# OpenAI-Compatible API Guide

Edge supports model discovery, Chat Completions, Responses, legacy Completions, streaming, standard tools, reasoning fields, and compatible error envelopes.

The request `model` selects a configured route. Edge then uses normalized provider execution or an OpenAI-compatible provider tunnel according to the selected provider capability. Caller metadata remains an ordinary bounded string map and is passed through according to the selected public API behavior.

Provider-native tool calls remain structured. A text fallback is attempted only when a backend explicitly rejects native tool fields. Cancellation follows the active run id, and correlation values do not resume local execution state.

The canonical contract is `agent-contract/outer/openai-compatible-api.md`.