claude-code - 💡(How to fix) Fix Windows: Bash/PowerShell tool calls flash visible conhost window [2 comments, 3 participants]

Preflight Checklist

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

What's Wrong?

Description

Every time Claude Code executes a Bash or PowerShell tool call on Windows, a conhost.exe window briefly flashes visibly on screen.

Root Cause (suspected)

bash.exe/powershell.exe spawned without CREATE_NO_WINDOW flag.

Suggested Fix

Pass CREATE_NO_WINDOW (0x08000000) when spawning shell processes on Windows.

Environment

• Windows 11, Claude Code 2.1.128+, Git Bash + PowerShell 5.1

What Should Happen?

Should not flash terminal window.

Error Messages/Logs

Steps to Reproduce

1. Install Claude Code on Windows 11 with Git Bash (git-scm.com) installed
2. Open Claude Desktop and start a new conversation
3. Ask Claude to run any shell command, e.g.: "List files in my home directory"
4. Observe: a black console window (conhost.exe) briefly flashes on screen and disappears

Verification

Run this in PowerShell to confirm conhost spawns from claude.exe:

Get-Process conhost | ForEach-Object { $ppid = (Get-CimInstance Win32_Process -Filter "ProcessId=$($.Id)").ParentProcessId [PSCustomObject]@{ PID=$.Id; Parent=(Get-Process -Id $ppid -EA SilentlyContinue).Name } }

Expected output during a tool call: PID Parent

13064 claude

Notes

• Happens with both Bash tool and PowerShell tool
• Window is visible for ~100–300ms per tool call
• Does NOT happen with pythonw.exe-based processes (correct behavior)
• Reproducible on Claude Code 2.1.128 and 2.1.140

Claude Model

Opus

Is this a regression?

No, this never worked

Last Working Version

No response

Claude Code Version

Claude Code 2.1.128 and 2.1.140

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

No response