wallet-core: support multi-batch p2p payments

7 files changed, 554 insertions, 120 deletions

diff --git a/packages/taler-harness/src/integrationtests/test-peer-pull-large.ts b/packages/taler-harness/src/integrationtests/test-peer-pull-large.ts
new file mode 100644
index 000000000..6de3c2e33
--- /dev/null
+++ b/packages/taler-harness/src/integrationtests/test-peer-pull-large.ts
@@ -0,0 +1,194 @@
+/*
+ This file is part of GNU Taler
+ (C) 2024 Taler Systems S.A.
+
+ GNU Taler is free software; you can redistribute it and/or modify it under the
+ terms of the GNU General Public License as published by the Free Software
+ Foundation; either version 3, or (at your option) any later version.
+
+ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License along with
+ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+/**
+ * Imports.
+ */
+import {
+  AbsoluteTime,
+  AmountString,
+  Duration,
+  j2s,
+  NotificationType,
+  TransactionMajorState,
+  TransactionMinorState,
+  TransactionType,
+  WalletNotification,
+} from "@gnu-taler/taler-util";
+import { WalletApiOperation } from "@gnu-taler/taler-wallet-core";
+import { CoinConfig } from "../harness/denomStructures.js";
+import {
+  BankServiceHandle,
+  ExchangeService,
+  GlobalTestState,
+  WalletClient,
+} from "../harness/harness.js";
+import {
+  createSimpleTestkudosEnvironmentV2,
+  createWalletDaemonWithClient,
+  withdrawViaBankV2,
+} from "../harness/helpers.js";
+
+const coinCommon = {
+  cipher: "RSA" as const,
+  durationLegal: "3 years",
+  durationSpend: "2 years",
+  durationWithdraw: "7 days",
+  feeDeposit: "TESTKUDOS:0",
+  feeRefresh: "TESTKUDOS:0",
+  feeRefund: "TESTKUDOS:0",
+  feeWithdraw: "TESTKUDOS:0",
+  rsaKeySize: 1024,
+};
+
+const coinConfigList: CoinConfig[] = [
+  {
+    ...coinCommon,
+    name: "n1",
+    value: "TESTKUDOS:1",
+  },
+];
+
+export async function runPeerPullLargeTest(t: GlobalTestState) {
+  // Set up test environment
+
+  const { bank, exchange } = await createSimpleTestkudosEnvironmentV2(
+    t,
+    coinConfigList,
+  );
+
+  let allW1Notifications: WalletNotification[] = [];
+  let allW2Notifications: WalletNotification[] = [];
+
+  const w1 = await createWalletDaemonWithClient(t, {
+    name: "w1",
+    persistent: true,
+    handleNotification(wn) {
+      allW1Notifications.push(wn);
+    },
+  });
+  const w2 = await createWalletDaemonWithClient(t, {
+    name: "w2",
+    persistent: true,
+    handleNotification(wn) {
+      allW2Notifications.push(wn);
+    },
+  });
+
+  // Withdraw digital cash into the wallet.
+  const wallet1 = w1.walletClient;
+  const wallet2 = w2.walletClient;
+
+  await checkNormalPeerPull(t, bank, exchange, wallet1, wallet2);
+}
+
+async function checkNormalPeerPull(
+  t: GlobalTestState,
+  bank: BankServiceHandle,
+  exchange: ExchangeService,
+  wallet1: WalletClient,
+  wallet2: WalletClient,
+): Promise<void> {
+  const withdrawRes = await withdrawViaBankV2(t, {
+    walletClient: wallet2,
+    bank,
+    exchange,
+    amount: "TESTKUDOS:500",
+  });
+
+  await withdrawRes.withdrawalFinishedCond;
+
+  const purseExpiration = AbsoluteTime.toProtocolTimestamp(
+    AbsoluteTime.addDuration(
+      AbsoluteTime.now(),
+      Duration.fromSpec({ days: 2 }),
+    ),
+  );
+
+  const resp = await wallet1.client.call(
+    WalletApiOperation.InitiatePeerPullCredit,
+    {
+      exchangeBaseUrl: exchange.baseUrl,
+      partialContractTerms: {
+        summary: "Hello World",
+        amount: "TESTKUDOS:200" as AmountString,
