diff --git a/src/utils/browser/chrome-reuse.ts b/src/utils/browser/chrome-reuse.ts
index eacefe8b..976c39ef 100644
--- a/src/utils/browser/chrome-reuse.ts
+++ b/src/utils/browser/chrome-reuse.ts
@@ -49,18 +49,7 @@ export function resolveDefaultChromeUserDataDir(
 }
 
 export function resolveConfiguredBrowserProfileDir(profileDir?: string): string | undefined {
-  if (profileDir?.trim()) {
-    return expandPath(profileDir);
-  }
-
-  try {
-    const defaultUserDataDir = resolveDefaultChromeUserDataDir();
-    return fs.existsSync(path.join(defaultUserDataDir, DEVTOOLS_ACTIVE_PORT_FILE))
-      ? defaultUserDataDir
-      : undefined;
-  } catch {
-    return undefined;
-  }
+  return profileDir?.trim() ? expandPath(profileDir) : undefined;
 }
 
 export async function resolveBrowserRuntimeEnv(
diff --git a/tests/unit/targets/default-profile-browser-launch.test.ts b/tests/unit/targets/default-profile-browser-launch.test.ts
index 1f42f749..2ee938a3 100644
--- a/tests/unit/targets/default-profile-browser-launch.test.ts
+++ b/tests/unit/targets/default-profile-browser-launch.test.ts
@@ -151,6 +151,40 @@ exit 0
     await expect(waitForMockDevtoolsPort(delayedPortFile, 500)).resolves.toBe('43123');
   });
 
+  it('ignores stale default Chrome DevTools metadata unless browser reuse is explicitly configured', () => {
+    if (process.platform === 'win32') return;
+
+    const defaultChromeDir = path.join(
+      tmpHome,
+      'Library',
+      'Application Support',
+      'Google',
+      'Chrome'
+    );
+    fs.mkdirSync(defaultChromeDir, { recursive: true });
+    fs.writeFileSync(
+      path.join(defaultChromeDir, 'DevToolsActivePort'),
+      '9222\n/devtools/browser/stale-default',
+      'utf8'
+    );
+
+    const result = runCcs(['default', 'smoke'], {
+      ...baseEnv,
+      HOME: tmpHome,
+      USERPROFILE: tmpHome,
+    });
+
+    expect(result.status).toBe(0);
+    expect(result.stderr).not.toContain('Chrome DevTools endpoint is unreachable');
+
+    const launchedArgs = fs.readFileSync(claudeArgsLogPath, 'utf8');
+    expect(launchedArgs).not.toContain(BROWSER_PROMPT_SNIPPET);
+
+    const launchedEnv = fs.readFileSync(claudeEnvLogPath, 'utf8');
+    expect(launchedEnv).not.toContain('9222');
+    expect(launchedEnv).not.toContain('devtools/browser/stale-default');
+  });
+
   it('passes browser runtime env through default Claude launches when reuse is configured', async () => {
     if (process.platform === 'win32') return;
 
diff --git a/tests/unit/utils/browser/chrome-reuse.test.ts b/tests/unit/utils/browser/chrome-reuse.test.ts
index e0b8ac8a..f9b90c5c 100644
--- a/tests/unit/utils/browser/chrome-reuse.test.ts
+++ b/tests/unit/utils/browser/chrome-reuse.test.ts
@@ -3,12 +3,15 @@ import * as fs from 'fs';
 import * as os from 'os';
 import * as path from 'path';
 import {
+  resolveConfiguredBrowserProfileDir,
   resolveBrowserRuntimeEnv,
   resolveDefaultChromeUserDataDir,
 } from '../../../../src/utils/browser/chrome-reuse';
 
 describe('chrome reuse resolver', () => {
+  const originalHome = process.env.HOME;
   const originalLocalAppData = process.env.LOCALAPPDATA;
+  const originalUserProfile = process.env.USERPROFILE;
   let tempDirs: string[] = [];
   let servers: Array<{ stop: () => void }> = [];
 
@@ -96,6 +99,18 @@ describe('chrome reuse resolver', () => {
     } else {
       process.env.LOCALAPPDATA = originalLocalAppData;
     }
+
+    if (originalHome === undefined) {
+      delete process.env.HOME;
+    } else {
+      process.env.HOME = originalHome;
+    }
+
+    if (originalUserProfile === undefined) {
+      delete process.env.USERPROFILE;
+    } else {
+      process.env.USERPROFILE = originalUserProfile;
+    }
   });
 
   it('uses explicit profile-dir before the default path and resolves the websocket target', async () => {
@@ -122,6 +137,23 @@ describe('chrome reuse resolver', () => {
     expect(fs.existsSync(path.join(defaultProfileDir, 'DevToolsActivePort'))).toBe(false);
   });
 
+  it('only enables browser reuse for an explicitly configured profile directory', () => {
+    const isolatedHome = createTempDir('ccs-chrome-config-home-');
+    const defaultProfileDir = path.join(
+      isolatedHome,
+      'Library',
+      'Application Support',
+      'Google',
+      'Chrome'
+    );
+    writeDevToolsActivePort(defaultProfileDir, '9222\n/devtools/browser/stale-default');
+    process.env.HOME = isolatedHome;
+    process.env.USERPROFILE = isolatedHome;
+
+    expect(resolveConfiguredBrowserProfileDir()).toBeUndefined();
+    expect(resolveConfiguredBrowserProfileDir(defaultProfileDir)).toBe(defaultProfileDir);
+  });
+
   it('uses an explicit devtools port override when metadata is missing', async () => {
     const profileDir = createTempDir('ccs-chrome-explicit-port-');
     const server = await startDevToolsServer({