harness: get rid of deprecated merchant API client

27 files changed, 306 insertions, 334 deletions

diff --git a/packages/taler-harness/src/harness/harness.ts b/packages/taler-harness/src/harness/harness.ts
index 99151b219..a16cef7ba 100644
--- a/packages/taler-harness/src/harness/harness.ts
+++ b/packages/taler-harness/src/harness/harness.ts
@@ -1364,6 +1364,9 @@ export const harnessHttpLib = createPlatformHttpLib({
   enableThrottling: false,
 });
 
+/**
+ * FIXME: Move this out of the harness.
+ */
 export class MerchantApiClient {
   /**
    * Base URL for the particular instance that this merchant API client
@@ -1513,95 +1516,32 @@ export class MerchantApiClient {
     );
   }
 
-  private makeAuthHeader(): Record<string, string> {
-    switch (this.auth.method) {
-      case "external":
-        return {};
-      case "token":
-        return {
-          Authorization: `Bearer ${this.auth.token}`,
-        };
-    }
-  }
-}
-
-/**
- * FIXME:  This should be deprecated in favor of MerchantApiClient
- *
- * @deprecated use MerchantApiClient instead
- */
-export namespace MerchantPrivateApi {
-  export async function createOrder(
-    merchantService: MerchantServiceInterface,
-    instanceName: string,
-    req: MerchantPostOrderRequest,
-    withAuthorization: WithAuthorization = {},
-  ): Promise<MerchantPostOrderResponse> {
-    const baseUrl = merchantService.makeInstanceBaseUrl(instanceName);
-    let url = new URL("private/orders", baseUrl);
-    const resp = await harnessHttpLib.fetch(url.href, {
-      method: "POST",
-      body: req,
-      headers: withAuthorization as Record<string, string>,
-    });
-    return readSuccessResponseJsonOrThrow(
-      resp,
-      codecForMerchantPostOrderResponse(),
-    );
-  }
-
-  export async function createTemplate(
-    merchantService: MerchantServiceInterface,
-    instanceName: string,
-    req: MerchantTemplateAddDetails,
-    withAuthorization: WithAuthorization = {},
-  ) {
-    const baseUrl = merchantService.makeInstanceBaseUrl(instanceName);
-    let url = new URL("private/templates", baseUrl);
-    const resp = await harnessHttpLib.fetch(url.href, {
+  async giveTip(req: RewardCreateRequest): Promise<RewardCreateConfirmation> {
+    const reqUrl = new URL(`private/tips`, this.baseUrl);
+    const resp = await harnessHttpLib.fetch(reqUrl.href, {
       method: "POST",
       body: req,
-      headers: withAuthorization as Record<string, string>,
     });
-    if (resp.status !== 204) {
-      throw Error("failed to create template");
-    }
+    // FIXME: validate
+    return resp.json();
   }
 
-  export async function queryPrivateOrderStatus(
-    merchantService: MerchantServiceInterface,
-    query: PrivateOrderStatusQuery,
-    withAuthorization: WithAuthorization = {},
-  ): Promise<MerchantOrderPrivateStatusResponse> {
-    const reqUrl = new URL(
-      `private/orders/${query.orderId}`,
-      merchantService.makeInstanceBaseUrl(query.instance),
-    );
-    if (query.sessionId) {
-      reqUrl.searchParams.set("session_id", query.sessionId);
-    }
+  async queryTippingReserves(): Promise<TippingReserveStatus> {
+    const reqUrl = new URL(`private/reserves`, this.baseUrl);
     const resp = await harnessHttpLib.fetch(reqUrl.href, {
-      headers: withAuthorization as Record<string, string>,
+      headers: this.makeAuthHeader(),
     });
-    return readSuccessResponseJsonOrThrow(
-      resp,
-      codecForMerchantOrderPrivateStatusResponse(),
-    );
+    // FIXME: validate
+    return resp.json();
   }
 
-  export async function giveRefund(
-    merchantService: MerchantServiceInterface,
-    r: {
-      instance: string;
-      orderId: string;
-      amount: string;
-      justification: string;
-    },
-  ): Promise<{ talerRefundUri: string }> {
-    const reqUrl = new URL(
-      `private/orders/${r.orderId}/refund`,
-      merchantService.makeInstanceBaseUrl(r.instance),
-    );
+  async giveRefund(r: {
+    instance: string;
+    orderId: string;
+    amount: string;
+    justification: string;
+  }): Promise<{ talerRefundUri: string }> {
+    const reqUrl = new URL(`private/orders/${r.orderId}/refund`, this.baseUrl);
     const resp = await harnessHttpLib.fetch(reqUrl.href, {
       method: "POST",
       body: {
@@ -1615,34 +1555,27 @@ export namespace MerchantPrivateApi {
     };
   }
 
-  export async function queryTippingReserves(
-    merchantService: MerchantServiceInterface,
-    instance: string,
-  ): Promise<TippingReserveStatus> {
-    const reqUrl = new URL(
-      `private/reserves`,
-      merchantService.makeInstanceBaseUrl(instance),
-    );
-    const resp = await harnessHttpLib.fetch(reqUrl.href);
-    // FIXME: validate
-    return resp.json();
-  }
-
-  export async function giveTip(
-    merchantService: MerchantServiceInterface,
-    instance: string,
-    req: RewardCreateRequest,
-  ): Promise<RewardCreateConfirmation> {
-    const reqUrl = new URL(
-      `private/tips`,
-      merchantService.makeInstanceBaseUrl(instance),
-    );
-    const resp = await harnessHttpLib.fetch(reqUrl.href, {
+  async createTemplate(req: MerchantTemplateAddDetails) {
+    let url = new URL("private/templates", this.baseUrl);
+    const resp = await harnessHttpLib.fetch(url.href, {
       method: "POST",
       body: req,
+      headers: this.makeAuthHeader(),
     });
-    // FIXME: validate
-    return resp.json();
+    if (resp.status !== 204) {
+      throw Error("failed to create template");
+    }
+  }
+
+  private makeAuthHeader(): Record<string, string> {
+    switch (this.auth.method) {
+      case "external":
+        return {};
+      case "token":
+        return {
+          Authorization: `Bearer ${this.auth.token}`,
+        };
+    }
   }
 }
 
diff --git a/packages/taler-harness/src/harness/helpers.ts b/packages/taler-harness/src/harness/helpers.ts
index ece003e1b..485e1baba 100644
--- a/packages/taler-harness/src/harness/helpers.ts
+++ b/packages/taler-harness/src/harness/helpers.ts
@@ -54,7 +54,6 @@ import {
   getPayto,
   GlobalTestState,
   MerchantApiClient,
-  MerchantPrivateApi,
   MerchantService,
   MerchantServiceInterface,
   setupDb,
diff --git a/packages/taler-harness/src/integrationtests/test-age-restrictions-merchant.ts b/packages/taler-harness/src/integrationtests/test-age-restrictions-merchant.ts
index 3072badc0..45a035cc4 100644
--- a/packages/taler-harness/src/integrationtests/test-age-restrictions-merchant.ts
+++ b/packages/taler-harness/src/integrationtests/test-age-restrictions-merchant.ts
@@ -27,8 +27,6 @@ import {
   getWireMethodForTest,
   GlobalTestState,
   MerchantApiClient,
-  MerchantPrivateApi,
-  WalletCli,
 } from "../harness/harness.js";
 import {
   createSimpleTestkudosEnvironmentV2,
@@ -214,7 +212,7 @@ export async function runAgeRestrictionsMerchantTest(t: GlobalTestState) {
 
     await exchange.runWirewatchOnce();
 
