Add opt-in GitHub Copilot SDK transport for @theia/ai-copilot

packages/ai-copilot/README.md

@@ -51,6 +51,41 @@ For GitHub Enterprise users, configure the enterprise URL via the `ai-features.c
 }
 ```
 
+### Experimental: Copilot SDK transport (`ai-features.copilot.useSdk`)
+
+By default the extension talks directly to the GitHub Copilot REST API. As an
+**opt-in experiment**, it can instead delegate to the official Copilot CLI via
+the [`@github/copilot-sdk`](https://github.com/github/copilot-sdk) package by
+enabling the `ai-features.copilot.useSdk` preference:
+
+```json
+{
+    "ai-features.copilot.useSdk": true
+}
+```
+
+Because the SDK is a *recognized* GitHub integration, this mode reports the full
+current model lineup (instead of only the baseline set such as GPT-4o that the
+raw REST integration is entitled to). Toggling the preference rebuilds the
+Copilot model set, so no restart is required.
+
+This mode is a prototype and has known limitations:
+
+- **Backend / Node only.** The SDK spawns the bundled `@github/copilot` CLI as a
+  subprocess over stdio, so it runs in the Theia backend.
+- **Single-turn, tools disabled.** The CLI owns its own agent loop, which is
+  incompatible with Theia's model-as-a-function contract where Theia drives the
+  tool loop. To keep behaviour predictable the session is created with no tools
+  and all permission requests are rejected, so requests are effectively
+  single-turn chat completions.
+- **Lossy history.** Multi-message histories (including tool-use/tool-result
+  turns) are flattened into a single prompt string; thinking messages are
+  dropped.
+- **No structured output.** Structured/JSON output is not supported in this mode.
+- **One CLI process per connection.** Each frontend connection currently spawns
+  its own CLI process; this is acceptable for prototyping but would need a
+  shared, per-user client for multi-user backends.
+
 ### Commands
 
 - **Copilot: Sign In** - Initiates the OAuth device flow authentication

packages/ai-copilot/package.json

@@ -3,6 +3,7 @@
   "version": "1.72.0",
   "description": "Theia - GitHub Copilot Integration",
   "dependencies": {
+    "@github/copilot-sdk": "^1.0.0",
     "@theia/ai-core": "1.72.0",
     "@theia/ai-openai": "1.72.0",
     "@theia/core": "1.72.0",

packages/ai-copilot/src/browser/copilot-frontend-application-contribution.ts

@@ -19,7 +19,7 @@ import { CommandService, nls, PreferenceService } from '@theia/core';
 import { FrontendApplicationContribution } from '@theia/core/lib/browser';
 import { MessageService } from '@theia/core/lib/common/message-service';
 import { CopilotAuthService, CopilotLanguageModelsManager, CopilotModelDescription, COPILOT_PROVIDER_ID } from '../common';
-import { COPILOT_ENABLED_PREF, COPILOT_MODEL_OVERRIDES_PREF, COPILOT_ENTERPRISE_URL_PREF } from '../common/copilot-preferences';
+import { COPILOT_ENABLED_PREF, COPILOT_MODEL_OVERRIDES_PREF, COPILOT_ENTERPRISE_URL_PREF, COPILOT_USE_SDK_PREF } from '../common/copilot-preferences';
 import { AICorePreferences, PREFERENCE_NAME_MAX_RETRIES } from '@theia/ai-core/lib/common/ai-core-preferences';
 import { CopilotCommands } from './copilot-command-contribution';
 
@@ -51,6 +51,7 @@ export class CopilotFrontendApplicationContribution implements FrontendApplicati
         this.preferenceService.ready.then(async () => {
             const enterpriseUrl = this.preferenceService.get<string>(COPILOT_ENTERPRISE_URL_PREF);
             this.manager.setEnterpriseUrl(enterpriseUrl || undefined);
+            this.manager.setUseSdk(this.preferenceService.get<boolean>(COPILOT_USE_SDK_PREF, false));
 
             if (this.isCopilotEnabled()) {
                 const authState = await this.authService.getAuthState();
@@ -86,6 +87,11 @@ export class CopilotFrontendApplicationContribution implements FrontendApplicati
                     } else {
                         this.manager.refreshModelsStatus();
                     }
+                } else if (event.preferenceName === COPILOT_USE_SDK_PREF && this.isCopilotEnabled()) {
+                    // Switching transport changes the model implementation, so rebuild the model set.
+                    this.manager.setUseSdk(this.preferenceService.get<boolean>(COPILOT_USE_SDK_PREF, false));
+                    this.removeAllCopilotModels();
+                    this.initializeModels();
                 }
             });
 

packages/ai-copilot/src/common/copilot-language-models-manager.ts

@@ -68,6 +68,11 @@ export interface CopilotLanguageModelsManager {
      * Set the GitHub Enterprise URL for Copilot API requests.
