fix(gateway): advertise reachable canvas host

src/gateway/server.ts

@@ -3204,6 +3204,10 @@ export async function startGatewayServer(
 
   const machineDisplayName = await getMachineDisplayName();
   const canvasHostPortForBridge = canvasHostServer?.port;
+  const canvasHostHostForBridge =
+    canvasHostServer && bridgeHost && bridgeHost !== "0.0.0.0" && bridgeHost !== "::"
+      ? bridgeHost
+      : undefined;
 
   if (bridgeEnabled && bridgePort > 0 && bridgeHost) {
     try {
@@ -3212,6 +3216,7 @@ export async function startGatewayServer(
         port: bridgePort,
         serverName: machineDisplayName,
         canvasHostPort: canvasHostPortForBridge,
+        canvasHostHost: canvasHostHostForBridge,
         onRequest: (nodeId, req) => handleBridgeRequest(nodeId, req),
         onAuthenticated: async (node) => {
           const host = node.displayName?.trim() || node.nodeId;

src/infra/bridge/server.ts

@@ -138,6 +138,7 @@ export type NodeBridgeServerOpts = {
   port: number; // 0 = ephemeral
   pairingBaseDir?: string;
   canvasHostPort?: number;
+  canvasHostHost?: string;
   onEvent?: (nodeId: string, evt: BridgeEventFrame) => Promise<void> | void;
   onRequest?: (
     nodeId: string,
@@ -187,10 +188,20 @@ export async function startNodeBridgeServer(
       ? opts.serverName.trim()
       : os.hostname();
 
+  const isLoopbackHost = (host: string) => {
+    const normalized = host.trim().toLowerCase();
+    if (normalized === "localhost") return true;
+    if (normalized === "::1") return true;
+    if (normalized === "0.0.0.0" || normalized === "::") return true;
+    return normalized.startsWith("127.");
+  };
+
   const buildCanvasHostUrl = (socket: net.Socket) => {
     const port = opts.canvasHostPort;
     if (!port) return undefined;
-    const host = socket.localAddress?.trim();
+    const localHost = socket.localAddress?.trim() ?? "";
+    const override = opts.canvasHostHost?.trim() ?? "";
+    const host = !localHost || isLoopbackHost(localHost) ? override : localHost;
     if (!host) return undefined;
     const formatted = host.includes(":") ? `[${host}]` : host;
     return `http://${formatted}:${port}`;