Claude Code enters infinite loop when hooks are enabled

Environment

• OS: macOS Tahoe
• Hook execution time: ~60ms (just touching a signal file)

Hook Configuration

"hooks": {
  "Notification": [{
    "matcher": "",
    "hooks": [{"type": "command", "command": "python3 ~/.claude/hooks/notification.py --notify"}]
  }],
  "Stop": [{
    "matcher": "",
    "hooks": [{"type": "command", "command": "python3 ~/.claude/hooks/stop.py --notify"}]
  }]
}

Hook Implementation

The hooks are extremely minimal - they just:

1. Read stdin (required by hook protocol)
2. Touch a signal file (~/.claude/tts_signals/notify or stop)
3. Exit immediately

No subprocess spawning, no blocking operations, execution time ~60ms.

Observed Behavior

When hooks are enabled, Claude Code enters an infinite loop during normal operation. When hooks are disabled, no issues occur.

Expected Behavior

Hooks should not cause Claude Code to loop, especially when they execute quickly and do not spawn subprocesses.

Reproduction

Configure fast hooks that touch signal files and observe Claude Code behavior during normal operation.