Compatibility, surface by surface
Know exactly which OpenAI, Anthropic, Gemini, and media-shaped routes are production-ready.
ReferenceAvailability: Informational
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Compatibility matrix
| Protocol surface | Public product-key status | Guidance |
|---|---|---|
POST /v1/chat/completions | Stable | Use for text/chat models across the routed catalog. |
GET /v1/models | Limited | Authenticated non-admin keys intentionally receive only an opaque auto entry. Use the public catalog/pricing feed for discovery. |
POST /v1/messages | Provider-specific | Requires a true Anthropic-wire target. It is not a general translation layer across the current NanoGPT/AIsa-backed pool. |
POST /v1/messages/count_tokens | Not a product-key surface | Registered legacy handler; do not rely on it. |
POST /v1/responses and Responses resources | Not a product-key surface | Use Chat Completions. A route name alone does not establish Responses semantics. |
POST /v1/embeddings | Not release-ready | A product handler is registered, but the endpoint-kind wiring does not currently meet the stable contract. |
| Images, audio, rerank, moderation | Not release-ready | Registered paths do not currently have a verified end-to-end product model-selection path. |
| Legacy completions, files, batches, fine-tuning, realtime | Not a product-key surface | Legacy gateway handlers are intentionally isolated from public product routing. |
Gemini generateContent | Not implemented | Gemini-family models are accessed through Chat Completions, not a native Gemini route. |
OpenAI SDK compatibility
Point the OpenAI JavaScript or Python client at https://api.impossi.build/v1 and use chat.completions.create. This is the primary supported integration.
Singular does not claim full OpenAI platform parity. In particular, Chat Completions support does not imply Responses, Assistants, Files, Batch, Realtime, fine-tuning, or every modern Chat field.
Anthropic Messages compatibility
Anthropic's native Messages protocol differs from OpenAI Chat in authentication, request shape, response content blocks, streaming event names, and error envelopes. Singular has a /v1/messages product handler, but it can only work when routing selects a provider target with an actual Anthropic Messages wire adapter.
The current NanoGPT/AIsa-backed targets use an OpenAI-compatible wire. For those targets:
- Call Claude-family models through
/v1/chat/completions. - Use the OpenAI SDK configuration from the quickstart.
- Do not advertise the Anthropic SDK as a drop-in client for the complete model pool.
- Do not assume native Anthropic named SSE events or Anthropic error envelopes.
OpenAI Responses compatibility
OpenAI Responses uses input, heterogeneous output[], typed streaming events, and resource lifecycle endpoints. Singular's current public runtime does not implement that contract end to end. Use Chat Completions and read choices[0].message.content.
Compatibility release gate
A surface moves to Stable only after tests cover its exact path, auth header, required and ignored fields, non-stream response envelope, streaming event protocol, tool-call deltas, usage, errors, rate limits, and current official JavaScript/Python SDK behavior.