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Documentation Index

Fetch the complete documentation index at: https://gomodel.enterpilot.io/docs/llms.txt

Use this file to discover all available pages before exploring further.

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Overview

GoModel accepts the Anthropic Messages API request dialect at POST /v1/messages, in addition to its OpenAI-compatible API. Clients and SDKs that speak the Anthropic format can point at GoModel unchanged. The request is translated to GoModel’s canonical chat type at ingress and runs through the same pipeline as /v1/chat/completions — so model aliases, workflow policy, budgets, failover, the response cache, usage/cost tracking, and audit logging all apply. Because every provider implements chat completion, an Anthropic-format request can be routed to any configured provider (OpenAI, Gemini, Bedrock, and others), not only Anthropic. This differs from the passthrough API: /p/anthropic/v1/messages forwards bytes verbatim to the Anthropic upstream only, while the managed /v1/messages endpoint routes anywhere and is fully managed.

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Supported endpoints

EndpointBehavior
POST /v1/messagesCreates a message through translated model routing. Supports streaming (stream: true) with Anthropic-format SSE events.
POST /v1/messages/count_tokensReturns a heuristic input token estimate.

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Example

curl https://your-gateway/v1/messages \
  -H "Authorization: Bearer $GOMODEL_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-4-6",
    "max_tokens": 256,
    "system": "Be concise.",
    "messages": [{"role": "user", "content": "Hello"}]
  }'
The response uses the Anthropic Messages shape (type: "message", content blocks, stop_reason, usage). Errors use the Anthropic error envelope ({"type": "error", "error": {...}}). max_tokens is required, as in the Anthropic API. Streaming responses emit the Anthropic SSE event sequence (message_start, content_block_start/content_block_delta/content_block_stop, message_delta, message_stop).

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Cost tracking and audit logs

/v1/messages requests are tracked and audited exactly like the OpenAI-compatible routes. Cost is computed from the actual provider that served the request, and usage is recorded under the /v1/messages endpoint so it can be filtered in the dashboard.

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Limitations

/v1/messages translates through GoModel’s canonical chat type. Anthropic-specific features that have no canonical equivalent are not preserved end to end:
  • cache_control breakpoints are dropped — prompt-caching cost benefits are not carried through the canonical hop.
  • Extended-thinking signatures and thinking blocks on input messages are dropped.
  • Server/built-in tools (web search, code execution, …) are rejected with a clear 400; only custom tools (type absent or "custom") translate.
  • top_k is dropped — it has no portable OpenAI-compatible equivalent, and OpenAI-family providers reject unknown request fields. temperature and top_p are forwarded.
  • document and other non-text/image content blocks are rejected with a clear 400 error rather than silently dropped.
  • stop_sequences are honored, but a stop-sequence-triggered completion reports stop_reason: "end_turn" instead of "stop_sequence" (the output is still truncated correctly).
  • count_tokens returns a provider-agnostic heuristic estimate (≈ characters / 4), not a tokenizer-exact count. Use it for budgeting and UX sizing, not hard context-limit decisions.
For byte-exact Anthropic fidelity (including prompt-cache breakpoints), use the /p/anthropic/v1/messages passthrough route instead. See ADR-0007 for the design rationale and tradeoffs.