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Kiro Agent - VS Code Extension

Overview

The Kiro Agent is a sophisticated AI-integrated, spec-based development environment that transforms how developers build software. This VS Code extension enables developers to define systems and their components using friendly, natural language specifications that generate production-ready code for deployment.

Key Features:

  • AI-powered coding assistant with multi-provider support
  • Specification-based development workflow
  • Advanced prompt engineering system
  • Comprehensive tool ecosystem
  • Real-time collaboration capabilities
  • Enterprise-grade security and authentication

Architecture

Extension Structure

The extension follows a monorepo architecture with 11 specialized packages:

  • @amzn/codewhisperer-runtime - AWS CodeWhisperer integration
  • continuedev/* - Core AI chat functionality (core, extension, GUI, config)
  • kiro-shared - Shared utilities and types
  • kiro-shared-types - TypeScript definitions
  • kiricons - Icon system (495+ SVG icons)
  • hook-editor - Automation hook editor
  • webview-components - UI components

Main Components

Extension Entry Point:

  • Main bundle: dist/extension.js (~764KB)
  • Activation lifecycle: activate() → dynamicImportAndActivate() → activateExtension()
  • Command registry: 52 commands with comprehensive VS Code integration

Core Modules:

  • VsCodeExtension: Central coordinator
  • VsCodeIde: VS Code API integration
  • DiffManager: Code change management
  • TabAutocompleteModel: AI-powered completions
  • Core: Main business logic processor

AI/LLM Integration

Supported AI Providers

OpenAI Models:

  • GPT-3.5-turbo, GPT-4, GPT-4o variants
  • Context lengths up to 128K tokens
  • Tokenizer mappings for accurate token counting

Anthropic Models:

  • Claude 3.5 Sonnet, Claude 3 Opus, Claude 3 Sonnet, Claude 3 Haiku
  • Context lengths up to 200K tokens
  • Specialized prompt formatting

Other Providers:

  • AWS Bedrock - Enterprise AI models
  • Ollama - Local model execution
  • Mistral - European AI models
  • Gemini - Google's AI models
  • Amazon Q Developer - AWS development assistant
  • Kiro - Custom provider integration

Model Configuration

Template System:

  • Model-specific prompt templates with auto-detection
  • Provider-specific formatting (OpenAI, Anthropic, Ollama, etc.)
  • Template factory pattern for consistent message handling

Streaming Support:

  • Real-time response streaming via streamComplete() methods
  • AWS CodeWhisperer streaming client integration
  • Bidirectional communication with webview components

Prompt Engineering System

Base System Prompt

The core system prompt (getBasePrompt()) establishes Kiro's comprehensive identity and operational framework. This prompt defines Kiro's personality, capabilities, response style, and key features.

Full prompt text: See prompts/system-prompt.md

Key Components:

  • Identity: Defines Kiro as an AI assistant and IDE for developers
  • Capabilities: File system operations, code assistance, infrastructure help
  • Rules: Security guidelines, PII handling, code quality requirements
  • Response Style: Warm, knowledgeable, developer-focused communication
  • System Information: OS, platform, shell, date/time context
  • Kiro Features: Autonomy modes, chat context, steering, specs, hooks, MCP

Dynamic Context Injection:

  • System information (OS, platform, shell)
  • Current workspace state
  • Open editor files
  • Active file information
  • Current date/time

Model-Specific Templates

Edit Prompt Templates for Different AI Models:

Kiro includes optimized edit prompts for 14+ different AI models and providers. Each prompt is carefully crafted to work with the specific formatting and instruction-following patterns of different models.

Available Edit Prompts:

Template Factory System:

  • Automatic model detection via autodetectPromptTemplates()
  • Provider-specific handling (OpenAI, Anthropic, Ollama, etc.)
  • Template compilation with Handlebars support
  • Message role management and formatting
  • Context-aware rendering with dynamic variables

Specialized Workflow Prompts

Specification Generation Workflow:

Kiro implements a sophisticated specification-based development workflow that guides users through requirements gathering, design, and implementation planning.

Available Workflow Prompts:

Intent Classification System

Multi-Modal Intent Detection: The IntentClassifier uses sophisticated prompt engineering for intent recognition:

Classify the user's intent from their message:
- DO: Imperative actions (default mode)
- CHAT: Questions and explanations
- SPEC: Specification creation and management

Consider context, tone, and explicit keywords to determine intent.
Provide confidence scores for classification accuracy.

