import type { ReasoningArtifact, TokenUsage } from "../types.js";
export type ProviderStreamEvent = {
    readonly type: "answer_delta";
    readonly text: string;
} | {
    readonly type: "commentary_delta";
    readonly text: string;
} | {
    readonly type: "reasoning_delta";
    readonly text: string;
} | {
    readonly type: "reasoning_artifact_available";
    readonly artifacts: readonly ReasoningArtifact[];
} | {
    readonly type: "tool_call_started";
    readonly index: number;
    readonly id?: string | undefined;
    readonly name: string;
} | {
    readonly type: "tool_arguments_delta";
    readonly index: number;
    readonly id?: string | undefined;
    readonly argumentsBytes: number;
} | {
    readonly type: "tool_call_completed";
    readonly index: number;
    readonly id?: string | undefined;
    readonly name: string;
} | {
    readonly type: "usage_observed";
    readonly usage: TokenUsage;
} | {
    readonly type: "provider_terminal";
    readonly finishReason?: string | undefined;
};
export type ProviderStreamEventSink = (event: ProviderStreamEvent) => void;
export declare function emitStreamReasoningDelta(sink: ProviderStreamEventSink | undefined, text: string): void;
export declare function emitStreamReasoningArtifacts(sink: ProviderStreamEventSink | undefined, artifacts: readonly ReasoningArtifact[] | undefined): void;
export declare function isSemanticStreamOutputEvent(event: ProviderStreamEvent): boolean;
export declare class StreamEventProtocolError extends Error {
    constructor(message: string);
}
export interface StreamEventGuard {
    accept(event: ProviderStreamEvent): void;
    readonly terminal: boolean;
}
export declare function createStreamEventGuard(): StreamEventGuard;