nvim_buf_set_text resets changelist to 0

[xiyaowong]

Problem

Video:

changelist.mp4

Steps to reproduce

test.lua

local api = vim.api

vim.opt.showmode = false

local c = 'a'
local function append_first_line()
  local col = #api.nvim_buf_get_lines(0, 0, 1, true)[1]
  api.nvim_buf_set_text(0, 0, col, 0, col, { c })
  c = c == 'a' and 'b' or 'a'
end

local timer = vim.loop.new_timer()
timer:start(
  500,
  500,
  vim.schedule_wrap(function()
    if api.nvim_get_mode().mode ~= 'i' then
      append_first_line()
    end
  end)
)

vim.cmd "au TextChanged,TextChangedI * echo getchangelist()"

1. nvim --clean -u ./test.lua
2. See the output changelist

Expected behavior

nvim_buf_set_text should not reset changelist to 0

Neovim version (nvim -v)

NVIM v0.9.5

Vim (not Nvim) behaves the same?

not sure

Operating system/version

Windows 11

Terminal name/version

Windows Terminal

$TERM environment variable

Installation

scoop

[justinmk]

Can you try the development version? The Releases page has pre-built archives for Linux/Windows/macOS.

I see a bunch of changes in the changelist, in 0.10 Confirmed with nvim --clean test.lua (sourcing the script with :%lua has different behavior)

[xiyaowong]

Tested the nightly version, the problem still exists

NVIM v0.10.0-dev-3070+gcf9f002f3
Build type: RelWithDebInfo
LuaJIT 2.1.1713484068