+        purse_expiration: purseExpiration,
+      },
+    },
+  );
+
+  const peerPullCreditReadyCond = wallet1.waitForNotificationCond(
+    (x) =>
+      x.type === NotificationType.TransactionStateTransition &&
+      x.transactionId === resp.transactionId &&
+      x.newTxState.major === TransactionMajorState.Pending &&
+      x.newTxState.minor === TransactionMinorState.Ready,
+  );
+
+  await peerPullCreditReadyCond;
+
+  const creditTx = await wallet1.call(WalletApiOperation.GetTransactionById, {
+    transactionId: resp.transactionId,
+  });
+
+  t.assertDeepEqual(creditTx.type, TransactionType.PeerPullCredit);
+  t.assertTrue(!!creditTx.talerUri);
+
+  const checkResp = await wallet2.client.call(
+    WalletApiOperation.PreparePeerPullDebit,
+    {
+      talerUri: creditTx.talerUri,
+    },
+  );
+
+  console.log(`checkResp: ${j2s(checkResp)}`);
+
+  const peerPullCreditDoneCond = wallet1.waitForNotificationCond(
+    (x) =>
+      x.type === NotificationType.TransactionStateTransition &&
+      x.transactionId === resp.transactionId &&
+      x.newTxState.major === TransactionMajorState.Done,
+  );
+
+  const peerPullDebitDoneCond = wallet2.waitForNotificationCond(
+    (x) =>
+      x.type === NotificationType.TransactionStateTransition &&
+      x.transactionId === checkResp.transactionId &&
+      x.newTxState.major === TransactionMajorState.Done,
+  );
+
+  await wallet2.client.call(WalletApiOperation.ConfirmPeerPullDebit, {
+    transactionId: checkResp.transactionId,
+  });
+
+  await peerPullCreditDoneCond;
+  await peerPullDebitDoneCond;
+
+  const txn1 = await wallet1.client.call(
+    WalletApiOperation.GetTransactions,
+    {},
+  );
+
+  const txn2 = await wallet2.client.call(
+    WalletApiOperation.GetTransactions,
+    {},
+  );
+
+  console.log(`txn1: ${j2s(txn1)}`);
+  console.log(`txn2: ${j2s(txn2)}`);
+}
+
+runPeerPullLargeTest.suites = ["wallet"];
diff --git a/packages/taler-harness/src/integrationtests/test-peer-push-large.ts b/packages/taler-harness/src/integrationtests/test-peer-push-large.ts
new file mode 100644
index 000000000..b7fbe9f6e
--- /dev/null
+++ b/packages/taler-harness/src/integrationtests/test-peer-push-large.ts
@@ -0,0 +1,177 @@
+/*
+ This file is part of GNU Taler
+ (C) 2020 Taler Systems S.A.
+
+ GNU Taler is free software; you can redistribute it and/or modify it under the
+ terms of the GNU General Public License as published by the Free Software
+ Foundation; either version 3, or (at your option) any later version.
+
+ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License along with
+ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+/**
+ * Imports.
+ */
+import {
+  AbsoluteTime,
+  AmountString,
+  Duration,
+  NotificationType,
+  TransactionMajorState,
+  TransactionMinorState,
+  TransactionType,
+  WalletNotification,
+  j2s,
+} from "@gnu-taler/taler-util";
+import { WalletApiOperation } from "@gnu-taler/taler-wallet-core";
+import { GlobalTestState } from "../harness/harness.js";
+import {
+  createSimpleTestkudosEnvironmentV2,
+  createWalletDaemonWithClient,
+  withdrawViaBankV2,
+} from "../harness/helpers.js";
+import { CoinConfig } from "../harness/denomStructures.js";
+
+const coinCommon = {
+  cipher: "RSA" as const,
+  durationLegal: "3 years",
+  durationSpend: "2 years",
+  durationWithdraw: "7 days",
+  feeDeposit: "TESTKUDOS:0",
+  feeRefresh: "TESTKUDOS:0",
+  feeRefund: "TESTKUDOS:0",
+  feeWithdraw: "TESTKUDOS:0",
+  rsaKeySize: 1024,
+};
+
+const coinConfigList: CoinConfig[] = [
+  {