-    const tip = await MerchantPrivateApi.giveTip(merchant, "default", {
+    const tip = await merchantClient.giveTip({
       amount: "TESTKUDOS:5",
       justification: "why not?",
       next_url: "https://example.com/after-tip",
diff --git a/packages/taler-harness/src/integrationtests/test-claim-loop.ts b/packages/taler-harness/src/integrationtests/test-claim-loop.ts
index 32706c28b..52841dbab 100644
--- a/packages/taler-harness/src/integrationtests/test-claim-loop.ts
+++ b/packages/taler-harness/src/integrationtests/test-claim-loop.ts
@@ -19,7 +19,10 @@
  */
 import { WalletApiOperation } from "@gnu-taler/taler-wallet-core";
 import { URL } from "url";
-import { GlobalTestState, MerchantPrivateApi } from "../harness/harness.js";
+import {
+  GlobalTestState,
+  MerchantApiClient,
+} from "../harness/harness.js";
 import {
   createSimpleTestkudosEnvironmentV2,
   withdrawViaBankV2,
@@ -44,8 +47,10 @@ export async function runClaimLoopTest(t: GlobalTestState) {
     amount: "TESTKUDOS:20",
   });
 
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
+
   // Set up order.
-  const orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  const orderResp = await merchantClient.createOrder({
     order: {
       summary: "Buy me!",
       amount: "TESTKUDOS:5",
@@ -54,12 +59,9 @@ export async function runClaimLoopTest(t: GlobalTestState) {
   });
 
   // Query private order status before claiming it.
-  let orderStatusBefore = await MerchantPrivateApi.queryPrivateOrderStatus(
-    merchant,
-    {
-      orderId: orderResp.order_id,
-    },
-  );
+  let orderStatusBefore = await merchantClient.queryPrivateOrderStatus({
+    orderId: orderResp.order_id,
+  });
   t.assertTrue(orderStatusBefore.order_status === "unpaid");
   let statusUrlBefore = new URL(orderStatusBefore.order_status_url);
 
@@ -71,12 +73,9 @@ export async function runClaimLoopTest(t: GlobalTestState) {
   });
 
   // Query private order status after claiming it.
-  let orderStatusAfter = await MerchantPrivateApi.queryPrivateOrderStatus(
-    merchant,
-    {
-      orderId: orderResp.order_id,
-    },
-  );
+  let orderStatusAfter = await merchantClient.queryPrivateOrderStatus({
+    orderId: orderResp.order_id,
+  });
   t.assertTrue(orderStatusAfter.order_status === "claimed");
 
   await t.shutdown();
diff --git a/packages/taler-harness/src/integrationtests/test-denom-unoffered.ts b/packages/taler-harness/src/integrationtests/test-denom-unoffered.ts
index 5a471b9aa..a9282f394 100644
--- a/packages/taler-harness/src/integrationtests/test-denom-unoffered.ts
+++ b/packages/taler-harness/src/integrationtests/test-denom-unoffered.ts
@@ -19,7 +19,10 @@
  */
 import { PreparePayResultType, TalerErrorCode } from "@gnu-taler/taler-util";
 import { WalletApiOperation } from "@gnu-taler/taler-wallet-core";
-import { GlobalTestState, MerchantPrivateApi } from "../harness/harness.js";
+import {
+  GlobalTestState,
+  MerchantApiClient,
+} from "../harness/harness.js";
 import {
   createSimpleTestkudosEnvironmentV2,
   withdrawViaBankV2,
@@ -62,11 +65,13 @@ export async function runDenomUnofferedTest(t: GlobalTestState) {
     fulfillment_url: "taler://fulfillment-success/thx",
   };
 
-  const orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
+
+  const orderResp = await merchantClient.createOrder({
     order: order,
   });
 
-  let orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  let orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
diff --git a/packages/taler-harness/src/integrationtests/test-merchant-exchange-confusion.ts b/packages/taler-harness/src/integrationtests/test-merchant-exchange-confusion.ts
index 2a8ae39d8..3c71e0f7e 100644
--- a/packages/taler-harness/src/integrationtests/test-merchant-exchange-confusion.ts
+++ b/packages/taler-harness/src/integrationtests/test-merchant-exchange-confusion.ts
@@ -35,10 +35,9 @@ import {
   getPayto,
   GlobalTestState,
   harnessHttpLib,
-  MerchantPrivateApi,
+  MerchantApiClient,
   MerchantService,
   setupDb,
-  WalletCli,
 } from "../harness/harness.js";
 import {
   createWalletDaemonWithClient,
@@ -170,7 +169,9 @@ export async function runMerchantExchangeConfusionTest(t: GlobalTestState) {
 
   const merchant = faultyMerchant;
 
-  let orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
+
+  let orderResp = await merchantClient.createOrder({
     order: {
       summary: "Buy me!",
       amount: "TESTKUDOS:5",
@@ -178,7 +179,7 @@ export async function runMerchantExchangeConfusionTest(t: GlobalTestState) {
     },
   });
 
-  let orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  let orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
     sessionId: "mysession-one",
   });
@@ -233,12 +234,9 @@ export async function runMerchantExchangeConfusionTest(t: GlobalTestState) {
     await publicOrderStatusResp.json(),
   );
 
-  const confirmPayRes = await walletClient.call(
-    WalletApiOperation.ConfirmPay,
-    {
-      proposalId: proposalId,
-    },
-  );
+  const confirmPayRes = await walletClient.call(WalletApiOperation.ConfirmPay, {
+    proposalId: proposalId,
+  });
 
   t.assertTrue(confirmPayRes.type === ConfirmPayResultType.Done);
 }
diff --git a/packages/taler-harness/src/integrationtests/test-merchant-longpolling.ts b/packages/taler-harness/src/integrationtests/test-merchant-longpolling.ts
index 8d271c5d1..d7ffa28d5 100644
--- a/packages/taler-harness/src/integrationtests/test-merchant-longpolling.ts
+++ b/packages/taler-harness/src/integrationtests/test-merchant-longpolling.ts
@@ -24,12 +24,15 @@ import {
   codecForMerchantOrderStatusUnpaid,
 } from "@gnu-taler/taler-util";
 import { WalletApiOperation } from "@gnu-taler/taler-wallet-core";
-import { GlobalTestState, MerchantPrivateApi, harnessHttpLib } from "../harness/harness.js";
+import {
+  GlobalTestState,
+  MerchantApiClient,
+  harnessHttpLib,
+} from "../harness/harness.js";
 import {
   createSimpleTestkudosEnvironmentV2,
   withdrawViaBankV2,
 } from "../harness/helpers.js";
-import { createPlatformHttpLib } from "@gnu-taler/taler-util/http";
 
 /**
  * Run test for basic, bank-integrated withdrawal.
@@ -50,6 +53,8 @@ export async function runMerchantLongpollingTest(t: GlobalTestState) {
 
   await wres.withdrawalFinishedCond;
 
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
+
   /**
    * =========================================================================
    * Create an order and let the wallet pay under a session ID
@@ -59,7 +64,7 @@ export async function runMerchantLongpollingTest(t: GlobalTestState) {
    * =========================================================================
    */
 
-  let orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  let orderResp = await merchantClient.createOrder({
     order: {
       summary: "Buy me!",
       amount: "TESTKUDOS:5",
@@ -68,7 +73,7 @@ export async function runMerchantLongpollingTest(t: GlobalTestState) {
     create_token: false,
   });
 
-  let orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  let orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
     sessionId: "mysession-one",
   });
@@ -81,7 +86,9 @@ export async function runMerchantLongpollingTest(t: GlobalTestState) {
   // First, request order status without longpolling
   {
     console.log("requesting", publicOrderStatusUrl.href);
-    let publicOrderStatusResp = await harnessHttpLib.fetch(publicOrderStatusUrl.href);
+    let publicOrderStatusResp = await harnessHttpLib.fetch(
+      publicOrderStatusUrl.href,
+    );
 
     if (publicOrderStatusResp.status != 402) {
       throw Error(
@@ -94,7 +101,9 @@ export async function runMerchantLongpollingTest(t: GlobalTestState) {
   publicOrderStatusUrl.searchParams.set("timeout_ms", "500");
 
   console.log("requesting", publicOrderStatusUrl.href);
-  let publicOrderStatusResp = await harnessHttpLib.fetch(publicOrderStatusUrl.href);
+  let publicOrderStatusResp = await harnessHttpLib.fetch(
+    publicOrderStatusUrl.href,
+  );
 
   if (publicOrderStatusResp.status != 402) {
     throw Error(
@@ -129,7 +138,9 @@ export async function runMerchantLongpollingTest(t: GlobalTestState) {
     preparePayResp.contractTermsHash,
   );
 
