feat(subagent): implement subagent lifecycle tracking and core loop reactive wakeup

- Implement bin/subagent_tracker.py with session registry in subagent-sessions.json
- Register spawned sessions automatically in super-cli.py cmd_deploy
- Add check_subagents() to bin/self_main_loop.py with thread updated watermark comparison
- Add 15-minute stall watchdog with automated parent alerting
- Support 'box subagent spawn' top-level command alias in super-cli.py
- Add symmetrical pip-opm sidechat routing in job-sidechats.json

bin/subagent_tracker.py

@@ -0,0 +1,95 @@
+#!/usr/bin/env python3
+"""
+subagent_tracker.py — Registry and lifecycle tracker for fleet subagents.
+
+Maintains subagent-sessions.json tracking active child sessions spawned
+by parent agents (646, pip, muse, opm), their last observed watermarks,
+and timeout/stall states for reactive wakeups by self_main_loop.py.
+"""
+
+import json
+import os
+import sys
+from datetime import datetime, timezone
+from pathlib import Path
+
+BASE = Path("/home/super/Projects/NetVM")
+SESSIONS_FILE = BASE / "subagent-sessions.json"
+
+
+def utcnow():
+    return datetime.now(timezone.utc).strftime("%Y-%m-%dT%H:%M:%SZ")
+
+
+def load_sessions():
+    if not SESSIONS_FILE.exists():
+        return {}
+    try:
+        with open(SESSIONS_FILE, "r", encoding="utf-8") as f:
+            data = json.load(f)
+            return data if isinstance(data, dict) else {}
+    except Exception:
+        return {}
+
+
+def save_sessions(data):
+    tmp = f"{SESSIONS_FILE}.tmp.{os.getpid()}"
+    with open(tmp, "w", encoding="utf-8") as f:
+        json.dump(data, f, indent=2)
+    os.replace(tmp, SESSIONS_FILE)
+
+
+def register_session(parent, session_id, title=None, prompt=None):
+    """Register newly spawned subagent session."""
+    data = load_sessions()
+    now_iso = utcnow()
+    entry = {
+        "session_id": session_id,
+        "parent": parent,
+        "title": title or "subagent",
+        "prompt": prompt or "",
+        "spawned_at": now_iso,
+        "last_watermark": None,
+        "status": "active",
+        "timeout_warned": False,
+        "last_activity_at": now_iso,
+    }
+    data[session_id] = entry
+    save_sessions(data)
+    return entry
+
+
+def get_active_sessions(parent=None):
+    """Retrieve all active subagent sessions, optionally filtered by parent."""
+    data = load_sessions()
+    results = []
+    for s in data.values():
+        if s.get("status") == "active":
+            if parent is None or s.get("parent") == parent:
+                results.append(s)
+    return results
+
+
+def update_session(session_id, **kwargs):
+    """Update fields on a tracked subagent session."""
+    data = load_sessions()
+    if session_id in data:
+        data[session_id].update(kwargs)
+        save_sessions(data)
+        return data[session_id]
+    return None
+
+
+def complete_session(session_id, note=None):
+    """Mark a subagent session completed."""
+    kwargs = {"status": "completed", "completed_at": utcnow()}
+    if note:
+        kwargs["completion_note"] = note
+    return update_session(session_id, **kwargs)
+
+
+if __name__ == "__main__":
+    if len(sys.argv) > 1 and sys.argv[1] == "list":
+        print(json.dumps(load_sessions(), indent=2))
+    else:
+        print("Usage: subagent_tracker.py list")