diff --git a/src/gateway/server-close.ts b/src/gateway/server-close.ts
index da9f5a39e..9977c0a3c 100644
--- a/src/gateway/server-close.ts
+++ b/src/gateway/server-close.ts
@@ -3,6 +3,7 @@ import type { WebSocketServer } from "ws";
 import type { CanvasHostHandler, CanvasHostServer } from "../canvas-host/server.js";
 import { type ChannelId, listChannelPlugins } from "../channels/plugins/index.js";
 import { stopGmailWatcher } from "../hooks/gmail-watcher.js";
+import { killAllChildren, killAllChildrenSync } from "../infra/child-registry.js";
 import type { HeartbeatRunner } from "../infra/heartbeat-runner.js";
 import type { PluginServicesHandle } from "../plugins/services.js";
 
@@ -124,5 +125,11 @@ export function createGatewayCloseHandler(params: {
         httpServer.close((err) => (err ? reject(err) : resolve())),
       );
     }
+
+    // Phase 3: Kill any orphaned children not stopped by their own managers
+    await killAllChildren("SIGTERM", { excludeManaged: true, timeoutMs: 2000 });
+
+    // Phase 4: Force cleanup of any remaining children
+    killAllChildrenSync();
   };
 }