-  let publicOrderStatusPromise = harnessHttpLib.fetch(publicOrderStatusUrl.href);
+  let publicOrderStatusPromise = harnessHttpLib.fetch(
+    publicOrderStatusUrl.href,
+  );
 
   t.assertTrue(preparePayResp.status === PreparePayResultType.PaymentPossible);
 
diff --git a/packages/taler-harness/src/integrationtests/test-merchant-refund-api.ts b/packages/taler-harness/src/integrationtests/test-merchant-refund-api.ts
index bc53cb533..ebca4f769 100644
--- a/packages/taler-harness/src/integrationtests/test-merchant-refund-api.ts
+++ b/packages/taler-harness/src/integrationtests/test-merchant-refund-api.ts
@@ -17,15 +17,13 @@
 /**
  * Imports.
  */
-import { createPlatformHttpLib } from "@gnu-taler/taler-util/http";
 import {
   GlobalTestState,
-  MerchantPrivateApi,
   MerchantServiceInterface,
-  WalletCli,
   ExchangeServiceInterface,
   harnessHttpLib,
   WalletClient,
+  MerchantApiClient,
 } from "../harness/harness.js";
 import {
   createSimpleTestkudosEnvironmentV2,
@@ -51,10 +49,12 @@ async function testRefundApiWithFulfillmentUrl(
     exchange: ExchangeServiceInterface;
   },
 ): Promise<void> {
-  const { walletClient, bank, exchange, merchant } = env;
+  const { walletClient, merchant } = env;
+
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
 
   // Set up order.
-  const orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  const orderResp = await merchantClient.createOrder({
     order: {
       summary: "Buy me!",
       amount: "TESTKUDOS:5",
@@ -65,7 +65,7 @@ async function testRefundApiWithFulfillmentUrl(
     ),
   });
 
-  let orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  let orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
@@ -93,7 +93,7 @@ async function testRefundApiWithFulfillmentUrl(
 
   // Check if payment was successful.
 
-  orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
@@ -110,14 +110,14 @@ async function testRefundApiWithFulfillmentUrl(
     preparePayResult.status === PreparePayResultType.AlreadyConfirmed,
   );
 
-  await MerchantPrivateApi.giveRefund(merchant, {
+  await merchantClient.giveRefund({
     amount: "TESTKUDOS:5",
     instance: "default",
     justification: "foo",
     orderId: orderResp.order_id,
   });
 
-  orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
@@ -165,10 +165,12 @@ async function testRefundApiWithFulfillmentMessage(
     exchange: ExchangeServiceInterface;
   },
 ): Promise<void> {
-  const { walletClient, bank, exchange, merchant } = env;
+  const { walletClient, merchant } = env;
+
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
 
   // Set up order.
-  const orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  const orderResp = await merchantClient.createOrder({
     order: {
       summary: "Buy me!",
       amount: "TESTKUDOS:5",
@@ -179,7 +181,7 @@ async function testRefundApiWithFulfillmentMessage(
     ),
   });
 
-  let orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  let orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
@@ -207,7 +209,7 @@ async function testRefundApiWithFulfillmentMessage(
 
   // Check if payment was successful.
 
-  orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
@@ -224,14 +226,14 @@ async function testRefundApiWithFulfillmentMessage(
     preparePayResult.status === PreparePayResultType.AlreadyConfirmed,
   );
 
-  await MerchantPrivateApi.giveRefund(merchant, {
+  await merchantClient.giveRefund({
     amount: "TESTKUDOS:5",
     instance: "default",
     justification: "foo",
     orderId: orderResp.order_id,
   });
 
-  orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
diff --git a/packages/taler-harness/src/integrationtests/test-merchant-spec-public-orders.ts b/packages/taler-harness/src/integrationtests/test-merchant-spec-public-orders.ts
index 08c9d4bb2..599a3fc16 100644
--- a/packages/taler-harness/src/integrationtests/test-merchant-spec-public-orders.ts
+++ b/packages/taler-harness/src/integrationtests/test-merchant-spec-public-orders.ts
@@ -29,9 +29,8 @@ import {
   BankService,
   ExchangeService,
   GlobalTestState,
-  MerchantPrivateApi,
+  MerchantApiClient,
   MerchantService,
-  WalletCli,
   harnessHttpLib,
 } from "../harness/harness.js";
 import {
@@ -66,7 +65,8 @@ async function testWithClaimToken(
   });
   await wres.withdrawalFinishedCond;
   const sessionId = "mysession";
-  const orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
+  const orderResp = await merchantClient.createOrder({
     order: {
       summary: "Buy me!",
       amount: "TESTKUDOS:5",
@@ -255,18 +255,14 @@ async function testWithClaimToken(
   t.assertTrue(confirmPayRes2.type === ConfirmPayResultType.Done);
 
   // Create another order with identical fulfillment URL to test the "already paid" flow
-  const alreadyPaidOrderResp = await MerchantPrivateApi.createOrder(
-    merchant,
-    "default",
-    {
-      order: {
-        summary: "Buy me!",
-        amount: "TESTKUDOS:5",
-        fulfillment_url: "https://example.com/article42",
-        public_reorder_url: "https://example.com/article42-share",
-      },
+  const alreadyPaidOrderResp = await merchantClient.createOrder({
+    order: {
+      summary: "Buy me!",
+      amount: "TESTKUDOS:5",
+      fulfillment_url: "https://example.com/article42",
+      public_reorder_url: "https://example.com/article42-share",
     },
-  );
+  });
 
   const apOrderId = alreadyPaidOrderResp.order_id;
   const apToken = alreadyPaidOrderResp.token;
@@ -319,6 +315,7 @@ async function testWithoutClaimToken(
   const sessionId = "mysession2";
   const { bank, exchange } = c;
   const { merchant, merchantBaseUrl } = c;
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
   const wres = await withdrawViaBankV2(t, {
     walletClient,
     bank,
@@ -326,7 +323,7 @@ async function testWithoutClaimToken(
     amount: "TESTKUDOS:20",
   });
   await wres.withdrawalFinishedCond;
-  const orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  const orderResp = await merchantClient.createOrder({
     order: {
       summary: "Buy me!",
       amount: "TESTKUDOS:5",
@@ -514,18 +511,14 @@ async function testWithoutClaimToken(
   t.assertTrue(confirmPayRes2.type === ConfirmPayResultType.Done);
 
   // Create another order with identical fulfillment URL to test the "already paid" flow
-  const alreadyPaidOrderResp = await MerchantPrivateApi.createOrder(
-    merchant,
-    "default",
-    {
-      order: {
-        summary: "Buy me!",
-        amount: "TESTKUDOS:5",
-        fulfillment_url: "https://example.com/article42",
-        public_reorder_url: "https://example.com/article42-share",
-      },
+  const alreadyPaidOrderResp = await merchantClient.createOrder({
+    order: {
+      summary: "Buy me!",
+      amount: "TESTKUDOS:5",
+      fulfillment_url: "https://example.com/article42",
+      public_reorder_url: "https://example.com/article42-share",
     },
-  );
+  });
 
   const apOrderId = alreadyPaidOrderResp.order_id;
   const apToken = alreadyPaidOrderResp.token;
diff --git a/packages/taler-harness/src/integrationtests/test-pay-paid.ts b/packages/taler-harness/src/integrationtests/test-pay-paid.ts
index 8d39ad4f6..4fe13b3ae 100644
--- a/packages/taler-harness/src/integrationtests/test-pay-paid.ts
+++ b/packages/taler-harness/src/integrationtests/test-pay-paid.ts
@@ -19,7 +19,7 @@
  */
 import {
   GlobalTestState,
-  MerchantPrivateApi,
+  MerchantApiClient,
   harnessHttpLib,
 } from "../harness/harness.js";
 import {
@@ -71,7 +71,9 @@ export async function runPayPaidTest(t: GlobalTestState) {
 
   const merchant = faultyMerchant;
 
