fix order of operations

nvim/lua/config/lsp.lua

@@ -82,9 +82,20 @@ vim.api.nvim_create_autocmd("BufWritePre", {
     local cpp_exts = { cpp = true, cxx = true, hpp = true, ixx = true }
 
     if cpp_exts[ext] then
-      local filepath = vim.fn.expand("%:p")
+      local lines = vim.api.nvim_buf_get_lines(0, 0, -1, false)
-      vim.fn.system({ "clang-format", "-i", filepath })
+      local input = table.concat(lines, "\n")
-      vim.cmd("edit!")  -- reload the buffer after in-place formatting
+
+      -- pass buffer content via stdin, get formatted output back
+      local result = vim.fn.systemlist(
+        { "clang-format", "--assume-filename=" .. vim.fn.expand("%:t") },
+        input
+      )
+
+      if vim.v.shell_error == 0 then
+        vim.api.nvim_buf_set_lines(0, 0, -1, false, result)
+      else
+        vim.notify("clang-format failed: " .. table.concat(result, "\n"), vim.log.levels.WARN)
+      end
       return
     end