cmd-acp

Expose Command Code (cmd) as an Agent Client Protocol (ACP) agent over stdio.

Command Code does not ship a native ACP mode, but its headless mode emits a machine-readable NDJSON stream (cmd -p --output-format json). cmd-acp is a small bridge that speaks ACP (JSON-RPC 2.0 over stdio) to ACP-compatible clients such as Circulo, Zed, JetBrains, and others, and drives cmd underneath — one cmd -p process per prompt.

Why

• ACP clients spawn an external agent subprocess and talk JSON-RPC over stdio.
• cmd already exposes everything needed: NDJSON events + a final result line.
• No PTY hacks or database parsing needed (unlike some adapters).

Install

npm i -g cmd-acp
# or run on demand:
npx -y cmd-acp

Prerequisites:

• Command Code installed: cmd on PATH (Node >= 22).
• Authenticated once: cmd login.

Override the cmd / cmd-acp binaries with env vars if needed:

CMD_BIN=/path/to/cmd CMD_ACP_BIN=/path/to/cmd-acp cmd-acp

Usage in an ACP client

Point your ACP client at the cmd-acp binary:

{
  "command": "cmd-acp"
}

Or via npx:

{
  "command": "npx",
  "args": ["-y", "cmd-acp"]
}

Protocol support

ACP method	Behavior
initialize	ACP v1, load_session: false
session/new	Records cwd; materializes injected MCP servers into .mcp.json; returns configOptions
session/prompt	Runs cmd -p "<text>" --output-format json in the session cwd; from turn 2 resumes via --resume <cmdSessionId>
session/cancel	SIGINT to the child cmd process
session/close	Kills child, restores any pre-existing .mcp.json, clears session state
session/set_config_option	model → --model, reasoning → --effort, permission_mode → --yolo, mode → --plan

Permissions

cmd -p is one-shot: there is no interactive permission request mid-turn (unlike native ACP agents such as OpenCode).

• Safe mode (default): run cmd without --yolo. Command Code itself blocks file edits and shell commands (fail-closed). The client sees tool calls as a log, not as a prompt gate.
• --yolo mode: opt-in via the permission_mode config option, for users who want edits and shell execution without a gate.
• Plan mode: the mode config option (plan) runs cmd -p --plan for read-only exploration.

The client's own permission engine still applies at session level.

Config options

• model — select a Command Code model (from cmd --list-models).
• reasoning — --effort level (low, medium, high).
• permission_mode — safe (default) or yolo.
• mode — normal (default) or plan (read-only).

Features

• Conversation continuity: each turn runs cmd -p --resume <cmdSessionId> from the 2nd turn on, so Command Code keeps the full conversation context.
• Usage tracking: emits ACP usage_update with the token usage from the result frame, so clients can show token consumption.
• MCP passthrough: MCP servers a client injects on session/new are written to a temporary .mcp.json in the session cwd (restored on close), so Command Code can use those tools.

Standalone binaries

Pre-compiled standalone binaries (no Node runtime needed) are attached to each GitHub Release:

• cmd-acp-darwin-arm64 / cmd-acp-darwin-x64 (macOS)
• cmd-acp-linux-x64 / cmd-acp-linux-arm64 (Linux)
• cmd-acp-windows-x64.exe (Windows)

Development

bun install
bun test          # deterministic fake CLI — no real cmd needed
bun run build     # bundle to dist/

License

MIT