feat: Implement multi-node support with MQTT and mDNS for service discovery and coordination

core/src/castle_core/generators/caddyfile.py

@@ -6,23 +6,49 @@ from castle_core.config import GENERATED_DIR, STATIC_DIR
 from castle_core.registry import NodeRegistry
 
 
-def generate_caddyfile_from_registry(registry: NodeRegistry) -> str:
+def generate_caddyfile_from_registry(
+    registry: NodeRegistry,
+    remote_registries: dict[str, NodeRegistry] | None = None,
+) -> str:
     """Generate Caddyfile from the node registry.
 
     Static files served from ~/.castle/static/castle-app/.
     No repo-relative paths.
+
+    If remote_registries is provided, cross-node routes are added for
+    remote services whose proxy_path doesn't conflict with local ones.
     """
     lines = [f":{registry.node.gateway_port} {{"]
 
+    # Track local proxy paths for precedence
+    local_paths: set[str] = set()
+
     for name, deployed in registry.deployed.items():
         if not deployed.proxy_path or not deployed.port:
             continue
 
+        local_paths.add(deployed.proxy_path)
         lines.append(f"    handle_path {deployed.proxy_path}/* {{")
         lines.append(f"        reverse_proxy localhost:{deployed.port}")
         lines.append("    }")
         lines.append("")
 
+    # Remote routes (cross-node) — local paths take precedence
+    if remote_registries:
+        for hostname, remote_reg in remote_registries.items():
+            for name, deployed in remote_reg.deployed.items():
+                if not deployed.proxy_path or not deployed.port:
+                    continue
+                if deployed.proxy_path in local_paths:
+                    continue
+
+                local_paths.add(deployed.proxy_path)
+                lines.append(f"    # {name} on {hostname}")
+                lines.append(f"    handle_path {deployed.proxy_path}/* {{")
+                lines.append(f"        reverse_proxy {hostname}:{deployed.port}")
+                lines.append("    }")
+                lines.append("")
+
     # SPA from static dir
     static_app = STATIC_DIR / "castle-app"
     if (static_app / "index.html").exists():

core/tests/test_caddyfile.py

@@ -113,3 +113,64 @@ class TestCaddyfileFromRegistry:
         assert "reverse_proxy localhost:9001" in caddyfile
         assert "handle_path /svc-b/*" in caddyfile
         assert "reverse_proxy localhost:9002" in caddyfile
+
+
+class TestCaddyfileRemoteRegistries:
+    """Tests for cross-node routing in Caddyfile."""
+
+    def test_remote_routes_included(self) -> None:
+        """Remote services get reverse_proxy entries to their hostname."""
+        local = _make_registry(
+            deployed={
+                "local-svc": DeployedComponent(
+                    runner="python", run_cmd=["svc"], port=9001, proxy_path="/local"
+                ),
+            }
+        )
+        remote = _make_registry(
+            deployed={
+                "remote-svc": DeployedComponent(
+                    runner="python", run_cmd=["svc"], port=9050, proxy_path="/remote"
+                ),
+            }
+        )
+        remote.node.hostname = "devbox"
+        caddyfile = generate_caddyfile_from_registry(local, remote_registries={"devbox": remote})
+        assert "reverse_proxy localhost:9001" in caddyfile
+        assert "reverse_proxy devbox:9050" in caddyfile
+        assert "handle_path /remote/*" in caddyfile
+
+    def test_local_takes_precedence(self) -> None:
+        """If local and remote use the same path, local wins."""
+        local = _make_registry(
+            deployed={
+                "svc": DeployedComponent(
+                    runner="python", run_cmd=["svc"], port=9001, proxy_path="/api"
+                ),
+            }
+        )
+        remote = _make_registry(
+            deployed={
+                "svc": DeployedComponent(
+                    runner="python", run_cmd=["svc"], port=9001, proxy_path="/api"
+                ),
+            }
+        )
+        remote.node.hostname = "devbox"
+        caddyfile = generate_caddyfile_from_registry(local, remote_registries={"devbox": remote})
+        assert "reverse_proxy localhost:9001" in caddyfile
+        assert "devbox" not in caddyfile
+
+    def test_no_remote_when_none(self) -> None:
+        """No remote routes when remote_registries is None."""
+        local = _make_registry(
+            deployed={
+                "svc": DeployedComponent(
+                    runner="python", run_cmd=["svc"], port=9001, proxy_path="/api"
+                ),
+            }
+        )
+        caddyfile = generate_caddyfile_from_registry(local, remote_registries=None)
+        assert "reverse_proxy localhost:9001" in caddyfile
+        # Only one reverse_proxy line
+        assert caddyfile.count("reverse_proxy") == 1