import type { StreamLifecycleError, StreamLifecycleFrame, StreamSignal, StreamSnapshot, StreamToolSnapshot } from "./types.js";
export interface StreamReducerState {
    snapshot: StreamSnapshot;
    sequence: number;
    activeTextId: string | null;
    activeReasoningId: string | null;
    nextTextIndex: number;
    tools: Map<string, StreamToolSnapshot>;
    terminal: boolean;
    terminalError: StreamLifecycleError | null;
}
export interface StreamReduction {
    state: StreamReducerState;
    frames: StreamLifecycleFrame[];
    semanticProgress: boolean;
}
export declare function createInitialReducerState(): StreamReducerState;
export declare function reduceStreamSignal(current: StreamReducerState, signal: StreamSignal, elapsedMs: number): StreamReduction;
export type LocalToolDeadlineResolution = {
    kind: "handoff";
    reduction: StreamReduction;
} | {
    kind: "failed";
    reduction: StreamReduction;
    code: "TOOL_INPUT_TIMEOUT" | "TOOL_INPUT_INCOMPLETE";
};
export declare function resolveLocalToolDeadline(current: StreamReducerState, _reason: "tool_input_idle" | "tool_commit_grace", elapsedMs: number): LocalToolDeadlineResolution;
/**
 * Close any open read-projection segments. This is a projection-only
 * finalizer: it does not set a provider finish reason, settle a Stream
 * Outcome, or change lifecycle terminal meaning.
 */
export declare function finalizeStreamProjection(current: StreamReducerState, elapsedMs: number): StreamReduction;
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