#!/usr/bin/env python3
"""
PostToolUse hook: Track chain/gate state from prompt_engine responses.
Triggers after: mcp__claude-prompts-mcp__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 (
load_session_state,
save_session_state,
parse_prompt_engine_response,
format_chain_reminder,
)
def parse_hook_input() -> dict:
"""Parse JSON input from Claude Code hook system."""
try:
data = json.load(sys.stdin)
# Debug: log what we receive
debug_log = Path(__file__).parent / "debug_hook.log"
with open(debug_log, "a") as f:
f.write(f"\n=== PostToolUse Hook ===\n")
f.write(f"tool_name: {data.get('tool_name', 'MISSING')}\n")
f.write(f"session_id: {data.get('session_id', 'MISSING')}\n")
f.write(f"keys: {list(data.keys())}\n")
return data
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)
# Output reminder if gate is pending
output_lines = []
if state.get("pending_gate"):
criteria = state.get("gate_criteria", [])
criteria_str = " | ".join(c[:40] for c in criteria[:3]) if criteria else ""
output_lines.append(f"[Gate] {state['pending_gate']}")
output_lines.append(" Respond: GATE_REVIEW: PASS|FAIL - <reason>")
if criteria_str:
output_lines.append(f" Check: {criteria_str}")
if state.get("current_step") > 0 and state.get("total_steps") > 0:
step = state["current_step"]
total = state["total_steps"]
if step < total:
output_lines.append(f"[Chain] Step {step}/{total} - call prompt_engine to continue")
# Use JSON format for proper PostToolUse hook protocol
# - additionalContext: injected to Claude for next steps
if output_lines:
output = "\n".join(output_lines)
hook_response = {
"hookSpecificOutput": {
"hookEventName": "PostToolUse",
"additionalContext": output
}
}
print(json.dumps(hook_response))
sys.exit(0)
else:
sys.exit(0) # No output needed
if __name__ == "__main__":
main()
