[BUG] Auto-generated Bash permission uses invalid syntax for prefix matching

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?

When approving a Bash command that starts with an environment variable (e.g., DEBUG=1 npm run dev), Claude Code auto-adds the permission to settings.local.json with invalid syntax:

"Bash(DEBUG=*)"

On the next startup, Claude Code shows a settings validation error:

Settings Error

/Users/username/project/.claude/settings.local.json
 └ permissions
   └ allow
     └ "Bash(DEBUG=*)": Use ":*" for prefix matching, not just "*". Change to "Bash(DEBUG=:*)" for prefix matching. Examples: Bash(npm run:*), Bash(git:*)

Files with errors are skipped entirely, not just the invalid settings.

What Should Happen?

When auto-generating a permission entry for prefix matching, Claude Code should use the correct syntax with :* instead of just *:

"Bash(DEBUG=:*)"

Error Messages/Logs

Settings Error

/Users/ptn677/personal/.claude/settings.local.json
 └ permissions
   └ allow
     └ "Bash(DEBUG=*)": Use ":*" for prefix matching, not just "*". Change to "Bash(DEBUG=:*)" for prefix matching. Examples: Bash(npm run:*), Bash(git:*)

Files with errors are skipped entirely, not just the invalid settings.

Steps to Reproduce

1. Start Claude Code in any project
2. Ask Claude to run a command with an environment variable prefix, e.g., DEBUG=1 npm run dev
3. When prompted, click "Allow" to permit the command
4. Close Claude Code
5. Reopen Claude Code
6. Settings error appears about invalid permission syntax

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.0.76 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

The permission validator correctly enforces the :* syntax for prefix matching, but the auto-generation logic that runs when users approve commands doesn't follow the same rule. This creates a mismatch where:

• Validator expects: Bash(DEBUG=:*)
• Auto-generator produces: Bash(DEBUG=*)

This affects any command approval where the command starts with ENV_VAR=value pattern.