+    ...coinCommon,
+    name: "n1",
+    value: "TESTKUDOS:1",
+  },
+];
+
+/**
+ * Run a test for a multi-batch peer push payment.
+ */
+export async function runPeerPushLargeTest(t: GlobalTestState) {
+  const { bank, exchange } = await createSimpleTestkudosEnvironmentV2(t, coinConfigList);
+
+  let allW1Notifications: WalletNotification[] = [];
+  let allW2Notifications: WalletNotification[] = [];
+
+  const w1 = await createWalletDaemonWithClient(t, {
+    name: "w1",
+    handleNotification(wn) {
+      allW1Notifications.push(wn);
+    },
+  });
+  const w2 = await createWalletDaemonWithClient(t, {
+    name: "w2",
+    handleNotification(wn) {
+      allW2Notifications.push(wn);
+    },
+  });
+
+  // Withdraw digital cash into the wallet.
+
+  const withdrawRes = await withdrawViaBankV2(t, {
+    walletClient: w1.walletClient,
+    bank,
+    exchange,
+    amount: "TESTKUDOS:300",
+  });
+
+  await withdrawRes.withdrawalFinishedCond;
+
+  const purse_expiration = AbsoluteTime.toProtocolTimestamp(
+    AbsoluteTime.addDuration(
+      AbsoluteTime.now(),
+      Duration.fromSpec({ days: 2 }),
+    ),
+  );
+
+  const checkResp0 = await w1.walletClient.call(
+    WalletApiOperation.CheckPeerPushDebit,
+    {
+      amount: "TESTKUDOS:200" as AmountString,
+    },
+  );
+
+  t.assertAmountEquals(checkResp0.amountEffective, "TESTKUDOS:200");
+
+  const resp = await w1.walletClient.call(
+    WalletApiOperation.InitiatePeerPushDebit,
+    {
+      partialContractTerms: {
+        summary: "Hello World 🥺",
+        amount: "TESTKUDOS:200" as AmountString,
+        purse_expiration,
+      },
+    },
+  );
+
+  console.log(resp);
+
+  const peerPushReadyCond = w1.walletClient.waitForNotificationCond(
+    (x) =>
+      x.type === NotificationType.TransactionStateTransition &&
+      x.newTxState.major === TransactionMajorState.Pending &&
+      x.newTxState.minor === TransactionMinorState.Ready &&
+      x.transactionId === resp.transactionId,
+  );
+
+  await peerPushReadyCond;
+
+  const txDetails = await w1.walletClient.call(
+    WalletApiOperation.GetTransactionById,
+    {
+      transactionId: resp.transactionId,
+    },
+  );
+  t.assertDeepEqual(txDetails.type, TransactionType.PeerPushDebit);
+  t.assertTrue(!!txDetails.talerUri);
+
+  const checkResp = await w2.walletClient.call(
+    WalletApiOperation.PreparePeerPushCredit,
+    {
+      talerUri: txDetails.talerUri,
+    },
+  );
+
+  console.log(checkResp);
+
+  const acceptResp = await w2.walletClient.call(
+    WalletApiOperation.ConfirmPeerPushCredit,
+    {
+      transactionId: checkResp.transactionId,
+    },
+  );
+
+  console.log(acceptResp);
+
+  await w2.walletClient.call(
+    WalletApiOperation.TestingWaitTransactionsFinal,
+    {},
+  );
+
+  const txn1 = await w1.walletClient.call(
+    WalletApiOperation.GetTransactions,
+    {},
+  );
+  const txn2 = await w2.walletClient.call(
+    WalletApiOperation.GetTransactions,
+    {},
+  );
+
+  console.log(`txn1: ${j2s(txn1)}`);
+  console.log(`txn2: ${j2s(txn2)}`);
+}
+
+runPeerPushLargeTest.suites = ["wallet"];
diff --git a/packages/taler-harness/src/integrationtests/test-wallet-blocked-pay-merchant.ts b/packages/taler-harness/src/integrationtests/test-wallet-blocked-pay-merchant.ts
index 15167d133..004de87c8 100644
--- a/packages/taler-harness/src/integrationtests/test-wallet-blocked-pay-merchant.ts
+++ b/packages/taler-harness/src/integrationtests/test-wallet-blocked-pay-merchant.ts
@@ -44,25 +44,25 @@ const coinCommon = {
   rsaKeySize: 1024,
 };
 
