diff --git a/packages/isomorphic/stackTrace.ts b/packages/isomorphic/stackTrace.ts
index f6c906e0613bf..a973a0a465573 100644
--- a/packages/isomorphic/stackTrace.ts
+++ b/packages/isomorphic/stackTrace.ts
@@ -37,7 +37,7 @@ export function captureRawStack(): RawStack {
   return stack.split('\n');
 }
 
-export function parseStackFrame(text: string, pathSeparator: string, showInternalStackFrames: boolean): StackFrame | null {
+export function parseStackFrame(text: string, pathSeparator: string): StackFrame | null {
   const match = text && text.match(re);
   if (!match)
     return null;
@@ -46,7 +46,7 @@ export function parseStackFrame(text: string, pathSeparator: string, showInterna
   let file = match[7];
   if (!file)
     return null;
-  if (!showInternalStackFrames && (file.startsWith('internal') || file.startsWith('node:')))
+  if (!_showInternalStackFrames && (file.startsWith('internal') || file.startsWith('node:')))
     return null;
 
   const line = match[8];
@@ -134,7 +134,7 @@ export function splitErrorMessage(message: string): { name: string, message: str
   };
 }
 
-export function parseErrorStack(stack: string, pathSeparator: string, showInternalStackFrames: boolean = false): {
+export function parseErrorStack(stack: string, pathSeparator: string): {
   message: string;
   stackLines: string[];
   location?: StackFrame;
@@ -147,7 +147,7 @@ export function parseErrorStack(stack: string, pathSeparator: string, showIntern
   const stackLines = lines.slice(firstStackLine);
   let location: StackFrame | undefined;
   for (const line of stackLines) {
-    const frame = parseStackFrame(line, pathSeparator, showInternalStackFrames);
+    const frame = parseStackFrame(line, pathSeparator);
     if (!frame || !frame.file)
       continue;
     if (belongsToNodeModules(frame.file, pathSeparator))
@@ -162,6 +162,29 @@ function belongsToNodeModules(file: string, pathSeparator: string) {
   return file.includes(`${pathSeparator}node_modules${pathSeparator}`);
 }
 
+export function filterStackFile(file: string) {
+  if (_showInternalStackFrames)
+    return true;
+  if (!!_coreDir && file.startsWith(_coreDir))
+    return false;
+  if (_boxedStackPrefixes.some(prefix => file.startsWith(prefix)))
+    return false;
+  return true;
+}
+
+export function filteredStackTrace(rawStack: RawStack, pathSeparator: string): StackFrame[] {
+  const frames: StackFrame[] = [];
+  for (const line of rawStack) {
+    const frame = parseStackFrame(line, pathSeparator);
+    if (!frame || !frame.file)
+      continue;
+    if (!filterStackFile(frame.file))
+      continue;
+    frames.push(frame);
+  }
+  return frames;
+}
+
 const re = new RegExp('^' +
   // Sometimes we strip out the '    at' because it's noisy
   '(?:\\s*at )?' +
@@ -216,12 +239,6 @@ export function setBoxedStackPrefixes(prefixes: string[]) {
   _boxedStackPrefixes = prefixes;
 }
 
-export function boxedStackPrefixes(): string[] {
-  if (_showInternalStackFrames)
-    return [];
-  return _coreDir ? [_coreDir, ..._boxedStackPrefixes] : _boxedStackPrefixes.slice();
-}
-
 export function setShowInternalStackFrames(value: boolean) {
   _showInternalStackFrames = value;
 }
diff --git a/packages/playwright-core/src/client/clientStackTrace.ts b/packages/playwright-core/src/client/clientStackTrace.ts
index 3f2e8fcd73219..7e55614ec1c95 100644
--- a/packages/playwright-core/src/client/clientStackTrace.ts
+++ b/packages/playwright-core/src/client/clientStackTrace.ts
@@ -16,7 +16,7 @@
 
 import path from 'path';
 
-import { boxedStackPrefixes, captureRawStack, coreDir, parseStackFrame, showInternalStackFrames } from '@isomorphic/stackTrace';
+import { captureRawStack, coreDir, filterStackFile, parseStackFrame } from '@isomorphic/stackTrace';
 
 import type { StackFrame } from '@isomorphic/stackTrace';
 
