Models & interaction

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Symbol	Kind	Purpose
chatCompletionFunctionOptions	function	Build the tool-selection request fields for a function-calling stage. The adapter expects exactly one function call per response, so tool use is required and parallel calls are disabled.
chatCompletionMessages	function	Map Core and provider messages to chat-completions message payloads. Only declared message fields are sent. Assistant tool declarations become nested tool_calls, and tool results become tool_call_id; both are rewritten explicitly rather than forwarded as-is. Messages with images become a content-block array; images are accepted only on user messages and only as http(s) or data:image URLs.
chatCompletionParts	function	Convert one streamed choice.delta into Core model parts. Text is emitted only when non-empty; each tool-call fragment carries its index so Core can reassemble arguments that arrive across chunks.
CompatibleModelConfig	interface	Configuration of one OpenAI-compatible endpoint.
CompatibleModelPorts	interface	Adapter ports the App may override without replacing the provider.
CompatibleModelProvider	class	HTTP/SSE lifecycle shared by hosts. Apps supply config and user-visible error mapping only. A static configuration is validated and frozen in the constructor. A configuration function is called once per request instead, so credentials and models may rotate between calls.
CompatibleModelProviderOptions	interface	Construction options for a compatible provider.
CompletionFailure	type	Build the classified failure a policy throws; the provider records it like its own failures.
CompletionPolicy	interface	Decision whether a finished stream satisfies the request.
completionPolicyCatalog	constant
CompletionRequestFacts	interface	Facts the provider reads from the request it actually sends. functions reports the Core call options and keeps the default policy equivalent to the behavior that existed before policies were configurable. toolChoice is the effective field of the serialized body, so a host override, or a field dropped for being undefined, is visible exactly as the upstream receives it.
CompletionSession	interface	Per-request completion state observed by one policy.
createJsonTransport	function	Create a typed JSON transport without a capability-selection envelope. The transport embeds the JSON Schema in the instruction and requires the response to be one complete JSON value. The returned response parser rejects native call events and invalid JSON, then validates the value through the supplied schema.
createModelStrategy	function	Compose runner options in precedence order: budget preset, selected model, declared reasoning, exact budget, then explicit Core fields. The result is validated through the same Core binding rules but creates no runner and spends no calls.
createProviderObservationScope	function	Bind provider observations to a caller-owned destination across diagnostic child spans. attach returns a scoped diagnostic context; contexts that were not attached through this scope produce no observations. Child contexts inherit the owner and a parent/child span path.
createReplyPreview	function	Create a model-output event handler that publishes preview bubbles. The handler resets on model.start, ignores other invocations, disables itself on unexpected output, and clears the preview when a call ends unsuccessfully. Rules are snapshotted at creation, and only explicitly registered prose fields are projected.
createReplyPreviewRules	function	Generate frozen preview rules from capability and stage declarations. Capabilities without preview metadata are skipped even when their stage opts in. Default paths are text and bubbles[*], each kept only when the capability schema declares it.
createSessionModelTransport	function	Create a session transport.
createStageModelTransport	function	Build a transport that projects a capability source through declared stage references.
createTextTransport	function	Create a plain-text transport that trims the assembled response.
defaultCompletionPolicy	constant
defineModelTools	function	Build a sealed capability catalog from typed declarations.
modelBudgetStrategies	constant
ModelBudgetStrategy	type	Preset name, or an explicit partial set of Core runner settings.
ModelChildrenOptions	interface	Group options: worker count, extra cancellation and accept/commit hooks.
ModelChildTask	interface	One child call in a group: its own limits plus the work to run with the child runner.
ModelChoiceIndex	interface	Minimal selector shape used while filtering the provider response choices.
modelInteractionCatalog	constant
ModelProviderErrorCode	type	Stable failure classification reported by the compatible provider adapter.
ModelProviderFailure	interface	Failure detail passed to the App's error factory.
ModelStageTransportRegistration	interface	Stage IDs and capability references are App-owned; this adapter only compiles their relation.
ModelStrategyOptions	type	Input of createModelStrategy: model selection, optional reasoning and budget plus explicit Core overrides. Explicit Core fields win over every generated value.
PreparedSessionTransport	interface	Prepared session transport handed to the runner.
prepareSessionFunctions	function	Build the session policy for one stage.
PreviewTool	interface	A model tool with an explicit, presentation-only streaming preview contract.
ProviderAssistantMessage	interface	Assistant turn; content may be empty when the turn is only a tool declaration.
ProviderErrorCapture	interface	Captured upstream error body and whether it had to be truncated.
ProviderEventDescriptor	interface	Provider event name plus its content class.
ProviderEventName	type	Union of provider event names.
ProviderEventPayloads	interface	Payload of each provider event. Content-bearing events are accepted explicitly.
ProviderMessage	type	Message list a host may pass to the compatible provider directly.
ProviderObservation	type	One observation: event name with its payload.
ProviderObserver	interface	The caller can correlate each observation using the original, request-local model options.
ProviderReasoningLevel	type	Supplier wire shape is explicit; levels express requested effort, not measured quality.
ProviderReasoningStrategy	type	How a reasoning level is translated into request fields. requestBody entries override generated fields, so a host can correct a provider that expects a different shape.
ProviderSystemMessage	interface	System instruction turn; text only, so the union rejects images and tool fields here.
ProviderToolCall	type	One tool call the assistant declared, in wire order; aliases the Core shape.
ProviderToolMessage	interface	Tool result answering one declared call.
ProviderUserMessage	interface	User turn; the only message type that may carry images, and never tool calls.
ReplyPreviewOptions	interface	Settings for createReplyPreview; sink receives every bubble list and is required.
ReplyPreviewRule	interface	One projection rule: which stage/capability it matches and which prose fields may be shown. A rule without toolId may only match a registered plain-text stage.
ReplyPreviewStage	interface	Stage declaration: which tools it exposes and whether it previews text or arguments.
ReplyPreviewTool	interface	Capability declaration used to derive preview rules. Omitted preview means the capability never previews, so previewing is an explicit opt-in.
ResolvedSessionCall	interface	One completed call with host-facing resolution; unknown tools and bad JSON stay non-fatal.
ResolvedSessionResult	interface	Complete result of one session response after host-facing resolution.
runChildren	function	Run child tasks concurrently and return their values in declaration order. The first failure aborts the remaining group, but an already in-flight commit is still awaited because cancellation does not mean the write was rolled back.
sessionCompletionPolicy	constant
SessionFunctionOptions	interface	Options a session transport may pass through to provider options.
SessionModelTransportRegistration	interface	Registration for one session transport.