feat(orch): agent self-registration and coordinator heartbeat loop

coordinator/app.py:
- Add POST /api/nodes — agents POST {node_id, agent_url} to self-register;
  coordinator immediately polls the new agent for GPU info
- Add lifespan context manager that starts/stops AgentSupervisor heartbeat
  loop (previously the loop was never started)

cli.py start:
- Add --node-id flag (default 'local')
- Pre-register the local agent URL (http://127.0.0.1:{agent_port}) so the
  heartbeat loop can poll it immediately on startup
- Drop redundant lease_manager.register_gpu() call — supervisor.poll_agent()
  now does this via the heartbeat after the agent responds

cli.py agent:
- Add --advertise-host flag for NATted/multi-homed nodes
- Fire registration POST to coordinator in a daemon thread (2s delay) so
  uvicorn.run() can start binding immediately; no double uvicorn.run()

circuitforge_core/resources/cli.py

@@ -32,9 +32,14 @@ def start(
     profile: Annotated[Optional[Path], typer.Option(help="Profile YAML path")] = None,
     host: str = "0.0.0.0",
     port: int = 7700,
+    node_id: str = "local",
     agent_port: int = 7701,
 ) -> None:
-    """Start the cf-orch coordinator (auto-detects GPU profile if not specified)."""
+    """Start the cf-orch coordinator (auto-detects GPU profile if not specified).
+
+    Automatically pre-registers the local agent so its GPUs appear on the
+    dashboard immediately. Remote nodes self-register via POST /api/nodes.
+    """
     from circuitforge_core.resources.coordinator.lease_manager import LeaseManager
     from circuitforge_core.resources.coordinator.profile_registry import ProfileRegistry
     from circuitforge_core.resources.coordinator.agent_supervisor import AgentSupervisor
@@ -52,8 +57,6 @@ def start(
             "Warning: no GPUs detected via nvidia-smi — coordinator running with 0 VRAM"
         )
     else:
-        for gpu in gpus:
-            lease_manager.register_gpu("local", gpu.gpu_id, gpu.vram_total_mb)
         typer.echo(f"Detected {len(gpus)} GPU(s)")
 
     if profile:
@@ -67,6 +70,11 @@ def start(
         )
         typer.echo(f"Auto-selected profile: {active_profile.name}")
 
+    # Pre-register the local agent — the heartbeat loop will poll it for live GPU data.
+    local_agent_url = f"http://127.0.0.1:{agent_port}"
+    supervisor.register(node_id, local_agent_url)
+    typer.echo(f"Registered local node '{node_id}' → {local_agent_url}")
+
     coordinator_app = create_coordinator_app(
         lease_manager=lease_manager,
         profile_registry=profile_registry,
@@ -83,10 +91,47 @@ def agent(
     node_id: str = "local",
     host: str = "0.0.0.0",
     port: int = 7701,
+    advertise_host: Optional[str] = None,
 ) -> None:
-    """Start a cf-orch node agent (for remote nodes like Navi, Huginn)."""
+    """Start a cf-orch node agent and self-register with the coordinator.
+
+    The agent starts its HTTP server, then POSTs its URL to the coordinator
+    so it appears on the dashboard without manual configuration.
+
+    Use --advertise-host to override the IP the coordinator should use to
+    reach this agent (e.g. on a multi-homed or NATted host).
+    """
+    import asyncio
+    import threading
+    import httpx
     from circuitforge_core.resources.agent.app import create_agent_app
 
+    # The URL the coordinator should use to reach this agent.
+    reach_host = advertise_host or ("127.0.0.1" if host in ("0.0.0.0", "::") else host)
+    agent_url = f"http://{reach_host}:{port}"
+
+    def _register_in_background() -> None:
+        """POST registration to coordinator after a short delay (uvicorn needs ~1s to bind)."""
+        import time
+        time.sleep(2.0)
+        try:
+            resp = httpx.post(
+                f"{coordinator}/api/nodes",
+                json={"node_id": node_id, "agent_url": agent_url},
+                timeout=5.0,
+            )
+            if resp.is_success:
+                typer.echo(f"Registered with coordinator at {coordinator} as '{node_id}'")
+            else:
+                typer.echo(
+                    f"Warning: coordinator registration returned {resp.status_code}", err=True
+                )
+        except Exception as exc:
+            typer.echo(f"Warning: could not reach coordinator at {coordinator}: {exc}", err=True)
+
+    # Fire registration in a daemon thread so uvicorn.run() can start blocking immediately.
+    threading.Thread(target=_register_in_background, daemon=True).start()
+
     agent_app = create_agent_app(node_id=node_id)
     typer.echo(f"Starting cf-orch agent [{node_id}] on {host}:{port}")
     uvicorn.run(agent_app, host=host, port=port)

circuitforge_core/resources/coordinator/app.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from contextlib import asynccontextmanager
 from pathlib import Path
 from typing import Any
 
@@ -7,13 +8,13 @@ from fastapi import FastAPI, HTTPException
 from fastapi.responses import HTMLResponse
 from pydantic import BaseModel
 
-_DASHBOARD_HTML = (Path(__file__).parent / "dashboard.html").read_text()
-
 from circuitforge_core.resources.coordinator.agent_supervisor import AgentSupervisor
 from circuitforge_core.resources.coordinator.eviction_engine import EvictionEngine
 from circuitforge_core.resources.coordinator.lease_manager import LeaseManager
 from circuitforge_core.resources.coordinator.profile_registry import ProfileRegistry
 
+_DASHBOARD_HTML = (Path(__file__).parent / "dashboard.html").read_text()
+
 
 class LeaseRequest(BaseModel):
     node_id: str
@@ -24,6 +25,11 @@ class LeaseRequest(BaseModel):
     ttl_s: float = 0.0
 
 
+class NodeRegisterRequest(BaseModel):
+    node_id: str
+    agent_url: str  # e.g. "http://10.1.10.71:7701"
+
+
 def create_coordinator_app(
     lease_manager: LeaseManager,
     profile_registry: ProfileRegistry,
@@ -31,7 +37,15 @@ def create_coordinator_app(
 ) -> FastAPI:
     eviction_engine = EvictionEngine(lease_manager=lease_manager)
 
-    app = FastAPI(title="cf-orch-coordinator")
+    @asynccontextmanager
+    async def _lifespan(app: FastAPI):  # type: ignore[type-arg]
+        import asyncio
+        task = asyncio.create_task(agent_supervisor.run_heartbeat_loop())
+        yield
+        agent_supervisor.stop()
+        task.cancel()
+
+    app = FastAPI(title="cf-orch-coordinator", lifespan=_lifespan)
 
     @app.get("/", response_class=HTMLResponse, include_in_schema=False)
     def dashboard() -> HTMLResponse:
@@ -65,6 +79,13 @@ def create_coordinator_app(
             ]
         }
 
+    @app.post("/api/nodes")
+    async def register_node(req: NodeRegisterRequest) -> dict[str, Any]:
+        """Agents call this to self-register. Coordinator immediately polls for GPU info."""
+        agent_supervisor.register(req.node_id, req.agent_url)
+        await agent_supervisor.poll_agent(req.node_id)
+        return {"registered": True, "node_id": req.node_id}
+
     @app.get("/api/profiles")
     def get_profiles() -> dict[str, Any]:
         return {