Handling Model Selection in ACP

[iamthebot]

Currently, ACP adapters work a little differently than traditional remote LLM adapters in that if, for example, you're using ACP to connect to claude code you only see a "default" adapter. This is because codecompanion doesn't yet support SetSessionModel*. Also, /model is not supported as a slash command in the ACP world (because SetSessionModel is in the ACP spec).

*In the ACP docs this is considered an unstable API, but alas it is the only way to select a model within a session and is already supported by the claude code ACP.

My thinking is in the same way that we update slash commands after they're broadcasted by the ACP host we can update the available models for the adapter after we receive the model list after session initialization. It does mean that, initially, you'd still only be able to select "default" as the model until a few seconds after you open the chat buffer (this limitation already exists for slash commands though).

Happy to throw up a PR again to add this. Any thoughts?

[olimorris]

The Zed guys dropped me a message about this a couple of weeks ago. It might be marked as unstable but my experience is that they're normally pretty full baked features by the time they let me know about them so happy to accept one of your awesome PRs to add it in.

From a usability perspective, this poses an interesting dilemma. Right now when users change model in the chat buffer with ga, it displays commands in place of models. I think this should change to display the available models and I propose that an ACP adapter's commands becomes a flat array, like:

commands = {
  "npx",
  "--silent",
  "--yes",
  "@zed-industries/claude-code-acp",
},