bug: notifier causes cursor flickering (especially with lsp progress - with possible solution)

[synic]

Did you check docs and existing issues?

• I have read all the snacks.nvim docs
• I have updated the plugin to the latest version before submitting this issue
• I have searched the existing issues of snacks.nvim
• I have searched the existing issues of plugins related to this issue

Neovim version (nvim -v)

v0.10.3

Operating system/version

MacOS 15.2

Describe the bug

Quick updates to notification windows causes the cursor to flicker (for instance, using the LSP progress update code, when updates are frequent, the cursor flickers quite noticeably)

Steps To Reproduce

Enable snacks notifier, use the LSP progress code, like below. Open a file where there are a lot of LSP progress updates, and you will see cursor flickering.

---@type table<number, {token:lsp.ProgressToken, msg:string, done:boolean}[]>
local progress = vim.defaulttable()
vim.api.nvim_create_autocmd("LspProgress", {
  ---@param ev {data: {client_id: integer, params: lsp.ProgressParams}}
  callback = function(ev)
    local client = vim.lsp.get_client_by_id(ev.data.client_id)
    local value = ev.data.params.value --[[@as {percentage?: number, title?: string, message?: string, kind: "begin" | "report" | "end"}]]
    if not client or type(value) ~= "table" then
      return
    end
    local p = progress[client.id]

    for i = 1, #p + 1 do
      if i == #p + 1 or p[i].token == ev.data.params.token then
        p[i] = {
          token = ev.data.params.token,
          msg = ("[%3d%%] %s%s"):format(
            value.kind == "end" and 100 or value.percentage or 100,
            value.title or "",
            value.message and (" **%s**"):format(value.message) or ""
          ),
          done = value.kind == "end",
        }
        break
      end
    end

    local msg = {} ---@type string[]
    progress[client.id] = vim.tbl_filter(function(v)
      return table.insert(msg, v.msg) or not v.done
    end, p)

    local spinner = { "⠋", "⠙", "⠹", "⠸", "⠼", "⠴", "⠦", "⠧", "⠇", "⠏" }
    vim.notify(table.concat(msg, "\n"), "info", {
      id = "lsp_progress",
      title = client.name,
      opts = function(notif)
        notif.icon = #progress[client.id] == 0 and " "
          or spinner[math.floor(vim.uv.hrtime() / (1e6 * 80)) % #spinner + 1]
      end,
    })
  end,
})

Expected Behavior

It should not flicker. The following hack fixes it, the key here being cursor = false being passed to nvim__redraw. Maybe there should be an option for the snacks.win to disable cursor redrawing?

---@type table<number, {token:lsp.ProgressToken, msg:string, done:boolean}[]>
local progress = vim.defaulttable()
vim.api.nvim_create_autocmd("LspProgress", {
  ---@param ev {data: {client_id: integer, params: lsp.ProgressParams}}
  callback = function(ev)
    local client = vim.lsp.get_client_by_id(ev.data.client_id)
    local value = ev.data.params.value --[[@as {percentage?: number, title?: string, message?: string, kind: "begin" | "report" | "end"}]]
    if not client or type(value) ~= "table" then
      return
    end
    local p = progress[client.id]

    for i = 1, #p + 1 do
      if i == #p + 1 or p[i].token == ev.data.params.token then
        p[i] = {
          token = ev.data.params.token,
          msg = ("[%3d%%] %s%s"):format(
            value.kind == "end" and 100 or value.percentage or 100,
            value.title or "",
            value.message and (" **%s**"):format(value.message) or ""
          ),
          done = value.kind == "end",
        }
        break
      end
    end

    local msg = {} ---@type string[]
    progress[client.id] = vim.tbl_filter(function(v)
      return table.insert(msg, v.msg) or not v.done
    end, p)

    local spinner = { "⠋", "⠙", "⠹", "⠸", "⠼", "⠴", "⠦", "⠧", "⠇", "⠏" }
    vim.notify(table.concat(msg, "\n"), "info", {
      id = "lsp_progress",
      title = client.name,
      opts = function(notif)
        if notif.win then
          notif.win.redraw = function(self)
            ---@diagnostic disable-next-line: need-check-nil
            vim.api.nvim__redraw({ win = self.win, valid = false, flush = true, cursor = false })
          end
        end

        notif.icon = #progress[client.id] == 0 and " "
          or spinner[math.floor(vim.uv.hrtime() / (1e6 * 80)) % #spinner + 1]
      end,
    })
  end,
})

Repro

vim.env.LAZY_STDPATH = ".repro"
load(vim.fn.system("curl -s https://raw.githubusercontent.com/folke/lazy.nvim/main/bootstrap.lua"))()
---@type table<number, {token:lsp.ProgressToken, msg:string, done:boolean}[]>
local progress = vim.defaulttable()
vim.api.nvim_create_autocmd("LspProgress", {
  ---@param ev {data: {client_id: integer, params: lsp.ProgressParams}}
  callback = function(ev)
    local client = vim.lsp.get_client_by_id(ev.data.client_id)
    local value = ev.data.params.value --[[@as {percentage?: number, title?: string, message?: string, kind: "begin" | "report" | "end"}]]
    if not client or type(value) ~= "table" then
      return
    end
    local p = progress[client.id]

    for i = 1, #p + 1 do
      if i == #p + 1 or p[i].token == ev.data.params.token then
        p[i] = {
          token = ev.data.params.token,
          msg = ("[%3d%%] %s%s"):format(
            value.kind == "end" and 100 or value.percentage or 100,
            value.title or "",
            value.message and (" **%s**"):format(value.message) or ""
          ),
          done = value.kind == "end",
        }
        break
      end
    end

    local msg = {} ---@type string[]
    progress[client.id] = vim.tbl_filter(function(v)
      return table.insert(msg, v.msg) or not v.done
    end, p)

    local spinner = { "⠋", "⠙", "⠹", "⠸", "⠼", "⠴", "⠦", "⠧", "⠇", "⠏" }
    vim.notify(table.concat(msg, "\n"), "info", {
      id = "lsp_progress",
      title = client.name,
      opts = function(notif)
        notif.icon = #progress[client.id] == 0 and " "
          or spinner[math.floor(vim.uv.hrtime() / (1e6 * 80)) % #spinner + 1]
      end,
    })
  end,
})

require("lazy.minit").repro({
  spec = {
    { "folke/snacks.nvim", opts = { notifier = {} } },
    -- add any other plugins here
  },
})

[synic]

I can probably add the fix for it, however, I am unsure of what to call the snacks.win option to disable cursor redrawing. Maybe redraw_opts? with the booleans valid, flush and cursor?

[folke]

This sounds more like a Neovim bug than anything else.
Have you tried on nightly?

[folke]

I just added cursor=false. Not really needed anyway.

[synic]

Unfortunately, I was wrong, this actually did not fix the issue. I tried it on neovim nightly as well, same situation. You can easily reproduce it by getting the lsp progress notification on the screen, and then start a search with /.

Looks like this:

[synic]

Just a note, if you start a search, but don't hit enter, the notification stays on the screenforever, and the flickering will always be there