@@ -30,7 +30,7 @@ export function captureLibraryStackTrace(): { frames: StackFrame[], apiName: str
     isPlaywrightLibrary: boolean;
   };
   let parsedFrames = stack.map(line => {
-    const frame = parseStackFrame(line, path.sep, showInternalStackFrames());
+    const frame = parseStackFrame(line, path.sep);
     if (!frame || !frame.file)
       return null;
     const isPlaywrightLibrary = !!playwrightCoreDir && frame.file.startsWith(playwrightCoreDir);
@@ -65,12 +65,7 @@ export function captureLibraryStackTrace(): { frames: StackFrame[], apiName: str
   }
 
   // This is for the inspector so that it did not include the test runner stack frames.
-  const filterPrefixes = boxedStackPrefixes();
-  parsedFrames = parsedFrames.filter(f => {
-    if (filterPrefixes.some(prefix => f.frame.file.startsWith(prefix)))
-      return false;
-    return true;
-  });
+  parsedFrames = parsedFrames.filter(f => filterStackFile(f.frame.file));
 
   return {
     frames: parsedFrames.map(p => p.frame),
diff --git a/packages/playwright/src/common/fixtures.ts b/packages/playwright/src/common/fixtures.ts
index b47c3f7d6a01c..64c95426fbaba 100644
--- a/packages/playwright/src/common/fixtures.ts
+++ b/packages/playwright/src/common/fixtures.ts
@@ -15,8 +15,9 @@
  */
 
 import crypto from 'crypto';
+import { filterStackFile } from '@isomorphic/stackTrace';
 
-import { filterStackFile, formatLocation } from '../util';
+import { formatLocation } from '../util';
 
 import type { FixturesWithLocation } from './config';
 import type { Fixtures } from '../../types/test';
diff --git a/packages/playwright/src/common/process.ts b/packages/playwright/src/common/process.ts
index 49ab3805d5cb3..ce722bdb234be 100644
--- a/packages/playwright/src/common/process.ts
+++ b/packages/playwright/src/common/process.ts
@@ -19,7 +19,9 @@ import 'playwright-core/lib/bootstrap';
 import { ManualPromise } from '@isomorphic/manualPromise';
 import { setTimeOrigin } from '@isomorphic/time';
 import { startProfiling, stopProfiling } from '@utils/profiler';
+import { setBoxedStackPrefixes } from '@isomorphic/stackTrace';
 
+import { packageRoot } from '../package';
 import { serializeError } from '../util';
 
 import type { EnvProducedPayload, ProcessInitParams, TestInfoErrorPayload } from './ipc';
@@ -61,6 +63,7 @@ let forceExitInitiated = false;
 let processRunner: ProcessRunner | undefined;
 let processName: string | undefined;
 const startingEnv = { ...process.env };
+setBoxedStackPrefixes([packageRoot]);
 
 export function startProcessRunner(create: (params: any) => ProcessRunner) {
   sendMessageToParent({ method: 'ready' });
diff --git a/packages/playwright/src/index.ts b/packages/playwright/src/index.ts
index c53f7a29e284f..d9be54325effd 100644
--- a/packages/playwright/src/index.ts
+++ b/packages/playwright/src/index.ts
@@ -20,7 +20,6 @@ import path from 'path';
 import * as playwrightLibrary from 'playwright-core';
 import { asLocatorDescription } from '@isomorphic/locatorGenerators';
 import { getActionGroup, renderTitleForCall } from '@isomorphic/protocolFormatter';
-import { setBoxedStackPrefixes } from '@isomorphic/stackTrace';
 import { escapeHTML } from '@isomorphic/stringUtils';
 import { jsonStringifyForceASCII } from '@utils/ascii';
 import { createGuid } from '@utils/crypto';
@@ -29,7 +28,6 @@ import { currentZone } from '@utils/zones';
 import { buildErrorContext } from './errorContext';
 import { config, testType } from './common';
 import * as globals from './globals';
-import { packageRoot } from './package';
 import { createCustomMessageHandler, runDaemonForContext } from './mcp/test/browserBackend';
 
 import type { Fixtures, PlaywrightTestArgs, PlaywrightTestOptions, PlaywrightWorkerArgs, PlaywrightWorkerOptions, ScreenshotMode, TestInfo, TestType, VideoMode } from '../types/test';
@@ -46,8 +44,6 @@ import type { BrowserContext, BrowserContextOptions, LaunchOptions, Page, Tracin
 export { expect } from './matchers/expect';
 export const _baseTest: TestType<{}, {}> = testType.rootTestType.test;
 
