diff --git a/packages/playwright-core/src/client/channelOwner.ts b/packages/playwright-core/src/client/channelOwner.ts
index a5d753507b..140389c596 100644
--- a/packages/playwright-core/src/client/channelOwner.ts
+++ b/packages/playwright-core/src/client/channelOwner.ts
@@ -148,15 +148,15 @@ export abstract class ChannelOwner<T extends channels.Channel = channels.Channel
           if (validator) {
             return async (params: any) => {
               return await this._wrapApiCall(async apiZone => {
-                const { apiName, frames, csi, callCookie, stepId } = apiZone.reported ? { apiName: undefined, csi: undefined, callCookie: undefined, frames: [], stepId: undefined } : apiZone;
-                apiZone.reported = true;
-                let currentStepId = stepId;
-                if (csi && apiName) {
-                  const out: { stepId?: string } = {};
-                  csi.onApiCallBegin(apiName, params, frames, callCookie, out);
-                  currentStepId = out.stepId;
+                const validatedParams = validator(params, '', { tChannelImpl: tChannelImplToWire, binary: this._connection.rawBuffers() ? 'buffer' : 'toBase64' });
+                if (!apiZone.isInternal && !apiZone.reported) {
+                  apiZone.params = params;
+                  apiZone.reported = true;
+                  logApiCall(this._logger, `=> ${apiZone.apiName} started`);
+                  apiZone.csi?.onApiCallBegin(apiZone);
+                  return await this._connection.sendMessageToServer(this, prop, validatedParams, apiZone.apiName, apiZone.frames, apiZone.stepId);
                 }
-                return await this._connection.sendMessageToServer(this, prop, validator(params, '', { tChannelImpl: tChannelImplToWire, binary: this._connection.rawBuffers() ? 'buffer' : 'toBase64' }), apiName, frames, currentStepId);
+                return await this._connection.sendMessageToServer(this, prop, validatedParams, undefined, [], undefined);
               });
             };
           }
@@ -170,9 +170,9 @@ export abstract class ChannelOwner<T extends channels.Channel = channels.Channel
 
   async _wrapApiCall<R>(func: (apiZone: ApiZone) => Promise<R>, isInternal?: boolean): Promise<R> {
     const logger = this._logger;
-    const apiZone = zones.zoneData<ApiZone>('apiZone');
-    if (apiZone)
-      return await func(apiZone);
+    const existingApiZone = zones.zoneData<ApiZone>('apiZone');
+    if (existingApiZone)
+      return await func(existingApiZone);
 
     const stackTrace = captureLibraryStackTrace();
     let apiName: string | undefined = stackTrace.apiName;
@@ -180,26 +180,23 @@ export abstract class ChannelOwner<T extends channels.Channel = channels.Channel
 
     if (isInternal === undefined)
       isInternal = this._isInternalType;
-    if (isInternal)
-      apiName = undefined;
 
     // Enclosing zone could have provided the apiName and wallTime.
     const expectZone = zones.zoneData<ExpectZone>('expectZone');
     const stepId = expectZone?.stepId;
-    if (!isInternal && expectZone)
+    if (expectZone)
       apiName = expectZone.title;
 
     // If we are coming from the expectZone, there is no need to generate a new
     // step for the API call, since it will be generated by the expect itself.
     const csi = isInternal || expectZone ? undefined : this._instrumentation;
-    const callCookie: any = {};
+    const apiZone: ApiZone = { apiName, frames, isInternal, reported: false, csi, userData: undefined, stepId };
 
     try {
-      logApiCall(logger, `=> ${apiName} started`, isInternal);
-      const apiZone: ApiZone = { apiName, frames, isInternal, reported: false, csi, callCookie, stepId };
       const result = await zones.run('apiZone', apiZone, async () => await func(apiZone));
-      csi?.onApiCallEnd(callCookie);
-      logApiCall(logger, `<= ${apiName} succeeded`, isInternal);
+      csi?.onApiCallEnd(apiZone);
+      if (!isInternal)
+        logApiCall(logger, `<= ${apiName} succeeded`);
       return result;
     } catch (e) {
       const innerError = ((process.env.PWDEBUGIMPL || isUnderTest()) && e.stack) ? '\n<inner error>\n' + e.stack : '';
@@ -210,8 +207,9 @@ export abstract class ChannelOwner<T extends channels.Channel = channels.Channel
         e.stack = e.message + stackFrames;
       else
         e.stack = '';
-      csi?.onApiCallEnd(callCookie, e);
-      logApiCall(logger, `<= ${apiName} failed`, isInternal);
+      csi?.onApiCallEnd(apiZone);
+      if (!isInternal)
+        logApiCall(logger, `<= ${apiName} failed`);
       throw e;
     }
   }
@@ -232,9 +230,7 @@ export abstract class ChannelOwner<T extends channels.Channel = channels.Channel
   }
 }
 
