Generative UI Actions

API Reference

ActionDispatchContext

Context handed to an ActionHandler when an $action fires.

ActionDispatchContext

payload : Action

The action payload. For fire-and-forget actions this is the `$action` as the model emitted it. For interactive components (`Select`/`Input`/ `DatePicker`) the user's runtime input is merged in under the reserved `$input` key, so the handler sees both the model payload and what the user did; a model-supplied `value` field is never clobbered.

type : string

ActionHandler

Resolves a single $action.type. Fire-and-forget actions return void or a promise that resolves to it; human-in-the-loop actions return a value the runtime uses to resume the run (see IR doc Open question #2 — the resume value is left as unknown and documented per-action). The return value is handed back to dispatch's caller as unknown.

type ActionHandler = (
  ctx: ActionDispatchContext,
) => unknown | Promise<unknown>;

ActionRegistry

The host-provided map from $action.type to ActionHandler. This is the single dispatch target for $action on web, shared by the model present renderer, the synthetic present produced from A2A/A2UI, and the decoded block_actions from Slack. Construct it with createActionRegistry and pass it to JSONGenerativeUI.

ActionRegistry

dispatch : (action: Action) => unknown
has : (type: string) => boolean

createActionRegistry

createActionRegistry

handlers : Readonly<Record<string, ActionHandler>>

emptyActionRegistry

A no-op registry used when no handlers are provided. Dispatch resolves to undefined and logs a warning in dev for unknown types, so a model-emitted action with no handler degrades to "does nothing" rather than throwing.

const emptyActionRegistry: ActionRegistry;