#!/usr/bin/env python3
"""
PostToolUse hook: Track chain/gate state from prompt_engine responses.
Triggers after: mcp__claude-prompts__prompt_engine
Parses the response to:
1. Track current chain step
2. Detect pending gates
3. Inject reminders for gate reviews
"""
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 (
save_session_state,
parse_prompt_engine_response,
)
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()
tool_name = hook_input.get("tool_name", "")
session_id = hook_input.get("session_id", "")
# Only process prompt_engine calls
if "prompt_engine" not in tool_name:
sys.exit(0)
tool_response = hook_input.get("tool_response", {})
tool_input = hook_input.get("tool_input", {})
# Parse response for chain/gate state
if isinstance(tool_response, dict):
content = tool_response.get("content", "")
# Handle array of content blocks
if isinstance(content, list):
content = " ".join(
block.get("text", "") if isinstance(block, dict) else str(block)
for block in content
)
else:
content = str(tool_response)
state = parse_prompt_engine_response(content)
if not state:
sys.exit(0)
# Extract chain_id from tool_input (higher priority than regex parsing)
if isinstance(tool_input, dict):
input_chain_id = tool_input.get("chain_id", "")
if input_chain_id:
state["chain_id"] = input_chain_id
# Save state for this session
save_session_state(session_id, state)
# Check if gate review is pending - guide Claude to submit verdict
chain_id = state.get("chain_id", "")
pending_gate = state.get("pending_gate")
step = state.get("current_step", 0)
total = state.get("total_steps", 0)
if pending_gate:
# CLAUDE DIRECTIVE ONLY: Guide Claude to submit verdict (token-efficient)
# User sees server's "Gate Review Required" message in tool response
directive = f'<GATE-REVIEW>chain_id="{chain_id}" gates="{pending_gate}" → Submit gate_verdict</GATE-REVIEW>'
hook_response = {
"hookSpecificOutput": {
"hookEventName": "PostToolUse",
"additionalContext": directive
}
}
print(json.dumps(hook_response))
sys.exit(0)
# Non-blocking: Just guide Claude to continue chain
if step > 0 and total > 0 and step < total:
hook_response = {
"hookSpecificOutput": {
"hookEventName": "PostToolUse",
"additionalContext": f'Continue chain: prompt_engine(chain_id="{chain_id}")'
}
}
print(json.dumps(hook_response))
sys.exit(0)
sys.exit(0) # No output needed
if __name__ == "__main__":
main()
