A Coding Agent That Never Compacts

Abhi walks through Mastra Code, a new open-source coding agent with observational memory that compresses context without losing it. When we built Observational Memory, we needed a way to test it in production. Instead of a standard bot, we dogfooded it: we built a coding agent and used it ourselves. Writing code every day quickly revealed whether the memory actually worked. Eventually, something clicked. Long, multi-day coding sessions ran smoothly, without hitting the compaction limits that trip up other agents. The agent actually seemed to understand the conversation. That gave us confidence to release Observational Memory... and the agent itself also  became something worth sharing. The core innovation is the Harness primitive. Rather than just a coding agent, Harness can power any type of agentic workflow: customer support, design tools, electrical engineering, and more. In this demo, you’ll see the Mastra Code CLI, a production-ready coding agent, and how Corbin from Artifact used the Harness to create an in-app agent for electrical engineering. Same primitive, completely different use case. 🔗 RESOURCES Mastra Code announcement: https://mastra.ai/blog/announcing-mastra-code Mastra Code GitHub: https://github.com/mastra-ai/mastra Mastra Code NPM: https://www.npmjs.com/package/mastra-code Observational Memory: https://mastra.ai/blog/observational-memory Mastra documentation: https://docs.mastra.ai AI Agents Hour is a weekly livestream hosted by Mastra CPO Shane Thomas and CTO Abhi Aiyer. Airing Mondays at 12PM Pacific on YouTube and X, the show covers breaking AI news, agent development techniques, and features interviews with industry experts building AI applications today. 📚 MASTRA RESOURCES Mastra: https://mastra.ai Learn Mastra in the world's first MCP-Based Course: https://mastra.ai/course Principles of Building AI Agents (Book): https://mastra.ai/book Patterns for Building AI Agents (New Book): https://mastra.ai/blog/patterns-book https://docs.google.com/forms/d/e/1FAIpQLSduJjc515f6RZJqtkR2ByqJZrB0iP8B7SUKnjjZE9IajH_I8w/viewform MASTRA? Mastra is an open-source TypeScript framework designed for building and shipping AI-powered applications and agents with minimal friction. It supports the full lifecycle of agent development—from prototype to production. You can integrate it with frontend and backend stacks (e.g., React, Next.js, Node) or run agents as standalone services. If you’re a JavaScript or TypeScript developer looking to build an agentic or AI-powered product without starting from first principles, Mastra provides the scaffolding, tools, and integrations to accelerate that process. CHAPTERS 00:00 – Intro & The Origin Story 02:09 – The Trend of Building Your Own Claude Code 03:11 – Demo 08:28 – No More Compaction 09:35 – Demo: Harness Primitive + Electrical Engineering Tool 14:08 – Getting Started