+const coinConfigList: CoinConfig[] = [
+  {
+    ...coinCommon,
+    name: "n1",
+    value: "TESTKUDOS:1",
+  },
+  {
+    ...coinCommon,
+    name: "n5",
+    value: "TESTKUDOS:5",
+  },
+];
+
 /**
  * Run test for paying a merchant with balance locked behind a pending refresh.
  */
 export async function runWalletBlockedPayMerchantTest(t: GlobalTestState) {
   // Set up test environment
 
-  const coinConfigList: CoinConfig[] = [
-    {
-      ...coinCommon,
-      name: "n1",
-      value: "TESTKUDOS:1",
-    },
-    {
-      ...coinCommon,
-      name: "n5",
-      value: "TESTKUDOS:5",
-    },
-  ];
-
   const { bank, exchange, merchant } = await createSimpleTestkudosEnvironmentV2(
     t,
     coinConfigList,
diff --git a/packages/taler-harness/src/integrationtests/testrunner.ts b/packages/taler-harness/src/integrationtests/testrunner.ts
index 54c211c6b..2f6304773 100644
--- a/packages/taler-harness/src/integrationtests/testrunner.ts
+++ b/packages/taler-harness/src/integrationtests/testrunner.ts
@@ -72,6 +72,8 @@ import { runPaymentTransientTest } from "./test-payment-transient.js";
 import { runPaymentZeroTest } from "./test-payment-zero.js";
 import { runPaymentTest } from "./test-payment.js";
 import { runPaywallFlowTest } from "./test-paywall-flow.js";
+import { runPeerPullLargeTest } from "./test-peer-pull-large.js";
+import { runPeerPushLargeTest } from "./test-peer-push-large.js";
 import { runPeerRepairTest } from "./test-peer-repair.js";
 import { runPeerToPeerPullTest } from "./test-peer-to-peer-pull.js";
 import { runPeerToPeerPushTest } from "./test-peer-to-peer-push.js";
@@ -224,6 +226,8 @@ const allTests: TestMainFunction[] = [
   runWalletBlockedPayPeerPullTest,
   runWalletExchangeUpdateTest,
   runWalletRefreshErrorsTest,
+  runPeerPullLargeTest,
+  runPeerPushLargeTest,
 ];
 
 export interface TestRunSpec {
diff --git a/packages/taler-wallet-core/src/crypto/cryptoImplementation.ts b/packages/taler-wallet-core/src/crypto/cryptoImplementation.ts
index 77ee65e52..0745d70c4 100644
--- a/packages/taler-wallet-core/src/crypto/cryptoImplementation.ts
+++ b/packages/taler-wallet-core/src/crypto/cryptoImplementation.ts
@@ -1468,15 +1468,12 @@ export const nativeCryptoR: TalerCryptoInterfaceR = {
     const hExchangeBaseUrl = hash(stringToBytes(req.exchangeBaseUrl + "\0"));
     const deposits: PurseDeposit[] = [];
     for (const c of req.coins) {
-      let haveAch: boolean;
       let maybeAch: Uint8Array;
       if (c.ageCommitmentProof) {
-        haveAch = true;
         maybeAch = decodeCrock(
           AgeRestriction.hashCommitment(c.ageCommitmentProof.commitment),
         );
       } else {
-        haveAch = false;
         maybeAch = new Uint8Array(32);
       }
       const sigBlob = buildSigPS(TalerSignaturePurpose.WALLET_PURSE_DEPOSIT)
diff --git a/packages/taler-wallet-core/src/pay-peer-pull-debit.ts b/packages/taler-wallet-core/src/pay-peer-pull-debit.ts
index 705317eb6..92eb44a87 100644
--- a/packages/taler-wallet-core/src/pay-peer-pull-debit.ts
+++ b/packages/taler-wallet-core/src/pay-peer-pull-debit.ts
@@ -33,6 +33,7 @@ import {
   HttpStatusCode,
   Logger,
   NotificationType,
+  ObservabilityEventType,
   PeerContractTerms,
   PreparePeerPullDebitRequest,
   PreparePeerPullDebitResponse,
@@ -425,6 +426,11 @@ async function processPeerPullDebitPendingDeposit(
   wex: WalletExecutionContext,
   peerPullInc: PeerPullPaymentIncomingRecord,
 ): Promise<TaskRunResult> {
+  const ctx = new PeerPullDebitTransactionContext(
+    wex,
+    peerPullInc.peerPullDebitId,
+  );
+
   const pursePub = peerPullInc.pursePub;
 