      */
     setEnterpriseUrl(url: string | undefined): void;
+    /**
+     * Enable or disable routing through the official Copilot CLI via `@github/copilot-sdk`
+     * instead of the direct REST API.
+     */
+    setUseSdk(useSdk: boolean): void;
     /**
      * Refresh the status of all Copilot models (e.g., after authentication state changes).
      */

packages/ai-copilot/src/common/copilot-preferences.ts

@@ -20,6 +20,7 @@ import { nls, PreferenceSchema } from '@theia/core';
 export const COPILOT_ENABLED_PREF = 'ai-features.copilot.enabled';
 export const COPILOT_MODEL_OVERRIDES_PREF = 'ai-features.copilot.modelOverrides';
 export const COPILOT_ENTERPRISE_URL_PREF = 'ai-features.copilot.enterpriseUrl';
+export const COPILOT_USE_SDK_PREF = 'ai-features.copilot.useSdk';
 
 export const CopilotPreferencesSchema: PreferenceSchema = {
     properties: {
@@ -49,6 +50,18 @@ export const CopilotPreferencesSchema: PreferenceSchema = {
                 'GitHub Enterprise domain for Copilot API (e.g., `github.mycompany.com`). Leave empty for GitHub.com.'),
             title: AI_CORE_PREFERENCES_TITLE,
             default: ''
+        },
+        [COPILOT_USE_SDK_PREF]: {
+            type: 'boolean',
+            markdownDescription: nls.localize('theia/ai/copilot/useSdk/mdDescription',
+                'Experimental: route GitHub Copilot through the official Copilot CLI via the `@github/copilot-sdk` instead of '
+                + 'the direct REST API. This makes the full, up-to-date model lineup available (the direct REST integration only '
+                + 'exposes a baseline set such as GPT-4o). The Copilot CLI is launched as a background process and authenticated '
+                + 'with your existing Copilot sign-in.\n\n'
+                + '**Known prototype limitations:** chat is handled as single-turn requests, tool calling is disabled, and '
+                + 'structured output is not supported on this path. Leave disabled to use the direct REST integration.'),
+            title: AI_CORE_PREFERENCES_TITLE,
+            default: false
         }
     }
 };

packages/ai-copilot/src/node/copilot-backend-module.ts

@@ -26,12 +26,15 @@ import {
 } from '../common';
 import { CopilotOAuthConfig, DEFAULT_COPILOT_OAUTH_CONFIG } from '../common/copilot-oauth-config';
 import { CopilotLanguageModelsManagerImpl } from './copilot-language-models-manager-impl';
+import { CopilotSdkClientProvider } from './copilot-sdk-client-provider';
 import { CopilotAuthServiceImpl } from './copilot-auth-service-impl';
 
 const copilotConnectionModule = ConnectionContainerModule.create(({ bind }) => {
     bind(CopilotAuthServiceImpl).toSelf().inSingletonScope();
     bind(CopilotAuthService).toService(CopilotAuthServiceImpl);
 
+    bind(CopilotSdkClientProvider).toSelf().inSingletonScope();
+
     bind(CopilotLanguageModelsManagerImpl).toSelf().inSingletonScope();
     bind(CopilotLanguageModelsManager).toService(CopilotLanguageModelsManagerImpl);
 

packages/ai-copilot/src/node/copilot-language-models-manager-impl.ts

@@ -14,12 +14,14 @@
 // SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0
 // *****************************************************************************
 
-import { LanguageModelRegistry, LanguageModelStatus } from '@theia/ai-core';
+import { LanguageModel, LanguageModelRegistry, LanguageModelStatus } from '@theia/ai-core';
 import { Disposable, DisposableCollection } from '@theia/core';
 import { inject, injectable, postConstruct } from '@theia/core/shared/inversify';
 import { CopilotLanguageModelsManager, CopilotModelDescription, COPILOT_PROVIDER_ID, getCopilotApiBaseUrl } from '../common';
 import { CopilotOAuthConfig } from '../common/copilot-oauth-config';
 import { CopilotLanguageModel } from './copilot-language-model';
+import { CopilotSdkLanguageModel } from './copilot-sdk-language-model';
+import { CopilotSdkClientProvider } from './copilot-sdk-client-provider';
 import { CopilotAuthServiceImpl } from './copilot-auth-service-impl';
 
 /**
@@ -38,7 +40,11 @@ export class CopilotLanguageModelsManagerImpl implements CopilotLanguageModelsMa
     @inject(CopilotOAuthConfig)
     protected readonly oauthConfig: CopilotOAuthConfig;
 
+    @inject(CopilotSdkClientProvider)
+    protected readonly sdkClientProvider: CopilotSdkClientProvider;
+
     protected enterpriseUrl: string | undefined;
+    protected useSdk = false;
     protected readonly toDispose = new DisposableCollection();
 
     @postConstruct()
@@ -56,6 +62,17 @@ export class CopilotLanguageModelsManagerImpl implements CopilotLanguageModelsMa
         this.enterpriseUrl = url;
     }
 
+    setUseSdk(useSdk: boolean): void {
+        if (this.useSdk === useSdk) {
+            return;
+        }
+        this.useSdk = useSdk;
+        // Release any running CLI process when leaving SDK mode.
