Possible Bug with Folding Logic

[amadeus]

Wasn't sure the right place to post this, but I believe I may have found a bug with the new folding logic. If the chat buffer is hidden when the patch is accepted, then the fold will fail and break the chat buffer completely.

Here's an example of the error (this is the automatic flow where the chat view gets closed on smaller windows to show the diff, i just have a recording starting right before the AI creates the diff):

bad.mp4

And here's the same scenario but I open the chat buffer before accepting the change:

good.mp4

[ThorstenRhau]

I have encountered the same error message.

Here are my options that are folding related

local o = vim.o
o.foldenable = false
o.foldexpr = "nvim_treesitter#foldexpr()"
o.foldlevel = 99
o.foldlevelstart = 99
o.foldmethod = "expr"

And here is my codecompanion configuration that solves the error by setting fold method to manual while codecompanion does it's thing.

---@module "lazy"
---@type LazySpec
return {
    "olimorris/codecompanion.nvim",
    dependencies = {
        "nvim-lua/plenary.nvim",
        "nvim-treesitter/nvim-treesitter",
    },
    cmd = {
        "CodeCompanion",
        "CodeCompanionActions",
        "CodeCompanionChat",
        "CodeCompanionCmd",
    },
    keys = {
        { "<leader>ci", "<cmd>CodeCompanion<cr>", desc = "CodeCompanion Inline Assistant" },
        { "<leader>cc", "<cmd>CodeCompanionChat Toggle<cr>", desc = "CodeCompanion Chat Buffer" },
        { "<leader>cx", "<cmd>CodeCompanionCmd<cr>", desc = "CodeCompanion CMD Generator" },
        { "<leader>cX", "<cmd>CodeCompanionActions<cr>", desc = "CodeCompanion Actions Palette" },
    },
    opts = {
        adapters = {
            openai = function()
                return require("codecompanion.adapters").extend("openai", {
                    env = { api_key = vim.env.OPENAI_API_KEY },
                    parameters = {
                        model = "gpt-4.1-mini",
                        temperature = 0.1,
                        stream = true,
                        max_tokens = 8192,
                        top_p = 1,
                        presence_penalty = 0,
                        frequency_penalty = 0,
                    },
                })
            end,
        },
        strategies = {
            chat = { adapter = "openai" },
            inline = { adapter = "openai" },
            cmd = { adapter = "openai" },
        },
    },
    config = function(_, opts)
        require("codecompanion").setup(opts)
        local tools = require("codecompanion.strategies.chat.ui.tools")
        local original = tools.create_fold

        tools.create_fold = function(bufnr, start_line)
            local win = vim.api.nvim_get_current_win()
            vim.api.nvim_win_call(win, function()
                local old = vim.wo[win].foldmethod
                vim.wo[win].foldmethod = "manual"

                pcall(original, bufnr, start_line)

                vim.defer_fn(function()
                    if vim.api.nvim_win_is_valid(win) then
                        vim.wo[win].foldmethod = old
                    end
                end, 50)
            end)
        end
    end,
}

I hope that this helps to get this fixed.

[olimorris]

What is the error? The videos weren't clear to me

[ThorstenRhau]

E350: Cannot create fold with current 'foldmethod'

[ThorstenRhau]

I have created PR #1795 that hopefully fixes this error without having to add the stuff that I have in my configuration.

[amadeus]

I’ll need to check your PR when I’m back on a computer, but some additional context.

I did try vibe coding a fix a bit with an AI, and it came up with something kinda similar to what I think you have, which negates the error, however it wasn’t really a fix because when I open the chat buffer back up again, there was no fold applied to the tool output. It just prevented the error from occurring.

Also not sure the fold method being set to manual is needed as the codecompanion chat buffers set that automatically.

I think the core bug is the folding logic is attempting to apply to code file, not the chat buffer which we shouldn’t be changing the fold method on.

If your code to search for the chat buffer does in fact work properly then it may just fix the problem, but if it can’t find the buffer then we may be back to square one.

Also I’m not too familiar with neovim/lua internals so maybe I have no idea what I’m talking about and this can be disregarded, just figured I’d throw in my findings in case it’s helpful.