feat(mesh-payment): offline Solana payments through beacon relay

mobile_app/src/services/meshExecutePayment.ts

@@ -0,0 +1,158 @@
+import "@/polyfills";
+
+import { PublicKey } from "@solana/web3.js";
+import { getAssociatedTokenAddress } from "@solana/spl-token";
+import { Buffer } from "buffer";
+
+import type { IRpcAdapter } from "@/src/infrastructure/network";
+import type { IWalletAdapter } from "@/src/infrastructure/wallet";
+
+// ── Types ─────────────────────────────────────────────────────────────────────
+
+// Mirror of useLxmf ExecutePaymentAccounts — all 64-char lowercase hex pubkeys.
+export interface ExecutePaymentAccounts {
+  payer:          string;
+  broadcaster:    string;
+  nonceAccount:   string;
+  payerAta:       string;
+  recipient:      string;
+  recipientAta:   string;
+  broadcasterAta: string;
+  mint:           string;
+}
+
+export interface ExecutePaymentParams {
+  compOffset:       number;  // broadcaster fee offset (u64)
+  amount:           number;  // raw token units (u64)
+  encryptedAmount:  string;  // 64-char hex → [u8; 32]
+  nonce:            string;  // decimal string → u128
+  encryptionPubKey: string;  // 64-char hex → [u8; 32]
+}
+
+export interface MeshPaymentRequest {
+  /** base58 pubkey of the token recipient */
+  recipient: string;
+  /** raw token units — NOT ui amount */
+  amount: number;
+  /** base58 mint pubkey */
+  mint: string;
+  /** base58 beacon/broadcaster pubkey (the relay node that co-signs and submits) */
+  broadcaster: string;
+  /** base58 durable nonce account pubkey — used instead of a recent blockhash */
+  nonceAccount: string;
+  // ── Encryption fields (anonmesh payment program) ─────────────────────────
+  encryptedAmount:  string; // 64-char hex
+  nonce:            string; // decimal u128 string
+  encryptionPubKey: string; // 64-char hex
+  compOffset:       number; // broadcaster compensation offset
+}
+
+export interface MeshPaymentResult {
+  /** Hex-encoded partially-signed transaction sent to the beacon. */
+  partialTxHex: string;
+}
+
+// ── Helpers ───────────────────────────────────────────────────────────────────
+
+function pubkeyToHex(pubkey: PublicKey): string {
+  return Buffer.from(pubkey.toBytes()).toString("hex");
+}
+
+// ── Core ──────────────────────────────────────────────────────────────────────
+
+const PAYMENT_MSG_TYPE = "anon0mesh::execute_payment::v1";
+
+/**
+ * Executes an offline mesh payment through a beacon relay node.
+ *
+ * Flow:
+ *  1. Fetch nonce account data via mesh RPC → extract durable blockhash
+ *  2. Derive ATAs for payer, recipient, and broadcaster
+ *  3. Partially sign the execute_payment transaction with the payer's key
+ *  4. Send the partial tx to the relay beacon via LXMF
+ *  5. Beacon adds broadcaster signature and submits to Solana
+ *
+ * The payer's secret key is zeroed immediately after signing — it never
+ * leaves the local signing call. No key material is sent over the mesh.
+ */
+export async function executeMeshPayment({
+  request,
+  walletAdapter,
+  rpcAdapter,
+  partialSignExecutePayment,
+  extractNonceBlockhash,
+  sendLxmf,
+  relayHash,
+}: {
+  request: MeshPaymentRequest;
+  walletAdapter: IWalletAdapter;
+  rpcAdapter: IRpcAdapter;
+  partialSignExecutePayment: (
+    payerKeyHex: string,
+    nonceBlockhashHex: string,
+    accounts: ExecutePaymentAccounts,
+    params: ExecutePaymentParams,
+  ) => string | null;
+  extractNonceBlockhash: (accountDataB64: string) => string | null;
+  sendLxmf: (destHex: string, bodyBase64: string) => Promise<number>;