   const coinSel = peerPullInc.coinSel;
@@ -512,70 +518,82 @@ async function processPeerPullDebitPendingDeposit(
     }
   }
 
-  const coins = await queryCoinInfosForSelection(wex, coinSel);
-
-  const depositSigsResp = await wex.cryptoApi.signPurseDeposits({
-    exchangeBaseUrl: peerPullInc.exchangeBaseUrl,
-    pursePub: peerPullInc.pursePub,
-    coins,
-  });
-
   const purseDepositUrl = new URL(
     `purses/${pursePub}/deposit`,
     peerPullInc.exchangeBaseUrl,
   );
 
-  const depositPayload: ExchangePurseDeposits = {
-    deposits: depositSigsResp.deposits,
-  };
+  // FIXME: We could skip batches that we've already submitted.
 
-  if (logger.shouldLogTrace()) {
-    logger.trace(`purse deposit payload: ${j2s(depositPayload)}`);
-  }
+  const coins = await queryCoinInfosForSelection(wex, coinSel);
 
-  const httpResp = await wex.http.fetch(purseDepositUrl.href, {
-    method: "POST",
-    body: depositPayload,
-    cancellationToken: wex.cancellationToken,
-  });
+  const maxBatchSize = 100;
 
-  const ctx = new PeerPullDebitTransactionContext(
-    wex,
-    peerPullInc.peerPullDebitId,
-  );
+  for (let i = 0; i < coins.length; i += maxBatchSize) {
+    const batchSize = Math.min(maxBatchSize, coins.length - i);
 
-  switch (httpResp.status) {
-    case HttpStatusCode.Ok: {
-      const resp = await readSuccessResponseJsonOrThrow(
-        httpResp,
-        codecForAny(),
-      );
-      logger.trace(`purse deposit response: ${j2s(resp)}`);
+    wex.oc.observe({
+      type: ObservabilityEventType.Message,
+      contents: `Depositing batch at ${i}/${coins.length} of size ${batchSize}`,
+    });
 
-      await ctx.transition(async (r) => {
-        if (r.status !== PeerPullDebitRecordStatus.PendingDeposit) {
-          return TransitionResultType.Stay;
-        }
-        r.status = PeerPullDebitRecordStatus.Done;
-        return TransitionResultType.Transition;
-      });
-      return TaskRunResult.finished();
-    }
-    case HttpStatusCode.Gone: {
-      await ctx.abortTransaction();
-      return TaskRunResult.backoff();
-    }
-    case HttpStatusCode.Conflict: {
-      return handlePurseCreationConflict(ctx, peerPullInc, httpResp);
+    const batchCoins = coins.slice(i, i + batchSize);
+    const depositSigsResp = await wex.cryptoApi.signPurseDeposits({
+      exchangeBaseUrl: peerPullInc.exchangeBaseUrl,
+      pursePub: peerPullInc.pursePub,
+      coins: batchCoins,
+    });
+
+    const depositPayload: ExchangePurseDeposits = {
+      deposits: depositSigsResp.deposits,
+    };
+
+    if (logger.shouldLogTrace()) {
+      logger.trace(`purse deposit payload: ${j2s(depositPayload)}`);
     }
-    default: {
-      const errResp = await readTalerErrorResponse(httpResp);
-      return {
-        type: TaskRunResultType.Error,
-        errorDetail: errResp,
-      };
+
+    const httpResp = await wex.http.fetch(purseDepositUrl.href, {
+      method: "POST",
+      body: depositPayload,
+      cancellationToken: wex.cancellationToken,
+    });
+
+    switch (httpResp.status) {
+      case HttpStatusCode.Ok: {
+        const resp = await readSuccessResponseJsonOrThrow(
+          httpResp,
+          codecForAny(),
+        );
+        logger.trace(`purse deposit response: ${j2s(resp)}`);
+        continue;
+      }
+      case HttpStatusCode.Gone: {
+        await ctx.abortTransaction();
+        return TaskRunResult.backoff();
+      }
+      case HttpStatusCode.Conflict: {
+        return handlePurseCreationConflict(ctx, peerPullInc, httpResp);
+      }
+      default: {
+        const errResp = await readTalerErrorResponse(httpResp);
+        return {
+          type: TaskRunResultType.Error,
+          errorDetail: errResp,
+        };
+      }
     }
   }
+
+  // All batches succeeded, we can transition!
+
+  await ctx.transition(async (r) => {
+    if (r.status !== PeerPullDebitRecordStatus.PendingDeposit) {
+      return TransitionResultType.Stay;
+    }
+    r.status = PeerPullDebitRecordStatus.Done;
+    return TransitionResultType.Transition;
+  });
+  return TaskRunResult.finished();
 }
 
