Support empty file-backed buffers.

Buffer.cpp

@@ -2,6 +2,7 @@
 
 #include <fstream>
 #include <sstream>
+#include <filesystem>
 
 
 Buffer::Buffer() = default;
@@ -17,11 +18,29 @@ Buffer::Buffer(const std::string &path)
 bool
 Buffer::OpenFromFile(const std::string &path, std::string &err)
 {
-	std::ifstream in(path, std::ios::in | std::ios::binary);
-	if (!in) {
-		err = "Failed to open file: " + path;
-		return false;
-	}
+    // If the file doesn't exist, initialize an empty, non-file-backed buffer
+    // with the provided filename. Do not touch the filesystem until Save/SaveAs.
+    if (!std::filesystem::exists(path)) {
+        rows_.clear();
+        nrows_          = 0;
+        filename_       = path;
+        is_file_backed_ = false;
+        dirty_          = false;
+
+        // Reset cursor/viewport state
+        curx_      = cury_    = rx_ = 0;
+        rowoffs_   = coloffs_ = 0;
+        mark_set_  = false;
+        mark_curx_ = mark_cury_ = 0;
+
+        return true;
+    }
+
+    std::ifstream in(path, std::ios::in | std::ios::binary);
+    if (!in) {
+        err = "Failed to open file: " + path;
+        return false;
+    }
 
 	rows_.clear();
 	std::string line;