/**
 * Debug Logger for Sequence0 SDK
 *
 * Optional logging that never exposes sensitive data:
 * - Private keys are never logged
 * - Wallet addresses are masked: 0x1234...abcd
 * - Full signatures are never logged
 * - Only method, endpoint, status code, and latency are logged
 */
export interface Logger {
    debug(message: string, meta?: Record<string, unknown>): void;
    warn(message: string, meta?: Record<string, unknown>): void;
    error(message: string, meta?: Record<string, unknown>): void;
}
/**
 * Mask an address for safe debug logging.
 * "0x1234567890abcdef..." -> "0x1234...cdef"
 */
export declare function maskAddress(address: string): string;
/**
 * Mask sensitive fields in an object for safe logging.
 * Returns a new object — never mutates the original.
 */
export declare function maskSensitive(data: Record<string, unknown>): Record<string, unknown>;
/**
 * Default console-based debug logger.
 * Only logs when debug mode is enabled.
 */
export declare class DebugLogger implements Logger {
    private enabled;
    private prefix;
    constructor(enabled?: boolean, prefix?: string);
    debug(message: string, meta?: Record<string, unknown>): void;
    warn(message: string, meta?: Record<string, unknown>): void;
    error(message: string, meta?: Record<string, unknown>): void;
}
/** No-op logger that suppresses all output */
export declare class NullLogger implements Logger {
    debug(_message: string, _meta?: Record<string, unknown>): void;
    warn(_message: string, _meta?: Record<string, unknown>): void;
    error(_message: string, _meta?: Record<string, unknown>): void;
}
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