CopilotChatCommitStaged fails with error `prompt token limit exceeded`

[bashtoni]

When trying to get Copilot to write a commit message for me with :CopilotChatCommitStaged I get the following error returned:

Failed to get response: {"error":{"message":"prompt token limit exceeded","param":"","code":"","type":""}}

This definitely worked previously - seems to have broken in the last week or two?

[masakiq]

I encountered a similar problem as well.

1. After executing git commit, .git/COMMIT_EDITMSG opens in Neovim (nvim).
2. When I run :CopilotChatCommitStaged, I receive a token limit exceeded error.

Cause

As stated in the error message, the token limit exceeded error occurs because the OpenAI API's token limit has been surpassed.

This error started occurring after the following commit:

b8d713a

In this commit, the following code was added to lua/CopilotChat/select.lua:

  local bufname = vim.api.nvim_buf_get_name(source.bufnr)
  local file_path = bufname:gsub('^%w+://', '')
  local dir = vim.fn.fnamemodify(file_path, ':h')
  if not dir or dir == '' then
    return nil
  end

In this change, the variable dir points to the .git directory, which causes the git diff output to become large, resulting in the token limit exceeded error.

FYI

As a reference, here are the steps to check the differences using git diff by specifying .git:

$ git clone git@github.com:CopilotC-Nvim/CopilotChat.nvim.git && cd CopilotChat.nvim
$ touch sample.txt
$ git add .
$ git commit

Once Neovim is launched, execute the following command:

:!git -C .git diff --staged

You should see a result that differs from your expectations.

Temporary Solution

I temporarily solved the problem as follows.
This is a workaround.

You can resolve the issue by reverting to the previous commit, ce68b1f.

$ git switch --detach ce68b1f5f3fe1aa7e27eccf19366f2a8ba94faac

Alternatively, you can edit lua/CopilotChat/select.lua and remove /.git from dir to fix the issue:

diff --git a/lua/CopilotChat/select.lua b/lua/CopilotChat/select.lua
index 5ba7a08..d089dca 100644
--- a/lua/CopilotChat/select.lua
+++ b/lua/CopilotChat/select.lua
@@ -164,6 +164,9 @@ function M.gitdiff(source, staged)
   local bufname = vim.api.nvim_buf_get_name(source.bufnr)
   local file_path = bufname:gsub('^%w+://', '')
   local dir = vim.fn.fnamemodify(file_path, ':h')
+  if dir:sub(-5) == '/.git' then
+    dir = dir:sub(1, -6)
+  end
   if not dir or dir == '' then
     return nil
   end

[deathbeam]

Thats very odd git behaviour, i guess while git commit message is open it creates bunch of temporary files in .git directory. Created PR with fix that should resolve this, thanks for debugging it @masakiq

[masakiq]

@deathbeam cc @bashtoni
I agree with the "odd git behaviour".
Thank you for creating the pull request for the fix!
I'm glad I could help.