Junie for ACP clients

What is ACP?

Agent Client Protocol (ACP) is a protocol that standardizes communication between code editors/IDEs and coding agents, similar in spirit to how the Language Server Protocol (LSP) unified language tools. In short, ACP decouples agents and editors so that:

• Agents that implement ACP can work with any ACP-compatible editor.

• Editors that support ACP can integrate any ACP-compatible agent.

ACP reuses MCP JSON structures where appropriate and adds types tailored for agentic coding UX (for example, diffs). Markdown is used as the default user-readable format.

For the full documentation index (entry point), see official site.

When to use ACP mode

Use ACP mode when:

• You are building an editor/IDE integration that expects an ACP-capable agent.

• You want Junie to serve requests initiated from an ACP client (instead of direct human interaction in the terminal).

Use standard (non-ACP) Junie CLI when:

• You operate Junie interactively in your terminal.

• You run Junie in headless/CI scripts without an ACP client.

Enable ACP mode in Junie CLI

To run Junie CLI in ACP mode, use the --acp flag:

Local vs. remote scenarios

ACP supports both local and remote agent setups:

• Local agents: subprocess communication via JSON-RPC over stdio.

• Remote agents: HTTP or WebSocket communication. Full support for remote agents is evolving in the ecosystem.

Refer to the official ACP documentation for the current transport recommendations and capabilities.