fix(core): unbind all services in connection container on close

CHANGELOG.md

@@ -8,6 +8,7 @@
 
 - [core] added `errorHandling` option to `Emitter` to control how listener exceptions are handled: `'log'` (default), `'propagate'` (collect and re-throw), or a custom callback [#17332](https://github.com/eclipse-theia/theia/pull/17332)
 - [editor] replaced the per-URI editor counter system in `EditorManager` with random counters [#17275](https://github.com/eclipse-theia/theia/pull/17275)
+- [core] the Inversify containers created in the backend for each frontend connection (connection-scoped child containers) now unbind all services via `Container::unbindAllAsync()` upon closure of the RPC channel. This allows clean-up methods annotated with `@preDestroy()` to run, releasing resources. Downstream applications should be aware that service instances deliberately shared between connection-scoped containers, and service instances obtained from the root container that are explicitly bound again in the connection-scoped module, will cause such shared services to be destroyed while still in use in other containers. Both of these scenarios are already Inversify anti-patterns, so are not expected to arise in practice. [#17384](https://github.com/eclipse-theia/theia/pull/17384)
 
 <a name="breaking_changes_1.71.0">[Breaking Changes:](#breaking_changes_1.71.0)</a>
 

packages/core/src/node/messaging/default-messaging-service.ts

@@ -71,6 +71,7 @@ export class DefaultMessagingService implements MessagingService, BackendApplica
     protected createMainChannelContainer(socket: Channel): Container {
         const connectionContainer: Container = this.container.createChild() as Container;
         connectionContainer.bind(MainChannel).toConstantValue(socket);
+        socket.onClose(() => connectionContainer.unbindAllAsync().catch(e => console.error(e)));
         return connectionContainer;
     }
 

packages/core/src/node/messaging/test/default-messaging-service.spec.ts

@@ -0,0 +1,85 @@
+// *****************************************************************************
+// Copyright (C) 2026 EclipseSource and others.
+//
+// This program and the accompanying materials are made available under the
+// terms of the Eclipse Public License v. 2.0 which is available at
+// http://www.eclipse.org/legal/epl-2.0.
+//
+// This Source Code may also be made available under the following Secondary
+// Licenses when the conditions for such availability set forth in the Eclipse
+// Public License v. 2.0 are satisfied: GNU General Public License, version 2
+// with the GNU Classpath Exception which is available at
+// https://www.gnu.org/software/classpath/license.html.
+//
+// SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0
+// *****************************************************************************
+
+import { expect } from 'chai';
+import { Container, injectable, preDestroy } from 'inversify';
+import { ConnectionHandler, bindContributionProvider, servicesPath } from '../../../common';
+import { BasicChannel, Channel } from '../../../common/message-rpc/channel';
+import { Uint8ArrayWriteBuffer } from '../../../common/message-rpc/uint8-array-message-buffer';
+import { ConnectionContainerModule } from '../connection-container-module';
+import { DefaultMessagingService, MessagingContainer } from '../default-messaging-service';
+import { FrontendConnectionService } from '../frontend-connection-service';
+import { MessagingService } from '../messaging-service';
+
+describe('DefaultMessagingService', () => {
+
+    describe('when a frontend connection closes', () => {
+
+        it('disposes the connection-scoped child container, invoking @preDestroy on bound singleton services', async () => {
+            let canaryDisposed = false;
+
+            @injectable()
+            class CanaryConnectionHandler implements ConnectionHandler {
+                readonly path = 'canary';
+                onConnection(_channel: Channel): void { /* not relevant for this test */ }
+
+                @preDestroy()
+                protected onPreDestroy(): void {
+                    canaryDisposed = true;
+                }
+            }
+
+            const canaryModule = ConnectionContainerModule.create(({ bind }) => {
+                bind(CanaryConnectionHandler).toSelf().inSingletonScope();
+                bind(ConnectionHandler).toService(CanaryConnectionHandler);
+            });
+
+            const container = new Container();
+            container.bind(MessagingContainer).toConstantValue(container);
+            container.bind(DefaultMessagingService).toSelf().inSingletonScope();
+            container.bind(ConnectionContainerModule).toConstantValue(canaryModule);
+            bindContributionProvider(container, ConnectionContainerModule);
+            bindContributionProvider(container, MessagingService.Contribution);
+
+            let serviceHandler: ((params: MessagingService.PathParams, mainChannel: Channel) => void) | undefined;
+            const frontendConnectionService: FrontendConnectionService = {
+                registerConnectionHandler(path, callback): void {
+                    if (path === servicesPath) {
+                        serviceHandler = callback;
+                    }
+                }
+            };
+            container.bind(FrontendConnectionService).toConstantValue(frontendConnectionService);
+
+            const messagingService = container.get(DefaultMessagingService);
+            messagingService.initialize();
+
+            expect(serviceHandler, 'connection handler not registered on the services path').to.not.be.undefined;
+
+            const mainChannel = new BasicChannel(() => new Uint8ArrayWriteBuffer());
+            serviceHandler!({}, mainChannel);
+
+            expect(canaryDisposed, 'canary should not be disposed before the channel is closed').to.be.false;
+
+            mainChannel.onCloseEmitter.fire({ reason: 'frontend connection closed' });
+            await new Promise<void>(resolve => setImmediate(resolve));
+
+            expect(canaryDisposed, 'canary @preDestroy was not invoked').to.be.true;
+        });
+
+    });
+
+});