ACP (IDE agents)

The Agent Client Protocol (ACP) is an open standard that lets editors and IDEs talk to coding agents over JSON-RPC on stdio — the client spawns the agent as a subprocess and streams prompts, tool activity, and permission requests through it. Zed, the JetBrains IDEs, and a growing list of clients (marimo, Toad, VS Code extensions) speak ACP.

apx acp turns the APX super-agent into an ACP agent. Whatever your editor, the agent behind it is the same one that answers on Telegram, the web panel, and apx code — same engines, same tools, same memory.

apx acp

The command serves the protocol on stdin/stdout until the client closes the pipe. You never run it by hand in a terminal — your editor launches it. Like every surface, it is a thin adapter over the local daemon (auto-started on first use): each prompt becomes a streaming super-agent turn on the code channel, so ACP sessions get the coding system prompt and the git/code tool set.

Connecting from Zed

1. Install APX globally so apx is on your PATH.

2. Add an agent_servers entry to your Zed settings.json:

   {
     "agent_servers": {
       "APX": {
         "command": "apx",
         "args": ["acp"]
       }
     }
   }

3. Open the Agent Panel, pick APX, and chat. Tool calls stream into the panel, and any action that needs confirmation shows Zed’s native Allow / Reject dialog.

Tip

Sessions resolve the APC project from the workspace folder the client reports (cwd), walking up to the nearest .apc/ root — exactly like the MCP bridge. If the folder isn’t an APC project yet, run apx init there first.

What the surface implements

ACP concept	APX behavior
initialize	Protocol version 1; declares loadSession: false, no image/audio/embeddedContext prompts, no MCP passthrough
session/new	Resolves the APC project for the client’s cwd, registers it with the daemon if needed
session/prompt	Streams a super-agent turn; replies resolve with stopReason: "end_turn"
session/update	agent_message_chunk for text, tool_call / tool_call_update for tool activity
session/request_permission	Emitted when APX’s permission mode requires confirmation; Allow/Reject answers the pending action
session/cancel	Aborts the in-flight turn and resolves it with stopReason: "cancelled"

Multi-turn context is kept in-process per session: every completed turn feeds the next one as conversation history, so follow-up prompts remember the thread without any extra setup.

Note

stdout carries the protocol, so the server never logs there. Diagnostics go to stderr (your editor’s agent log view) and to the unified log — apx log -f.