-  let orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
+
+  let orderResp = await merchantClient.createOrder({
     order: {
       summary: "Buy me!",
       amount: "TESTKUDOS:5",
@@ -80,7 +82,7 @@ export async function runPayPaidTest(t: GlobalTestState) {
     },
   });
 
-  let orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  let orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
     sessionId: "mysession-one",
   });
@@ -127,12 +129,9 @@ export async function runPayPaidTest(t: GlobalTestState) {
     publicOrderStatusResp.json(),
   );
 
-  const confirmPayRes = await walletClient.call(
-    WalletApiOperation.ConfirmPay,
-    {
-      proposalId: proposalId,
-    },
-  );
+  const confirmPayRes = await walletClient.call(WalletApiOperation.ConfirmPay, {
+    proposalId: proposalId,
+  });
 
   t.assertTrue(confirmPayRes.type === ConfirmPayResultType.Done);
 
@@ -153,7 +152,7 @@ export async function runPayPaidTest(t: GlobalTestState) {
    * =========================================================================
    */
 
-  orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
     sessionId: "mysession-two",
   });
@@ -180,7 +179,7 @@ export async function runPayPaidTest(t: GlobalTestState) {
     },
   });
 
-  let orderRespTwo = await MerchantPrivateApi.createOrder(merchant, "default", {
+  let orderRespTwo = await merchantClient.createOrder({
     order: {
       summary: "Buy me!",
       amount: "TESTKUDOS:5",
@@ -189,13 +188,10 @@ export async function runPayPaidTest(t: GlobalTestState) {
     },
   });
 
-  let orderStatusTwo = await MerchantPrivateApi.queryPrivateOrderStatus(
-    merchant,
-    {
-      orderId: orderRespTwo.order_id,
-      sessionId: "mysession-two",
-    },
-  );
+  let orderStatusTwo = await merchantClient.queryPrivateOrderStatus({
+    orderId: orderRespTwo.order_id,
+    sessionId: "mysession-two",
+  });
 
   t.assertTrue(orderStatusTwo.order_status === "unpaid");
 
diff --git a/packages/taler-harness/src/integrationtests/test-payment-abort.ts b/packages/taler-harness/src/integrationtests/test-payment-abort.ts
index 99140b2ee..22e087161 100644
--- a/packages/taler-harness/src/integrationtests/test-payment-abort.ts
+++ b/packages/taler-harness/src/integrationtests/test-payment-abort.ts
@@ -19,7 +19,7 @@
  */
 import {
   GlobalTestState,
-  MerchantPrivateApi,
+  MerchantApiClient,
   harnessHttpLib,
 } from "../harness/harness.js";
 import {
@@ -55,7 +55,9 @@ export async function runPaymentAbortTest(t: GlobalTestState) {
 
   const merchant = faultyMerchant;
 
-  let orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
+
+  let orderResp = await merchantClient.createOrder({
     order: {
       summary: "Buy me!",
       amount: "TESTKUDOS:5",
@@ -64,7 +66,7 @@ export async function runPaymentAbortTest(t: GlobalTestState) {
     },
   });
 
-  let orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  let orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
     sessionId: "mysession-one",
   });
diff --git a/packages/taler-harness/src/integrationtests/test-payment-claim.ts b/packages/taler-harness/src/integrationtests/test-payment-claim.ts
index 3e52cb5dd..df86b3cbf 100644
--- a/packages/taler-harness/src/integrationtests/test-payment-claim.ts
+++ b/packages/taler-harness/src/integrationtests/test-payment-claim.ts
@@ -19,11 +19,7 @@
  */
 import { PreparePayResultType, TalerErrorCode } from "@gnu-taler/taler-util";
 import { WalletApiOperation } from "@gnu-taler/taler-wallet-core";
-import {
-  GlobalTestState,
-  MerchantPrivateApi,
-  WalletCli,
-} from "../harness/harness.js";
+import { GlobalTestState, MerchantApiClient, WalletCli } from "../harness/harness.js";
 import {
   createSimpleTestkudosEnvironmentV2,
   withdrawViaBankV2,
@@ -38,6 +34,8 @@ export async function runPaymentClaimTest(t: GlobalTestState) {
   const { walletClient, bank, exchange, merchant } =
     await createSimpleTestkudosEnvironmentV2(t);
 
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
+
   const walletTwo = new WalletCli(t, "two");
 
   // Withdraw digital cash into the wallet.
@@ -53,7 +51,7 @@ export async function runPaymentClaimTest(t: GlobalTestState) {
 
   // Set up order.
 
-  const orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  const orderResp = await merchantClient.createOrder({
     order: {
       summary: "Buy me!",
       amount: "TESTKUDOS:5",
@@ -61,7 +59,7 @@ export async function runPaymentClaimTest(t: GlobalTestState) {
     },
   });
 
-  let orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  let orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
@@ -94,7 +92,7 @@ export async function runPaymentClaimTest(t: GlobalTestState) {
 
   // Check if payment was successful.
 
-  orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
diff --git a/packages/taler-harness/src/integrationtests/test-payment-fault.ts b/packages/taler-harness/src/integrationtests/test-payment-fault.ts
index 0cc369a6e..5d0fe6e13 100644
--- a/packages/taler-harness/src/integrationtests/test-payment-fault.ts
+++ b/packages/taler-harness/src/integrationtests/test-payment-fault.ts
@@ -28,8 +28,8 @@ import {
   setupDb,
   BankService,
   WalletCli,
-  MerchantPrivateApi,
   getPayto,
+  MerchantApiClient,
 } from "../harness/harness.js";
 import {
   FaultInjectedExchangeService,
@@ -120,6 +120,8 @@ export async function runPaymentFaultTest(t: GlobalTestState) {
     paytoUris: [getPayto("merchant-default")],
   });
 
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
+
   console.log("setup done!");
 
   const wallet = new WalletCli(t);
@@ -161,7 +163,7 @@ export async function runPaymentFaultTest(t: GlobalTestState) {
 
   // Set up order.
 
-  const orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  const orderResp = await merchantClient.createOrder({
     order: {
       summary: "Buy me!",
       amount: "TESTKUDOS:5",
@@ -169,7 +171,7 @@ export async function runPaymentFaultTest(t: GlobalTestState) {
     },
   });
 
-  let orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  let orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
@@ -218,7 +220,7 @@ export async function runPaymentFaultTest(t: GlobalTestState) {
 
   // Check if payment was successful.
 
-  orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
diff --git a/packages/taler-harness/src/integrationtests/test-payment-idempotency.ts b/packages/taler-harness/src/integrationtests/test-payment-idempotency.ts
index 6373c2393..e06ef1322 100644
--- a/packages/taler-harness/src/integrationtests/test-payment-idempotency.ts
+++ b/packages/taler-harness/src/integrationtests/test-payment-idempotency.ts
@@ -19,7 +19,7 @@
  */
 import { PreparePayResultType } from "@gnu-taler/taler-util";
 import { WalletApiOperation } from "@gnu-taler/taler-wallet-core";
-import { GlobalTestState, MerchantPrivateApi } from "../harness/harness.js";
+import { GlobalTestState, MerchantApiClient } from "../harness/harness.js";
 import {
   createSimpleTestkudosEnvironmentV2,
   withdrawViaBankV2,
@@ -46,9 +46,11 @@ export async function runPaymentIdempotencyTest(t: GlobalTestState) {
 
   await wres.withdrawalFinishedCond;
 
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
+
   // Set up order.
 
