Dev Container improvements

packages/dev-container/src/electron-browser/container-connection-contribution.ts

@@ -14,7 +14,7 @@
 // SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0
 // *****************************************************************************
 
-import { inject, injectable } from '@theia/core/shared/inversify';
+import { inject, injectable, postConstruct } from '@theia/core/shared/inversify';
 import { AbstractRemoteRegistryContribution, RemoteRegistry } from '@theia/remote/lib/electron-browser/remote-registry-contribution';
 import { DevContainerFile, LastContainerInfo, RemoteContainerConnectionProvider } from '../electron-common/remote-container-connection-provider';
 import { WorkspaceStorageService } from '@theia/workspace/lib/browser/workspace-storage-service';
@@ -32,9 +32,29 @@ export namespace RemoteContainerCommands {
         label: 'Reopen in Container',
         category: 'Dev Container'
     }, 'theia/remote/dev-container/connect');
+
+    export const ATTACH_TO_CONTAINER = Command.toLocalizedCommand({
+        id: 'dev-container:attach-to-container',
+        label: 'Attach to Running Container',
+        category: 'Dev Container'
+    }, 'theia/remote/dev-container/attach');
+
+    export const REBUILD_CONTAINER = Command.toLocalizedCommand({
+        id: 'dev-container:rebuild-container',
+        label: 'Rebuild Container',
+        category: 'Dev Container'
+    }, 'theia/remote/dev-container/rebuild');
 }
 
 const LAST_USED_CONTAINER = 'lastUsedContainer';
+const ACTIVE_DEV_CONTAINER_CONTEXT = 'activeDevContainerContext';
+
+interface DevContainerContext {
+    devcontainerFilePath: string;
+    devcontainerFileName: string;
+    hostWorkspacePath: string;
+    containerId: string;
+}
 @injectable()
 export class ContainerConnectionContribution extends AbstractRemoteRegistryContribution implements WorkspaceOpenHandlerContribution {
 
@@ -65,28 +85,85 @@ export class ContainerConnectionContribution extends AbstractRemoteRegistryContr
     @inject(ContainerOutputProvider)
     protected readonly containerOutputProvider: ContainerOutputProvider;
 
+    protected hasDevContainerFiles = false;
+
+    @postConstruct()
+    protected init(): void {
+        // Mark that we're in a remote session. sessionStorage survives page
+        // reloads (disconnect) but is cleared on window close (restart).
+        // This lets canHandle() distinguish disconnect from restart.
+        if (this.isRemoteSession()) {
+            sessionStorage.setItem('devcontainer:wasRemote', 'true');
+        }
+        this.workspaceService.ready.then(() => this.checkForDevContainerFiles());
+        this.workspaceService.onWorkspaceChanged(() => this.checkForDevContainerFiles());
+    }
+
+    protected async checkForDevContainerFiles(): Promise<void> {
+        if (this.isRemoteSession()) {
+            this.hasDevContainerFiles = true;
+            return;
+        }
+        const workspace = this.workspaceService.workspace;
+        if (!workspace) {
+            this.hasDevContainerFiles = false;
+            return;
+        }
+        try {
+            const files = await this.connectionProvider.getDevContainerFiles(workspace.resource.path.toString());
+            this.hasDevContainerFiles = files.length > 0;
+        } catch (error) {
+            // Failed to check for devcontainer files, assume none exist
+            this.hasDevContainerFiles = false;
+        }
+    }
+
     registerRemoteCommands(registry: RemoteRegistry): void {
         registry.registerCommand(RemoteContainerCommands.REOPEN_IN_CONTAINER, {
-            execute: () => this.openInContainer()
+            execute: () => this.openInContainer(),
+            isVisible: () => !this.isRemoteSession() && this.hasDevContainerFiles
         });
+        registry.registerCommand(RemoteContainerCommands.ATTACH_TO_CONTAINER, {
+            execute: () => this.attachToContainer()
+        });
+        registry.registerCommand(RemoteContainerCommands.REBUILD_CONTAINER, {
+            execute: () => this.rebuildContainer(),
+            isVisible: () => this.isRemoteSession()
+        });
+    }
+
+    protected isRemoteSession(): boolean {
+        return new URLSearchParams(window.location.search).has('localPort');
     }
 
