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:

When Junie CLI is connected to a JetBrains IDE for the same project, you can also use the /ide command to inspect the current JetBrains IDE connection state and the JetBrains IDE features available to the session. For details, see Junie CLI and JetBrains IDE integration.

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.