-  const orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  const orderResp = await merchantClient.createOrder({
     order: {
       summary: "Buy me!",
       amount: "TESTKUDOS:5",
@@ -56,7 +58,7 @@ export async function runPaymentIdempotencyTest(t: GlobalTestState) {
     },
   });
 
-  let orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  let orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
@@ -102,7 +104,7 @@ export async function runPaymentIdempotencyTest(t: GlobalTestState) {
 
   // Check if payment was successful.
 
-  orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
diff --git a/packages/taler-harness/src/integrationtests/test-payment-multiple.ts b/packages/taler-harness/src/integrationtests/test-payment-multiple.ts
index 29047e102..b22bba43f 100644
--- a/packages/taler-harness/src/integrationtests/test-payment-multiple.ts
+++ b/packages/taler-harness/src/integrationtests/test-payment-multiple.ts
@@ -23,9 +23,8 @@ import {
   BankService,
   ExchangeService,
   MerchantService,
-  WalletCli,
-  MerchantPrivateApi,
   getPayto,
+  MerchantApiClient,
 } from "../harness/harness.js";
 import { coin_ct10, coin_u1 } from "../harness/denomStructures.js";
 import { WalletApiOperation } from "@gnu-taler/taler-wallet-core";
@@ -120,6 +119,8 @@ export async function runPaymentMultipleTest(t: GlobalTestState) {
     name: "default",
   });
 
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
+
   // Withdraw digital cash into the wallet.
 
   await withdrawViaBankV2(t, {
@@ -131,7 +132,7 @@ export async function runPaymentMultipleTest(t: GlobalTestState) {
 
   // Set up order.
 
-  const orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  const orderResp = await merchantClient.createOrder({
     order: {
       summary: "Buy me!",
       amount: "TESTKUDOS:80",
@@ -139,7 +140,7 @@ export async function runPaymentMultipleTest(t: GlobalTestState) {
     },
   });
 
-  let orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  let orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
@@ -157,7 +158,7 @@ export async function runPaymentMultipleTest(t: GlobalTestState) {
 
   // Check if payment was successful.
 
-  orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
diff --git a/packages/taler-harness/src/integrationtests/test-payment-share.ts b/packages/taler-harness/src/integrationtests/test-payment-share.ts
index 156571372..c12140d06 100644
--- a/packages/taler-harness/src/integrationtests/test-payment-share.ts
+++ b/packages/taler-harness/src/integrationtests/test-payment-share.ts
@@ -22,7 +22,7 @@ import {
   PreparePayResultType,
 } from "@gnu-taler/taler-util";
 import { WalletApiOperation } from "@gnu-taler/taler-wallet-core";
-import { GlobalTestState, MerchantPrivateApi } from "../harness/harness.js";
+import { GlobalTestState, MerchantApiClient } from "../harness/harness.js";
 import {
   createSimpleTestkudosEnvironmentV2,
   createWalletDaemonWithClient,
@@ -41,6 +41,8 @@ export async function runPaymentShareTest(t: GlobalTestState) {
     merchant,
   } = await createSimpleTestkudosEnvironmentV2(t);
 
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
+
   // Withdraw digital cash into the wallet.
   await withdrawViaBankV2(t, {
     walletClient: firstWallet,
@@ -62,7 +64,7 @@ export async function runPaymentShareTest(t: GlobalTestState) {
   });
   await secondWallet.call(WalletApiOperation.TestingWaitTransactionsFinal, {});
 
-  //create two orders to pay
+  // create two orders to pay
   async function createOrder(amount: string) {
     const order = {
       summary: "Buy me!",
@@ -70,26 +72,16 @@ export async function runPaymentShareTest(t: GlobalTestState) {
       fulfillment_url: "taler://fulfillment-success/thx",
     };
 
-    const instance = "default";
     const args = { order };
     const auth = {};
 
-    const orderResp = await MerchantPrivateApi.createOrder(
-      merchant,
-      instance,
-      {
-        order: args.order,
-      },
-      auth,
-    );
+    const orderResp = await merchantClient.createOrder({
+      order: args.order,
+    });
 
-    const orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(
-      merchant,
-      {
-        orderId: orderResp.order_id,
-      },
-      auth,
-    );
+    const orderStatus = await merchantClient.queryPrivateOrderStatus({
+      orderId: orderResp.order_id,
+    });
 
     t.assertTrue(orderStatus.order_status === "unpaid");
     return { id: orderResp.order_id, uri: orderStatus.taler_pay_uri };
diff --git a/packages/taler-harness/src/integrationtests/test-payment-template.ts b/packages/taler-harness/src/integrationtests/test-payment-template.ts
index 707be52e1..2058991d0 100644
--- a/packages/taler-harness/src/integrationtests/test-payment-template.ts
+++ b/packages/taler-harness/src/integrationtests/test-payment-template.ts
@@ -17,12 +17,16 @@
 /**
  * Imports.
  */
-import { ConfirmPayResultType, Duration, PreparePayResultType } from "@gnu-taler/taler-util";
+import {
+  ConfirmPayResultType,
+  Duration,
+  PreparePayResultType,
+} from "@gnu-taler/taler-util";
 import { WalletApiOperation } from "@gnu-taler/taler-wallet-core";
-import { GlobalTestState, MerchantPrivateApi } from "../harness/harness.js";
+import { GlobalTestState, MerchantApiClient } from "../harness/harness.js";
 import {
   createSimpleTestkudosEnvironmentV2,
-  withdrawViaBankV2
+  withdrawViaBankV2,
 } from "../harness/helpers.js";
 
 /**
@@ -34,7 +38,9 @@ export async function runPaymentTemplateTest(t: GlobalTestState) {
   const { walletClient, bank, exchange, merchant } =
     await createSimpleTestkudosEnvironmentV2(t);
 
-  await MerchantPrivateApi.createTemplate(merchant, "default", {
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
+
+  await merchantClient.createTemplate({
     template_id: "template1",
     template_description: "my test template",
     template_contract: {
@@ -50,7 +56,12 @@ export async function runPaymentTemplateTest(t: GlobalTestState) {
 
   // Withdraw digital cash into the wallet.
 
-  const wres = await withdrawViaBankV2(t, { walletClient, bank, exchange, amount: "TESTKUDOS:20" });
+  const wres = await withdrawViaBankV2(t, {
+    walletClient,
+    bank,
+    exchange,
+    amount: "TESTKUDOS:20",
+  });
   await wres.withdrawalFinishedCond;
 
   // Request a template payment
@@ -79,13 +90,10 @@ export async function runPaymentTemplateTest(t: GlobalTestState) {
 
   // Check if payment was successful.
 
