its now using enum fully for the highlight mode

client/src/state/app/highlight.rs

@@ -0,0 +1,20 @@
+// src/state/app/highlight.rs
+
+/// Represents the different states of text highlighting.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum HighlightState {
+    /// Highlighting is inactive.
+    Off,
+    /// Highlighting character by character. Stores the anchor point (line index, char index).
+    Characterwise { anchor: (usize, usize) },
+    /// Highlighting line by line. Stores the anchor line index.
+    Linewise { anchor_line: usize },
+}
+
+impl Default for HighlightState {
+    /// The default state is no highlighting.
+    fn default() -> Self {
+        HighlightState::Off
+    }
+}
+