Classification Strategies:

  • Local Rule-Based: Pattern matching for common intents
  • LLM-Based: Sophisticated intent detection with confidence scoring
  • Hybrid Approach: Combines local and LLM results with weighted scoring

Built-in Tool Prompts

File System Operations:

Search and Discovery:

System Operations:

MCP (Model Context Protocol) Prompt Integration

Protocol-Level Prompts:

  • System prompt configuration through MCP servers
  • Template argument handling and injection
  • Provider-specific prompt customization
  • Context injection from external MCP servers

Dynamic Template Loading:

  • External prompt templates via MCP
  • Runtime template compilation
  • Context-aware template selection
  • Error handling for template failures

Advanced Prompt Engineering Techniques

Hierarchical Prompt Structure:

  1. Base System Prompt - Core identity and capabilities
  2. Model-Specific Formatting - Provider optimization layer
  3. Context Injection - Dynamic environment data
  4. Task-Specific Prompts - Workflow-oriented instructions
  5. Tool Integration - Action-specific prompting

Context Management:

  • History Pruning: Intelligent conversation history management
  • Token Counting: Accurate token usage tracking per model
  • Message Compilation: Role-based message formatting
  • Context Preservation: Prefix/suffix preservation in code edits

Error Handling & Fallbacks:

  • Template Detection Failures: Graceful fallback to generic templates
  • Unknown Model Handling: Default template assignment
  • Context Injection Failures: Safe degradation without context
  • Prompt Rendering Errors: Error recovery and user notification

Handlebars Template System

Template Utilities:

  • renderTemplatedString() - Handlebars compilation and rendering
  • renderPromptTemplate() - Context-aware template processing
  • Helper function registration for complex operations
  • Promise resolution for async template data

Template Features:

  • Variable interpolation with {{variable}} syntax
  • Conditional rendering with {{#if condition}}
  • Loop handling with {{#each items}}
  • File path replacement and context provider integration
  • Custom helper functions for development tasks

Tool System

Built-in System Tools

File System Operations:

  • ToolReadFile - Read single files
  • ToolReadMultipleFiles - Batch file reading
  • ToolFsWrite - Write to files
  • ToolFsAppend - Append to files
  • DeleteFileTool - Delete files

Development Tools:

  • ToolExecuteBash - Execute shell commands
  • ToolListDirectory - Directory listing
  • ToolFileSearch - Find files
  • ToolGrepSearch - Text pattern search
  • ToolStrReplace - String replacement

MCP (Model Context Protocol) Integration

External Tool Discovery:

  • Dynamic tool discovery through MCP servers
  • ToolMCPWrapper for external tool execution
  • Server lifecycle management
  • Auto-approval settings for trusted tools

Configuration:

  • MCP server definitions in .kiro/settings/mcp.json
  • Environment variable support
  • Command-line argument handling
  • Disabled server management

User Interface

Webview Architecture

Framework Stack:

  • React 18 with TypeScript
  • Tailwind CSS for styling
  • VS Code Webview API for communication

Main Components:

  • Chat Interface - Primary AI interaction
  • Spec Explorer - Specification management
  • Hook Editor - Automation configuration
  • Steering Explorer - Agent guidance system

Custom Editors

Specialized Editors:

  • Chat context viewer (.chat files)
  • Test specification editor
  • Hook configuration editor
  • Steering document editor

Theme System

Built-in Themes:

  • 8 pre-configured themes (dark/light variants)
  • Tailwind CSS configuration
  • Custom VS Code theme integration
  • Responsive design support

Specification System

Workflow Management

Spec Generation Process:

  1. Requirements Clarification - Natural language requirement gathering
  2. Design Document Creation - Technical specification generation
  3. Implementation Planning - Task breakdown and planning
  4. Task Execution - Step-by-step implementation

File Organization:

  • .kiro/specs/ - Specification documents
  • .kiro/steering/ - Agent guidance documents
  • .hooks/ - Automation hook definitions

Hook System

Hook Types:

  • FileEditedHook - File modification triggers
  • FileCreatedHook - File creation triggers
  • FileDeletedHook - File deletion triggers
  • UserTriggeredHook - Manual triggers
  • AlertHook - Notification system
  • AskAgentHook - Automated agent queries

Configuration Schema:

{
  "hooks": [{
    "type": "FileEditedHook",
    "filePattern": "*.js",
    "action": {
      "type": "AskAgentHook",
      "message": "Review this JavaScript file for potential issues"
    }
  }]
}

Configuration System

Extension Settings

Core Configuration:

  • kiroAgent.enableDevMode - Development mode features
  • kiroAgent.trustedCommands - Auto-approved shell commands
  • kiroAgent.autoApproveAgentCommands - Auto-approved agent actions
  • kiroAgent.configureMCP - MCP server configuration

MCP Server Configuration

Location: .kiro/settings/mcp.json

{
  "mcpServers": {
    "serverName": {
      "command": "node",
      "args": ["server.js"],
      "env": {"API_KEY": "value"},
      "disabled": false,
      "autoApprove": ["tool1", "tool2"]
    }
  }
}

Environment-Specific Settings

Development vs Production:

  • NODE_ENV environment detection
  • CI/CD pipeline integration
  • Debug logging configuration
  • Performance optimization settings

Security & Authentication

Authentication System

Multi-Provider Support:

  • OAuth 2.0 with PKCE flow
  • Social authentication (Google, GitHub)
  • SSO and OIDC integration
  • JWT token management

Token Management:

  • Secure token storage in ~/.aws/sso/cache/
  • Automatic token refresh
  • Session lifecycle management
  • Cryptographic validation (SHA-256, PKCE)

Security Features

Input Validation:

  • Zod schema validation for all inputs
  • XSS prevention with HTML encoding
  • CSRF protection with XSRF tokens
  • PII detection and masking

Data Protection:

  • End-to-end encryption for sensitive data
  • Certificate validation and TLS enforcement
  • Privacy-first design with local processing
  • Secure communication protocols

Access Control:

  • Role-based authentication
  • Permission validation
  • Trusted command whitelisting
  • Sandbox execution for shell commands

Bundled Resources

Local AI Models

Embedding Model:

  • all-MiniLM-L6-v2 sentence transformer
  • ONNX quantized model for efficiency
  • Local codebase embeddings
  • Privacy-preserving semantic search

Language Support

Tree-sitter Parsers:

  • 27 language parsers including JavaScript, TypeScript, Python, Rust, Go, Java, C++
  • Code snippet extraction queries
  • Import statement detection
  • Function/method definition parsing

Tokenizers:

  • Llama tokenizer with worker pool
  • Tiktoken for OpenAI models
  • Multi-threaded tokenization
  • Accurate token counting

Assets & Icons

Icon System:

  • 495+ SVG icons for comprehensive UI coverage
  • Development tool icons
  • File type indicators
  • Custom Kiro branding

Development Workflow

Build System

Bundling Strategy:

  • ESBuild for main extension bundle
  • Selective external dependencies
  • Native binary preservation
  • Platform-specific optimizations

Build Commands:

npm run compile     # Build all components
npm run package     # Compile code only
npm run release     # Full build with packaging
npm run analyze-externals  # Update dependencies

Testing Framework

Test Configuration:

  • Mocha framework with XML reporting
  • Chai assertions and Sinon mocks
  • Test discovery in __tests__ directories
  • VS Code extension testing support

Extension Activation

Activation Events

File System Support:

  • Custom schemes: kiro-diff, kiro-meta, kiro-spec
  • Language detection: JavaScript, TypeScript variants
  • Webview activation: onboarding, GUI, hooks

Command Activation:

  • Startup commands and configuration
  • Execution triggers and event handlers
  • Language server integration

Key Bindings

Essential Shortcuts:

  • Cmd+L - Focus chat input
  • Cmd+I - Start inline chat
  • Shift+Cmd+Enter - Accept changes
  • Shift+Cmd+Backspace - Reject changes
  • Cmd+K Cmd+A - Toggle tab autocomplete

Advanced Features

VS Code API Integration

Experimental APIs:

  • 21 experimental VS Code APIs
  • Chat participants and diff commands
  • Terminal integration and file search
  • Semantic tokens and inline actions

Custom Providers:

  • File system providers for custom schemes
  • Language servers for syntax highlighting
  • Webview providers for rich UI
  • Authentication providers for secure access

Performance Optimizations

Efficient Processing:

  • Streaming AI responses
  • Incremental parsing and analysis
  • Lazy loading of heavy components
  • Worker-based tokenization

Memory Management:

  • Context pruning for large conversations
  • Efficient bundling strategy
  • Resource cleanup and disposal
  • Optimized asset loading

Extensibility

Plugin Architecture

MCP Integration:

  • External tool discovery
  • Server lifecycle management
  • Protocol-level communication
  • Custom tool development

Hook System:

  • Event-driven automation
  • Custom trigger conditions
  • Flexible action definitions
  • Workspace-specific configuration

API Surface

Extension Points:

  • Custom tool definitions
  • Prompt template customization
  • Authentication provider integration
  • UI component extensions

Troubleshooting

Common Issues

Configuration Problems:

  • Check .kiro/settings/mcp.json for MCP server issues
  • Verify authentication tokens in ~/.aws/sso/cache/
  • Review extension logs for error details

Performance Issues:

  • Disable unnecessary MCP servers
  • Reduce context window size for large files
  • Enable development mode for detailed logging

Debug Tools

Logging System:

  • Extension output channel
  • LLM request/response logging
  • MCP server communication logs
  • Performance metrics tracking

Contributing

Development Setup

  1. Clone the repository
  2. Install dependencies: npm install
  3. Build the extension: npm run compile
  4. Launch VS Code with the extension: F5

Adding External Dependencies

  1. Add package to UNBUNDLEABLE_PACKAGES in scripts/analyze-externals.mjs
  2. Categorize appropriately (native binaries, runtime dependencies, etc.)
  3. Run npm run analyze-externals to update configuration

Security Guidelines

  • Never commit secrets or API keys
  • Use proper input validation for all user inputs
  • Follow VS Code security best practices
  • Report security issues through proper channels

License

This project is licensed under the Apache-2.0 License.

Support

For issues and questions:

This extension represents a comprehensive AI-powered development environment that combines the power of large language models with sophisticated tooling and workflow management to create a next-generation coding experience.

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