-setBoxedStackPrefixes([packageRoot]);
-
 if ((process as any)['__pw_initiator__']) {
   const originalStackTraceLimit = Error.stackTraceLimit;
   Error.stackTraceLimit = 200;
diff --git a/packages/playwright/src/matchers/expect.ts b/packages/playwright/src/matchers/expect.ts
index 412196154e0bf..79255f2227b4c 100644
--- a/packages/playwright/src/matchers/expect.ts
+++ b/packages/playwright/src/matchers/expect.ts
@@ -115,7 +115,7 @@ export interface ExpectTestInfo {
 
 export type ExpectConfig = {
   testInfo: ExpectTestInfo | null;
-  filteredStackTrace: (rawStack: string[]) => StackFrame[];
+  filteredStackTrace: (rawStack: string[], pathSeparator: string) => StackFrame[];
   ignoreSnapshots: boolean;
   updateSnapshots: 'all' | 'changed' | 'missing' | 'none';
   timeout?: number;
@@ -143,8 +143,8 @@ export type ExpectConfig = {
   toPass?: { timeout?: number; intervals?: number[] };
 };
 
-function unfilteredStackTrace(rawStack: string[]): StackFrame[] {
-  return rawStack.map(frame => parseStackFrame(frame, path.sep, !!process.env.PWDEBUGIMPL)).filter(f => !!f);
+function unfilteredStackTrace(rawStack: string[], pathSeparator: string): StackFrame[] {
+  return rawStack.map(frame => parseStackFrame(frame, pathSeparator)).filter(f => !!f);
 }
 
 let _expectConfig: ExpectConfig = { testInfo: null, filteredStackTrace: unfilteredStackTrace, ignoreSnapshots: false, updateSnapshots: 'missing' };
@@ -339,7 +339,7 @@ function callMatcherAsStep(matcherName: string, info: ExpectMetaInfo, actual: un
 
   // This looks like it is unnecessary, but it isn't - we need to filter
   // out all the frames that belong to the test runner from caught runtime errors.
-  const stackFrames = expectConfig().filteredStackTrace(captureRawStack());
+  const stackFrames = expectConfig().filteredStackTrace(captureRawStack(), path.sep);
   const stepData = {
     category: 'expect' as const,
     apiName,
diff --git a/packages/playwright/src/program.ts b/packages/playwright/src/program.ts
index 242f7eee8b7e5..109aa1e54ae30 100644
--- a/packages/playwright/src/program.ts
+++ b/packages/playwright/src/program.ts
@@ -20,19 +20,21 @@ import 'playwright-core/lib/bootstrap';
 
 import { libCli, tools } from 'playwright-core/lib/coreBundle';
 import { program } from 'commander';
+import { setBoxedStackPrefixes } from '@isomorphic/stackTrace';
 import { gracefullyProcessExitDoNotHang } from '@utils/processLauncher';
 import { builtInReporters, config, configLoader } from './common';
 import { runTests, clearCache, runTestServerAction } from './cli/testActions';
 import { showReport, mergeReports } from './cli/reportActions';
 import { TestServerBackend, testServerBackendTools } from './mcp/test/testBackend';
 import { ClaudeGenerator, CodexGenerator, OpencodeGenerator, VSCodeGenerator, CopilotGenerator } from './agents/generateAgents';
-import { packageJSON } from './package';
+import { packageRoot, packageJSON } from './package';
 
 export { program };
 
 import type { TraceMode } from '../types/test';
 import type { Command } from 'commander';
 
