fix(tui): preserve insert and visual unicode edits

Keep an opened trailing line navigable while insert mode is active so `o` at EOF keeps the cursor on the new line.

Convert visual selections from grapheme positions to Rope character positions before deleting text.

Author: fcoury

src/editor.rs

@@ -1142,7 +1142,11 @@ impl Editor {
 
     fn check_bounds(&mut self) -> bool {
         let old_position = (self.cx, self.cy, self.vtop);
-        let last_line = self.last_navigable_line();
+        let last_line = if self.is_insert() {
+            self.current_buffer().len()
+        } else {
+            self.last_navigable_line()
+        };
         let viewport_height = self.vheight().max(1);
         let max_vtop = last_line.saturating_sub(viewport_height.saturating_sub(1));
 
@@ -3751,14 +3755,18 @@ impl Editor {
 
                         for y in y0..=y1 {
                             if let Some(line) = self.current_buffer().get(y) {
-                                let line_len = line.trim_end_matches('\n').chars().count();
+                                let line = line.trim_end_matches('\n');
+                                let line_len = grapheme_len(line);
                                 if min_x >= line_len {
                                     continue;
                                 }
+                                let start = self.grapheme_to_char_on_line(min_x, y);
+                                let end =
+                                    self.grapheme_to_char_on_line((max_x + 1).min(line_len), y);
                                 self.replace_range(
                                     TextRange::new(
-                                        TextPosition::new(y, min_x),
-                                        TextPosition::new(y, (max_x + 1).min(line_len)),
+                                        TextPosition::new(y, start),
+                                        TextPosition::new(y, end),
                                     ),
                                     "",
                                 );
@@ -3767,18 +3775,22 @@ impl Editor {
                     }
                     Mode::Visual => {
                         if y0 == y1 {
+                            let start = self.grapheme_to_char_on_line(x0, y0);
+                            let end = self.grapheme_to_char_on_line(x1 + 1, y0);
                             self.replace_range(
                                 TextRange::new(
-                                    TextPosition::new(y0, x0),
-                                    TextPosition::new(y0, x1 + 1),
+                                    TextPosition::new(y0, start),
+                                    TextPosition::new(y0, end),
                                 ),
                                 "",
                             );
                         } else {
+                            let start = self.grapheme_to_char_on_line(x0, y0);
+                            let end = self.grapheme_to_char_on_line(x1 + 1, y1);
                             self.replace_range(
                                 TextRange::new(
-                                    TextPosition::new(y0, x0),
-                                    TextPosition::new(y1, x1 + 1),
+                                    TextPosition::new(y0, start),
+                                    TextPosition::new(y1, end),
                                 ),
                                 "",
                             );

src/editor/rendering.rs

@@ -109,7 +109,7 @@ impl Editor {
             );
 
             // Render the gutter for this window
-            self.render_gutter_in_window(buffer, &window)?;
+            self.render_gutter_in_window(buffer, &window, window_id)?;
 
             // Render the window content with proper boundaries
             self.render_main_content_in_window(buffer, &window)?;
@@ -1157,6 +1157,7 @@ impl Editor {
         &mut self,
         buffer: &mut RenderBuffer,
         window: &crate::window::Window,
+        window_id: usize,
     ) -> anyhow::Result<()> {
         use crate::log;
         let width = self.gutter_width_for_window(window);
@@ -1175,7 +1176,10 @@ impl Editor {
 
         for y in 0..window.inner_height() {
             let line_number = y + 1 + window.vtop;
-            let line_count = window_buffer.navigable_line_count();
+            let mut line_count = window_buffer.navigable_line_count();
+            if self.window_manager.active_window_id() == window_id && self.is_insert() {
+                line_count = line_count.max(window.vtop + window.cy + 1);
+            }
             let text = if line_number <= line_count {
                 format!("{:>width$} ", line_number)
             } else {

tests/common/editor_harness.rs

@@ -435,6 +435,22 @@ mod tests {
         assert_eq!(third_row.chars().take(3).collect::<String>(), "   ");
     }
 
+    #[tokio::test]
+    async fn test_insert_mode_gutter_keeps_opened_trailing_line_visible() {
+        let mut harness = EditorHarness::with_content("Line 1");
+
+        harness
+            .execute_action(Action::InsertLineBelowCursor)
+            .await
+            .unwrap();
+
+        harness.assert_mode(Mode::Insert);
+        harness.assert_cursor_at(0, 1);
+
+        let second_row = harness.render_row(1).unwrap();
+        assert_eq!(second_row.chars().take(3).collect::<String>(), " 2 ");
+    }
+
     #[test]
     fn test_search_commandline_renders_search_text_on_small_width() {
         let mut harness = EditorHarness::new();

tests/unicode.rs

@@ -162,6 +162,31 @@ async fn test_family_emoji_zwj_sequence() {
     assert_eq!(line, "\n", "Entire emoji sequence should be deleted");
 }
 
+#[tokio::test]
+async fn test_visual_delete_removes_entire_zwj_grapheme() {
+    let mut h = EditorHarness::with_content("👨‍👩‍👧‍👦 family");
+
+    h.execute_action(Action::EnterMode(Mode::Visual))
+        .await
+        .unwrap();
+    h.execute_action(Action::Delete).await.unwrap();
+
+    h.assert_buffer_contents(" family");
+}
+
+#[tokio::test]
+async fn test_visual_block_delete_removes_entire_combining_grapheme() {
+    let mut h = EditorHarness::with_content("e\u{301}x\ne\u{301}y");
+
+    h.execute_action(Action::EnterMode(Mode::VisualBlock))
+        .await
+        .unwrap();
+    h.execute_action(Action::MoveDown).await.unwrap();
+    h.execute_action(Action::Delete).await.unwrap();
+
+    h.assert_buffer_contents("x\ny");
+}
+
 #[tokio::test]
 async fn test_flag_emoji() {
     let mut h = EditorHarness::new();