 async function processPeerPullDebitAbortingRefresh(
diff --git a/packages/taler-wallet-core/src/pay-peer-push-debit.ts b/packages/taler-wallet-core/src/pay-peer-push-debit.ts
index b6771be89..63a02d7a7 100644
--- a/packages/taler-wallet-core/src/pay-peer-push-debit.ts
+++ b/packages/taler-wallet-core/src/pay-peer-push-debit.ts
@@ -20,6 +20,7 @@ import {
   CheckPeerPushDebitResponse,
   CoinRefreshRequest,
   ContractTermsUtil,
+  ExchangePurseDeposits,
   HttpStatusCode,
   InitiatePeerPushDebitRequest,
   InitiatePeerPushDebitResponse,
@@ -564,12 +565,6 @@ async function processPeerPushDebitCreateReserve(
     peerPushInitiation.coinSel,
   );
 
-  const depositSigsResp = await wex.cryptoApi.signPurseDeposits({
-    exchangeBaseUrl: peerPushInitiation.exchangeBaseUrl,
-    pursePub: peerPushInitiation.pursePub,
-    coins,
-  });
-
   const encryptContractRequest: EncryptContractRequest = {
     contractTerms: contractTermsRecord.contractTermsRaw,
     mergePriv: peerPushInitiation.mergePriv,
@@ -580,66 +575,115 @@ async function processPeerPushDebitCreateReserve(
     nonce: peerPushInitiation.contractEncNonce,
   };
 
-  logger.trace(`encrypt contract request: ${j2s(encryptContractRequest)}`);
-
   const econtractResp = await wex.cryptoApi.encryptContractForMerge(
     encryptContractRequest,
   );
 
-  const createPurseUrl = new URL(
-    `purses/${peerPushInitiation.pursePub}/create`,
-    peerPushInitiation.exchangeBaseUrl,
-  );
+  const maxBatchSize = 100;
 
-  const reqBody = {
-    amount: peerPushInitiation.amount,
-    merge_pub: peerPushInitiation.mergePub,
-    purse_sig: purseSigResp.sig,
-    h_contract_terms: hContractTerms,
-    purse_expiration: timestampProtocolFromDb(purseExpiration),
-    deposits: depositSigsResp.deposits,
-    min_age: 0,
-    econtract: econtractResp.econtract,
-  };
+  for (let i = 0; i < coins.length; i += maxBatchSize) {
+    const batchSize = Math.min(maxBatchSize, coins.length - i);
+    const batchCoins = coins.slice(i, i + batchSize);
 
-  logger.trace(`request body: ${j2s(reqBody)}`);
+    const depositSigsResp = await wex.cryptoApi.signPurseDeposits({
+      exchangeBaseUrl: peerPushInitiation.exchangeBaseUrl,
+      pursePub: peerPushInitiation.pursePub,
+      coins: batchCoins,
+    });
 
-  const httpResp = await wex.http.fetch(createPurseUrl.href, {
-    method: "POST",
-    body: reqBody,
-    cancellationToken: wex.cancellationToken,
-  });
+    if (i == 0) {
+      // First batch creates the purse!
 
