Summary

Multiple issues with the Claude Code hooks system preventing proper validation and blocking of unsafe operations.

Environment

• Platform: macOS (Darwin 24.5.0)
• Claude Code Version: 1.0.38 (Claude Code)
• Working Directory: Git repository
• Configuration File: .claude/settings.local.json

Issues Identified

1. Template Variable Interpolation Failure

Expected: Template variables like {{tool.name}}, {{timestamp}}, and {{tool.input.file_path}} should be replaced with actual values.

Actual: Template variables appear literally in executed commands.

Evidence:

# Debug log shows literal template variables instead of interpolated values
$ tail /tmp/claude-hook-debug.log
[DEBUG] Hook fired for tool: {{tool.name}} at {{timestamp}}
[DEBUG] Hook fired for tool: {{tool.name}} at {{timestamp}}

2. Hook Configuration Changes Not Respected

Expected: Changes to .claude/settings.local.json should take effect after Claude Code restart.

Actual: Configuration changes are ignored; old hook behavior persists even after restart.

Evidence:

• Modified hook configuration multiple times
• Restarted Claude Code after each change
• Old debug hook continues executing despite being removed from config
• New simple test hooks never execute

3. Hook Commands Not Blocking Operations

Expected: When a PreToolUse hook command exits with non-zero status, the tool operation should be blocked.

Actual: Tool operations proceed regardless of hook command exit status.

Evidence:

• Created validation script that exits with code 1 on unsafe patterns
• Hook wrapper correctly returns exit code 1 when validation fails
• File operations still succeed despite validation failures

Configuration Tested

Final Hook Configuration

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Write",
        "hooks": [
          {
            "type": "command", 
            "command": "echo 'Write hook fired' >> /tmp/claude-simple-test.log"
          }
        ]
      }
    ]
  }
}

Validation Script

• Created working validation script that detects unsafe patterns
• Returns proper exit codes (0 for safe, 1 for unsafe)
• Tested independently - works correctly outside Claude Code

Steps to Reproduce

1. Create .claude/settings.local.json with PreToolUse hooks
2. Configure hooks with template variables and command that can fail
3. Restart Claude Code
4. Perform Write/Edit operations that should trigger hooks
5. Observe that:
   • Template variables aren't interpolated
   • Hook commands execute but don't block operations
   • Configuration changes aren't respected

Expected Behavior

1. Template variables should be replaced with actual values
2. Hook configuration changes should take effect after restart
3. PreToolUse hooks returning non-zero exit codes should block tool operations
4. Hooks should provide effective validation/blocking capabilities

Workarounds Implemented

Since Claude Code hooks are not functional, we've implemented alternative safeguards:

• ESLint rules with custom patterns detection
• Pre-commit hooks for validation
• Git safety rules to prevent bypassing quality gates

Request

Please investigate and fix the Claude Code hooks system to enable proper validation and blocking of unsafe operations as documented.