Letta AI — the company that emerged from the MemGPT research project at UC Berkeley — released Letta Code in December 2025 as an application of its persistent memory architecture to coding agents. The MemGPT research had demonstrated that LLMs could be given effective long-term memory through hierarchical memory management, compensating for the context window limitation that caused most AI tools to start each session fresh.
Letta Code applied this to software development: the agent maintained long-term semantic memory of codebase facts, working memory of the current task context, and episodic memory of past session history. On the first session with a new repository, Letta Code behaved like any other coding agent; by the third or fourth session, it had accumulated understanding of the project’s patterns, conventions, and architectural decisions — functioning more like a team member familiar with the codebase than a stateless tool.
At launch, Letta Code ranked first among model-agnostic open-source agents on Terminal-Bench, the benchmark for autonomous engineering task completion. The npm-based installation (npm install -g @letta-ai/letta-code) and support for Claude, GPT-4o, Gemini, and local models made it accessible without Letta’s proprietary server. The project was Apache 2.0 licensed, with v0.27.9 released on June 12, 2026 confirming active development.