[BUG] Windows: hooks spawn bash with -i flag creating visible console window on every hook execution

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?

Summary

On Windows, Claude Code spawns hook commands via bash --login -i -c "command".
The -i flag creates a visible console window on every hook execution — every
user prompt (UserPromptSubmit) and every file edit (PostToolUse).

Environment

• OS: Windows 11 Home 10.0.26200
• Claude Code: 2.1.87 (VS Code extension)
• Shell: Git Bash MINGW64

Root Cause

Hooks are spawned as: bash --login -i -c "<command>"

The -i flag + no CREATE_NO_WINDOW flag = visible console window every time.

The Fix (one line)

Add windowsHide: true to the hook spawn options in Node.js:

child_process.spawn('bash', ['--login', '-i', '-c', command], {
windowsHide: true, // <-- this is all it needs
...existingOptions
})

Or remove the -i flag — hooks don't need an interactive shell.

Related: #18469, #18856, #19294, #19057

What Should Happen?

Hook commands should execute without creating any visible console window.
The hook output should be captured silently in the background.

Error Messages/Logs

2026-03-30T11:15:58.684Z [DEBUG] Getting matching hook commands for SessionEnd with query: other
/usr/bin/bash --login -i -c bash $CLAUDE_PROJECT_DIR/.claude/hooks/skill-activation-prompt.sh

Window title observed: /usr/bin/bash --login -i -c bash $CLAUDE_PROJECT_DIR/.claude/hooks/skill-activation-prompt.sh

Steps to Reproduce

1. Configure any hook in .claude/settings.json:

{ "hooks": { "UserPromptSubmit": [{ "hooks": [{ "type": "command", "command": "echo hello" }] }] } }

1. Send any message in Claude Code
2. A visible CMD/bash console window flashes on screen for every message sent

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

unknown (hooks may have always behaved this way on Windows

Claude Code Version

2.1.87

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

Root cause: hooks are spawned via bash --login -i -c "command".
The -i flag + no CREATE_NO_WINDOW = visible window every hook call.

Fix: add windowsHide: true to the Node.js spawn options for hooks.
This is a one-line change.

Related: #18469, #18856, #19294, #19057