Fix line-based editing behavior for cut and duplicate commands

- Cut to temp buffer:
  - Respect selections by expanding to full line boundaries
  - Normalize end iterator to include full line + newline
  - Ensure consistent newline handling for last line
  - Preserve cursor position after delete
  - Prevent line merging when accumulating cut buffer

- Duplicate line:
  - Simplify logic using line-based iter APIs
  - Fix incorrect selection handling and off-by-one issues
  - Ensure full-line duplication for both selection and cursor cases
  - Correct cursor/selection restoration after duplication

plugins/code/commands/nanoesq_temp_buffer/cut_to_temp_buffer.py

@@ -14,16 +14,24 @@ from .helpers import clear_temp_cut_buffer_delayed, set_temp_cut_buffer_delayed
 
 class Handler:
     @staticmethod
-    def execute(
+    def execute(view: GtkSource.View, *args, **kwargs):
-        view: GtkSource.View,
-        *args,
-        **kwargs
-    ):
         logger.debug("Command: Cut to Temp Buffer")
 
         clear_temp_cut_buffer_delayed(view)
 
         buffer = view.get_buffer()
+
+        if buffer.get_has_selection():
+            start_itr, end_itr = buffer.get_selection_bounds()
+
+            start_itr.set_line_offset(0)
+
+            if not end_itr.ends_line():
+                end_itr.forward_to_line_end()
+
+            if not end_itr.is_end():
+                end_itr.forward_char()
+        else:
             itr = buffer.get_iter_at_mark(buffer.get_insert())
 
             start_itr = itr.copy()
@@ -36,9 +44,14 @@ class Handler:
         if not hasattr(view, "_cut_buffer"):
             view._cut_buffer = ""
 
-        line_str = buffer.get_text(start_itr, end_itr, True)
+        text = buffer.get_text(start_itr, end_itr, True)
-        view._cut_buffer += line_str
+
+        if not text.endswith("\n"):
+            text += "\n"
+
+        view._cut_buffer += text
 
         buffer.delete(start_itr, end_itr)
+        buffer.place_cursor(start_itr)
 
         set_temp_cut_buffer_delayed(view)

src/core/widgets/code/command_system/commands/duplicate_line.py

@@ -11,45 +11,45 @@ from gi.repository import GtkSource
 
 
 
-def execute(
+def execute(view: GtkSource.View, *args, **kwargs):
-    view: GtkSource.View,
-    *args,
-    **kwargs
-):
     logger.debug("Command: Duplicate Line")
 
     buffer = view.get_buffer()
 
-    if not buffer.get_has_selection():
+    if buffer.get_has_selection():
-        had_selection = False
+        start_itr, \
+        end_itr    = buffer.get_selection_bounds()
+        start_line = start_itr.get_line()
+        end_line   = end_itr.get_line()
+        scol       = start_itr.get_line_offset()
+        ecol       = end_itr.get_line_offset()
+    else:
         itr        = buffer.get_iter_at_mark(buffer.get_insert())
-        start_itr  = itr.copy()
+        start_line = end_line = itr.get_line()
-        end_itr    = itr.copy()
+        col        = itr.get_line_offset()
-        start_line = itr.get_line() + 1
-        start_char = itr.get_line_offset()
-    else:
-        had_selection = True
-        start_itr, end_itr = buffer.get_selection_bounds()
-        sline      = start_itr.get_line()
-        eline      = end_itr.get_line()
-        start_line = eline + 1
-        start_char = start_itr.get_line_offset()
-        end_char   = end_itr.get_line_offset()
-        range_line_size  = eline - sline
 
-    start_itr.backward_visible_line()
+    start_itr = buffer.get_iter_at_line(start_line)
-    start_itr.forward_line()
+    end_itr   = buffer.get_iter_at_line(end_line)
-    end_itr.forward_line()
-    end_itr.backward_char()
 
-    line_str = buffer.get_slice(start_itr, end_itr, True)
+    if not end_itr.ends_line():
+        end_itr.forward_to_line_end()
+
+    if not end_itr.is_end():
         end_itr.forward_char()
-    buffer.insert(end_itr, f"{line_str}\n", -1)
 
-    if not had_selection:
+    text       = buffer.get_text(start_itr, end_itr, True)
-        new_itr = buffer.get_iter_at_line_offset(start_line, start_char)
+    insert_itr = buffer.get_iter_at_line(end_line)
-        buffer.place_cursor(new_itr)
+
+    insert_itr.forward_to_line_end()
+    if not insert_itr.is_end():
+        insert_itr.forward_char()
+
+    buffer.insert(insert_itr, text)
+
+    if buffer.get_has_selection():
+        new_start = buffer.get_iter_at_line_offset(end_line + 1, scol)
+        new_end   = buffer.get_iter_at_line_offset(end_line + 1 + (end_line - start_line), ecol)
+        buffer.select_range(new_start, new_end)
     else:
-        new_itr     = buffer.get_iter_at_line_offset(start_line, start_char)
+        new_start = buffer.get_iter_at_line_offset(end_line + 1, col)
-        new_end_itr = buffer.get_iter_at_line_offset((start_line + range_line_size), end_char)
+        buffer.place_cursor(new_start)
-        buffer.select_range(new_itr, new_end_itr)

src/core/widgets/code/source_file.py

@@ -61,7 +61,20 @@ class SourceFile(GtkSource.File):
         location: Gtk.TextIter,
         text: str, length: int
     ):
-        ...
+        event = Event_Factory.create_event(
+            "text_insert",
+            file     = self,
+            buffer   = self.buffer,
+            location = location,
+            text     = text,
+            length   = length
+        )
+
+        # Note: 'idle_add' needed b/c markers don't get thir positions
+        #      updated relative to the initial insert.
+        #      If not used, seg faults galor during multi insert.
+        # GLib.idle_add(self.emit, event)
+        self.emit(event)
 
     def _after_insert_text(
         self,