Supported agents
How Kettu runs your agents, what it installs for you, where installs go, how they update and who you pay.
Kettu implements no agent of its own. It runs the agents you choose, with your own accounts, models, settings and rules. It talks to them in one of two ways:
- Claude Code and Codex through their own interfaces: the Claude Agent SDK, and
codex app-server. - Every other agent through the open Agent Client Protocol (ACP).
Kettu knows 46 agents. Each one has a page on this site, such as Claude Code, Codex, OpenCode or Gemini CLI, and the home page lists them all.
Harnesses and agents
Settings splits each agent in two. The program is a harness: Settings › Harnesses installs and updates it and shows which program runs. The agent is what you pick for a session: Settings › Agents shows its account, sign-in and plan limits. Claude Code and Codex can carry more than one agent, such as one on a subscription and one on a company API key, each in a configuration folder of its own (Add agent).
What Kettu installs and what you install
| Kind | Who installs it | Where it goes |
|---|---|---|
| Claude Code, Codex, OpenCode and other programs of their own | You, or Install in Settings › Harnesses, which runs a way its maker documents | Wherever that way puts it |
| The Claude Agent SDK | Kettu, the first time you use Claude Code | Kettu’s data folder |
| ACP agents published on npm | Kettu, when you click Install | Kettu’s data folder, run on your Node.js |
| Release archives from the ACP Registry | Kettu, when you click Install and your own copy is not on PATH | Kettu’s data folder |
| Python packages (fast-agent, Minion Code) | uvx, on first use | Managed by uv |
Kettu’s installs go in the agents folder of its data folder. Your own copy of a program always wins over Kettu’s, so your sign-in and configuration stay as they are.
Updates
Kettu checks npm once a day for the packages it installed and for your own Claude Code and Codex, and right away when you click Check for updates in Settings › Harnesses. The sidebar shows a card when there is an update. A package of Kettu’s updates next to the current version: running sessions keep going, and the agent uses the new one from its next start. Claude Code and Codex update the way you installed them. Kettu does not update archives, uvx packages or other programs you installed yourself.
Signing in and paying
Each agent signs in its own way, usually with its own command in a terminal, which Kettu runs for you in its terminal. Kettu never sees your credentials and has no account or server of its own.
Every request goes from the agent to its own provider, as it does in your terminal, and counts against your plan, credits or API key there. Two settings in Settings › General also send requests through the agent, to its small model: Write titles for new sessions and Summarize messages in the outline. They count against the same plan or credits.