-  {
-    const resp = await httpResp.json();
-    logger.info(`resp: ${j2s(resp)}`);
-  }
+      logger.trace(`encrypt contract request: ${j2s(encryptContractRequest)}`);
 
-  switch (httpResp.status) {
-    case HttpStatusCode.Ok:
-      break;
-    case HttpStatusCode.Forbidden: {
-      // FIXME: Store this error!
-      await ctx.failTransaction();
-      return TaskRunResult.finished();
-    }
-    case HttpStatusCode.Conflict: {
-      // Handle double-spending
-      return handlePurseCreationConflict(wex, peerPushInitiation, httpResp);
-    }
-    default: {
-      const errResp = await readTalerErrorResponse(httpResp);
-      return {
-        type: TaskRunResultType.Error,
-        errorDetail: errResp,
+      const createPurseUrl = new URL(
+        `purses/${peerPushInitiation.pursePub}/create`,
+        peerPushInitiation.exchangeBaseUrl,
+      );
+
+      const reqBody = {
+        amount: peerPushInitiation.amount,
+        merge_pub: peerPushInitiation.mergePub,
+        purse_sig: purseSigResp.sig,
+        h_contract_terms: hContractTerms,
+        purse_expiration: timestampProtocolFromDb(purseExpiration),
+        deposits: depositSigsResp.deposits,
+        min_age: 0,
+        econtract: econtractResp.econtract,
       };
+
+      if (logger.shouldLogTrace()) {
+        logger.trace(`request body: ${j2s(reqBody)}`);
+      }
+
+      const httpResp = await wex.http.fetch(createPurseUrl.href, {
+        method: "POST",
+        body: reqBody,
+        cancellationToken: wex.cancellationToken,
+      });
+
+      switch (httpResp.status) {
+        case HttpStatusCode.Ok:
+          // Possibly on to the next batch.
+          continue;
+        case HttpStatusCode.Forbidden: {
+          // FIXME: Store this error!
+          await ctx.failTransaction();
+          return TaskRunResult.finished();
+        }
+        case HttpStatusCode.Conflict: {
+          // Handle double-spending
+          return handlePurseCreationConflict(wex, peerPushInitiation, httpResp);
+        }
+        default: {
+          const errResp = await readTalerErrorResponse(httpResp);
+          return {
+            type: TaskRunResultType.Error,
+            errorDetail: errResp,
+          };
+        }
+      }
+    } else {
+      const purseDepositUrl = new URL(
+        `purses/${pursePub}/deposit`,
+        peerPushInitiation.exchangeBaseUrl,
+      );
+
+      const depositPayload: ExchangePurseDeposits = {
+        deposits: depositSigsResp.deposits,
+      };
+
+      const httpResp = await wex.http.fetch(purseDepositUrl.href, {
+        method: "POST",
+        body: depositPayload,
+        cancellationToken: wex.cancellationToken,
+      });
+
+      switch (httpResp.status) {
+        case HttpStatusCode.Ok:
+          // Possibly on to the next batch.
+          continue;
+        case HttpStatusCode.Forbidden: {
+          // FIXME: Store this error!
+          await ctx.failTransaction();
+          return TaskRunResult.finished();
+        }
+        case HttpStatusCode.Conflict: {
+          // Handle double-spending
+          return handlePurseCreationConflict(wex, peerPushInitiation, httpResp);
+        }
+        default: {
+          const errResp = await readTalerErrorResponse(httpResp);
+          return {
+            type: TaskRunResultType.Error,
+            errorDetail: errResp,
+          };
+        }
+      }
     }
   }
 
-  if (httpResp.status !== HttpStatusCode.Ok) {
-    // FIXME: do proper error reporting
-    throw Error("got error response from exchange");
-  }
+  // All batches done!
 
   await transitionPeerPushDebitTransaction(wex, pursePub, {
     stFrom: PeerPushDebitStatus.PendingCreatePurse,