-function logApiCall(logger: Logger | undefined, message: string, isNested: boolean) {
-  if (isNested)
-    return;
+function logApiCall(logger: Logger | undefined, message: string) {
   if (logger && logger.isEnabled('api', 'info'))
     logger.log('api', 'info', message, [], { color: 'cyan' });
   debugLogger.log('api', message);
@@ -247,11 +243,13 @@ function tChannelImplToWire(names: '*' | string[], arg: any, path: string, conte
 }
 
 type ApiZone = {
-  apiName: string | undefined;
+  apiName: string;
+  params?: Record<string, any>;
   frames: channels.StackFrame[];
   isInternal: boolean;
   reported: boolean;
   csi: ClientInstrumentation | undefined;
-  callCookie: any;
+  userData: any;
   stepId?: string;
+  error?: Error;
 };
diff --git a/packages/playwright-core/src/client/clientInstrumentation.ts b/packages/playwright-core/src/client/clientInstrumentation.ts
index 55c787df05..e2e8c6678e 100644
--- a/packages/playwright-core/src/client/clientInstrumentation.ts
+++ b/packages/playwright-core/src/client/clientInstrumentation.ts
@@ -18,12 +18,22 @@ import type { StackFrame } from '@protocol/channels';
 import type { BrowserContext } from './browserContext';
 import type { APIRequestContext } from './fetch';
 
+// Instrumentation can mutate the data, for example change apiName or stepId.
+export interface ApiCallData {
+  apiName: string;
+  params?: Record<string, any>;
+  frames: StackFrame[];
+  userData: any;
+  stepId?: string;
+  error?: Error;
+}
+
 export interface ClientInstrumentation {
   addListener(listener: ClientInstrumentationListener): void;
   removeListener(listener: ClientInstrumentationListener): void;
   removeAllListeners(): void;
-  onApiCallBegin(apiCall: string, params: Record<string, any>, frames: StackFrame[], userData: any, out: { stepId?: string }): void;
-  onApiCallEnd(userData: any, error?: Error): void;
+  onApiCallBegin(apiCall: ApiCallData): void;
+  onApiCallEnd(apiCal: ApiCallData): void;
   onWillPause(options: { keepTestTimeout: boolean }): void;
 
   runAfterCreateBrowserContext(context: BrowserContext): Promise<void>;
@@ -33,8 +43,8 @@ export interface ClientInstrumentation {
 }
 
 export interface ClientInstrumentationListener {
-  onApiCallBegin?(apiName: string, params: Record<string, any>, frames: StackFrame[], userData: any, out: { stepId?: string }): void;
-  onApiCallEnd?(userData: any, error?: Error): void;
+  onApiCallBegin?(apiCall: ApiCallData): void;
+  onApiCallEnd?(apiCall: ApiCallData): void;
   onWillPause?(options: { keepTestTimeout: boolean }): void;
 
   runAfterCreateBrowserContext?(context: BrowserContext): Promise<void>;
diff --git a/packages/playwright/src/index.ts b/packages/playwright/src/index.ts
index 27f1e9320b..c117c695b6 100644
--- a/packages/playwright/src/index.ts
+++ b/packages/playwright/src/index.ts
@@ -23,7 +23,7 @@ import type { Fixtures, PlaywrightTestArgs, PlaywrightTestOptions, PlaywrightWor
 import type { TestInfoImpl, TestStepInternal } from './worker/testInfo';
 import { rootTestType } from './common/testType';
 import type { ContextReuseMode } from './common/config';
-import type { ClientInstrumentation, ClientInstrumentationListener } from '../../playwright-core/src/client/clientInstrumentation';
+import type { ApiCallData, ClientInstrumentation, ClientInstrumentationListener } from '../../playwright-core/src/client/clientInstrumentation';
 import { currentTestInfo } from './common/globals';
 export { expect } from './matchers/expect';
 export const _baseTest: TestType<{}, {}> = rootTestType.test;
@@ -258,34 +258,33 @@ const playwrightFixtures: Fixtures<TestFixtures, WorkerFixtures> = ({
 
     const tracingGroupSteps: TestStepInternal[] = [];
     const csiListener: ClientInstrumentationListener = {
-      onApiCallBegin: (apiName: string, params: Record<string, any>, frames: StackFrame[], userData: any, out: { stepId?: string }) => {
-        userData.apiName = apiName;
+      onApiCallBegin: (data: ApiCallData) => {
         const testInfo = currentTestInfo();
-        if (!testInfo || apiName.includes('setTestIdAttribute') || apiName === 'tracing.groupEnd')
+        if (!testInfo || data.apiName.includes('setTestIdAttribute') || data.apiName === 'tracing.groupEnd')
           return;
         const step = testInfo._addStep({
-          location: frames[0] as any,
+          location: data.frames[0],
           category: 'pw:api',
-          title: renderApiCall(apiName, params),
-          apiName,
-          params,
+          title: renderApiCall(data.apiName, data.params),
+          apiName: data.apiName,
+          params: data.params,
         }, tracingGroupSteps[tracingGroupSteps.length - 1]);
-        userData.step = step;
-        out.stepId = step.stepId;
-        if (apiName === 'tracing.group')
+        data.userData = step;
+        data.stepId = step.stepId;
+        if (data.apiName === 'tracing.group')
           tracingGroupSteps.push(step);
       },
-      onApiCallEnd: (userData: any, error?: Error) => {
+      onApiCallEnd: (data: ApiCallData) => {
         // "tracing.group" step will end later, when "tracing.groupEnd" finishes.
-        if (userData.apiName === 'tracing.group')
+        if (data.apiName === 'tracing.group')
           return;
-        if (userData.apiName === 'tracing.groupEnd') {
+        if (data.apiName === 'tracing.groupEnd') {
           const step = tracingGroupSteps.pop();
-          step?.complete({ error });
+          step?.complete({ error: data.error });
           return;
         }
-        const step = userData.step;
-        step?.complete({ error });
+        const step = data.userData;
+        step?.complete({ error: data.error });
       },
       onWillPause: ({ keepTestTimeout }) => {
         if (!keepTestTimeout)