MegaMemory: give Claude Code a decision memory you can see

MegaMemory is a free, MIT-licensed MCP server that gives Claude Code a knowledge graph of your project. Each entry is a concept, like a module or a decision, with what it is, why it was done that way and the exact file. Claude Code's built-in memory is plain notes. This is a graph your agent searches before each task, and you can open it in your browser and click any node. By the end of this guide you'll have it installed in Claude Code, one real decision saved, and proof of what a brand new session recalls. I tested every step on Windows 11 with Claude Code 2.1.289 and MegaMemory 1.6.2 on a small demo project.