> This page is for NeMo Relay, version dev.
> For other versions, use one of these documentation indexes:
> - Latest (v0.11.1) (default): https://docs.nvidia.com/nemo/relay/latest/llms.txt
> - dev: https://docs.nvidia.com/nemo/relay/dev/llms.txt
> - v0.11.1: https://docs.nvidia.com/nemo/relay/v0.11.1/llms.txt
> - v0.10.4: https://docs.nvidia.com/nemo/relay/v0.10.4/llms.txt
> - v0.9.4: https://docs.nvidia.com/nemo/relay/v0.9.4/llms.txt
> - v0.8.4: https://docs.nvidia.com/nemo/relay/v0.8.4/llms.txt
> - v0.7.3: https://docs.nvidia.com/nemo/relay/v0.7.3/llms.txt

> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.nvidia.com/nemo/relay/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.nvidia.com/nemo/relay/_mcp/server.

# Module openai_responses

> Built-in codec for the OpenAI Responses API.

Generated from `cargo doc --no-deps -p nemo-relay-builtins -p nemo-relay-diagnostics -p nemo-relay-logging -p nemo-relay-plugin-host -p nemo-relay-codecs -p nemo-relay -p nemo-relay-runtime -p nemo-relay-model-pricing -p nemo-relay-resource-metrics -p nemo-relay-observability -p nemo-relay-adaptive -p nemo-relay-pii-redaction -p nemo-relay-ffi -p nemo-relay-types -p nemo-relay-plugin -p nemo-relay-worker-proto -p nemo-relay-worker`.

Built-in codec for the OpenAI Responses API.

Implements \[`LlmCodec`] (request decode/encode) and \[`LlmResponseCodec`] (response decode) for the OpenAI Responses API format.

The Responses API differs significantly from Chat Completions:

* **Response**: Heterogeneous `output` array (message, function_call, reasoning) instead of `choices[0].message`.
* **Finish reason**: Derived from `status` + `incomplete_details.reason` instead of `finish_reason` field.
* **Request**: Uses `input` (string or array) instead of `messages`, and `instructions` (top-level) instead of system message.
* **Max tokens**: `max_output_tokens` instead of `max_tokens`.

## Structs

* [OpenAIResponsesCodec](/nemo/relay/dev/reference/api/rust-library-reference/nemo-relay-codecs/openai_responses/struct-openairesponsescodec): Built-in codec for the OpenAI Responses API.
* [OpenAIResponsesStreamingCodec](/nemo/relay/dev/reference/api/rust-library-reference/nemo-relay-codecs/openai_responses/struct-openairesponsesstreamingcodec): Streaming counterpart to [`OpenAIResponsesCodec`](/nemo/relay/dev/reference/api/rust-library-reference/nemo-relay-codecs/openai_responses/struct-openairesponsescodec).