Pipe character in regex patterns incorrectly triggers bash permission check

Environment

• Platform (select one):
• [x] Anthropic API
• [ ] AWS Bedrock
• [ ] Google Vertex AI
• [ ] Other: <!-- specify -->
• Claude CLI version: v1.0.92
• Operating System: macOS (Darwin 24.6.0)
• Terminal: iTerm

Bug Description

Slash commands that use bash patterns containing the pipe character | inside regex or glob patterns (e.g., grep -E '(\.idea|\.claude|bruno)') are incorrectly flagged by the security permission system. The system interprets the | inside the pattern string as a bash pipe operator requiring separate permissions, when it's actually part of a regex alternation pattern.

Steps to Reproduce

1. Create a slash command with a bash command like: git ls-files --cached --others --exclude-standard '*.md' | grep -v -E '(\.idea|\.claude|bruno|\.yarn|CLAUDE\.md)'
2. Add appropriate permissions in the command's frontmatter: allowed-tools: Bash(git:*), Bash(grep:*)
3. Execute the slash command
4. Command fails with error: "Bash command permission check failed for pattern... This Bash command contains multiple operations. The following part requires approval: grep -v -E '(\.idea|\.claude|bruno|\.yarn|CLAUDE\.md)'"

Expected Behavior

The command should execute successfully since:

• The | between git ls-files and grep is correctly recognized as a bash pipe
• The | characters inside the grep regex pattern '(\.idea|\.claude|bruno)' should be recognized as part of the regex pattern, not as bash pipes
• The Bash(grep:*) permission should cover the entire grep command including its regex pattern

Actual Behavior

The security system incorrectly interprets the | characters inside the regex pattern as bash pipe operators, causing the permission check to fail even with appropriate Bash(grep:*) permissions.

Additional Context

Workaround: Replace regex patterns containing | with multiple chained commands:

• Instead of: grep -v -E '(\.idea|\.claude|bruno)'
• Use: grep -v '\.idea' | grep -v '\.claude' | grep -v 'bruno'

This issue affects any slash command that needs to use regex alternation patterns with tools like grep, sed, or awk.