# Z.AI VS Code Extension - Project Summary

## Overview

This extension brings Z.AI's powerful GLM language models (GLM-4.7 and GLM-4.5-Air) to Visual Studio Code through the Language Model Chat Provider API. It enables users to access these advanced coding and reasoning models directly within VS Code's Copilot Chat interface.

## Architecture

### Core Components

1. **Extension Entry Point** (`extension.ts`)
   - Activates the extension
   - Registers the language model provider
   - Sets up commands for API key management
   - Shows welcome message on first activation

2. **Language Model Provider** (`provider.ts`)
   - Implements `LanguageModelChatProvider` interface
   - Provides model information (GLM-4.7 and GLM-4.5-Air)
   - Handles chat requests and streams responses
   - Provides token counting functionality

3. **API Client** (`apiClient.ts`)
   - Manages communication with Z.AI API
   - Converts VS Code message format to Z.AI format
   - Handles streaming responses
   - Supports tool calling and thinking mode
   - Manages timeouts and cancellation

4. **API Key Manager** (`apiKeyManager.ts`)
   - Securely stores API keys using VS Code's secret storage
   - Provides methods to get, set, and clear API keys

5. **Models Configuration** (`models.ts`)
   - Defines available models with their specifications
   - Includes context windows, capabilities, and metadata

## Features

### Model Support
- **GLM-4.7**: 200K context, 128K output, advanced reasoning
- **GLM-4.5-Air**: 128K context, 96K output, fast and efficient

### Capabilities
- ✅ Streaming responses
- ✅ Tool calling / function calling
- ✅ Thinking mode (Interleaved, Preserved, Turn-level)
- ✅ Secure API key storage
- ✅ Configurable endpoints and timeouts
- ✅ Token counting estimation
- ✅ Cancellation support
- ❌ Image input (not supported by models)

### User Experience
- Simple API key management commands
- Welcome message on first activation
- Clear error messages with actionable guidance
- Model picker integration in Copilot Chat
- Configuration options for customization

## Technical Details

### API Integration

**Endpoint**: `https://api.z.ai/api/coding/paas/v4/chat/completions`

**Authentication**: Bearer token (API key)

**Request Format**:
```json
{
  "model": "glm-4.7",
  "messages": [...],
  "stream": true,
  "max_tokens": 4096,
  "enable_thinking": true,
  "tools": [...],
  "tool_choice": "auto"
}
```

**Response Format**: Server-Sent Events (SSE) stream with JSON chunks

### Message Conversion

The extension converts between VS Code's `LanguageModelChatRequestMessage` format and Z.AI's API format, handling:
- Text content
- Tool calls
- Tool results
- Role mapping (user/assistant/system)

### Streaming Implementation

Uses Node.js streams to process SSE responses:
1. Buffers incoming chunks
2. Parses JSON data from each line
3. Extracts text and tool call deltas
4. Reports progress to VS Code via `Progress<LanguageModelResponsePart>`

## Configuration

### Extension Settings

| Setting | Type | Default | Description |
|---------|------|---------|-------------|
| `zai.apiEndpoint` | string | `https://api.z.ai/api/coding/paas/v4` | API endpoint |
| `zai.enableThinkingMode` | boolean | `true` | Enable thinking mode |
| `zai.timeout` | number | `60000` | Request timeout (ms) |

### Commands

| Command | ID | Description |
|---------|-----|-------------|
| Manage Z.AI API Key | `zai.manageApiKey` | Set/update API key |
| Clear Z.AI API Key | `zai.clearApiKey` | Remove stored API key |

## Requirements

- **VS Code Version**: 1.104.0 or higher
- **GitHub Copilot**: Individual plan (Free/Pro/Pro+)
- **Node.js**: 20.x or higher (for development)
- **Z.AI API Key**: Required for operation

