# Harnesses

> Connect AI clients to DevHub, set up a folder for each one and keep the files DevHub wrote up to date.

A harness is an AI client such as Claude Code, Codex, Copilot or OpenCode. The **Setup** group of the sidebar has two screens for them. **Harnesses List** shows the clients on this computer and which ones are connected. **Harnesses Manage** sets up a folder for a client: DevHub writes the files the client reads, so it already knows the project, the vault and the tools it may use when you start it there.

## Harnesses List

[Screenshot: The Harnesses List screen with clients grouped as Connected, Found not connected and Not found, each with its path, version and the buttons Test, Change path and Disconnect. The sample data shown is made up.]

DevHub looks for clients on this computer and groups them as **Connected**, **Found, not connected** and **Not found**. The filters at the top are **All**, **Connected**, **To connect** and **Not found**. The line under them says when the search was last done. Click **Check again** to search again.

1. Click **Connect a client**, or **Connect** on a client that was found. Nothing is connected until you pick it.
2. If DevHub cannot see the program, click **Point at the program…** and choose its full path. **Check and save** runs it to see that it answers.
3. Click **Test** on a connected client. The row says when it last answered and, for clients that can, which models it offers.

A packaged application does not inherit the PATH of your shell. For that reason a client you installed can show as not found. **Copy prompt** copies a prompt for an agent that finds the program and gives you its full path. **Change path…** changes the saved path and **Disconnect** removes the connection.

A connected client can get files from DevHub and start work, and, if it can answer as a model, lend its models on [Vartari Hub](/devhub/features/hub/index.md). Which clients can is shown on the row.

## Harnesses Manage

[Screenshot: The Harnesses Manage screen with installations as rows, each with a folder, a client, the number of files written and the buttons Copy command, Guide, Show memory, Edit, Update and Remove. The sample data shown is made up.]

An installation is one client in one folder. One folder can hold installations of several clients, and each gets its own files.

1. Click **Set up a folder**.
2. Choose the **Folder** and the **Harness**. Add a **Name** and the vault the client should know.
3. Choose the **Instructions file**, the **User profile** that decides which skills, rules and commands it carries, and the **Agent intelligence** it collects into.
4. Under **Accepting hooks** say which hooks the client may run. The default is only the ones DevHub wrote.
5. Read **What will be written**, then click **Create and write files**.

DevHub writes into the folder:

- the instructions file the client reads;
- the MCP configuration, so the client reaches DevHub. For Copilot the configuration is done in the client itself, and the dialog says so;
- the skills, rules and commands of the chosen profile;
- hooks, where the client supports them. DevHub uses them to collect what fails into Agent Intelligence.

If a file with a name DevHub would use already exists and is yours, DevHub merges its part in and never deletes the file. Removing an installation deletes only the files DevHub wrote.

### On each row

**Copy command** copies a command that goes to the folder and starts the client. **Guide** shows how DevHub talks to that client: whether its rules reach it as a file in the folder or through a hook, and whether each rule arrives. **Show memory** shows where the client keeps its own memory, when that is known. **Edit** changes the installation, and the folder and the client stay fixed. **Update** writes the files again. **Remove** deletes what DevHub wrote.

### Update every installation

An installation written by an older version of DevHub may miss something new, for example the address of the MCP server or the hook that collects learning. The screen then says so and offers **Update N installations**. It rewrites all of them and afterwards says which it updated and which it left alone. A session that is already open keeps its old address until it reconnects.

### Files changed on disk

DevHub notices when somebody changed files it wrote. The banner **N installation has files changed on disk** offers **Show the changes**. On the row, **Restore** discards the edits. To keep them, move them into the [Library](/devhub/features/library/index.md) so the next update carries them. An update leaves an edited installation alone until you decide.

> **Note:** Harnesses List needs a permission for connectors in your Vartari plan, and Harnesses Manage the
> manage level. A screen your account does not include stays visible but disabled.

## Related

- [Connect an AI client](/devhub/getting-started/connect-client/index.md)
- [Library](/devhub/features/library/index.md)
- [Agent Intelligence](/devhub/features/agent-intelligence/index.md)
- [MCP server](/devhub/features/mcp-server/index.md)
- [Vartari Hub](/devhub/features/hub/index.md)
- [DevHub says my AI client is not found, but it works in the terminal](/devhub/troubleshooting/client-not-found/index.md)
- [My AI client lists the DevHub skills but never uses them](/devhub/troubleshooting/skills-not-firing/index.md)