Add Harbor Gateway auto-detection for client routing

test/server/singbox-client-mode.test.js

@@ -32,3 +32,13 @@ test('client exposes one local proxy and routes it through the selected VPN', ()
   assert.equal(config.route.final, 'test-vpn');
   assert.equal(config.route.auto_detect_interface, undefined);
 });
+
+test('client keeps its local proxy but routes directly when Harbor Gateway is ahead', () => {
+  const config = buildGatewayConfig(subscriptionConfig, 'test-vpn', { clientDirect: true });
+
+  assert.deepEqual(config.route.rules, [
+    { inbound: ['mixed-in'], outbound: 'direct' },
+  ]);
+  assert.equal(config.route.final, 'direct');
+  assert.deepEqual(config.outbounds.map((outbound) => outbound.tag), ['direct', 'block']);
+});