+        if (!useSdk) {
+            this.sdkClientProvider.reset();
+        }
+    }
+
     protected async calculateStatus(): Promise<LanguageModelStatus> {
         const authState = await this.authService.getAuthState();
         if (authState.isAuthenticated) {
@@ -71,35 +88,53 @@ export class CopilotLanguageModelsManagerImpl implements CopilotLanguageModelsMa
             const model = await this.languageModelRegistry.getLanguageModel(modelDescription.id);
 
             if (model) {
-                if (!(model instanceof CopilotLanguageModel)) {
+                if (model instanceof CopilotSdkLanguageModel) {
+                    await this.languageModelRegistry.patchLanguageModel<CopilotSdkLanguageModel>(modelDescription.id, {
+                        model: modelDescription.model,
+                        status,
+                        maxRetries: modelDescription.maxRetries
+                    });
+                } else if (model instanceof CopilotLanguageModel) {
+                    await this.languageModelRegistry.patchLanguageModel<CopilotLanguageModel>(modelDescription.id, {
+                        model: modelDescription.model,
+                        enableStreaming: modelDescription.enableStreaming,
+                        supportsStructuredOutput: modelDescription.supportsStructuredOutput,
+                        status,
+                        maxRetries: modelDescription.maxRetries
+                    });
+                } else {
                     console.warn(`Copilot: model ${modelDescription.id} is not a Copilot model`);
                     continue;
                 }
-                await this.languageModelRegistry.patchLanguageModel<CopilotLanguageModel>(modelDescription.id, {
-                    model: modelDescription.model,
-                    enableStreaming: modelDescription.enableStreaming,
-                    supportsStructuredOutput: modelDescription.supportsStructuredOutput,
-                    status,
-                    maxRetries: modelDescription.maxRetries
-                });
             } else {
-                this.languageModelRegistry.addLanguageModels([
-                    new CopilotLanguageModel(
-                        modelDescription.id,
-                        modelDescription.model,
-                        status,
-                        modelDescription.enableStreaming,
-                        modelDescription.supportsStructuredOutput,
-                        modelDescription.maxRetries,
-                        () => this.authService.getAccessToken(),
-                        () => this.enterpriseUrl,
-                        () => this.oauthConfig.userAgent
-                    )
-                ]);
+                this.languageModelRegistry.addLanguageModels([this.createLanguageModel(modelDescription, status)]);
             }
         }
     }
 
+    protected createLanguageModel(modelDescription: CopilotModelDescription, status: LanguageModelStatus): LanguageModel {
+        if (this.useSdk) {
+            return new CopilotSdkLanguageModel(
+                modelDescription.id,
+                modelDescription.model,
+                status,
+                modelDescription.maxRetries,
+                () => this.sdkClientProvider.getClient()
+            );
+        }
+        return new CopilotLanguageModel(
+            modelDescription.id,
+            modelDescription.model,
+            status,
+            modelDescription.enableStreaming,
+            modelDescription.supportsStructuredOutput,
+            modelDescription.maxRetries,
+            () => this.authService.getAccessToken(),
+            () => this.enterpriseUrl,
+            () => this.oauthConfig.userAgent
+        );
+    }
+
     removeLanguageModels(...modelIds: string[]): void {
         this.languageModelRegistry.removeLanguageModels(modelIds);
     }
@@ -109,7 +144,7 @@ export class CopilotLanguageModelsManagerImpl implements CopilotLanguageModelsMa
         const allModels = await this.languageModelRegistry.getLanguageModels();
 
         for (const model of allModels) {
-            if (model instanceof CopilotLanguageModel && model.id.startsWith(`${COPILOT_PROVIDER_ID}/`)) {
+            if ((model instanceof CopilotLanguageModel || model instanceof CopilotSdkLanguageModel) && model.id.startsWith(`${COPILOT_PROVIDER_ID}/`)) {
                 await this.languageModelRegistry.patchLanguageModel<CopilotLanguageModel>(model.id, {
                     status
                 });
@@ -118,6 +153,15 @@ export class CopilotLanguageModelsManagerImpl implements CopilotLanguageModelsMa
     }
 
     async fetchAvailableModelIds(): Promise<string[]> {
+        if (this.useSdk) {
+            try {
+                return await this.sdkClientProvider.listModelIds();
+            } catch (error) {
+                console.warn('Copilot: failed to fetch available models via the Copilot SDK:', error);
+                return [];
+            }
+        }
+
         const accessToken = await this.authService.getAccessToken();
         if (!accessToken) {
             return [];