# How DevHub works

> What DevHub is, what runs on your computer, and how an AI agent reaches your folders and notes.

DevHub is a desktop application for macOS. It sits between your AI clients and your work. You decide which repositories and which notes an agent may see. DevHub serves exactly those, and records each call.

## The parts

- **Your folders and vaults.** Repositories and folders of Markdown notes that stay on your disk. DevHub keeps its own data on your computer too.
- **The MCP server.** A local server inside DevHub. An AI client, such as Claude Code, Codex, Copilot or OpenCode, connects to it over MCP (Model Context Protocol) and calls tools. See [MCP server](/devhub/features/mcp-server/index.md).
- **The tools.** Search a vault, read a repository index, queue context, work on plans, run an agent. Each tool belongs to an area, and your Vartari plan says which areas agents may use. See the [catalog of DevHub tools](/devhub/reference/mcp-tools/index.md).
- **The screens.** The Dashboard, the vaults, the library, plans and agents are how you set things up and watch what happens.

## What happens when an agent works

1. You start a client in a folder that DevHub set up for it.
2. The client calls a tool, for example to list the workspaces it can see.
3. DevHub checks that the folder or vault is exposed, that its access level allows the call, and that your account may use that area.
4. DevHub answers, and the call appears on the [Dashboard](/devhub/features/dashboard/index.md) and in Activity with its result and duration.

An agent sees only what you added. A folder or vault you disabled does not exist for it.

## Your account

You sign in with Vartari ID in your browser. A session lasts seven days. DevHub never sees your password. What you may do comes from your Vartari plan. Anything it does not include stays visible but disabled, with the permission it needs. The sign-in sends only the device name and the system; code and notes do not leave your computer.

## Where to go next

- [Structure of DevHub](/devhub/concepts/structure/index.md): organizations, projects, folders and vaults.
- [Knowledge and code](/devhub/concepts/knowledge-vs-code/index.md): when an agent asks a vault and when it reads code.
- [Glossary](/devhub/concepts/glossary/index.md).