-  const orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(
-    merchant,
-    {
-      orderId: preparePayResult.contractTerms.order_id,
-      instance: "default",
-    },
-  );
+  const orderStatus = await merchantClient.queryPrivateOrderStatus({
+    orderId: preparePayResult.contractTerms.order_id,
+    instance: "default",
+  });
 
   t.assertTrue(orderStatus.order_status === "paid");
   await walletClient.call(WalletApiOperation.TestingWaitTransactionsFinal, {});
diff --git a/packages/taler-harness/src/integrationtests/test-payment-transient.ts b/packages/taler-harness/src/integrationtests/test-payment-transient.ts
index 2cc0af309..3bc59aa8f 100644
--- a/packages/taler-harness/src/integrationtests/test-payment-transient.ts
+++ b/packages/taler-harness/src/integrationtests/test-payment-transient.ts
@@ -27,12 +27,16 @@ import {
 } from "@gnu-taler/taler-util";
 import { WalletApiOperation } from "@gnu-taler/taler-wallet-core";
 import { FaultInjectionResponseContext } from "../harness/faultInjection.js";
-import { GlobalTestState, MerchantPrivateApi, harnessHttpLib } from "../harness/harness.js";
 import {
-  createFaultInjectedMerchantTestkudosEnvironment, withdrawViaBankV2,
+  GlobalTestState,
+  MerchantApiClient,
+  harnessHttpLib,
+} from "../harness/harness.js";
+import {
+  createFaultInjectedMerchantTestkudosEnvironment,
+  withdrawViaBankV2,
 } from "../harness/helpers.js";
 
-
 /**
  * Run test for a payment where the merchant has a transient
  * failure in /pay
@@ -40,9 +44,13 @@ import {
 export async function runPaymentTransientTest(t: GlobalTestState) {
   // Set up test environment
 
-  const { walletClient, bank, exchange, faultyMerchant, faultyExchange } =
+  const { walletClient, bank, faultyMerchant, faultyExchange } =
     await createFaultInjectedMerchantTestkudosEnvironment(t);
 
+  const merchantClient = new MerchantApiClient(
+    faultyMerchant.makeInstanceBaseUrl(),
+  );
+
   // Withdraw digital cash into the wallet.
 
   await withdrawViaBankV2(t, {
@@ -54,7 +62,7 @@ export async function runPaymentTransientTest(t: GlobalTestState) {
 
   const merchant = faultyMerchant;
 
-  let orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  let orderResp = await merchantClient.createOrder({
     order: {
       summary: "Buy me!",
       amount: "TESTKUDOS:5",
@@ -63,7 +71,7 @@ export async function runPaymentTransientTest(t: GlobalTestState) {
     },
   });
 
-  let orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  let orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
     sessionId: "mysession-one",
   });
diff --git a/packages/taler-harness/src/integrationtests/test-paywall-flow.ts b/packages/taler-harness/src/integrationtests/test-paywall-flow.ts
index 5f63d4fac..fd13f37d6 100644
--- a/packages/taler-harness/src/integrationtests/test-paywall-flow.ts
+++ b/packages/taler-harness/src/integrationtests/test-paywall-flow.ts
@@ -17,7 +17,11 @@
 /**
  * Imports.
  */
-import { GlobalTestState, MerchantPrivateApi, harnessHttpLib } from "../harness/harness.js";
+import {
+  GlobalTestState,
+  MerchantApiClient,
+  harnessHttpLib,
+} from "../harness/harness.js";
 import {
   PreparePayResultType,
   codecForMerchantOrderStatusUnpaid,
@@ -39,6 +43,8 @@ export async function runPaywallFlowTest(t: GlobalTestState) {
   const { walletClient, bank, exchange, merchant } =
     await createSimpleTestkudosEnvironmentV2(t);
 
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
+
   // Withdraw digital cash into the wallet.
 
   const wres = await withdrawViaBankV2(t, {
@@ -59,7 +65,7 @@ export async function runPaywallFlowTest(t: GlobalTestState) {
    * =========================================================================
    */
 
-  let orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  let orderResp = await merchantClient.createOrder({
     order: {
       summary: "Buy me!",
       amount: "TESTKUDOS:5",
@@ -70,7 +76,7 @@ export async function runPaywallFlowTest(t: GlobalTestState) {
 
   const firstOrderId = orderResp.order_id;
 
-  let orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  let orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
     sessionId: "mysession-one",
   });
@@ -82,7 +88,9 @@ export async function runPaywallFlowTest(t: GlobalTestState) {
   t.assertTrue(orderStatus.already_paid_order_id === undefined);
   let publicOrderStatusUrl = new URL(orderStatus.order_status_url);
 
-  let publicOrderStatusResp = await harnessHttpLib.fetch(publicOrderStatusUrl.href);
+  let publicOrderStatusResp = await harnessHttpLib.fetch(
+    publicOrderStatusUrl.href,
+  );
 
   if (publicOrderStatusResp.status != 402) {
     throw Error(
@@ -142,7 +150,7 @@ export async function runPaywallFlowTest(t: GlobalTestState) {
    * =========================================================================
    */
 
-  orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
     sessionId: "mysession-two",
   });
@@ -169,7 +177,7 @@ export async function runPaywallFlowTest(t: GlobalTestState) {
    * =========================================================================
    */
 
-  orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  orderResp = await merchantClient.createOrder({
     order: {
       summary: "Buy me!",
       amount: "TESTKUDOS:5",
@@ -181,7 +189,7 @@ export async function runPaywallFlowTest(t: GlobalTestState) {
 
   const secondOrderId = orderResp.order_id;
 
-  orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: secondOrderId,
     sessionId: "mysession-three",
   });
@@ -206,7 +214,7 @@ export async function runPaywallFlowTest(t: GlobalTestState) {
 
   // The first order should now be paid under "mysession-three",
   // as the wallet did re-purchase detection
-  orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: firstOrderId,
     sessionId: "mysession-three",
   });
@@ -215,7 +223,7 @@ export async function runPaywallFlowTest(t: GlobalTestState) {
 
   // Check that with a completely new session ID, the status would NOT
   // be paid.
-  orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: firstOrderId,
     sessionId: "mysession-four",
   });
diff --git a/packages/taler-harness/src/integrationtests/test-refund-auto.ts b/packages/taler-harness/src/integrationtests/test-refund-auto.ts
index 5648835d5..9e1f31af2 100644
--- a/packages/taler-harness/src/integrationtests/test-refund-auto.ts
+++ b/packages/taler-harness/src/integrationtests/test-refund-auto.ts
@@ -19,7 +19,7 @@
  */
 import { Duration, durationFromSpec } from "@gnu-taler/taler-util";
 import { WalletApiOperation } from "@gnu-taler/taler-wallet-core";
-import { GlobalTestState, MerchantPrivateApi } from "../harness/harness.js";
+import { GlobalTestState, MerchantApiClient } from "../harness/harness.js";
 import {
   createSimpleTestkudosEnvironmentV2,
   withdrawViaBankV2,
@@ -34,6 +34,8 @@ export async function runRefundAutoTest(t: GlobalTestState) {
   const { walletClient, bank, exchange, merchant } =
     await createSimpleTestkudosEnvironmentV2(t);
 
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
+
   // Withdraw digital cash into the wallet.
 
   const wres = await withdrawViaBankV2(t, {
@@ -46,7 +48,7 @@ export async function runRefundAutoTest(t: GlobalTestState) {
   await wres.withdrawalFinishedCond;
 
   // Set up order.
-  const orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  const orderResp = await merchantClient.createOrder({
     order: {
       summary: "Buy me!",
       amount: "TESTKUDOS:5",
@@ -60,7 +62,7 @@ export async function runRefundAutoTest(t: GlobalTestState) {
     ),
   });
 
-  let orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  let orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
@@ -78,13 +80,13 @@ export async function runRefundAutoTest(t: GlobalTestState) {
 
   // Check if payment was successful.
 
-  orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
   t.assertTrue(orderStatus.order_status === "paid");
 
-  const ref = await MerchantPrivateApi.giveRefund(merchant, {
+  const ref = await merchantClient.giveRefund({
     amount: "TESTKUDOS:5",
     instance: "default",
     justification: "foo",
diff --git a/packages/taler-harness/src/integrationtests/test-refund-gone.ts b/packages/taler-harness/src/integrationtests/test-refund-gone.ts
index 8e402f3fc..954262826 100644
--- a/packages/taler-harness/src/integrationtests/test-refund-gone.ts
+++ b/packages/taler-harness/src/integrationtests/test-refund-gone.ts
@@ -17,7 +17,7 @@
 /**
  * Imports.
  */
-import { GlobalTestState, MerchantPrivateApi } from "../harness/harness.js";
+import { GlobalTestState, MerchantApiClient } from "../harness/harness.js";
 import {
   applyTimeTravelV2,
   createSimpleTestkudosEnvironmentV2,
@@ -39,6 +39,8 @@ export async function runRefundGoneTest(t: GlobalTestState) {
   const { walletClient, bank, exchange, merchant } =
     await createSimpleTestkudosEnvironmentV2(t);
 
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
+
   // Withdraw digital cash into the wallet.
 
   await withdrawViaBankV2(t, {
@@ -50,7 +52,7 @@ export async function runRefundGoneTest(t: GlobalTestState) {
 
   // Set up order.
 
