import type { JsonObject } from '../contracts/common';
export type PageStreamReducerErrorCode = 'PAGE_STREAM_INVALID_FRAME' | 'PAGE_STREAM_ID_MISMATCH' | 'PAGE_STREAM_SNAPSHOT_REQUIRED' | 'PAGE_STREAM_SEQUENCE_CONFLICT' | 'PAGE_STREAM_SEQUENCE_GAP' | 'PAGE_STREAM_TERMINATED' | 'PAGE_STREAM_CAPACITY_EXCEEDED';
export declare class PageStreamReducerError extends Error {
    readonly code: PageStreamReducerErrorCode;
    constructor(code: PageStreamReducerErrorCode);
}
export interface PageStreamState {
    readonly streamId: string;
    readonly status: 'awaiting-snapshot' | 'open' | 'ended' | 'error';
    readonly model: JsonObject | undefined;
    readonly events: readonly JsonObject[];
    readonly sequence: number;
    readonly cursor: string | undefined;
    readonly error: {
        code: string;
        retryable: boolean;
    } | undefined;
    readonly seen: Readonly<Record<string, string>>;
    readonly retainedBytes: number;
}
export declare function createPageStreamState(streamId: string): PageStreamState;
/** Verified snapshots replace presentation state; deltas retain every event or reject atomically. */
export declare function applyPageStreamEvent(state: PageStreamState, input: unknown): PageStreamState;
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