What is Mastra Code?

Mastra Code is an advanced, terminal-based AI coding agent designed to integrate seamlessly into developer workflows. Built upon Mastra's robust Harness, Agent, and Memory primitives, it brings the power of large language models directly into your command line interface. It acts as an intelligent pair programmer, capable of understanding context, executing commands, and managing complex coding tasks without ever leaving the terminal environment.

This powerful agent connects to over 70 different AI models, allowing developers to leverage the best model for specific tasks or compare outputs across providers mid-conversation. Its core purpose is to enhance productivity by providing immediate access to code reading, searching, editing, and execution capabilities, all managed through an intuitive Text User Interface (TUI).

Key Features

• Multi-Model Support: Connects to and supports over 70 AI models, enabling dynamic switching between providers (like Anthropic or OpenAI) within a single session for optimal performance or cost management.
• Workflow Modes: Offers distinct operational modes—Build (general development), Plan (architectural analysis and planning), and Fast (low-latency quick lookups/edits)—to match the developer's current focus.
• Integrated Tooling: Provides built-in tools for essential development tasks, including file viewing, editing, code searching, executing shell commands, and performing web searches.
• Persistent Context & Configuration: Supports project-scoped conversation threads, MCP servers, custom hooks, and skills. Thread persistence ensures continuity across sessions.
• Extensibility: Highly customizable, allowing developers to extend functionality programmatically by adding custom modes, new tools, subagents, and alternative storage solutions.
• Polished TUI: Features a modern, responsive terminal interface built with pi-tui components, offering clear visibility into operations, tool outputs, and token usage.

How to Use Mastra Code

Getting started with Mastra Code is straightforward, requiring Node.js (version 22.13.0 or later) as a prerequisite.

1. Installation: Install Mastra Code globally using npm, yarn, bun, or run it directly via npx or bun x:

npm install -g mastracode
# OR
bun x mastracode

2. Initialization: Navigate to your project directory and launch the agent:

cd your-project
mastracode

3. Authentication: Set your API key as an environment variable (e.g., export ANTHROPIC_API_KEY=...) or use the /login slash command to authenticate via OAuth providers.

4. Interaction: Once authenticated, simply type your request or command into the TUI. The agent will stream responses and can actively read, edit, and execute code within your project context. Use slash commands like /mode to switch workflows or /threads to manage conversations.

Use Cases

1. Day-to-Day Refactoring and Debugging: Quickly ask the agent to explain complex functions, suggest refactoring improvements, generate unit tests for specific modules, or manage simple Git operations directly from the terminal.
2. Architectural Planning: Utilize Plan Mode to feed the agent high-level requirements. It can analyze existing code structure, propose detailed implementation plans, and outline necessary file changes before any code is written.
3. Rapid Context Switching: When working on a legacy system or unfamiliar codebase, use Mastra Code for quick lookups (/mode Fast) to instantly search documentation or find where a specific variable is initialized without opening multiple files.
4. Model Comparison Testing: Developers working on performance-critical tasks can switch between models mid-conversation (e.g., comparing GPT-4o latency vs. Claude 3 Opus reasoning) to select the most appropriate and cost-effective AI for the current task.
5. Custom Tool Integration: Teams can define custom slash commands or subagents tailored to internal deployment scripts or proprietary database interactions, embedding specialized workflows directly into the agent's capabilities.

FAQ

Q: What are the minimum system requirements for running Mastra Code? A: Mastra Code requires Node.js version 22.13.0 or later to run effectively. Ensure your environment meets this prerequisite before installation.

Q: How does Mastra Code handle conversation history and context? A: It utilizes LibSQL Storage for thread persistence, message history, and token usage tracking. Conversations are often scoped to the project directory, ensuring the agent remembers relevant context across sessions.

Q: Can I define my own commands for the agent? A: Yes, Mastra Code is highly extensible. You can define custom slash commands by creating markdown files, allowing you to tailor the agent's functionality to your specific organizational needs or internal tooling.

Q: What happens if the agent is running a long operation? A: You can interrupt the current operation using the standard keyboard shortcut Ctrl+C. This allows you to stop a running shell command or an ongoing generation process immediately.

Q: How do I manage which AI provider I am using? A: You can switch models mid-conversation using the /models slash command, or by setting the relevant API key environment variables. The agent supports authentication with major providers like Anthropic and OpenAI.