model.APIFormat names a wire dialect. It is intentionally an open string: unknown values are valid in the model package when a caller supplies matching codec and router implementations.

Labels

type APIFormat string

const (
	APIFormatOpenAI            APIFormat = "openai"
	APIFormatOpenAIResponses   APIFormat = "openai-responses"
	APIFormatAnthropic         APIFormat = "anthropic"
	APIFormatGemini            APIFormat = "gemini"
	APIFormatBedrockConverse   APIFormat = "bedrock-converse"
)

The label does not carry credentials, endpoint defaults, or provider policy. Model.Validate checks structural safety, while composition code binds the label to a codec, router, and credential source.

Routing

Format	Route helper	Invoke	Stream
OpenAI Chat	`route.StaticChat("/chat/completions")`	same path	same path, body flag
OpenAI Responses	`route.StaticChat("/responses")`	same path	same path, body flag
Anthropic	`route.StaticChat("/messages")`	same path	same path, body flag
Gemini	`route.GeminiGenerateContent()`	`:generateContent`	`:streamGenerateContent?alt=sse`
Bedrock Converse	caller-supplied route	same body	route/API operation chooses stream

Source and proof

Run go test ./model ./route.