/**
 * Custom API provider registry.
 *
 * Allows extensions to register streaming functions for custom API types
 * (e.g., "vertex-claude-api") that are not built into stream.ts.
 */
import type { Api, AssistantMessageEventStream, Context, Model, SimpleStreamOptions, StreamOptions } from "./types";
export type CustomStreamFn = (model: Model<Api>, context: Context, options?: StreamOptions) => AssistantMessageEventStream;
export type CustomStreamSimpleFn = (model: Model<Api>, context: Context, options?: SimpleStreamOptions) => AssistantMessageEventStream;
export interface RegisteredCustomApi {
    stream: CustomStreamFn;
    streamSimple: CustomStreamSimpleFn;
    sourceId?: string;
}
/**
 * Register a custom API streaming function.
 */
export declare function registerCustomApi(api: string, streamSimple: CustomStreamSimpleFn, sourceId?: string, stream?: CustomStreamFn): void;
/**
 * Get a custom API provider by API identifier.
 */
export declare function getCustomApi(api: string): RegisteredCustomApi | undefined;
/**
 * Remove all custom APIs registered by a specific source (e.g., extension path).
 */
export declare function unregisterCustomApis(sourceId: string): void;
/**
 * Clear all custom API registrations.
 */
export declare function clearCustomApis(): void;