feat: move network topology into a first-party plugin

src/backend/database/routes/network-topology-dispatch.ts

@@ -0,0 +1,47 @@
+// Mounted at /network-topology. Network Topology ships as a first-party
+// in-process plugin (plugins/network-topology) rather than a route file
+// imported directly here, so this module exists to keep /network-topology/*
+// working at its original path without handing the plugin a reference to the
+// shared app instance. The plugin runtime registers its router via
+// registerNetworkTopologyRouter when it activates, and clears it on
+// deactivate, so a disabled plugin falls back to the 404 below.
+//
+// Unlike /plugin-api, this dispatcher applies no auth of its own: it forwards
+// to exactly one first-party router (the Network Topology plugin's own), and
+// every route in that router already applies authenticateJWT itself, the same
+// as every other router mounted alongside it here (/users, /host, /snippets,
+// ...). /plugin-api gates at the mount point because it forwards to arbitrary
+// third-party plugin code that cannot be assumed to gate itself; that
+// reasoning does not apply to a single first-party router that already does.
+
+import type { Request, Response, NextFunction, Router } from "express";
+import { databaseLogger } from "../../utils/logger.js";
+
+let activeRouter: Router | null = null;
+
+export function registerNetworkTopologyRouter(router: Router): void {
+  activeRouter = router;
+  databaseLogger.info("Registered Network Topology plugin router", {
+    operation: "network_topology_dispatch_register",
+  });
+}
+
+export function unregisterNetworkTopologyRouter(): void {
+  if (!activeRouter) return;
+  activeRouter = null;
+  databaseLogger.info("Unregistered Network Topology plugin router", {
+    operation: "network_topology_dispatch_register",
+  });
+}
+
+export default function networkTopologyDispatch(
+  req: Request,
+  res: Response,
+  next: NextFunction,
+): void {
+  if (!activeRouter) {
+    res.status(404).json({ error: "Network Topology is not available" });
+    return;
+  }
+  activeRouter(req, res, next);
+}