ACP agents

QodeAssist can talk to external coding agents that speak the Agent Client Protocol (ACP). The QodeAssist > Agents settings page lists the agents it knows about and lets you verify that one starts and answers the ACP handshake.

Where the list comes from

The list is merged from three sources. When the same agent id appears in more than one, the higher entry wins:

Your JSON files in qodeassist/agents/ inside the Qt Creator user resource directory (Open Agents Folder... opens it). Press Reload after editing.
The ACP registry, downloaded from https://cdn.agentclientprotocol.com/registry/v1/latest/registry.json when you press Refresh from Registry and cached on disk. There is no background polling: the list only changes when you ask for it.
A bundled snapshot, so the list is never empty on a fresh install or offline.

If a download fails, the cached copy and the bundled snapshot stay in place.

Finding the agent's executable

Qt Creator started from the Dock or a launcher does not inherit your shell's PATH, so npx or uvx installed through Homebrew, nvm or uv is often invisible to it — the agent then fails to start with execve: No such file or directory. Extra PATH for launching agents on the Agents page lists directories that are both searched for the executable and prepended to the agent's own PATH. On macOS it defaults to /opt/homebrew/bin:/usr/local/bin. An env entry in the agent definition still wins over it.

Credentials and other environment variables

Some agents authenticate through an environment variable rather than the ACP handshake — the Claude adapter, for instance, declares no authMethods at all and reads CLAUDE_CODE_OAUTH_TOKEN. Since a Qt Creator started from the dock inherits no shell environment, that variable never reaches the agent and it fails with an expired-session error.

Forward these variables to agents on the Agents page takes variable names, not values, and defaults to CLAUDE_CODE_OAUTH_TOKEN. For each name QodeAssist uses the value from its own environment when it has one — which covers Windows, and any platform when Qt Creator was launched from a terminal. On macOS and Linux the remaining names are read once per session from a login shell ($SHELL -l -i -c env), so a token exported in your shell profile works without being copied anywhere. Nothing is stored in the settings but the names.

An env entry in the agent definition still wins over a forwarded variable.

Distributions

An entry describes how the agent is started:

npx — launched as npx -y <package> <args>. Requires Node.js on PATH.
uvx — launched as uvx <package> <args>. Requires uv on PATH.
command — launched directly. This is the QodeAssist extension used by your own JSON files.
binary — a downloadable platform archive. QodeAssist does not download binaries, so these agents are listed but cannot be started. Install the agent yourself and add a command entry for it.

Defining your own agent

Create a .json file in the agents folder. A file holds either a single agent object or a registry-shaped {"agents": [...]} document.

{
  "id": "my-agent",
  "name": "My Agent",
  "version": "1.0.0",
  "description": "Locally installed agent",
  "distribution": {
    "command": {
      "cmd": "/usr/local/bin/my-agent",
      "args": ["acp"],
      "env": { "MY_AGENT_LOG": "debug" }
    }
  }
}

Reusing an id from the registry overrides that entry — which is how you make a binary agent launchable after installing it manually:

{
  "id": "cursor",
  "name": "Cursor",
  "distribution": {
    "command": { "cmd": "/usr/local/bin/cursor-agent", "args": ["acp"] }
  }
}

Agent definitions hold no secrets. Agents that need credentials authenticate through the ACP handshake.

Testing an agent

Select an agent and press Test. QodeAssist starts the process, runs the ACP initialize handshake and reports the agent's name, version, protocol version, whether it supports session persistence (loadSession), its prompt and MCP capabilities, and its authentication methods. On failure it shows the error together with the agent's own output.

Long conversations and reopened sessions

When an agent conversation grows long, the Hand over button in the chat bottom bar summarizes the transcript with your Chat Assistant configuration and continues in a fresh agent session seeded with that summary — see chat-summarization.md for details. The same handover is offered on the read-only banner when a saved agent session can no longer be resumed.

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