+setBoxedStackPrefixes([packageRoot]);
 libCli.decorateProgram(program);
 
 function addTestCommand(program: Command) {
diff --git a/packages/playwright/src/reporters/base.ts b/packages/playwright/src/reporters/base.ts
index e1d0737af599b..cc1886d7f98fc 100644
--- a/packages/playwright/src/reporters/base.ts
+++ b/packages/playwright/src/reporters/base.ts
@@ -631,7 +631,7 @@ export function prepareErrorStack(stack: string): {
   stackLines: string[];
   location?: Location;
 } {
-  return parseErrorStack(stack, path.sep, !!process.env.PWDEBUGIMPL);
+  return parseErrorStack(stack, path.sep);
 }
 
 function resolveFromEnv(name: string): string | undefined {
diff --git a/packages/playwright/src/util.ts b/packages/playwright/src/util.ts
index c0c36ec2524b4..2fe4eb8b47622 100644
--- a/packages/playwright/src/util.ts
+++ b/packages/playwright/src/util.ts
@@ -24,24 +24,20 @@ import minimatch from 'minimatch';
 import { calculateSha1 } from '@utils/crypto';
 import { sanitizeForFilePath } from '@utils/fileUtils';
 import { isRegExp } from '@isomorphic/rtti';
-import { parseStackFrame, stringifyStackFrames } from '@isomorphic/stackTrace';
+import { stringifyStackFrames, filteredStackTrace } from '@isomorphic/stackTrace';
 import { ansiRegex, isString, stripAnsiEscapes } from '@isomorphic/stringUtils';
 
-import type { RawStack, StackFrame } from '@isomorphic/stackTrace';
 import type { Location } from './../types/testReporter';
 import type { TestInfoError } from './../types/test';
 import type { TestCase } from './common/test';
 
-const PLAYWRIGHT_TEST_PATH = path.join(__dirname, '..');
-const PLAYWRIGHT_CORE_PATH = path.dirname(require.resolve('playwright-core/package.json'));
-
-export function filterStackTrace(e: Error): { message: string, stack: string, cause?: ReturnType<typeof filterStackTrace> } {
+export function filterStackTrace(e: Error): TestInfoError {
   const name = e.name ? e.name + ': ' : '';
   const cause = e.cause instanceof Error ? filterStackTrace(e.cause) : undefined;
   if (process.env.PWDEBUGIMPL)
     return { message: name + e.message, stack: e.stack || '', cause };
 
-  const stackLines = stringifyStackFrames(filteredStackTrace(e.stack?.split('\n') || []));
+  const stackLines = stringifyStackFrames(filteredStackTrace(e.stack?.split('\n') || [], path.sep));
   return {
     message: name + e.message,
     stack: `${name}${e.message}${stackLines.map(line => '\n' + line).join('')}`,
@@ -49,29 +45,6 @@ export function filterStackTrace(e: Error): { message: string, stack: string, ca
   };
 }
 
-export function filterStackFile(file: string) {
-  if (process.env.PWDEBUGIMPL)
-    return true;
-  if (file.startsWith(PLAYWRIGHT_TEST_PATH))
-    return false;
-  if (file.startsWith(PLAYWRIGHT_CORE_PATH))
-    return false;
-  return true;
-}
-
-export function filteredStackTrace(rawStack: RawStack): StackFrame[] {
-  const frames: StackFrame[] = [];
-  for (const line of rawStack) {
-    const frame = parseStackFrame(line, path.sep, !!process.env.PWDEBUGIMPL);
-    if (!frame || !frame.file)
-      continue;
-    if (!filterStackFile(frame.file))
-      continue;
-    frames.push(frame);
-  }
-  return frames;
-}
-
 export function serializeError(error: Error | any): TestInfoError {
   if (error instanceof Error)
     return filterStackTrace(error);
diff --git a/packages/playwright/src/worker/fixtureRunner.ts b/packages/playwright/src/worker/fixtureRunner.ts
index acba16fa278d2..b13fd9feaf499 100644
--- a/packages/playwright/src/worker/fixtureRunner.ts
+++ b/packages/playwright/src/worker/fixtureRunner.ts
@@ -16,9 +16,10 @@
 
 import { ManualPromise } from '@isomorphic/manualPromise';
 import { escapeWithQuotes } from '@isomorphic/stringUtils';
+import { filterStackFile } from '@isomorphic/stackTrace';
 
 import { fixtures } from '../common';
-import { filterStackFile, formatLocation } from '../util';
+import { formatLocation } from '../util';
 
 import type { TestInfoImpl } from './testInfo';
 import type { FixtureDescription, RunnableDescription } from './timeoutManager';
diff --git a/packages/playwright/src/worker/testInfo.ts b/packages/playwright/src/worker/testInfo.ts
index 58ee006bee26a..546c63cfd9a2a 100644
--- a/packages/playwright/src/worker/testInfo.ts
+++ b/packages/playwright/src/worker/testInfo.ts
@@ -18,7 +18,7 @@ import fs from 'fs';
 import path from 'path';
 
