/**
 * Atomic, immutable project snapshots for long-running runtime operations.
 *
 * A candidate is built completely before it replaces the current snapshot.
 * Failed candidates never expose partially-built state; callers may continue to
 * read the last good snapshot with `stale: true` and an attached failure.
 *
 * Acceptance: CTX-002, PERF-001.
 */
export interface ProjectSnapshot<T> {
    readonly snapshotId: string;
    readonly sourceVersion: string;
    readonly value: T;
    readonly stale: boolean;
    readonly error?: string;
}
export declare class ProjectSnapshotMismatchError extends Error {
    readonly expectedSnapshotId: string;
    readonly currentSnapshotId: string;
    readonly code = "PROJECT_SNAPSHOT_MISMATCH";
    constructor(expectedSnapshotId: string, currentSnapshotId: string);
}
export declare class ProjectSnapshotService<T> {
    #private;
    current(): ProjectSnapshot<T> | null;
    invalidate(): void;
    refresh(sourceVersion: string, buildCandidate: () => T): ProjectSnapshot<T>;
    assertCurrent(snapshotId: string): void;
}
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