemas/ChatMessage" stream: type: boolean default: false temperature: type: number description: Set to exactly 0 to make the request response-cache eligible. max_tokens: type: integer example: 16 top_p: type: number required: - model - messages additionalProperties: true ChatCompletionResponse: type: object description: model is the slug that ACTUALLY served the request (honest billing) — it may differ from the requested model/first models[] entry after a failover. properties: id: type: string object: type: string model: type: string description: The model that served this response — bill and log both key on this value. choices: type: array items: type: object usage: type: object properties: prompt_tokens: type: integer completion_tokens: type: integer total_tokens: type: integer required: - id - object - model - choices ChatMessage: type: object properties: role: type: string enum: - system - user - assistant - tool example: user content: type: string example: Say hi in three words required: - role - content CompatError: type: object description: "OpenRouter's error envelope, worn by every /api/v1 error (guide 5.0, 5.7): a numeric `code` equal to the HTTP status, the Ocean detail in `metadata`. No X-Error-Code header." properties: error: type: object properties: code: type: integer description: The HTTP status message: type: string metadata: type: object properties: error_type: type: string description: "OpenRouter's error type: authentication, payment_required, rate_limit_exceeded, not_found, invalid_request, …" ocean_code: type: string description: The /v1 envelope's string error.code ocean_type: type: string request_id: type: string description: Equals the x-request-id header required: - error_type - ocean_code - request_id additionalProperties: true required: - code - message - metadata additionalProperties: true required: - error securitySchemes: ozkBearer: type: http scheme: bearer description: "ozk_ platform API key (Authorization: Bearer ozk_…)" skOcean: type: http scheme: bearer description: "Legacy sk-ocean- inference key: still accepted on the money plane until the sk-ocean- sunset; new integrations use the ozk_ key" ```