 import { ManualPromise } from '@isomorphic/manualPromise';
-import { captureRawStack, stringifyStackFrames } from '@isomorphic/stackTrace';
+import { captureRawStack, stringifyStackFrames, filteredStackTrace } from '@isomorphic/stackTrace';
 import { escapeWithQuotes } from '@isomorphic/stringUtils';
 import { monotonicTime } from '@isomorphic/time';
 import { createGuid } from '@utils/crypto';
@@ -26,7 +26,7 @@ import { sanitizeForFilePath, trimLongString } from '@utils/fileUtils';
 import { currentZone } from '@utils/zones';
 
 import { TimeoutManager, TimeoutManagerError } from './timeoutManager';
-import { addSuffixToFilePath, filteredStackTrace, getContainedPath, normalizeAndSaveAttachment, sanitizeFilePathBeforeExtension, windowsFilesystemFriendlyLength } from '../util';
+import { addSuffixToFilePath, getContainedPath, normalizeAndSaveAttachment, sanitizeFilePathBeforeExtension, windowsFilesystemFriendlyLength } from '../util';
 import { TestTracing } from './testTracing';
 import { testInfoError } from './util';
 import { ipc, transform } from '../common';
@@ -295,7 +295,7 @@ export class TestInfoImpl implements TestInfo {
         parentStep = this._parentStep();
     }
 
-    const filteredStack = filteredStackTrace(captureRawStack());
+    const filteredStack = filteredStackTrace(captureRawStack(), path.sep);
     let boxedStack = parentStep?.boxedStack;
     let location = data.location;
     if (!boxedStack && data.box) {
diff --git a/packages/playwright/src/worker/testTracing.ts b/packages/playwright/src/worker/testTracing.ts
index d6373496f55ba..049eae8bfbfd9 100644
--- a/packages/playwright/src/worker/testTracing.ts
+++ b/packages/playwright/src/worker/testTracing.ts
@@ -24,8 +24,7 @@ import { monotonicTime } from '@isomorphic/time';
 import { calculateSha1, createGuid } from '@utils/crypto';
 import { SerializedFS } from '@utils/serializedFS';
 import { getPlaywrightVersion } from 'playwright-core/lib/coreBundle';
-
-import { filteredStackTrace } from '../util';
+import { filteredStackTrace } from '@isomorphic/stackTrace';
 
 import type { TestStepCategory, TestInfoImpl } from './testInfo';
 import type { PlaywrightWorkerOptions, TestInfo, TestInfoError, TraceMode } from '../../types/test';
@@ -251,7 +250,7 @@ export class TestTracing {
 
   appendForError(error: TestInfoError) {
     const rawStack = error.stack?.split('\n') || [];
-    const stack = rawStack ? filteredStackTrace(rawStack) : [];
+    const stack = rawStack ? filteredStackTrace(rawStack, path.sep) : [];
     this._appendTraceEvent({
       type: 'error',
       message: this._formatError(error),
diff --git a/packages/playwright/src/worker/workerMain.ts b/packages/playwright/src/worker/workerMain.ts
index 22e8f46451639..a566e37f217b9 100644
--- a/packages/playwright/src/worker/workerMain.ts
+++ b/packages/playwright/src/worker/workerMain.ts
@@ -18,11 +18,12 @@ import colors from 'colors/safe';
 import { ManualPromise } from '@isomorphic/manualPromise';
 import { removeFolders } from '@utils/fileUtils';
 import { gracefullyCloseAll } from '@utils/processLauncher';
+import { filteredStackTrace } from '@isomorphic/stackTrace';
 
 import { configLoader, fixtures, ipc, poolBuilder, ProcessRunner, suiteUtils, testLoader } from '../common';
 import * as globals from '../globals';
 import { setExpectConfig } from '../matchers/expect';
-import { debugTest, filteredStackTrace, relativeFilePath } from '../util';
+import { debugTest, relativeFilePath } from '../util';
 import { FixtureRunner } from './fixtureRunner';
 import { TestSkipError, TestInfoImpl, emtpyTestInfoCallbacks } from './testInfo';
 import { testInfoError } from './util';