fix(vpn): handle VPN forwarding mode downgrades and support runtime VPN config updates

test/test.vpn-runtime.node.ts

@@ -0,0 +1,110 @@
+import { expect, tap } from '@git.zone/tstest/tapbundle';
+import { DcRouter } from '../ts/classes.dcrouter.js';
+import { VpnManager } from '../ts/vpn/classes.vpn-manager.js';
+
+tap.test('VpnManager downgrades back to socket mode when no host-IP clients remain', async () => {
+  const manager = new VpnManager({ forwardingMode: 'socket' });
+
+  let stopCalls = 0;
+  let startCalls = 0;
+
+  (manager as any).vpnServer = { running: true };
+  (manager as any).resolvedForwardingMode = 'hybrid';
+  (manager as any).clients = new Map([
+    ['client-1', { useHostIp: false }],
+  ]);
+  (manager as any).stop = async () => {
+    stopCalls++;
+  };
+  (manager as any).start = async () => {
+    startCalls++;
+    (manager as any).resolvedForwardingMode = (manager as any).forwardingModeOverride ?? 'socket';
+    (manager as any).forwardingModeOverride = undefined;
+    (manager as any).vpnServer = { running: true };
+  };
+
+  const restarted = await (manager as any).reconcileForwardingMode();
+
+  expect(restarted).toEqual(true);
+  expect(stopCalls).toEqual(1);
+  expect(startCalls).toEqual(1);
+  expect((manager as any).resolvedForwardingMode).toEqual('socket');
+});
+
+tap.test('VpnManager keeps explicit hybrid mode even without host-IP clients', async () => {
+  const manager = new VpnManager({ forwardingMode: 'hybrid' });
+
+  let stopCalls = 0;
+  let startCalls = 0;
+
+  (manager as any).vpnServer = { running: true };
+  (manager as any).resolvedForwardingMode = 'hybrid';
+  (manager as any).clients = new Map([
+    ['client-1', { useHostIp: false }],
+  ]);
+  (manager as any).stop = async () => {
+    stopCalls++;
+  };
+  (manager as any).start = async () => {
+    startCalls++;
+  };
+
+  const restarted = await (manager as any).reconcileForwardingMode();
+
+  expect(restarted).toEqual(false);
+  expect(stopCalls).toEqual(0);
+  expect(startCalls).toEqual(0);
+  expect((manager as any).resolvedForwardingMode).toEqual('hybrid');
+});
+
+tap.test('DcRouter.updateVpnConfig swaps the runtime VPN resolver and restarts VPN services', async () => {
+  const dcRouter = new DcRouter({
+    smartProxyConfig: { routes: [] },
+    dbConfig: { enabled: false },
+    vpnConfig: { enabled: false },
+  });
+
+  let stopCalls = 0;
+  let setupCalls = 0;
+  let applyCalls = 0;
+  const resolverValues: Array<unknown> = [];
+
+  dcRouter.vpnManager = {
+    stop: async () => {
+      stopCalls++;
+    },
+  } as any;
+  (dcRouter as any).routeConfigManager = {
+    setVpnClientIpsResolver: (resolver: unknown) => {
+      resolverValues.push(resolver);
+    },
+    applyRoutes: async () => {
+      applyCalls++;
+    },
+  };
+  (dcRouter as any).setupVpnServer = async () => {
+    setupCalls++;
+    dcRouter.vpnManager = {
+      stop: async () => {
+        stopCalls++;
+      },
+    } as any;
+  };
+
+  await dcRouter.updateVpnConfig({ enabled: true, subnet: '10.9.0.0/24' });
+
+  expect(stopCalls).toEqual(1);
+  expect(setupCalls).toEqual(1);
+  expect(applyCalls).toEqual(0);
+  expect(typeof resolverValues.at(-1)).toEqual('function');
+
+  await dcRouter.updateVpnConfig({ enabled: false });
+
+  expect(stopCalls).toEqual(2);
+  expect(setupCalls).toEqual(1);
+  expect(applyCalls).toEqual(1);
+  expect(resolverValues.at(-1)).toBeUndefined();
+  expect(dcRouter.vpnManager).toBeUndefined();
+});
+
+export default tap.start()