/**
 * Flow Chain Adapter
 *
 * Builds Flow transactions using manual RLP encoding (no external deps),
 * signs with ECDSA_secp256k1 + SHA2-256 via FROST threshold signing,
 * and broadcasts via Flow Access API (REST).
 *
 * Flow signing scheme: SHA2-256 of ("FLOW-V0.0-transaction" domain tag + RLP payload)
 * Key algorithm: ECDSA_secp256k1 (algorithm ID 2 on Flow)
 *
 * No external dependencies required.
 */
import { ChainAdapter, FlowTransaction } from '../core/types';
export declare class FlowAdapter implements ChainAdapter {
    private rpcUrl;
    private network;
    constructor(network?: 'mainnet' | 'testnet', rpcUrl?: string);
    getRpcUrl(): string;
    /**
     * Build an unsigned Flow transaction.
     *
     * Fetches account info and latest block from the Flow Access API,
     * constructs a Cadence FlowToken.transfer transaction, and returns
     * the hex-encoded JSON envelope containing the RLP payload and metadata.
     */
    buildTransaction(tx: FlowTransaction, fromAddress: string): Promise<string>;
    /**
     * Extract the signing payload (SHA2-256 hash) from the unsigned transaction.
     *
     * Flow signing: SHA2-256(domainTag + RLP(payload))
     * The hash is computed during buildTransaction and stored in the envelope.
     */
    getSigningPayload(unsignedTx: string): string;
    /**
     * Attach a secp256k1 ECDSA signature to the Flow transaction envelope.
     *
     * For simple transactions where proposer = payer = authorizer,
     * the signature goes into the envelope signatures list.
     */
    attachSignature(unsignedTx: string, signature: string): Promise<string>;
    /**
     * Broadcast a signed Flow transaction via the Access API.
     *
     * POST /v1/transactions with the signed transaction in the expected format.
     */
    broadcast(signedTx: string): Promise<string>;
    /**
     * Get FLOW token balance for an address.
     *
     * Uses the Flow Access API /v1/accounts/{address} endpoint.
     * Returns balance in FLOW (UFix64 format).
     */
    getBalance(address: string): Promise<string>;
}
export declare function createFlowAdapter(rpcUrl?: string): FlowAdapter;
export declare function createFlowTestnetAdapter(rpcUrl?: string): FlowAdapter;
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