Google Agent Platform for Copilot Chat - Vertex AI Models Chat Provider

Native Gemini, Claude & open-weight models, powered by Google Agent Platform ( Vertex AI ) for Copilot Chat.

Experience enterprise-grade AI directly within the standard VS Code Chat panel.

This extension registers Google Gemini, Anthropic Claude, and MaaS open-weight models as first-class providers—no separate UI, no extra windows, no friction.

• 🔒 Zero API Keys — Securely uses your native Google Cloud identity or Service Accounts.
• 🏢 Automatic Billing — Costs follow your project settings as you switch workspaces.
• ⚡ Native Integration — First-class support for Gemini, Claude, and open-weight models within Copilot Chat.
• 🛡️ Private Auth — Support for Service Account JSON keys with "Zero-Pollution" local storage.
• 📊 Cost Transparency — Real-time session tracking, interactive usage dashboard, and opt-in labels for precise Google Cloud Billing attribution.

☁️ Google Cloud Prerequisites

⚠️ Important: Before using this extension, ensure your Google Cloud project is properly configured to avoid authentication or permission errors.

1. Enable APIs: Enable the Agent Platform API (aiplatform.googleapis.com) in the Cloud Console (Docs).
2. IAM Roles: Your account requires the Agent Platform User (roles/aiplatform.user) role (Docs).
3. Model Access: For Anthropic Claude models, find them in the Google Agent Platform Model Garden and click Enable (Docs).

🚀 Quick Start

1. Install: Find Google Agent Platform for Copilot Chat in the VS Code Marketplace and click Install.
2. Authenticate: Choose one of the following methods:
   • Option A (Standard): Run gcloud auth application-default login in your terminal.
   • Option B (Service Account): Run the command Google Agent Platform: Paste Service Account JSON Key in VS Code and paste your JSON key.
3. Configure: Open VS Code Settings (Ctrl+,) and set your GCP Project ID in vertexAiChat.projectId.
4. Chat: Open the Chat panel (Ctrl+Shift+I) and select a Google Agent Platform model from the picker.

📖 Documentation & Wiki

For detailed guides, troubleshooting, and advanced configuration, visit our Wiki:

• 📖 Quick Start Guide
• 🛡️ Service Account Authentication
• ⚙️ Setup & Configuration
• 📊 Usage & Billing Dashboard
• 🔍 Diagnostics & Troubleshooting

🛡️ Enterprise-Grade Authentication

This extension moves away from traditional API keys in favor of Identity and Project-based authentication. By using your native Google Cloud credentials or Service Accounts, you gain several professional advantages:

• 🔒 Secure by Design: No sensitive API keys to paste, rotate, or leak. Credentials stay in your OS keychain (via SecretStorage) or the gcloud secure store.
• 🏢 Automatic Billing Switching: Simply set a Project ID in your workspace settings. Billing follows your context as you switch between different client or internal projects.
• 📈 Centralized Governance: Admins can manage model quotas and IAM permissions centrally. Opt-in request labeling provides granular visibility into cost distribution across your organization.
• ⚡ Dedicated Performance: Leveraging your own GCP project ensures you aren't sharing rate limits with other users on a global API key.

Supported Methods

Choose the workflow that fits your environment:

• Standard ADC: Uses your system's gcloud identity. Ideal for standard local development.
• Encrypted Secrets: Paste a Service Account JSON key directly into VS Code. It is stored securely in your OS keychain (via SecretStorage) and never touches your repository or settings.json.
• Local File Paths: Reference a JSON key file on your machine. The path is stored privately in your workspace state, preventing platform-specific conflicts in shared repos.
• Environment Variables: Automatically respects GOOGLE_APPLICATION_CREDENTIALS if set.

✨ Key Features

• 🧠 Advanced Gemini Support: Full support for Gemini 3 Flash & Pro, including "High Thinking" modes with thought block rendering and signature preservation.

• ⚡ Anthropic Performance: Native support for Claude Opus, Sonnet, and Haiku, featuring automated Prompt Caching (Ephemeral) to reduce latency and costs for long conversations.

• 🔑 Smart Auth Recovery: Intelligent detection of expired credentials or missing keys with one-click recovery and "Silent Fallback" logic to ensure zero-friction development.

• 🪄 AI Commit Messages: Generate professional, conventional commit messages from staged Git changes with one click from the Source Control view.

• 🏷️ Cost Attribution Labels: Opt-in to propagate user email and workspace names as GCP labels for granular cost tracking in the Google Cloud Console.

• 📊 Local Usage Dashboard and Real Time Costs Estimation: An interactive, ECharts-powered dashboard to track your individual costs, token consumption, and payload metrics—all stored locally and updated in real time.

• 🔍 Smart Discovery: Automatically probes regional endpoints (global, us-east5, europe-west1, asia-southeast1) to find and register only the models available in your specific GCP project.

• 👁️ Multimodal Vision: Paste images directly into chat for analysis by vision-capable models like Claude 4.6 and Gemini 3.

• 🛠️ Tool Calling: Support for streaming parallel tool execution, enabling models to interact with VS Code agents and external tools.

🤖 Supported Models

MaaS (Model-as-a-Service) brings open-weight third-party models via an OpenAI-compatible API on Google Agent Platform. See the MaaS wiki page for details.

⚙️ Configuration

Settings (settings.json)

Private Configuration (Command-Managed)

Authentication methods are managed privately per-workspace to avoid platform-specific path conflicts and Git pollution.

🔍 Diagnostics & Logs

For detailed request/response mapping and troubleshooting:

1. Open the Output panel (Ctrl+Shift+U).
2. Select Google Agent Platform for Copilot Chat from the dropdown.
3. View region probing results, token usage metadata, and raw API transformations.

🛠️ Installation from Source

If you prefer to build the extension manually:

1. Clone the repository:

   git clone https://github.com/jorsm/vertex-ai-models-chat-provider.git
   

2. Install dependencies:

   npm install
   

3. Compile and launch:

   • Press F5 in VS Code to launch the Extension Development Host.
   • Or run npm run compile to build the TypeScript source.

📜 License

Distributed under the MIT License. See LICENSE for more information.