# System Patterns
## Architecture Overview
```mermaid
graph TD
C[Cline] --- M[MCP Protocol Layer]
M --- S[Server Core]
S --- GH[GitHub API Client]
GH --- API[GitHub REST API]
```
## Core Components
### 1. MCP Protocol Layer
- Handles communication with Cline
- Implements MCP server protocol
- Exposes tools and resources
- Manages request/response lifecycle
### 2. Server Core
- Central coordination layer
- Authentication management
- Error handling and logging
- Request validation
### 3. GitHub API Client
- GitHub REST API interaction
- Rate limiting management
- Response parsing
- Error translation
## Design Patterns
### 1. Command Pattern
- Each GitHub operation encapsulated as a command
- Standardized execution flow
- Consistent error handling
```python
class IssueCommand:
def execute(self):
pass
```
### 2. Factory Pattern
- Tool and resource creation
- Command instantiation
- Response formatting
```python
class ToolFactory:
def create_tool(self, name: str):
pass
```
### 3. Strategy Pattern
- Authentication strategies
- Response formatting
- Rate limiting approaches
```python
class AuthStrategy:
def authenticate(self):
pass
```
## Component Relationships
### Tool Implementation
```mermaid
graph LR
T[Tool Request] --> V[Validator]
V --> C[Command]
C --> G[GitHub API]
G --> R[Response]
R --> F[Formatter]
F --> TR[Tool Response]
```
### Resource Implementation
```mermaid
graph LR
R[Resource Request] --> C[Cache Check]
C --> |Miss| G[GitHub API]
C --> |Hit| RC[Return Cached]
G --> S[Store Cache]
S --> RR[Return Response]
```
## Error Handling
- Hierarchical error types
- Consistent error translation
- Clear error messages
- Rate limit handling
## Data Flow
1. Request received through MCP
2. Request validated
3. Command created and executed
4. Response formatted
5. Response returned through MCP
## Security Patterns
- Credential encryption
- Token-based authentication
- Secure storage practices
- Request validation
## Testing Patterns
- Unit tests per component
- Integration tests for GitHub API
- Mock MCP client for testing
- Error scenario coverage