-  const orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  const orderResp = await merchantClient.createOrder({
     order: {
       summary: "Buy me!",
       amount: "TESTKUDOS:5",
@@ -69,7 +71,7 @@ export async function runRefundGoneTest(t: GlobalTestState) {
     ),
   });
 
-  let orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  let orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
@@ -82,12 +84,12 @@ export async function runRefundGoneTest(t: GlobalTestState) {
   });
 
   const r2 = await walletClient.call(WalletApiOperation.ConfirmPay, {
-    proposalId: r1.proposalId,
+    transactionId: r1.transactionId,
   });
 
   // Check if payment was successful.
 
-  orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
@@ -102,7 +104,7 @@ export async function runRefundGoneTest(t: GlobalTestState) {
 
   await exchange.runAggregatorOnce();
 
-  const ref = await MerchantPrivateApi.giveRefund(merchant, {
+  const ref = await merchantClient.giveRefund({
     amount: "TESTKUDOS:5",
     instance: "default",
     justification: "foo",
diff --git a/packages/taler-harness/src/integrationtests/test-refund-incremental.ts b/packages/taler-harness/src/integrationtests/test-refund-incremental.ts
index 8ac0948f2..7c895ad2b 100644
--- a/packages/taler-harness/src/integrationtests/test-refund-incremental.ts
+++ b/packages/taler-harness/src/integrationtests/test-refund-incremental.ts
@@ -26,7 +26,7 @@ import {
 import { WalletApiOperation } from "@gnu-taler/taler-wallet-core";
 import {
   GlobalTestState,
-  MerchantPrivateApi,
+  MerchantApiClient,
   delayMs,
 } from "../harness/harness.js";
 import {
@@ -43,6 +43,8 @@ export async function runRefundIncrementalTest(t: GlobalTestState) {
   const { walletClient, bank, exchange, merchant } =
     await createSimpleTestkudosEnvironmentV2(t);
 
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
+
   // Withdraw digital cash into the wallet.
 
   const wres = await withdrawViaBankV2(t, {
@@ -56,7 +58,7 @@ export async function runRefundIncrementalTest(t: GlobalTestState) {
 
   // Set up order.
 
-  const orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  const orderResp = await merchantClient.createOrder({
     order: {
       summary: "Buy me!",
       amount: "TESTKUDOS:10",
@@ -67,7 +69,7 @@ export async function runRefundIncrementalTest(t: GlobalTestState) {
     ),
   });
 
-  let orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  let orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
@@ -85,13 +87,13 @@ export async function runRefundIncrementalTest(t: GlobalTestState) {
 
   // Check if payment was successful.
 
-  orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
   t.assertTrue(orderStatus.order_status === "paid");
 
-  let ref = await MerchantPrivateApi.giveRefund(merchant, {
+  let ref = await merchantClient.giveRefund({
     amount: "TESTKUDOS:2.5",
     instance: "default",
     justification: "foo",
@@ -120,7 +122,7 @@ export async function runRefundIncrementalTest(t: GlobalTestState) {
   // refund will be grouped with the previous one.
   await delayMs(1200);
 
-  ref = await MerchantPrivateApi.giveRefund(merchant, {
+  ref = await merchantClient.giveRefund({
     amount: "TESTKUDOS:5",
     instance: "default",
     justification: "bar",
@@ -133,7 +135,7 @@ export async function runRefundIncrementalTest(t: GlobalTestState) {
   // refund will be grouped with the previous one.
   await delayMs(1200);
 
-  ref = await MerchantPrivateApi.giveRefund(merchant, {
+  ref = await merchantClient.giveRefund({
     amount: "TESTKUDOS:10",
     instance: "default",
     justification: "bar",
@@ -153,7 +155,7 @@ export async function runRefundIncrementalTest(t: GlobalTestState) {
     console.log(wr);
   }
 
-  orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
diff --git a/packages/taler-harness/src/integrationtests/test-refund.ts b/packages/taler-harness/src/integrationtests/test-refund.ts
index 44848d88a..3dc2748fe 100644
--- a/packages/taler-harness/src/integrationtests/test-refund.ts
+++ b/packages/taler-harness/src/integrationtests/test-refund.ts
@@ -24,7 +24,7 @@ import {
   TransactionMajorState,
 } from "@gnu-taler/taler-util";
 import { WalletApiOperation } from "@gnu-taler/taler-wallet-core";
-import { GlobalTestState, MerchantPrivateApi } from "../harness/harness.js";
+import { GlobalTestState, MerchantApiClient } from "../harness/harness.js";
 import {
   createSimpleTestkudosEnvironmentV2,
   withdrawViaBankV2,
@@ -43,6 +43,8 @@ export async function runRefundTest(t: GlobalTestState) {
     merchant,
   } = await createSimpleTestkudosEnvironmentV2(t);
 
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
+
   // Withdraw digital cash into the wallet.
 
   const withdrawalRes = await withdrawViaBankV2(t, {
@@ -56,7 +58,7 @@ export async function runRefundTest(t: GlobalTestState) {
 
   // Set up order.
 
-  const orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  const orderResp = await merchantClient.createOrder({
     order: {
       summary: "Buy me!",
       amount: "TESTKUDOS:5",
@@ -67,7 +69,7 @@ export async function runRefundTest(t: GlobalTestState) {
     ),
   });
 
-  let orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  let orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
@@ -85,13 +87,13 @@ export async function runRefundTest(t: GlobalTestState) {
 
   // Check if payment was successful.
 
-  orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });
 
   t.assertTrue(orderStatus.order_status === "paid");
 
-  const ref = await MerchantPrivateApi.giveRefund(merchant, {
+  const ref = await merchantClient.giveRefund({
     amount: "TESTKUDOS:5",
     instance: "default",
     justification: "foo",
diff --git a/packages/taler-harness/src/integrationtests/test-timetravel-autorefresh.ts b/packages/taler-harness/src/integrationtests/test-timetravel-autorefresh.ts
index 602b6629a..420e4fddc 100644
--- a/packages/taler-harness/src/integrationtests/test-timetravel-autorefresh.ts
+++ b/packages/taler-harness/src/integrationtests/test-timetravel-autorefresh.ts
@@ -32,14 +32,16 @@ import {
   BankService,
   ExchangeService,
   GlobalTestState,
-  MerchantPrivateApi,
   MerchantService,
   setupDb,
-  WalletCli,
   getPayto,
+  MerchantApiClient,
 } from "../harness/harness.js";
-import { applyTimeTravelV2, createWalletDaemonWithClient, withdrawViaBankV2 } from "../harness/helpers.js";
-
+import {
+  applyTimeTravelV2,
+  createWalletDaemonWithClient,
+  withdrawViaBankV2,
+} from "../harness/helpers.js";
 
 /**
  * Basic time travel test.
@@ -110,19 +112,29 @@ export async function runTimetravelAutorefreshTest(t: GlobalTestState) {
     name: "w1",
   });
 
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
+
   // Withdraw digital cash into the wallet.
 
