/** JSON-stringify a value and cap its length for log/error previews.
 *  Leaf module on purpose: imported by both ipc.ts and
 *  failurePropagation.ts, which must not pull in each other's graphs
 *  (ipc.ts loads the subprocess machinery; failurePropagation.ts sits on
 *  the hot path of every call via agencyFunction.ts). */
export declare function truncate(val: any, maxLen?: number): string;