/** Application authorization for the native USDG/RHC signing client. */
export declare const RHC_PAYMENT_NETWORK = "eip155:4663";
export declare const RHC_PAYMENT_ASSET = "0x5fc5360d0400a0fd4f2af552add042d716f1d168";
export declare class PaymentPolicyError extends Error {
    constructor(message: string);
}
export interface PaymentProposal {
    readonly url: string;
    readonly network: typeof RHC_PAYMENT_NETWORK;
    readonly scheme: "exact";
    readonly asset: typeof RHC_PAYMENT_ASSET;
    readonly payTo: string;
    readonly amount: string;
    readonly maxTimeoutSeconds: number;
}
export interface PaymentPolicy {
    /** Trusted recipient obtained independently of the HTTP 402 challenge. */
    payTo: string;
    /** USDG atomic units (6 decimals); decimal string or bigint, never float. */
    maxAmountAtomic: string | bigint;
    /** Lifetime authorization budget for this client instance, shared by concurrent calls. */
    maxTotalAmountAtomic: string | bigint;
    /** Whole keyless request deadline, including policy/signing. Default 30 seconds. */
    timeoutMs?: number;
    /** Maximum signed authorization lifetime, 1–300 seconds. Default 60. */
    authorizationTtlSeconds?: number;
    /** Optional additional approval. Only literal true approves; built-in checks still apply. */
    beforePayment?: (proposal: Readonly<PaymentProposal>) => boolean | Promise<boolean>;
}
export declare function paymentUrl(value: string): URL;
/** A reserved amount is released only before a signer has been invoked. */
export declare class PaymentBudget {
    readonly timeoutMs: number;
    readonly authorizationTtlSeconds: number;
    private readonly payTo;
    private readonly maxAmount;
    private readonly maxTotal;
    private readonly approve?;
    private used;
    constructor(policy: PaymentPolicy | undefined);
    /** Reserved plus signer-attempted amount; not a claim about settled on-chain spend. */
    get authorizedAmountAtomic(): string;
    select(challenge: unknown, url: string): Readonly<PaymentProposal>;
    reserve(proposal: Readonly<PaymentProposal>): {
        signerInvoked(): void;
        release(): void;
    };
    checkApproval(proposal: Readonly<PaymentProposal>, signal: AbortSignal): Promise<void>;
}
/** Observe the losing promise too; a timed-out signer must never trigger a later send. */
export declare function withinDeadline<T>(promise: Promise<T>, signal: AbortSignal): Promise<T>;
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