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/super-cli.py

@@ -2530,6 +2530,12 @@ def cmd_deploy(args):
         session_id = res.get("session_id")
         print(c_green(f"✔ Subagent session spawned: {session_id}"))
 
+        try:
+            import subagent_tracker
+            subagent_tracker.register_session(agent, session_id, title=title, prompt=prompt)
+        except Exception:
+            pass
+
         if prompt:
             print(f"  Dispatching task prompt to subagent (waiting up to {wait}s)...")
             send_res, send_err = muse_hybrid.send_message(agent, prompt, thread_id=session_id, wait=wait)
@@ -3404,6 +3410,15 @@ def build_parser():
     p_dep_sub.add_argument("prompt", help="Task prompt for the subagent")
     p_dep_sub.add_argument("--wait", type=int, default=30, help="Seconds to wait for subagent response")
 
+    # Domain: subagent (Direct alias for spawning & managing subagents)
+    p_subagent = subparsers.add_parser("subagent", parents=[common], help="Spawn sub-agent session and dispatch task")
+    subagent_sub = p_subagent.add_subparsers(dest="action")
+    p_sub_spawn = subagent_sub.add_parser("spawn", parents=[common], help="Spawn sub-agent session and dispatch task")
+    p_sub_spawn.add_argument("--agent", required=True, choices=VALID_NODES, help="Agent node to spawn subagent on")
+    p_sub_spawn.add_argument("--title", default="subagent-task", help="Title for the subagent session")
+    p_sub_spawn.add_argument("prompt", help="Task prompt for the subagent")
+    p_sub_spawn.add_argument("--wait", type=int, default=30, help="Seconds to wait for subagent response")
+
     # Domain: muse (fast headless gateway via muse-cli-node with isolated per-node Cloudflare WARP egress)
     p_muse = subparsers.add_parser("muse", parents=[common], help="Direct headless gateway client (muse-cli-node)")
     p_muse.add_argument("node", choices=VALID_NODES, help="Target agent node")
@@ -3577,7 +3592,9 @@ def main():
         cmd_loop_strat(args)
     elif args.domain == "vars":
         cmd_loop_vars(args)
-    elif args.domain == "deploy":
+    elif args.domain in ("deploy", "subagent"):
+        if args.domain == "subagent":
+            args.action = "subagent"
         cmd_deploy(args)
     elif args.domain == "muse":
         cmd = [str(BIN_DIR / "muse-cli-node"), args.node] + (args.muse_args or [])