/** Read a metadata object, tolerating a missing/empty/corrupt file as `null`
 *  (never throws). Callers that reindex/revive the whole canvas must not crash on
 *  one damaged node. Read only while holding {@link withMetaLock} for any
 *  read-modify-write that races other writers. */
export declare function readMetaObject(path: string): Record<string, unknown> | null;
/** Serialize every read-modify-write to one node's meta.json behind a single
 *  cross-process lock, so a migration and a normal identity update can never
 *  interleave into a lost write or a restored-legacy-prefix. The lock is NOT
 *  re-entrant — the operation must use {@link writeMetaObjectLocked}, never the
 *  lock-taking {@link writeJsonFileDurably}. */
export declare function withMetaLock<T>(path: string, operation: () => T): T;
/** Collision-free durable write (fsync file + parent dir), assuming the caller
 *  already holds {@link withMetaLock} for `path`. */
export declare function writeMetaObjectLocked(path: string, value: unknown): void;
/** Serialize a normal identity write with migrations and use a collision-free durable temp file. */
export declare function writeJsonFileDurably(path: string, value: unknown): void;
/** Transform one metadata object in place while holding the same lock normal
 *  writes honor. The transform MUTATES the passed object and returns whether it
 *  changed anything; only a `true` return persists the mutated object. */
export declare function updateJsonFileDurably(path: string, transform: (value: Record<string, unknown>) => boolean): boolean;