/**
 * Shared snapshot diff computation for session memory history.
 *
 * Compare two MemoryHistorySnapshot states to derive what changed between them.
 * Because persistence is snapshot-based (not event-sourced), each snapshot
 * represents the complete memory state at that point in time.
 *
 * This diff is derived from adjacent real persisted snapshots and is NOT
 * a true operation log — it cannot tell you which specific add/update/delete
 * operation produced a given change.
 */
import type { MemoryHistorySnapshot } from "./memory.js";
/** A key present only in the current snapshot (added) */
export interface DiffAdded {
    type: "added";
    key: string;
    value: string;
}
/** A key present only in the previous snapshot (removed) */
export interface DiffRemoved {
    type: "removed";
    key: string;
    value: string;
}
/** A key present in both snapshots, but with different values */
export interface DiffChanged {
    type: "changed";
    key: string;
    previousValue: string;
    currentValue: string;
}
/** Result of comparing two memory snapshots */
export interface MemorySnapshotDiff {
    /** Keys that exist only in the current snapshot */
    added: DiffAdded[];
    /** Keys that exist only in the previous snapshot */
    removed: DiffRemoved[];
    /** Keys that exist in both snapshots but have different values */
    changed: DiffChanged[];
    /** True when previous was undefined (current is the initial/earliest snapshot) */
    isInitialSnapshot: boolean;
}
/**
 * Compute the diff between two memory snapshots.
 *
 * Semantics:
 * - `added`: key only in current (not in previous)
 * - `removed`: key only in previous (not in current)
 * - `changed`: key in both, value strings differ
 * - Unchanged keys are omitted from the result
 *
 * If `previous` is undefined (initial snapshot / nothing to diff against),
 * all current keys are treated as added and `isInitialSnapshot` is set to true.
 *
 * @param previous - The earlier snapshot (or undefined for initial state)
 * @param current  - The later snapshot
 */
export declare function computeMemorySnapshotDiff(previous: MemoryHistorySnapshot | undefined, current: MemoryHistorySnapshot): MemorySnapshotDiff;
//# sourceMappingURL=memory-diff.d.ts.map