     canHandle(uri: URI): MaybePromise<boolean> {
-        return uri.scheme === DEV_CONTAINER_WORKSPACE_SCHEME;
+        if (uri.scheme !== DEV_CONTAINER_WORKSPACE_SCHEME) {
+            return false;
+        }
+        // After disconnect (reload), sessionStorage still has the flag from
+        // the remote session's init. Skip auto-reopen so the user gets their
+        // local workspace. After restart (close+open), sessionStorage is
+        // cleared, so auto-reopen works.
+        const wasRemote = sessionStorage.getItem('devcontainer:wasRemote');
+        if (wasRemote) {
+            sessionStorage.removeItem('devcontainer:wasRemote');
+            return false;
+        }
+        return true;
     }
 
     async openWorkspace(uri: URI, options?: WorkspaceInput | undefined): Promise<void> {
         const filePath = new URLSearchParams(uri.query).get(DEV_CONTAINER_PATH_QUERY);
 
         if (!filePath) {
-            throw new Error('No devcontainer file specified for workspace');
+            throw new Error(nls.localize('theia/dev-container/noDevcontainerFileSpecified', 'No devcontainer file specified for workspace'));
         }
 
         const devcontainerFiles = await this.connectionProvider.getDevContainerFiles(uri.path.toString());
         const devcontainerFile = devcontainerFiles.find(file => file.path === filePath);
 
         if (!devcontainerFile) {
-            throw new Error(`Devcontainer file at ${filePath} not found in workspace`);
+            throw new Error(nls.localize('theia/dev-container/devcontainerFileNotFound', 'Devcontainer file at {0} not found in workspace', filePath));
         }
 
         return this.doOpenInContainer(devcontainerFile, uri.path.toString());
@@ -110,26 +187,115 @@ export class ContainerConnectionContribution extends AbstractRemoteRegistryContr
         this.doOpenInContainer(devcontainerFile);
     }
 
+    async attachToContainer(): Promise<void> {
+        const containers = await this.connectionProvider.listRunningContainers();
+        if (containers.length === 0) {
+            this.messageService.info(nls.localize('theia/remote/dev-container/noRunningContainers', 'No running containers found.'));
+            return;
+        }
+
+        const selected = await this.quickInputService.pick(containers.map(container => ({
+            type: 'item' as const,
+            label: container.name || container.id.substring(0, 12),
+            description: container.image,
+            detail: container.status,
+            container
+        })), {
+            title: nls.localize('theia/remote/dev-container/selectContainer', 'Select a running container to attach to')
+        });
+
+        if (!selected) {
+            return;
+        }
+
+        this.containerOutputProvider.openChannel();
+
+        const connectionResult = await this.connectionProvider.attachToContainer(selected.container.id);
+        this.openRemote(connectionResult.port, false, connectionResult.workspacePath);
+    }
+
+    async rebuildContainer(): Promise<void> {
+        this.containerOutputProvider.openChannel();
+        const progress = await this.messageService.showProgress({
+            text: nls.localize('theia/remote/dev-container/rebuilding', 'Rebuilding dev container...')
+        });
+
+        try {
+            // When inside a remote container, read the stored context instead of
+            // scanning the filesystem (the RPC goes to the local backend which
+            // doesn't have the container's workspace path).
+            const ctx = await this.storageService.getData<DevContainerContext | undefined>(ACTIVE_DEV_CONTAINER_CONTEXT);
+            if (ctx) {
+                progress.report({ message: nls.localize('theia/dev-container/removingOldContainer', 'Removing old container...') });
+                try {
+                    await this.connectionProvider.removeContainer(ctx.containerId);
+                } catch (error) {
+                    // Container may already be gone, ignore error
+                }
+                const lastContainerKey = `${LAST_USED_CONTAINER}:${ctx.devcontainerFilePath}`;
+                await this.storageService.setData(lastContainerKey, undefined);
+                progress.cancel();
+                this.doOpenInContainer(
+                    { path: ctx.devcontainerFilePath, name: ctx.devcontainerFileName },
+                    ctx.hostWorkspacePath
+                );
+                return;
+            }
+
+            // Fallback: local workspace — scan for devcontainer files
+            const devcontainerFile = await this.getOrSelectDevcontainerFile();
+            if (!devcontainerFile) {
+                return;
+            }
+            const lastContainerInfoKey = `${LAST_USED_CONTAINER}:${devcontainerFile.path}`;
+            const lastContainerInfo = await this.storageService.getData<LastContainerInfo | undefined>(lastContainerInfoKey);
+            if (lastContainerInfo) {
+                progress.report({ message: nls.localize('theia/dev-container/removingOldContainer', 'Removing old container...') });
+                try {
+                    await this.connectionProvider.removeContainer(lastContainerInfo.id);
+                } catch (error) {
+                    // Container may already be gone, ignore error
+                }
+                await this.storageService.setData(lastContainerInfoKey, undefined);
+            }
+            progress.cancel();
+            this.doOpenInContainer(devcontainerFile);
+        } catch (e) {
+            progress.cancel();
+            this.messageService.error(nls.localize('theia/dev-container/failedToRebuild', 'Failed to rebuild container: {0}', (e as Error).message));
+        }
+    }
+
     async doOpenInContainer(devcontainerFile: DevContainerFile, workspacePath?: string): Promise<void> {
         const lastContainerInfoKey = `${LAST_USED_CONTAINER}:${devcontainerFile.path}`;
         const lastContainerInfo = await this.storageService.getData<LastContainerInfo | undefined>(lastContainerInfoKey);
 
