
---
title: Architecture Documentation
description: System architecture and design patterns
category: architecture
status: stable
last_updated: 2025-01-15
version: 1.0.0
tags:
  - level: intermediate
  - component: architecture
  - status: stable
---

# Architecture Documentation

Complete system architecture and design patterns for Kollabor CLI.

## Overview

The Kollabor CLI application follows a modular, event-driven architecture with clear separation of concerns. Each component has well-defined responsibilities and communicates through the central event bus.

## Documents

### System Architecture
**[System Architecture](system-architecture.md)** - High-level system overview

**Description**: Complete system architecture document covering all major components, their interactions, and data flow patterns.

**Topics**:
- Component overview
- Event-driven architecture
- Plugin system integration
- I/O system design
- LLM integration layer
- Configuration management

**Level**: Intermediate  
**Status**: Stable

---

### Event System
**[Event System Architecture](event-system.md)** - Event bus and hook system

**Description**: Detailed architecture of the event system, including EventBus, HookRegistry, HookExecutor, and EventProcessor components.

**Topics**:
- Four-component architecture
- Three-phase processing model (PRE → MAIN → POST)
- Hook lifecycle and execution
- Event flow and data transformation
- Error handling and retry logic
- Performance considerations

**Level**: Advanced  
**Status**: Stable

**Key Concepts**:
- Event-driven communication
- Hook registration and execution
- Priority-based processing
- Event cancellation
- Data transformation across phases

**Related**:
- [Hook System SDK](../hook-system-sdk.md)
- [Event Types Reference](../event-types-reference.md)

---

### Hook System SDK
**[Hook System SDK](../hook-system-sdk.md)** - Complete hook programming guide

**Description**: Comprehensive SDK documentation for hook system programming, including hook types, registration patterns, and best practices.

**Topics**:
- Hook types and use cases
- Registration patterns
- Hook configuration
- Error handling
- Best practices and patterns

**Level**: Intermediate  
**Status**: Stable

**Related**:
- [Event System Architecture](event-system.md)
- [Plugin Development Tutorial](../plugin-development/plugin-development-tutorial.md)

---

## Architecture Diagrams

### High-Level Architecture

```mermaid
graph TB
    subgraph "Input Layer"
        IH[Input Handler]
    end
    
    subgraph "Processing Layer"
        EB[Event Bus]
        CM[Command Manager]
    end
    
    subgraph "Output Layer"
        TR[Terminal Renderer]
        SR[Status Renderer]
    end
    
    subgraph "Extension Layer"
        PS[Plugin System]
    end
    
    subgraph "Integration Layer"
        LS[LLM Service]
        TE[Tool Executor]
    end
    
    IH --> EB
    EB --> CM
    CM --> TR
    EB --> PS
    PS --> EB
    CM --> LS
    LS --> TE
    TE --> TR
```

### Event System Architecture

```mermaid
graph TB
    subgraph "Event System"
        EB[EventBus<br/>Coordinator]
        HR[HookRegistry<br/>Organization]
        HE[HookExecutor<br/>Execution]
        EP[EventProcessor<br/>Phases]
    end
    
    subgraph "Plugins"
        P[Plugins]
    end
    
    subgraph "Core"
        C[Core Systems]
    end
    
    P -->|register_hook| EB
    C -->|emit_event| EB
    EB --> EP
    EP --> HR
    HR --> HE
    HE --> EP
    EP --> EB
```

---

## Key Architectural Patterns

### Event-Driven Architecture
- **Description**: Components communicate through events
- **Benefits**: Loose coupling, extensibility, testability
- **Implementation**: EventBus with hook system
- **Documentation**: [Event System Architecture](event-system.md)

### Plugin System
- **Description**: Modular extension through plugins
- **Benefits**: Extensibility without core changes, isolation
- **Implementation**: PluginDiscovery, PluginFactory, PluginRegistry
- **Documentation**: [Plugin System](../core-systems/plugin-system.md)

### Facade Pattern
- **Description**: Simplified interface to complex subsystems
- **Benefits**: Easy to use, hides complexity
- **Implementation**: InputHandler, TerminalRenderer
- **Documentation**: [Input Handling](../core-systems/input-handling.md)

### Dependency Injection
- **Description**: Components receive dependencies at initialization
- **Benefits**: Testability, flexibility, loose coupling
- **Implementation**: Plugin __init__, event_bus injection
- **Documentation**: [Plugin System](../core-systems/plugin-system.md)

---

## Component Relationships

### Core Dependencies

| Component | Depends On | Used By |
|-----------|-----------|----------|
| EventBus | - | All components |
| Plugin System | EventBus | Extensions |
| Input Handler | EventBus, TerminalRenderer | Core |
| Terminal Renderer | - | All components |
| LLM Service | EventBus, Config | Core |
| Tool Executor | EventBus, MCP | LLM Service |

### Data Flow

```
User Input → Input Handler → Event Bus → LLM Service → Tool Executor
                                                      ↓
Terminal Renderer ← Message Display ← Response Parser ← API Service
```

---

## Design Principles

### Separation of Concerns
Each component has a single, well-defined responsibility.

### Loose Coupling
Components communicate through events and well-defined interfaces.

### Extensibility
Plugins can extend functionality without modifying core code.

### Testability
Dependency injection and event-driven design enable easy testing.

### Performance
Async/await patterns throughout, caching where appropriate.

---

## Related Documentation

### Core Systems
- [Input Handling System](../core-systems/input-handling.md)
- [Terminal Rendering System](../core-systems/terminal-rendering.md)
- [LLM Service Architecture](../llm-integration/llm-service.md)

### Plugin Development
- [Plugin System Architecture](../core-systems/plugin-system.md)
- [Plugin Development Tutorial](../plugin-development/plugin-development-tutorial.md)

### API References
- [Event Bus API](../apis/event-bus-api.md)
- [Plugin API](../apis/plugin-api.md)

---

## Glossary

**Event**: A structured notification emitted by one component and processed by others

**Hook**: A callback function registered to be called when specific events occur

**Event Bus**: Central coordinator for event emission and hook execution

**Plugin**: Modular extension that adds functionality to the application

**Facade**: Simplified interface to a complex subsystem

**Dependency Injection**: Pattern where dependencies are provided to components rather than created internally

---

**Last Updated**: 2025-01-15  
**Status**: Stable  
**Version**: 1.0.0
