Why? Because agents already know how to use files. Claude Code writes notes to ~/.claude/. Cursor stores context in project files. Every coding agent that works well has converged on the same pattern: just use files. The model doesn't need to learn a new API, and you don't need a retrieval pipeline.
The problem is that real filesystems don't work in production.
agent-vfs gives each user a virtual filesystem backed by a single database table. 11 operations (read, write, edit, ls, grep, glob, etc.), SQLite for local dev, Postgres for production. Works with the Vercel AI SDK, OpenAI SDK, and Anthropic SDK out of the box.
npm install agent-vfs