Add OpenCode ACP support

[codegirl-007]

Add ACP (Agent Client Protocol) support for OpenCode. This works for all functions (fill in, over-range, refactor, etc). This implementation is faster (especially when trying to refactor with 99 across multiple files) than using the CLI to get responses because we're able to persist the session (which I don't do yet) and parallelize the requests to OpenCode (which is implemented).

Tested in Neovim but some of tests fail despite the feature working. I never updated them really so probably need to fix them. and the tests pass.

If you also want to trade higher complexity for better performance 😉, configure 99 with:

{
  "ThePrimeagen/99",
  config = function()
    local _99 = require("99")
    _99.setup({
      -- Use the ACP provider instead of the default CLI provider
      provider = _99.ACPProvider,
      -- Optional: specify model (defaults to anthropic/claude-sonnet-4-5)
      model = "anthropic/claude-sonnet-4-5",
      -- Standard config...
      logger = {
        level = _99.DEBUG,
        path = "/tmp/99.debug",
      },
      md_files = { "AGENT.md" },
    })
    vim.keymap.set("n", "<leader>9f", function()
      _99.fill_in_function()
    end)
    vim.keymap.set("v", "<leader>9v", function()
      _99.visual()
    end)
    vim.keymap.set("n", "<leader>9r", function()
      _99.refactor()
    end)
  end,
}

Demo videos:
ACP:

acpprovider.mp4

Open Code
https://github.com/user-attachments/assets/3a294e1d-79bd-4904-8dd6-d45471457509

Claude Code

Screen.Recording.2026-01-26.at.6.44.25.PM.mov

Cursor

Screen.Recording.2026-01-26.at.6.53.53.PM.mov

[codegirl-007]

It occurs to me now that maybe those failing tests are from parallelizing requests in the refactor command and the other providers don’t have ACP available. I didn’t read which tests failed but this is an issue regardless.

I probably screwed the pooch and need to fallback to cli prompting sequentially when ACP is not available (unless you can parallelize CLI commands but I imagine the other providers have locking mechanisms where you can’t do that).

Just a note for my future self.

[ThePrimeagen]

ill look at this at some point :)

I dont know what this is so ill have to read up on it before proceeding!

[codegirl-007]

ill look at this at some point :)

I dont know what this is so ill have to read up on it before proceeding!

There’s still stuff I need to fix so no rush.

[ThePrimeagen]

Let me look at this in the morning :)

After I get skills in. I think it's good to go... But I want to make sure it's good

[codegirl-007]

Let me look at this in the morning :)

After I get skills in. I think it's good to go... But I want to make sure it's good

No rush. Just easier to review in PR.

[XandeCommits]

Hey this looks really cool, I want to use it!

Is this gonna be merged soon??

[codegirl-007]

Hey this looks really cool, I want to use it!

Technically it works but I think it can be better organized to make it more self explanatory. Right now when I read the code, it reads like I'm building the entire internet instead of just using the ACP protocol. Unfortunately, I couldn't find an Agent Client Protocol library for lua so I had to reinvent some wheels. Would have been a nice abstraction to have though.

Is this gonna be merged soon??

Don't know but thanks for coming to my tech talk.

[ThePrimeagen]

I will likely merge tonight, but first I have to merge skills-v2

[codegirl-007]

The minimal config you'd need to try the acp stuff is:

_99.setup({
  -- this by default uses `opencode acp` command instead of `opencode run`
  provider = _99.ACPProvider, 
  add_to_quickfix = true,  -- This enables quickfix tracking for any changes (not just refactor)
})

To refactor across multiple files, I mapped it with this. Interested to see the limitations on this. This finds references via LSP so I'm sure we'll find some limitations.

vim.keymap.set('n', '<leader>9r', function()
    _99.refactor_prompt()
end)

The ACP code is gnarly looking (to me) but it's ready to go (as in working functionally) as is.

[codegirl-007]

Okay, I'm done. I'll stop now. I have beaten the dead horse because of borderline pedantics.