fix(stellar): restore wallet-compatible sponsored authorization

CHANGELOG.md

@@ -2,6 +2,18 @@
 
 All notable changes to `@fundable/sdk` are documented here.
 
+## 0.2.2
+
+### Added
+
+- a typed Stellar sponsorship intent for exact, backend-validated token
+  approvals used by gasless Lockup funding.
+
+### Fixed
+
+- sign the Soroban authorization preimage through the wallet and insert the
+  returned signature into the relayer authorization entry before submission.
+
 ## 0.2.1
 
 ### Fixed

package.json

@@ -1,6 +1,6 @@
 {
     "name": "@fundable/sdk",
-    "version": "0.2.1",
+    "version": "0.2.2",
     "private": false,
     "description": "Multichain TypeScript SDK for Fundable Protocol; Stellar adapter included",
     "license": "MIT",

src/stellar/client.test.ts

@@ -1,4 +1,4 @@
-import { StrKey } from "@stellar/stellar-sdk";
+import { Address, Contract, hash, Keypair, nativeToScVal, StrKey, xdr } from "@stellar/stellar-sdk";
 import { describe, expect, it, vi } from "vitest";
 import { FundableError } from "../core/index.js";
 import { createFundableClient } from "../client.js";
@@ -7,6 +7,31 @@ function contractId(): string {
   return StrKey.encodeContract(new Uint8Array(32));
 }
 
+function unsignedAuthorizationEntry(): { entryXdr: string; signer: Keypair } {
+  const signer = Keypair.random();
+  const entryXdr = new xdr.SorobanAuthorizationEntry({
+    credentials: xdr.SorobanCredentials.sorobanCredentialsAddress(
+      new xdr.SorobanAddressCredentials({
+        address: Address.fromString(signer.publicKey()).toScAddress(),
+        nonce: xdr.Int64.fromString("1"),
+        signatureExpirationLedger: 2_000,
+        signature: xdr.ScVal.scvVec([]),
+      }),
+    ),
+    rootInvocation: new xdr.SorobanAuthorizedInvocation({
+      function: xdr.SorobanAuthorizedFunction.sorobanAuthorizedFunctionTypeContractFn(
+        new xdr.InvokeContractArgs({
+          contractAddress: new Contract(contractId()).address().toScAddress(),
+          functionName: "forward",
+          args: [nativeToScVal(signer.publicKey(), { type: "address" })],
+        }),
+      ),
+      subInvocations: [],
+    }),
+  }).toXDR("base64");
+  return { entryXdr, signer };
+}
+
 describe("createFundableClient", () => {
   it("creates the Stellar adapter with Flow capabilities", () => {
     const client = createFundableClient({
@@ -55,8 +80,11 @@ describe("createFundableClient", () => {
   });
 
   it("signs a current sponsorship build with the configured wallet", async () => {
-    const signAuthEntry = vi.fn(async () => ({
-      signedAuthEntry: "signed-entry",
+    const authorization = unsignedAuthorizationEntry();
+    const signAuthEntry = vi.fn(async (preimageXdr: string) => ({
+      signedAuthEntry: authorization.signer
+        .sign(hash(Buffer.from(preimageXdr, "base64")))
+        .toString("base64"),
       signerAddress: "GACCOUNT",
     }));
     const client = createFundableClient({
@@ -73,20 +101,20 @@ describe("createFundableClient", () => {
       },
     });
 
-    await expect(
-      client.signSponsorshipAuthorization({
+    const result = await client.signSponsorshipAuthorization({
         transactionXdr: "built-xdr",
-        userAuthEntry: "auth-entry",
+        userAuthEntry: authorization.entryXdr,
         feeToken: "CFEE",
         networkFeeStroops: "100",
         estimatedFee: "123",
         estimatedFeeUi: "0.0000123",
         maximumFee: "130",
         maximumFeeUi: "0.0000130",
         validUntil: "2030-01-01T00:00:00.000Z",
-      }),
-    ).resolves.toBe("signed-entry");
-    expect(signAuthEntry).toHaveBeenCalledWith("auth-entry", {
+      });
+    const signed = xdr.SorobanAuthorizationEntry.fromXDR(result, "base64");
+    expect(signed.credentials().address().signature().switch().name).toBe("scvVec");
+    expect(signAuthEntry).toHaveBeenCalledWith(expect.any(String), {
       networkPassphrase: "Test SDF Network ; September 2015",
       address: "GACCOUNT",
     });

src/stellar/client.ts

@@ -1,4 +1,5 @@
 import { FUNDABLE_ERROR_CODES, FundableError } from "../core/index.js";
+import { authorizeEntry, xdr } from "@stellar/stellar-sdk";
 import { StellarFlowClient } from "./flow-client.js";
 import { StellarLockupClient } from "./lockup-client.js";
 import { StellarPaymasterClient } from "./paymaster-client.js";
@@ -9,6 +10,11 @@ import type { StellarSponsorBuild } from "./sponsorship-client.js";
 import type { StellarFundableClientConfig } from "./types.js";
 import { assertContractId } from "./validation.js";
 
+function base64ToBytes(value: string): Uint8Array {
+  const binary = atob(value);
+  return Uint8Array.from(binary, (character) => character.charCodeAt(0));
+}
+
 export class StellarFundableClient {
   readonly chain = "stellar" as const;
   readonly flows: StellarFlowClient;
@@ -86,17 +92,31 @@ export class StellarFundableClient {
         chain: "stellar",
       });
     }
-    const result = await this.config.signAuthEntry(build.userAuthEntry, {
-      networkPassphrase: this.config.networkPassphrase,
-      address: this.config.publicKey,
-    });
-    if (result.error || !result.signedAuthEntry) {
-      throw new FundableError({
-        code: FUNDABLE_ERROR_CODES.TRANSACTION_FAILED,
-        message: result.error?.message ?? "The wallet did not sign the authorization entry.",
-        chain: "stellar",
-      });
-    }
-    return result.signedAuthEntry;
+    const entry = xdr.SorobanAuthorizationEntry.fromXDR(
+      build.userAuthEntry,
+      "base64",
+    );
+    const expirationLedger = entry.credentials().address().signatureExpirationLedger();
+    const signedEntry = await authorizeEntry(
+      entry,
+      async (preimage) => {
+        const result = await this.config.signAuthEntry!(preimage.toXDR("base64"), {
+          networkPassphrase: this.config.networkPassphrase,
+          address: this.config.publicKey,
+        });
+        if (result.error || !result.signedAuthEntry) {
+          throw new FundableError({
+            code: FUNDABLE_ERROR_CODES.TRANSACTION_FAILED,
+            message:
+              result.error?.message ?? "The wallet did not sign the authorization entry.",
+            chain: "stellar",
+          });
+        }
+        return base64ToBytes(result.signedAuthEntry);
+      },
+      expirationLedger,
+      this.config.networkPassphrase,
+    );
+    return signedEntry.toXDR("base64");
   }
 }

src/stellar/sponsorship-client.ts

@@ -48,6 +48,14 @@ interface ExistingStreamIntent {
 }
 
 export type StellarSponsorIntent =
+  | {
+      operation: "approve";
+      owner: string;
+      token: string;
+      spender: string;
+      amount: string;
+      expiration_ledger: number;
+    }
   | {
       operation: "create";
       stream_kind: "lockup";