What is Mastra Code?

Mastra Code is a terminal-based AI coding agent that never compacts. Built on Mastra's Harness, Agent, and Memory primitives, it runs in your terminal and connects to thousands of AI models. It provides tools for reading, searching, editing, and executing code—all while maintaining precise context through its state-of-the-art Observational Memory system.

Who it's for

• Long-running project developers – who need persistent threads that maintain context across days or weeks without losing critical details.
• Multi-model power users – who want to compare responses across different AI providers by switching models mid-conversation.
• Code explorers and architects – who use Plan mode to analyze codebase architecture and create implementation plans before writing code.

Key features

Observational Memory

Mastra Code's core innovation is its ability to watch, reflect, and compress context without losing important details. Unlike traditional agents that compact and lose key information when the context window fills up, Mastra Code automatically manages what to remember and what to forget.

Flexible mode switching

Switch between Build, Plan, and Fast modes to match your workflow. Build mode handles complex coding tasks, Plan mode analyzes architecture before writing code, and Fast mode provides brief answers with minimal latency.

Built-in tool ecosystem

Mastra Code includes tools for file viewing, editing, searching, shell commands, and web search. You can extend it programmatically with custom modes, tools, subagents, and storage configurations.

Project-scoped configuration

Each project gets its own threads, MCP servers, hooks, custom commands, skills, and database settings. This keeps your work organized and context-specific across different codebases.

What stands out

"Mastra Code is a terminal-based AI coding agent that never compacts."

This isn't just marketing—it's the product's defining technical advantage. While other coding agents lose context as conversations grow, Mastra Code's Observational Memory actively watches and compresses information without dropping critical details. The result is long-running coding sessions that stay precise, letting you build faster, merge sooner, and ship more.

Worth checking out if…

You're tired of coding agents that forget what you were working on mid-session. Mastra Code is particularly valuable for developers working on complex, long-running projects where context continuity matters. It's also ideal if you want to experiment with multiple AI models without switching tools, or if you prefer a terminal-based workflow that integrates directly with your existing development environment.