Keep PreparedTextArea's wrapped document when width and tab size match

src/textual/widgets/_prepared_text_area.py

@@ -76,6 +76,17 @@ async def _prepare_wrapping(self) -> None:
         while self.is_attached and not self._pruning:
             document = self.document
             width, tabs = self.wrap_width, self.indent_width
+            wrapped = self.wrapped_document
+            if (wrapped.document is document and
+                    (wrapped._width, wrapped._tab_width) == (width, tabs)):
+                # Native edits update this same view incrementally. A resize
+                # with unchanged wrapping inputs needs scrollbar/size refresh,
+                # not another detached document and navigator.
+                self._refresh_size()
+                if (width, tabs) == (self.wrap_width, self.indent_width):
+                    return
+                # Scrollbar publication can itself change the wrapping width.
+                continue
             prepared = await self._prepare_document(document, width, tabs)
             if not self.is_attached or self._pruning:
                 return
@@ -97,4 +108,5 @@ async def _prepare_wrapping(self) -> None:
             offset = prepared.location_to_offset(reader)
             self.scroll_to(x=offset.x, y=offset.y, animate=False, immediate=True)
             self.record_cursor_width()
-            return
+            # Admit the resulting scrollbar geometry through the same matching
+            # resource decision before declaring this worker complete.

tests/text_area/test_prepared_document.py

@@ -32,10 +32,25 @@ async def test_prepared_load_keeps_selection_and_source_reader_on_resize():
         wrapped = area.wrapped_document
         await area.load_text_prepared(text).wait()
         assert area.document is document and area.wrapped_document is wrapped
+        navigator = area.navigator
+        for _ in range(3):
+            area._rewrap_and_refresh_virtual_size()
+            await settle(area, pilot)
+            assert area.wrapped_document is wrapped
+            assert area.navigator is navigator
+        assert (wrapped._width, wrapped._tab_width) == (area.wrap_width, area.indent_width)
         await pilot.resize_terminal(44, 18)
         await settle(area, pilot)
         assert area.document is document and area.selected_text == selected
         assert area.wrapped_document.offset_to_location(area.scroll_offset)[0] == reader[0]
+        resized = area.wrapped_document
+        assert resized is not wrapped
+        assert (resized._width, resized._tab_width) == (area.wrap_width, area.indent_width)
+        area.indent_width = 8
+        await settle(area, pilot)
+        assert area.wrapped_document is not resized
+        assert area.wrapped_document.document is document
+        assert (area.wrapped_document._width, area.wrapped_document._tab_width) == (area.wrap_width, 8)
 
 
 async def test_new_prepared_source_replaces_only_its_original_native_load():