# Supported harnesses Patterm runs three agent CLIs, Claude Code, Codex and OpenCode, plus a raw terminal, and leaves each CLI's own login, permissions and resume behaviour in place. A harness is the CLI Patterm hosts. Patterm does not call any model API itself. Every agent is the real CLI, running under your user account. ## Summary | Harness | Command on `PATH` | Presets | Resume | | ------------ | ----------------- | -------------------- | ------------------------- | | Claude Code | `claude` | Yes | `claude --resume ` | | Codex | `codex` | Yes, including speed | `codex resume ` | | OpenCode | `opencode` | Yes | `opencode --session ` | | Raw terminal | Your `$SHELL` | No | Not resumable | Both the TUI and [Integrated](https://patterm.com/docs/agents-and-processes.md#integrated-and-tui-agents) interfaces work with Claude Code, Codex and OpenCode. The raw terminal has TUI only. ## What you need installed Install each CLI you want separately and sign in to it, the same way you would outside Patterm. Patterm does not store or manage your CLI credentials. Patterm finds a CLI by searching the `PATH` of the account running it for the commands above, then runs `--version` to confirm it works. If the **Launch agent** menu says **No agent CLIs found on PATH**, Patterm could not find any. In **Settings › Harnesses**, each CLI shows its version when it was found, or **Not discovered**. > [!TIP] > If you run Patterm as a background service, the service has its own `PATH`, recorded when you installed it. Put the CLIs somewhere that `PATH` includes, and keep their logins available to the same account. See [Linux server](https://patterm.com/docs/linux-server.md). The raw terminal needs nothing. It starts your shell. ## Models and presets Each CLI uses its own configured model unless you choose a preset. A preset is a name, a model, a reasoning effort and, for Codex, a speed. Add them in **Settings › Harnesses**. **Discover models** reads the model list from each installed CLI: - Claude Code: the CLI's model list, falling back to aliases for the latest model in each family. Reasoning levels are `low`, `medium`, `high`, `xhigh` and `max`. - Codex: the models Codex lists for its model picker, with their reasoning levels and speed tiers. - OpenCode: the models its server offers, named `provider/model`. You can also enter a model ID by hand with **Custom model ID…**, which is how you use a model that is too new for the list. The raw terminal has no model, so presets do not apply to it. ## How resume works Every harness keeps its own conversation ID. Patterm records it and uses the CLI's native resume command, listed in the table above, when you resume a conversation. A resumed conversation keeps the model it had, unless you choose a preset when resuming. See [Resume behaviour](https://patterm.com/docs/agents-and-processes.md#resume-behaviour) for how to resume and what survives a restart. ## How Patterm connects each CLI to its tools Each agent gets Patterm's MCP server, so it can use tools such as `spawn_agent`, `report_to_parent` and the todo and worktree tools. Patterm adds the server for each launch and leaves the CLI's own configuration alone. It does not edit `~/.claude.json`, `~/.codex/config.toml` or your OpenCode settings. | Harness | How the launch gets Patterm's tools | | ----------- | ----------------------------------------------------------------------------------------------------------------------------- | | Claude Code | A per-launch MCP config file in Patterm's own runtime directory, passed with `--mcp-config`. | | Codex | Inline configuration overrides on the command line, using `-c`. | | OpenCode | A registration with OpenCode's shared server for that session, made when the agent starts and not written to any config file. | The same launch also gives the agent Patterm's startup instructions: through `--append-system-prompt` for Claude Code, `developer_instructions` for Codex, and the session API for OpenCode. The MCP servers you add under **Settings › MCP servers** are delivered the same way, only to the harnesses you assign them to. Secrets such as tokens and headers never go on a command line, where `ps` would show them. Patterm passes them through helper commands that fetch them at run time. See [Your MCP servers](https://patterm.com/docs/mcp-servers.md). ## Permission prompts stay native Patterm does not add its own approval layer and does not auto-approve anything for you. Each CLI asks for permission the way it normally does: - In TUI mode, you answer the CLI's own prompt in its terminal. - In Integrated mode, the CLI's request appears as a card in the conversation, and your answer goes back to the CLI. The agent's tab shows **Needs permission** while it waits. Routines have no permission setting of their own, so unattended runs keep the CLI's native prompts. > [!NOTE] > Patterm starts Claude Code with `--permission-mode auto`, which is Claude Code's own mode. Anything that mode asks about still reaches you. ## Notes for each CLI ### Claude Code Sign in with `claude` as you normally would. Each launch gets its own MCP config file, so agents started together keep separate identities. ### Codex Codex keeps its own saved logins for MCP servers, and it uses those instead of the headers Patterm supplies. If Codex reports that an MCP server's login failed to refresh, remove Codex's saved login for that server and restart the agent. If it reports the server as not logged in, sign in to the server under **Settings › MCP servers**, then restart the agent. Patterm shows a notification that explains which applies. ### OpenCode Patterm launches the native OpenCode terminal interface against OpenCode's shared background server. Before attaching, it creates or finds the session, adds its instructions, and registers its MCP bridge for that directory. Stopping or closing an agent, and a normal Patterm shutdown, interrupt the OpenCode sessions Patterm attached, but not the shared server or other OpenCode sessions. If Patterm crashes, check OpenCode for work still running before you resume. If a launch fails because the shared server is older than the CLI, Patterm offers to restart the server and launch again. The restart interrupts any running OpenCode turns, so it only happens when you click it. Patterm keeps a copy of OpenCode's `cli.json` for its terminal preferences. It merges in changes from your main OpenCode config, and settings you change inside Patterm win a conflict. Resuming needs the session to still exist in the OpenCode server. ### Raw terminal The raw terminal starts your shell in the project with none of Patterm's tools. In the app it is offered as a process (**New terminal** in the command palette), not as an agent. ## Related - [Agents and processes](https://patterm.com/docs/agents-and-processes.md) - [Your MCP servers](https://patterm.com/docs/mcp-servers.md) - [Settings](https://patterm.com/docs/settings.md) - [MCP tool reference](https://patterm.com/docs/mcp-tools.md) --- This is one page of the Patterm documentation. The index of every page is at https://patterm.com/llms.txt.