         this.containerOutputProvider.openChannel();
 
+        const hostWorkspacePath = workspacePath ?? this.workspaceService.workspace?.resource.path.toString();
+
         const connectionResult = await this.connectionProvider.connectToContainer({
             nodeDownloadTemplate: this.remotePreferences['remote.nodeDownloadTemplate'],
             lastContainerInfo,
             devcontainerFile: devcontainerFile.path,
-            workspacePath: workspacePath
+            workspacePath: hostWorkspacePath
         });
 
         this.storageService.setData<LastContainerInfo>(lastContainerInfoKey, {
             id: connectionResult.containerId,
             lastUsed: Date.now()
         });
 
+        // Store full context so rebuild works from inside the container
+        this.storageService.setData<DevContainerContext>(ACTIVE_DEV_CONTAINER_CONTEXT, {
+            devcontainerFilePath: devcontainerFile.path,
+            devcontainerFileName: devcontainerFile.name,
+            hostWorkspacePath: hostWorkspacePath ?? '',
+            containerId: connectionResult.containerId,
+        });
+
         this.workspaceServer.setMostRecentlyUsedWorkspace(
-            `${DEV_CONTAINER_WORKSPACE_SCHEME}:${workspacePath ?? this.workspaceService.workspace?.resource.path}?${DEV_CONTAINER_PATH_QUERY}=${devcontainerFile.path}`);
+            `${DEV_CONTAINER_WORKSPACE_SCHEME}:${hostWorkspacePath}?${DEV_CONTAINER_PATH_QUERY}=${devcontainerFile.path}`);
 
         this.openRemote(connectionResult.port, false, connectionResult.workspacePath);
     }

packages/dev-container/src/electron-browser/dev-container-frontend-module.ts

@@ -23,6 +23,7 @@ import { ContainerInfoContribution } from './container-info-contribution';
 import { FrontendApplicationContribution, LabelProviderContribution } from '@theia/core/lib/browser';
 import { WorkspaceOpenHandlerContribution } from '@theia/workspace/lib/browser/workspace-service';
 import { WindowTitleContribution } from '@theia/core/lib/browser/window/window-title-service';
+import { DevContainerSuggestionContribution } from './dev-container-suggestion-contribution';
 
 export default new ContainerModule(bind => {
     bind(ContainerConnectionContribution).toSelf().inSingletonScope();
@@ -40,4 +41,7 @@ export default new ContainerModule(bind => {
     bind(FrontendApplicationContribution).toService(ContainerInfoContribution);
     bind(WindowTitleContribution).toService(ContainerInfoContribution);
     bind(LabelProviderContribution).toService(ContainerInfoContribution);
+
+    bind(DevContainerSuggestionContribution).toSelf().inSingletonScope();
+    bind(FrontendApplicationContribution).toService(DevContainerSuggestionContribution);
 });

packages/dev-container/src/electron-browser/dev-container-suggestion-contribution.ts

