#!/usr/bin/env python3
"""
PreCompact hook: Remind Claude of active chain state before context compaction.
Triggers before: Context compaction (manual /compact or auto)
Reads existing session state and injects a reminder so Claude knows how to
resume the chain after compaction completes.
"""
import json
import sys
from pathlib import Path
# Add hooks lib to path
sys.path.insert(0, str(Path(__file__).parent / "lib"))
from session_state import load_session_state, format_chain_reminder
def parse_hook_input() -> dict:
"""Parse JSON input from Claude Code hook system."""
try:
return json.load(sys.stdin)
except json.JSONDecodeError:
return {}
def main():
hook_input = parse_hook_input()
session_id = hook_input.get("session_id", "")
if not session_id:
sys.exit(0)
# Load existing chain state (written by post-prompt-engine.py)
state = load_session_state(session_id)
if not state:
sys.exit(0)
# Only inject if there's active chain/gate/verify state
has_chain = state.get("current_step", 0) > 0
has_gate = state.get("pending_gate") is not None
has_verify = state.get("pending_shell_verify") is not None
if not has_chain and not has_gate and not has_verify:
sys.exit(0)
# Format reminder using existing function
reminder = format_chain_reminder(state)
# Output for Claude to remember after compaction
hook_response = {
"hookSpecificOutput": {
"hookEventName": "PreCompact",
"additionalContext": f"## Chain State (preserve across compaction)\n{reminder}"
}
}
print(json.dumps(hook_response))
sys.exit(0)
if __name__ == "__main__":
main()
