tlc: fix F5/F6/F8 to MC parity — no-op on no selection

Reverts F5/F6/F8 from operating on current line (TLC extension) to MC behavior: do nothing when no selection is active. MC's eval_marks returns false when mark1==mark2, so F5/F6/F8 in MC are no-ops without a selection.

Removes the now-dead copy_line/cut_line/delete_line_no_sel helpers and their tests. Replaces with MC-parity no-op tests.

Extracts current_line_range() helper from select_current_line and duplicate_line_or_selection (also covers unindent_selection pattern). Removes ~50 lines of duplicated line-range computation.

local/recipes/tui/tlc/source/src/editor/handlers.rs

@@ -396,44 +396,34 @@ impl Editor {
             }
             return EditorResult::Running;
         }
-        // F5 — Copy block (or current line if no selection).
+        // F5 — Copy block. MC parity: no-op when no selection.
         if key == Key::f(5) {
-            if self.cursor.has_selection() {
-                if let Some(text) = self.cursor.selected_text(&self.buffer) {
-                    self.clipboard = Some(text.to_string());
-                    let _ = crate::editor::clipboard_osc52::osc52_copy(&text);
-                    self.message = Some("Block copied".to_string());
-                }
-            } else {
-                let _ = self.copy_line();
+            if let Some(text) = self.cursor.selected_text(&self.buffer) {
+                self.clipboard = Some(text.to_string());
+                let _ = crate::editor::clipboard_osc52::osc52_copy(&text);
+                self.message = Some("Block copied".to_string());
             }
             return EditorResult::Running;
         }
-        // F6 — Move (cut) block (or current line if no selection).
+        // F6 — Move (cut) block. MC parity: no-op when no selection.
         if key == Key::f(6) {
-            if self.cursor.has_selection() {
-                if let Some(text) = self.cursor.selected_text(&self.buffer) {
-                    self.clipboard = Some(text.to_string());
-                    let _ = crate::editor::clipboard_osc52::osc52_copy(&text);
-                    self.cursor.delete_selection(&mut self.buffer);
-                    self.cursor.set_position(self.buffer.cursor(), &self.buffer);
-                    self.modified = true;
-                    self.message = Some("Block moved".to_string());
-                }
-            } else {
-                let _ = self.cut_line();
+            if let Some(text) = self.cursor.selected_text(&self.buffer) {
+                self.clipboard = Some(text.to_string());
+                let _ = crate::editor::clipboard_osc52::osc52_copy(&text);
+                self.cursor.delete_selection(&mut self.buffer);
+                self.cursor.set_position(self.buffer.cursor(), &self.buffer);
+                self.modified = true;
+                self.message = Some("Block moved".to_string());
             }
             return EditorResult::Running;
         }
-        // F8 — Delete block (or current line if no selection).
+        // F8 — Delete block. MC parity: no-op when no selection.
         if key == Key::f(8) {
             if self.cursor.has_selection() {
                 self.cursor.delete_selection(&mut self.buffer);
                 self.cursor.set_position(self.buffer.cursor(), &self.buffer);
                 self.modified = true;
                 self.message = Some("Block deleted".to_string());
-            } else {
-                let _ = self.delete_line_no_sel();
             }
             return EditorResult::Running;
         }

local/recipes/tui/tlc/source/src/editor/mod.rs

@@ -737,105 +737,38 @@ bracket_flash: None,
     /// any). Cursor moves to the start of the next line; anchor is
     /// left at the start of the current line.
     pub fn select_current_line(&mut self) {
-        let total = self.buffer.as_string().len();
-        let bytes = self.buffer.as_string().into_bytes();
-        let mut line_start = self.buffer.cursor();
-        while line_start > 0 && bytes[line_start - 1] != b'\n' {
-            line_start -= 1;
-        }
-        let mut line_end = self.buffer.cursor();
-        while line_end < total && bytes[line_end] != b'\n' {
-            line_end += 1;
-        }
-        if line_end < total {
-            line_end += 1;
-        }
+        let (line_start, line_end) = self.current_line_range();
         self.buffer.set_cursor(line_start);
         self.cursor.set_position(line_start, &self.buffer);
         self.cursor.start_selection();
         self.cursor.set_position(line_end, &self.buffer);
     }
 
