[BUG] Claude Code 2.1.260 crashes with exit code 3221226505 when spawned by Windows desktop app; 2.1.258 works

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

What's wrong

The Claude Code desktop app (Microsoft Store install) crashes on every
session with "Claude Code process exited with code 3221226505"
(0xC0000409, STATUS_STACK_BUFFER_OVERRUN) using bundled binary 2.1.260.

The 2.1.260 binary itself is NOT broken — running it directly from
PowerShell works fine:

& "...\claude-code\2.1.260\claude.exe" --version
2.1.260 (Claude Code)

The crash only occurs when the desktop app spawns it as a subprocess.

Workaround

Renaming the 2.1.260 version folder so the app falls back to 2.1.258
resolves it completely. The app has worked normally since.

Rename-Item "...\claude-code\2.1.260" "2.1.260.bak"

Is this a regression?

Yes. Last working version: 2.1.258

Environment

• OS: Windows (Microsoft Store install)
• Package path: %LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc\
• Claude Code: 2.1.260 (crashes), 2.1.258 (works)
• Model: Opus 5
• No standalone CLI or npm install present

What Should Happen?

The desktop app should spawn the bundled 2.1.260 binary and start a
working session, the same way it does with 2.1.258.

Error Messages/Logs

Claude Code process exited with code 3221226505

Steps to Reproduce

1. Install the Claude Code desktop app from the Microsoft Store on Windows
2. Let it update to bundled binary 2.1.260
3. Open the app and start any Code session
4. Send a message
5. Session crashes: "Claude Code process exited with code 3221226505"

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.258

Claude Code Version

2.1.260

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

The bundled binary is not itself broken. Verified from PowerShell:

& "C:\Users\<user>\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\claude-code\2.1.260\claude.exe" --version
2.1.260 (Claude Code)

It only crashes when the desktop app spawns it as a subprocess, which
points at the spawn path rather than the binary.

Both 2.1.258 and 2.1.260 were present in the version folder. Renaming
2.1.260 so the app fell back to 2.1.258 fixed it immediately and it has
been stable since.

No standalone CLI and no npm install on this machine — only the Store
app's bundled binaries, so there is no PATH or multiple-install conflict.

<img width="1320" height="823" alt="Image" src="https://github.com/user-attachments/assets/38cbdd84-aded-4f8b-a5de-b578b8ae651a" />