"""PreToolUse hook on matcher 'Skill': writes a per-session flag so the
skill-check hook knows a Skill was invoked at least once in this session.
Reads hook input JSON from stdin. Silent on failure - never blocks the tool."""
import json
import os
import sys
import tempfile


def main() -> None:
    try:
        data = json.load(sys.stdin)
    except Exception:
        return
    sid = data.get("session_id") or "unknown"
    flag = os.path.join(tempfile.gettempdir(), f"claude-skill-{sid}.flag")
    try:
        with open(flag, "w", encoding="utf-8") as f:
            f.write(data.get("tool_input", {}).get("skill", "") or "")
    except Exception:
        return


if __name__ == "__main__":
    main()