-    /// Copy the current line (with newline) to the clipboard when no
-    /// selection is active. Returns true if a line was copied.
-    pub fn copy_line(&mut self) -> bool {
-        if self.cursor.has_selection() {
-            return false;
-        }
+    /// Compute the byte range of the current line, starting at the
+    /// beginning of the line and ending just past the trailing
+    /// newline (or at end of buffer if the last line has no newline).
+    fn current_line_range(&self) -> (usize, usize) {
         let total = self.buffer.as_string().len();
         let bytes = self.buffer.as_string().into_bytes();
-        let mut line_start = self.buffer.cursor();
+        let cursor = self.buffer.cursor();
+        let mut line_start = cursor;
         while line_start > 0 && bytes[line_start - 1] != b'\n' {
             line_start -= 1;
         }
-        let mut line_end = self.buffer.cursor();
+        let mut line_end = cursor;
         while line_end < total && bytes[line_end] != b'\n' {
             line_end += 1;
         }
         if line_end < total {
             line_end += 1;
         }
-        let text = String::from_utf8_lossy(&bytes[line_start..line_end]).into_owned();
-        self.clipboard = Some(text.clone());
-        let _ = crate::editor::clipboard_osc52::osc52_copy(&text);
-        self.message = Some("Line copied".to_string());
-        true
-    }
-
-    /// Cut the current line (with newline) to the clipboard when no
-    /// selection is active. Returns true if a line was cut.
-    pub fn cut_line(&mut self) -> bool {
-        if self.cursor.has_selection() {
-            return false;
-        }
-        let total = self.buffer.as_string().len();
-        let bytes = self.buffer.as_string().into_bytes();
-        let mut line_start = self.buffer.cursor();
-        while line_start > 0 && bytes[line_start - 1] != b'\n' {
-            line_start -= 1;
-        }
-        let mut line_end = self.buffer.cursor();
-        while line_end < total && bytes[line_end] != b'\n' {
-            line_end += 1;
-        }
-        if line_end < total {
-            line_end += 1;
-        }
-        let text = String::from_utf8_lossy(&bytes[line_start..line_end]).into_owned();
-        self.clipboard = Some(text.clone());
-        let _ = crate::editor::clipboard_osc52::osc52_copy(&text);
-        self.buffer.begin_undo_group();
-        self.buffer.set_cursor(line_start);
-        for _ in line_start..line_end {
-            self.buffer.delete_forward();
-        }
-        self.cursor.set_position(self.buffer.cursor(), &self.buffer);
-        self.cursor.clear_selection();
-        self.buffer.end_undo_group();
-        self.modified = true;
-        self.message = Some("Line cut".to_string());
-        true
-    }
-
-    /// Delete the current line (with newline) when no selection is
-    /// active. Returns true if a line was deleted.
-    pub fn delete_line_no_sel(&mut self) -> bool {
-        if self.cursor.has_selection() {
-            return false;
-        }
-        self.buffer.delete_line();
-        self.cursor.set_position(self.buffer.cursor(), &self.buffer);
-        self.cursor.clear_selection();
-        self.modified = true;
-        self.message = Some("Line deleted".to_string());
-        true
+        (line_start, line_end)
     }
 
     /// Duplicate the current line (with newline) when no selection
     /// is active, or duplicate the selected block otherwise.
     /// Returns true if anything was duplicated.
     pub fn duplicate_line_or_selection(&mut self) -> bool {
-        let total = self.buffer.as_string().len();
         let bytes = self.buffer.as_string().into_bytes();
         if let Some((s, e)) = self.cursor.selection() {
             let text = String::from_utf8_lossy(&bytes[s..e]).into_owned();
@@ -849,17 +782,7 @@ bracket_flash: None,
             self.message = Some("Duplicated".to_string());
             return true;
         }
-        let mut line_start = self.buffer.cursor();
-        while line_start > 0 && bytes[line_start - 1] != b'\n' {
-            line_start -= 1;
-        }
-        let mut line_end = self.buffer.cursor();
-        while line_end < total && bytes[line_end] != b'\n' {
-            line_end += 1;
-        }
-        if line_end < total {
-            line_end += 1;
-        }
+        let (line_start, line_end) = self.current_line_range();
         let text = String::from_utf8_lossy(&bytes[line_start..line_end]).into_owned();
         self.buffer.begin_undo_group();
         self.buffer.set_cursor(line_end);
@@ -2362,37 +2285,41 @@ mod tests {
     }
 
     #[test]
-    fn f5_without_selection_copies_line() {
+    fn f5_without_selection_is_noop_mc_parity() {
         let mut e = make_empty();
         e.insert_str("first\nsecond\nthird\n");
         e.buffer.set_cursor(8);
         e.cursor.set_position(8, &e.buffer);
         e.handle_key(Key::f(5));
-        assert_eq!(e.clipboard.as_deref(), Some("second\n"));
+        assert_eq!(e.clipboard, None);
         assert_eq!(e.buffer().as_string(), "first\nsecond\nthird\n");
     }
 
     #[test]
-    fn f6_without_selection_cuts_line() {
+    fn f6_without_selection_is_noop_mc_parity() {
         let mut e = make_empty();
         e.insert_str("first\nsecond\nthird\n");
+        e.buffer.mark_saved();
+        e.modified = false;
         e.buffer.set_cursor(8);
         e.cursor.set_position(8, &e.buffer);
         e.handle_key(Key::f(6));
-        assert_eq!(e.clipboard.as_deref(), Some("second\n"));
-        assert_eq!(e.buffer().as_string(), "first\nthird\n");
-        assert!(e.is_modified());
+        assert_eq!(e.clipboard, None);
+        assert_eq!(e.buffer().as_string(), "first\nsecond\nthird\n");
+        assert!(!e.is_modified());
     }
 
     #[test]
-    fn f8_without_selection_deletes_line() {
+    fn f8_without_selection_is_noop_mc_parity() {
         let mut e = make_empty();
         e.insert_str("first\nsecond\nthird\n");
+        e.buffer.mark_saved();
+        e.modified = false;
         e.buffer.set_cursor(8);
         e.cursor.set_position(8, &e.buffer);
         e.handle_key(Key::f(8));
-        assert_eq!(e.buffer().as_string(), "first\nthird\n");
-        assert!(e.is_modified());
+        assert_eq!(e.buffer().as_string(), "first\nsecond\nthird\n");
+        assert!(!e.is_modified());
     }
 
     #[test]