## File Structure

```
zai-vscode-extension/
├── src/
│   ├── extension.ts          # Entry point
│   ├── provider.ts            # Provider implementation
│   ├── apiClient.ts           # API communication
│   ├── apiKeyManager.ts       # Credential management
│   └── models.ts              # Model definitions
├── out/                       # Compiled JavaScript (generated)
├── package.json               # Extension manifest
├── tsconfig.json              # TypeScript config
├── README.md                  # User documentation
├── QUICKSTART.md              # Quick start guide
├── DEVELOPMENT.md             # Developer guide
├── CHANGELOG.md               # Version history
├── LICENSE                    # MIT License
└── .vscodeignore             # Package exclusions
```

## Development Workflow

1. **Install dependencies**: `npm install`
2. **Compile**: `npm run compile`
3. **Watch mode**: `npm run watch`
4. **Debug**: Press F5 in VS Code
5. **Lint**: `npm run lint`
6. **Package**: `vsce package`
7. **Publish**: `vsce publish`

## API Compatibility

### Supported Features
- ✅ Text streaming
- ✅ Tool/function calling
- ✅ Thinking mode
- ✅ Multi-turn conversations
- ✅ Cancellation

### Not Yet Supported
- ❌ Image inputs (model limitation)
- ❌ Context caching (API feature)
- ❌ Custom temperature/top_p (can be added)

## Security Considerations

1. **API Key Storage**: Uses VS Code's secure secret storage API
2. **No Key Logging**: API keys are never logged or displayed
3. **HTTPS Only**: All API communication over HTTPS
4. **Timeout Protection**: Configurable timeouts prevent hanging requests
5. **Cancellation**: Users can cancel long-running requests

## Performance

### Token Counting
Currently uses estimation (4 chars/token). Future improvement: actual tokenizer.

### Streaming
Real-time response streaming provides immediate feedback to users.

### Thinking Mode
Adds reasoning overhead but improves output quality for complex tasks. Can be disabled for faster responses.

## Error Handling

The extension handles various error scenarios:
- **No API Key**: Prompts user to configure
- **Invalid API Key**: Shows clear error with setup action
- **Network Errors**: Displays timeout/connection messages
- **API Errors**: Parses and shows Z.AI error responses
- **Cancellation**: Gracefully handles user cancellation

## Future Enhancements

### Planned Features
1. Actual tokenizer for precise token counting
2. Model-specific parameter controls (temperature, top_p)
3. Usage statistics and cost tracking
4. Context caching support
5. Vision support (when available from Z.AI)
6. Custom prompt templates
7. Model performance metrics
8. Response quality feedback mechanism

### Potential Improvements
- Better error recovery
- Retry logic with exponential backoff
- Request queuing for rate limit management
- Local model fallback option
- Multi-provider support

## Testing Strategy

### Manual Testing
- API key management flows
- Model discovery and selection
- Chat functionality with various prompts
- Tool calling scenarios
- Error handling paths
- Configuration changes
- Extension activation/deactivation

### Automated Testing
- Unit tests for API client
- Message conversion tests
- Token counting tests
- Error handling tests

## Distribution

### VS Code Marketplace
- Extension will be published to the official marketplace
- Users can install via Extensions view
- Auto-updates enabled

### Manual Installation
- Can distribute as `.vsix` file
- Users install via "Install from VSIX" command

## Support Resources

- **GitHub Repository**: Source code and issue tracking
- **README**: Comprehensive user documentation
- **QUICKSTART**: Fast onboarding guide
- **DEVELOPMENT**: Contributor guide
- **Z.AI Docs**: API documentation
- **Discord**: Community support

## License

MIT License - Free to use, modify, and distribute

## Credits

- Built using VS Code Extension API
- Powered by Z.AI and Zhipu AI's GLM models
- Follows VS Code extension best practices
- Uses Language Model Chat Provider API

---

**Version**: 0.1.0  
**Status**: Ready for initial release  
**Last Updated**: January 7, 2026