@@ -0,0 +1,93 @@
+// *****************************************************************************
+// 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 { inject, injectable } from '@theia/core/shared/inversify';
+import { CommandService, MessageService, nls } from '@theia/core';
+import { FrontendApplicationContribution, LocalStorageService } from '@theia/core/lib/browser';
+import { WorkspaceService } from '@theia/workspace/lib/browser/workspace-service';
+import { RemoteContainerConnectionProvider } from '../electron-common/remote-container-connection-provider';
+import { RemoteContainerCommands } from './container-connection-contribution';
+import { RemoteStatusService } from '@theia/remote/lib/electron-common/remote-status-service';
+
+const DONT_SHOW_AGAIN_KEY = 'dev-container.suggestion.dontShowAgain';
+
+@injectable()
+export class DevContainerSuggestionContribution implements FrontendApplicationContribution {
+
+    @inject(WorkspaceService)
+    protected readonly workspaceService: WorkspaceService;
+
+    @inject(RemoteContainerConnectionProvider)
+    protected readonly connectionProvider: RemoteContainerConnectionProvider;
+
+    @inject(MessageService)
+    protected readonly messageService: MessageService;
+
+    @inject(CommandService)
+    protected readonly commandService: CommandService;
+
+    @inject(RemoteStatusService)
+    protected readonly remoteStatusService: RemoteStatusService;
+
+    @inject(LocalStorageService)
+    protected readonly storageService: LocalStorageService;
+
+    onStart(): void {
+        this.checkForDevContainer();
+    }
+
+    protected async checkForDevContainer(): Promise<void> {
+        const containerPort = parseInt(new URLSearchParams(location.search).get('port') ?? '0');
+        if (containerPort > 0) {
+            const status = await this.remoteStatusService.getStatus(containerPort);
+            if (status?.alive) {
+                return;
+            }
+        }
+
+        const dontShowAgain = await this.storageService.getData<boolean>(DONT_SHOW_AGAIN_KEY);
+        if (dontShowAgain) {
+            return;
+        }
+
+        await this.workspaceService.ready;
+        const workspace = this.workspaceService.workspace;
+        if (!workspace) {
+            return;
+        }
+
+        try {
+            const devcontainerFiles = await this.connectionProvider.getDevContainerFiles(workspace.resource.path.toString());
+            if (devcontainerFiles.length > 0) {
+                const reopenAction = nls.localize('theia/remote/dev-container/reopenInContainer', 'Reopen in Container');
+                const dontShowAgainAction = nls.localizeByDefault("Don't Show Again");
+                const result = await this.messageService.info(
+                    nls.localize('theia/remote/dev-container/suggestion',
+                        'This workspace has a dev container configuration. Would you like to reopen it in a container?'),
+                    reopenAction,
+                    dontShowAgainAction
+                );
+                if (result === reopenAction) {
+                    this.commandService.executeCommand(RemoteContainerCommands.REOPEN_IN_CONTAINER.id);
+                } else if (result === dontShowAgainAction) {
+                    await this.storageService.setData(DONT_SHOW_AGAIN_KEY, true);
+                }
+            }
+        } catch (error) {
+            // Silently ignore if we can't check for devcontainer files
+        }
+    }
+}

packages/dev-container/src/electron-common/remote-container-connection-provider.ts

@@ -45,8 +45,18 @@ export interface DevContainerFile {
     path: string;
 }
 
+export interface RunningContainerInfo {
+    id: string;
+    name: string;
+    image: string;
+    status: string;
+}
+
 export interface RemoteContainerConnectionProvider extends RpcServer<ContainerOutputProvider> {
     connectToContainer(options: ContainerConnectionOptions): Promise<ContainerConnectionResult>;
     getDevContainerFiles(workspacePath: string): Promise<DevContainerFile[]>;
     getCurrentContainerInfo(port: number): Promise<ContainerInspectInfo | undefined>;
+    listRunningContainers(): Promise<RunningContainerInfo[]>;
+    attachToContainer(containerId: string): Promise<ContainerConnectionResult>;
+    removeContainer(containerId: string): Promise<void>;
 }