Custom models

CustomModel is the convenience constructor for a user-asserted descriptor. It sets only the four wire-relevant values and starts every optional capability and limit at a conservative zero value.

API surface

func CustomModel(
	p ProviderName, f APIFormat, baseURL, name string,
	opts ...ModelOption,
) Model

type ModelOption func(*Model)

func WithContextLimits(limits ContextLimits) ModelOption
func WithTools() ModelOption
func WithImages() ModelOption
func WithThinking() ModelOption
func WithPromptCaching() ModelOption
func WithStructuredOutput() ModelOption
func WithStructuredOutputWithTools() ModelOption
func WithSampling(s Sampling) ModelOption

temperature := 0.1
descriptor := model.CustomModel(
	model.ProviderName("local"), model.APIFormatOpenAI,
	"http://127.0.0.1:8080", "my-model",
	model.WithTools(),
	model.WithImages(),
	model.WithStructuredOutputWithTools(),
	model.WithSampling(model.Sampling{Temperature: &temperature}),
)
if err := descriptor.Validate(); err != nil {
	panic(err)
}

WithStructuredOutputWithTools opts in all three related booleans: tools, structured output, and structured output with tools. WithSampling deep-copies its argument. Origin remains OriginCustom, and Limits remains unknown unless explicitly configured.

Endpoint safety

An HTTPS base URL is accepted. Plain HTTP is accepted only for 127.0.0.1, localhost, or ::1; userinfo credentials and hostless URLs are rejected. An empty base URL is a wildcard for a later trust boundary, not a usable endpoint by itself.

Proof

• Source: inference/model/model.go
• Tests: inference/model/model_test.go covers defaults, options, deep-copy sampling, and endpoint rules.

Related: Model, Model validation.