/**
 * EmailLogger: superset of ChannelLogSink, compatible with SubsystemLogger.
 * All log methods accept an optional meta object for structured fields.
 * The optional child() method mirrors SubsystemLogger.child(name).
 */
export type EmailLogger = {
    info: (msg: string, meta?: Record<string, unknown>) => void;
    warn: (msg: string, meta?: Record<string, unknown>) => void;
    error: (msg: string, meta?: Record<string, unknown>) => void;
    debug?: (msg: string, meta?: Record<string, unknown>) => void;
    child?: (name: string) => EmailLogger;
};
/**
 * Create an EmailLogger from an optional log sink.
 * Falls back to console.* if no sink is provided (e.g. in tests or old OpenClaw versions).
 */
export declare function createEmailLogger(sink?: EmailLogger): EmailLogger;
/**
 * Wrap a logger to inject accountId into every log entry.
 *
 * Strategy:
 * - If the underlying logger supports child() (SubsystemLogger at runtime),
 *   use child(accountId) so the framework adds it as a structured field.
 * - Otherwise, prepend "[accountId] " to every message string so multi-account
 *   logs are always distinguishable, even in the console fallback path.
 */
export declare function withAccountId(log: EmailLogger, accountId: string): EmailLogger;