fix: ensure try_add() runs after filetype detection

Sometimes, BufNewFile triggers before 'filetype' is set. Using
vim.schedule() should ensure filetype detection runs before the
callback.

lua/lspconfig/configs.lua

@@ -101,7 +101,11 @@ function configs.__newindex(t, config_name, config_def)
       api.nvim_create_autocmd(event_conf.event, {
         pattern = event_conf.pattern or '*',
         callback = function(opt)
-          M.manager:try_add(opt.buf)
+          -- Use vim.schedule() to ensure filetype detection happens first.
+          -- Sometimes, BufNewFile triggers before 'filetype' is set.
+          vim.schedule(function()
+            M.manager:try_add(opt.buf)
+          end)
         end,
         group = lsp_group,
         desc = string.format(
@@ -139,7 +143,11 @@ function configs.__newindex(t, config_name, config_def)
           api.nvim_create_autocmd({ 'BufReadPost', 'BufNewFile' }, {
             pattern = fn.fnameescape(root_dir) .. '/*',
             callback = function(arg)
-              M.manager:try_add_wrapper(arg.buf, root_dir)
+              -- Use vim.schedule() to ensure filetype detection happens first.
+              -- Sometimes, BufNewFile triggers before 'filetype' is set.
+              vim.schedule(function()
+                M.manager:try_add_wrapper(arg.buf, root_dir)
+              end)
             end,
             group = lsp_group,
             desc = string.format(