/**
 * Three-dimensional buyer-side circuit breaker for createX402Fetch.
 *
 * Inspected BEFORE budget checks / EIP-3009 signing on HTTP 402 pay paths:
 * 1. Rate — max paid 402s per rolling 60s window
 * 2. Minute spend — max USDC paid in rolling 60s
 * 3. Fingerprint dead-loop — same sanitized request fingerprint ≥2 prior times
 */
/** Rolling window for rate / spend / fingerprint (ms). */
export declare const CIRCUIT_BREAKER_WINDOW_MS = 60000;
/** Default max paid 402s in the rolling window (N_max). */
export declare const DEFAULT_MAX_PAID_REQUESTS_PER_MINUTE = 10;
/** Default max USDC paid in the rolling window (S_max). */
export declare const DEFAULT_MAX_SPEND_USDC_PER_MINUTE = 0.05;
/** Truncate non-JSON / oversized body strings before hashing. */
export declare const FINGERPRINT_BODY_MAX_CHARS = 4096;
export type CircuitBreakerLimits = {
    maxPaidRequestsPerMinute: number;
    maxSpendUsdcPerMinute: number;
    enableFingerprintBreaker: boolean;
};
export type CircuitBreakerEvent = {
    at: number;
    fingerprint: string;
    amountUsdc: number;
};
export type CircuitBreaker = {
    events: CircuitBreakerEvent[];
    readonly limits: CircuitBreakerLimits;
    readonly windowMs: number;
};
export type CircuitBreakerConfig = Partial<CircuitBreakerLimits> & {
    windowMs?: number;
};
export declare function createCircuitBreaker(config?: CircuitBreakerConfig): CircuitBreaker;
/** Drop events older than the rolling window. */
export declare function pruneCircuitBreaker(breaker: CircuitBreaker, now?: number): void;
/**
 * Recursively strip dynamic keys from JSON-compatible values.
 * Used so fingerprints ignore uuid / timestamp / nonce churn.
 */
export declare function stripDynamicKeys(value: unknown): unknown;
/**
 * Sanitize a request body for fingerprinting:
 * - JSON: parse → strip dynamic keys → stable stringify
 * - non-JSON: raw string truncated to FINGERPRINT_BODY_MAX_CHARS
 */
export declare function sanitizeBodyForFingerprint(body: string): string;
/** SHA-256 hex of method + url + sanitized body. */
export declare function fingerprintRequest(method: string, url: string, body: string): string;
/**
 * Convert fetch body init to a string for fingerprinting.
 * Best-effort: strings / URLSearchParams / buffers; otherwise empty.
 */
export declare function bodyInitToString(body: BodyInit | null | undefined): Promise<string>;
/** Resolve method / url / body text from fetch arguments. */
export declare function resolveRequestParts(input: RequestInfo | URL, init?: RequestInit): Promise<{
    method: string;
    url: string;
    bodyText: string;
}>;
/**
 * Enforce the three circuit dimensions before signing a 402 payment.
 * @throws Error with a `CIRCUIT_BREAKER:` prefix when halted
 */
export declare function assertCircuitAllowsPayment(breaker: CircuitBreaker, fingerprint: string, amountUsdc: number, now?: number): void;
/** Record a successfully signed paid 402 into the rolling window. */
export declare function recordCircuitPayment(breaker: CircuitBreaker, fingerprint: string, amountUsdc: number, now?: number): void;