Capo

A Rust-native coding agent CLI. Single binary, library-first, focused on shipping correct code through a small set of well-understood tools.

$ capo

Install

cargo install capo-cli

The crate is published as capo-cli (the name capo was already taken on crates.io); the installed binary is still capo.

Or grab a pre-built binary from the latest GitHub Release.

Quickstart

export ANTHROPIC_API_KEY=sk-ant-...
capo                  # interactive TUI
capo -p "fix the failing test in src/auth/mod.rs"   # print mode
capo -c               # continue the most recent session in this directory
capo --resume         # pick a recent session

Capo reads AGENTS.md / CLAUDE.md from the current directory upward, so per-project context is automatic.

Supported models

Default: claude-sonnet-4-6 (Anthropic). Configure in ~/.capo/agent/settings.json:

{
  "model": { "provider": "anthropic", "name": "claude-sonnet-4-6", "max_tokens": 8192 }
}

API keys live in ~/.capo/agent/auth.json (mode 0600) or the ANTHROPIC_API_KEY env var.

Tools

Tool	What it does
`read`	Read a file. Always allowed.
`grep`	Regex search over file contents. Always allowed.
`find`	List files/directories by glob. Always allowed.
`ls`	List a directory's entries. Always allowed.
`write`	Create or overwrite a file. Prompts unless allowlisted.
`edit`	Patch an existing file via unique-string replacement. Prompts unless allowlisted.
`bash`	Run a shell command via PTY. Prompts every time unless allowlisted.

Configure allowlists in ~/.capo/agent/permissions.toml. See docs/superpowers/specs/2026-04-23-capo-design.md §4 for the full permission model.

Commands & editor

Inside the TUI:

Type / for the command palette — /help, /quit, /new, /model, /compact, /resume.
Type @ to fuzzy-search and insert a project file path.
A line starting with ! runs a shell command and sends its output to the agent; !! runs it and shows the output without sending.
--resume (or /resume) opens an interactive picker of recent sessions for the current directory.

Skills

Markdown files in ~/.capo/agent/skills/<name>/SKILL.md (or flat <name>.md) become discoverable skills. They follow the Agent Skills standard:

---
name: rust-error-triage
description: Use when debugging Rust compile errors or runtime panics
---

Body content (loaded by the model via the `read` tool when the description matches).

Per-project skills live at <repo>/.capo/skills/.

MCP

Capo speaks the Model Context Protocol. Servers configured in ~/.capo/agent/mcp.toml are connected at startup; their tools become available as <server>__<tool> (rendered as <server>:<tool> in the UI):

[servers.github]
transport = "stdio"
command = "github-mcp-server"
args = ["--scope", "read-only"]
env = { GITHUB_TOKEN = "${GITHUB_TOKEN}" }

Using `capo-agent` as a library

use capo_agent::{AppBuilder, Auth, Settings};

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    let agent_dir = capo_agent::agent_dir();
    let app = AppBuilder::new()
        .with_settings(Settings::load(&Default::default())?)
        .with_auth(Auth::load(&agent_dir)?)
        .with_builtin_tools()
        .build()
        .await?;

    let stream = app.send_user_message("list every .rs file in src/".into());
    use futures::StreamExt;
    futures::pin_mut!(stream);
    while let Some(_event) = stream.next().await { /* render UI events */ }
    Ok(())
}

See crates/capo-agent/examples/list_rust_files.rs for a runnable version.

Architecture

Three crates, all under crates/:

capo-tui — Elm-style MVU TUI runtime/rendering; consumes capo-agent UI event types.
capo-agent — coding-agent SDK; built on motosan-agent-loop.
capo — the binary you install.

Detailed design lives in docs/superpowers/specs/2026-04-23-capo-design.md.

License

MIT — see LICENSE.

capo-agent 0.3.0