bug: Can't restore buffer order with pre_save hook

[eljamm]

Did you check the docs and existing issues?

• [X] I have read the docs
• [X] I have searched the existing issues

Neovim version (nvim -v)

NVIM v0.10.0

Operating system/version

NixOS 24.11.20240704.a6f2adf (Vicuna) x86_64

Describe the bug

I'm using barbar as a buffer tabline and I want to preserve the buffer order when reloading the session. According to the plugin's documentation:

barbar.nvim can restore the order that your buffers were in, as well as whether a buffer was pinned. To do this, sessionoptions must contain globals, and the User SessionSavePre event must be executed before :mksession.

Now, following resession's documentation, I did this using the pre_save hook like so:

  {
    'stevearc/resession.nvim',
    config = true,
    init = function()
      vim.opt.sessionoptions:append 'globals'
      require('resession').add_hook('pre_save', function()
        vim.api.nvim_exec_autocmds('User', { pattern = 'SessionSavePre' })
      end)
    end,
  },

I've set up resession to auto load the session on login by following the Create one session per directory guide, but when the session auto-loads, the buffer order is reset to before I re-ordered them.

I also tried to use ResessionSavePre autocmd, but it's the same case:

vim.opt.sessionoptions:append 'globals'
vim.api.nvim_create_autocmd({ 'User' }, {
  pattern = 'ResessionSavePre',
  callback = function()
    vim.api.nvim_exec_autocmds('User', { pattern = 'SessionSavePre' })
  end,
})

I really want to switch to resession since it's light and fast, but I also want to be able to re-order my buffers.

What is the severity of this bug?

minor (annoyance)

Steps To Reproduce

1. nvim -u repro.lua
2. Open at least two buffers: :e file1.txt, :e file2.txt, ...
3. Switch their order using Alt-Shift-J or Alt-Shift-K
4. Quit neovim
5. nvim -u repro.lua

Expected Behavior

After reordering the buffers, the next time the session auto loads the buffers are loaded in their new positions.

Directory structure

./file1.txt ./file2.txt ./repro.lua

Repro

local root = vim.fn.fnamemodify('./.repro', ':p')

for _, name in ipairs { 'config', 'data', 'state', 'runtime', 'cache' } do
  vim.env[('XDG_%s_HOME'):format(name:upper())] = root .. '/' .. name
end

-- bootstrap lazy
local lazypath = root .. '/plugins/lazy.nvim'
if not vim.loop.fs_stat(lazypath) then
  vim.fn.system {
    'git',
    'clone',
    '--filter=blob:none',
    '--single-branch',
    'https://github.com/folke/lazy.nvim.git',
    lazypath,
  }
end
vim.opt.runtimepath:prepend(lazypath)

-- install plugins
local plugins = {
  'folke/tokyonight.nvim',
  {
    'stevearc/resession.nvim',
    config = true,
    init = function()
      vim.opt.sessionoptions:append 'globals'
      require('resession').add_hook('pre_save', function()
        vim.api.nvim_exec_autocmds('User', { pattern = 'SessionSavePre' })
      end)
    end,
  },
  -- extra plugins
  {
    'romgrk/barbar.nvim',
    config = true,
    event = 'BufEnter',
    dependencies = {
      -- optional
      'lewis6991/gitsigns.nvim', -- git status
      'nvim-tree/nvim-web-devicons', -- file icons
    },
    init = function()
      vim.g.barbar_auto_setup = false

      local map = vim.api.nvim_set_keymap
      local opts = function(desc)
        return { desc = desc, noremap = true, silent = true }
      end

      -- Move to previous/next
      map('n', '<A-j>', '<Cmd>BufferPrevious<CR>', opts 'Go to Previous Buffer')
      map('n', '<A-k>', '<Cmd>BufferNext<CR>', opts 'Go to Next Buffer')

      -- Re-order to previous/next
      map('n', '<A-S-j>', '<Cmd>BufferMovePrevious<CR>', opts 'Move Buffer Left')
      map('n', '<A-S-k>', '<Cmd>BufferMoveNext<CR>', opts 'Move Buffer Right')
    end,
    version = '^1.0.0', -- optional: only update when a new 1.x version is released
  },
}
require('lazy').setup(plugins, {
  root = root .. '/plugins',
})

vim.cmd.colorscheme 'tokyonight'

-- Create one session per directory
vim.api.nvim_create_autocmd('VimEnter', {
  callback = function()
    -- Only load the session if nvim was started with no args
    if vim.fn.argc(-1) == 0 then
      -- Save these to a different directory, so our manual sessions don't get polluted
      require('resession').load(vim.fn.getcwd(), { dir = 'dirsession', silence_errors = true })
    end
  end,
  nested = true,
})
vim.api.nvim_create_autocmd('VimLeavePre', {
  callback = function()
    require('resession').save(vim.fn.getcwd(), { dir = 'dirsession', notify = false })
  end,
})

Did you check the bug with a clean config?

• [X] I have confirmed that the bug reproduces with nvim -u repro.lua using the repro.lua file above.