+  relayHash: string;
+}): Promise<MeshPaymentResult> {
+  const payerPubkey = walletAdapter.getPublicKey();
+  if (!payerPubkey) throw new Error("Wallet not connected");
+
+  // 1. Fetch nonce account via mesh — works with no internet
+  const nonceAccountPubkey = new PublicKey(request.nonceAccount);
+  const accountInfo = await rpcAdapter.getAccountInfo(nonceAccountPubkey);
+  if (!accountInfo) throw new Error("Nonce account not found on mesh");
+
+  const nonceBlockhashHex = extractNonceBlockhash(accountInfo.data.toString("base64"));
+  if (!nonceBlockhashHex) throw new Error("Failed to extract nonce blockhash");
+
+  // 2. Derive ATAs
+  const mintPubkey        = new PublicKey(request.mint);
+  const recipientPubkey   = new PublicKey(request.recipient);
+  const broadcasterPubkey = new PublicKey(request.broadcaster);
+
+  const [payerAta, recipientAta, broadcasterAta] = await Promise.all([
+    getAssociatedTokenAddress(mintPubkey, payerPubkey),
+    getAssociatedTokenAddress(mintPubkey, recipientPubkey),
+    getAssociatedTokenAddress(mintPubkey, broadcasterPubkey),
+  ]);
+
+  const accounts: ExecutePaymentAccounts = {
+    payer:          pubkeyToHex(payerPubkey),
+    broadcaster:    pubkeyToHex(broadcasterPubkey),
+    nonceAccount:   pubkeyToHex(nonceAccountPubkey),
+    payerAta:       pubkeyToHex(payerAta),
+    recipient:      pubkeyToHex(recipientPubkey),
+    recipientAta:   pubkeyToHex(recipientAta),
+    broadcasterAta: pubkeyToHex(broadcasterAta),
+    mint:           pubkeyToHex(mintPubkey),
+  };
+
+  const paymentParams: ExecutePaymentParams = {
+    compOffset:       request.compOffset,
+    amount:           request.amount,
+    encryptedAmount:  request.encryptedAmount,
+    nonce:            request.nonce,
+    encryptionPubKey: request.encryptionPubKey,
+  };
+
+  // 3. Export key, sign, zero immediately
+  const secretKey = await walletAdapter.exportSecretKey();
+  const payerKeyHex = Buffer.from(secretKey).toString("hex");
+  secretKey.fill(0);
+
+  const partialTxHex = partialSignExecutePayment(
+    payerKeyHex, nonceBlockhashHex, accounts, paymentParams,
+  );
+  if (!partialTxHex) throw new Error("partialSignExecutePayment returned null");
+
+  // 4. Send partial tx to beacon — beacon co-signs and submits to Solana
+  const msgBody = Buffer.from(
+    JSON.stringify({ type: PAYMENT_MSG_TYPE, tx: partialTxHex }),
+  ).toString("base64");
+  await sendLxmf(relayHash, msgBody);
+
+  return { partialTxHex };
+}

mobile_app/src/services/sendTransaction.ts

@@ -303,7 +303,6 @@ async function buildSplTransferTransaction({
   mintAddress,
   decimals,
   programId,
-  rpcAdapter,
 }: {
   rpcAdapter: IRpcAdapter;
   fromPubkey: PublicKey;
@@ -312,7 +311,6 @@ async function buildSplTransferTransaction({
   mintAddress: string;
   decimals: number;
   programId?: string;
-  rpcAdapter: IRpcAdapter;
 }): Promise<Transaction> {
   // Bottom-line guard against any caller (including direct deep-links to
   // /send/review with a tampered programId param) trying to build an SPL
@@ -476,7 +474,6 @@ export async function estimateSplTransferFeeLamports({
     mintAddress,
     decimals,
     programId,
-    rpcAdapter,
   });
   const { blockhash } = await withTimeout(
     rpcAdapter.getLatestBlockhash(),
@@ -546,7 +543,6 @@ export async function sendSplTransfer({
     mintAddress,
     decimals,
     programId,
-    rpcAdapter,
   });
   return signAndSubmitTransaction({ walletAdapter, rpcAdapter, tx, expectedPubkey: fromPubkey });
 }