-  const wres = await withdrawViaBankV2(t, { walletClient, bank, exchange, amount: "TESTKUDOS:15" });
+  const wres = await withdrawViaBankV2(t, {
+    walletClient,
+    bank,
+    exchange,
+    amount: "TESTKUDOS:15",
+  });
   await wres.withdrawalFinishedCond;
 
   // Travel into the future, the deposit expiration is two years
   // into the future.
   console.log("applying first time travel");
-  await applyTimeTravelV2(Duration.toMilliseconds(durationFromSpec({ days: 400 })), {
-    walletClient,
-    exchange,
-    merchant,
-  });
+  await applyTimeTravelV2(
+    Duration.toMilliseconds(durationFromSpec({ days: 400 })),
+    {
+      walletClient,
+      exchange,
+      merchant,
+    },
+  );
 
   await walletClient.call(WalletApiOperation.TestingWaitTransactionsFinal, {});
 
@@ -144,11 +156,14 @@ export async function runTimetravelAutorefreshTest(t: GlobalTestState) {
   // Travel into the future, the deposit expiration is two years
   // into the future.
   console.log("applying second time travel");
-  await applyTimeTravelV2(Duration.toMilliseconds(durationFromSpec({ years: 2, months: 6 })), {
-    walletClient,
-    exchange,
-    merchant,
-  });
+  await applyTimeTravelV2(
+    Duration.toMilliseconds(durationFromSpec({ years: 2, months: 6 })),
+    {
+      walletClient,
+      exchange,
+      merchant,
+    },
+  );
 
   // At this point, the original coins should've been refreshed.
   // It would be too late to refresh them now, as we're past
@@ -156,7 +171,7 @@ export async function runTimetravelAutorefreshTest(t: GlobalTestState) {
 
   await walletClient.call(WalletApiOperation.TestingWaitTransactionsFinal, {});
 
-  const orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  const orderResp = await merchantClient.createOrder({
     order: {
       fulfillment_url: "http://example.com",
       summary: "foo",
@@ -164,13 +179,10 @@ export async function runTimetravelAutorefreshTest(t: GlobalTestState) {
     },
   });
 
-  const orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(
-    merchant,
-    {
-      orderId: orderResp.order_id,
-      instance: "default",
-    },
-  );
+  const orderStatus = await merchantClient.queryPrivateOrderStatus({
+    orderId: orderResp.order_id,
+    instance: "default",
+  });
 
   t.assertTrue(orderStatus.order_status === "unpaid");
 
diff --git a/packages/taler-harness/src/integrationtests/test-tipping.ts b/packages/taler-harness/src/integrationtests/test-tipping.ts
index 53d7f08c8..93855f546 100644
--- a/packages/taler-harness/src/integrationtests/test-tipping.ts
+++ b/packages/taler-harness/src/integrationtests/test-tipping.ts
@@ -25,7 +25,6 @@ import {
 import {
   GlobalTestState,
   MerchantApiClient,
-  MerchantPrivateApi,
   getWireMethodForTest,
 } from "../harness/harness.js";
 import { createSimpleTestkudosEnvironmentV2 } from "../harness/helpers.js";
@@ -46,12 +45,7 @@ export async function runTippingTest(t: GlobalTestState) {
   });
   const mbu = await bankAccessApiClient.createRandomBankUser();
 
-  const merchantClient = new MerchantApiClient(
-    merchant.makeInstanceBaseUrl("default"),
-    {
-      method: "external",
-    },
-  );
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
 
   const tipReserveResp = await merchantClient.createTippingReserve({
     exchange_url: exchange.baseUrl,
@@ -85,7 +79,7 @@ export async function runTippingTest(t: GlobalTestState) {
   await merchant.start();
   await merchant.pingUntilAvailable();
 
-  const r = await MerchantPrivateApi.queryTippingReserves(merchant, "default");
+  const r = await merchantClient.queryTippingReserves();
   console.log("tipping reserves:", JSON.stringify(r, undefined, 2));
 
   t.assertTrue(r.reserves.length === 1);
@@ -94,7 +88,7 @@ export async function runTippingTest(t: GlobalTestState) {
     r.reserves[0].merchant_initial_amount,
   );
 
-  const tip = await MerchantPrivateApi.giveTip(merchant, "default", {
+  const tip = await merchantClient.giveTip({
     amount: "TESTKUDOS:5",
     justification: "why not?",
     next_url: "https://example.com/after-tip",
diff --git a/packages/taler-harness/src/integrationtests/test-wallet-backup-doublespend.ts b/packages/taler-harness/src/integrationtests/test-wallet-backup-doublespend.ts
index 99adc1754..62ae89137 100644
--- a/packages/taler-harness/src/integrationtests/test-wallet-backup-doublespend.ts
+++ b/packages/taler-harness/src/integrationtests/test-wallet-backup-doublespend.ts
@@ -19,7 +19,7 @@
  */
 import { PreparePayResultType } from "@gnu-taler/taler-util";
 import { WalletApiOperation } from "@gnu-taler/taler-wallet-core";
-import { GlobalTestState, MerchantPrivateApi } from "../harness/harness.js";
+import { GlobalTestState, MerchantApiClient } from "../harness/harness.js";
 import {
   createSimpleTestkudosEnvironmentV2,
   createWalletDaemonWithClient,
@@ -34,6 +34,8 @@ export async function runWalletBackupDoublespendTest(t: GlobalTestState) {
   const { commonDb, merchant, walletClient, bank, exchange } =
     await createSimpleTestkudosEnvironmentV2(t);
 
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
+
   const sync = await SyncService.create(t, {
     currency: "TESTKUDOS",
     annualFee: "TESTKUDOS:0.5",
@@ -116,7 +118,7 @@ export async function runWalletBackupDoublespendTest(t: GlobalTestState) {
   {
     const instance = "default";
 
-    const orderResp = await MerchantPrivateApi.createOrder(merchant, instance, {
+    const orderResp = await merchantClient.createOrder({
       order: {
         amount: "TESTKUDOS:8",
         summary: "bla",
@@ -124,8 +126,7 @@ export async function runWalletBackupDoublespendTest(t: GlobalTestState) {
       },
     });
 
-    let orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(
-      merchant,
+    let orderStatus = await merchantClient.queryPrivateOrderStatus(
       {
         orderId: orderResp.order_id,
       },
diff --git a/packages/taler-harness/src/integrationtests/test-wallet-balance.ts b/packages/taler-harness/src/integrationtests/test-wallet-balance.ts
index 15b0fd427..9711aff26 100644
--- a/packages/taler-harness/src/integrationtests/test-wallet-balance.ts
+++ b/packages/taler-harness/src/integrationtests/test-wallet-balance.ts
@@ -19,7 +19,7 @@
  */
 import { Amounts, PreparePayResultType } from "@gnu-taler/taler-util";
 import { WalletApiOperation } from "@gnu-taler/taler-wallet-core";
-import { GlobalTestState, MerchantPrivateApi } from "../harness/harness.js";
+import { GlobalTestState, MerchantApiClient } from "../harness/harness.js";
 import {
   createSimpleTestkudosEnvironmentV2,
   withdrawViaBankV2,
@@ -37,6 +37,8 @@ export async function runWalletBalanceTest(t: GlobalTestState) {
   const { merchant, walletClient, exchange, bank } =
     await createSimpleTestkudosEnvironmentV2(t);
 
+  const merchantClient = new MerchantApiClient(merchant.makeInstanceBaseUrl());
+
   // Withdraw digital cash into the wallet.
 
   const wres = await withdrawViaBankV2(t, {
@@ -54,11 +56,11 @@ export async function runWalletBalanceTest(t: GlobalTestState) {
     fulfillment_url: "taler://fulfillment-success/thx",
   };
 
-  const orderResp = await MerchantPrivateApi.createOrder(merchant, "default", {
+  const orderResp = await merchantClient.createOrder({
     order,
   });
 
-  let orderStatus = await MerchantPrivateApi.queryPrivateOrderStatus(merchant, {
+  let orderStatus = await merchantClient.queryPrivateOrderStatus({
     orderId: orderResp.order_id,
   });