Stop hook — block until background_tasks and session_crons drain

#!/usr/bin/env python3
# Save as .claude/hooks/wait-for-background.py and wire up under Stop.
import json, sys

data = json.load(sys.stdin)
pending_bg = [
    t for t in data.get("background_tasks", [])
    if t.get("status") in ("running", "starting")
]
pending_cron = data.get("session_crons", [])

if pending_bg or pending_cron:
    reason_bits = []
    if pending_bg:
        names = ", ".join(t.get("description") or t.get("id", "?") for t in pending_bg[:3])
        reason_bits.append(f"{len(pending_bg)} background task(s) still running: {names}")
    if pending_cron:
        reason_bits.append(f"{len(pending_cron)} scheduled task(s) still queued")
    print(json.dumps({"decision": "block", "reason": "; ".join(reason_bits)}))
    sys.exit(0)

# Nothing pending — let Claude stop.
sys.exit(0)