Add source caret and block indentation keyboard editing

crates/oa-desktop/src/source_navigation/selection.rs

@@ -1,10 +1,12 @@
-//! Effective selected-byte ranges for a committed departure from a source view.
+//! Effective selected-byte ranges for committed source departures and edits.
 //!
 //! Iced's `Cursor` omits cosmic-text's Word/Line selection kind. Saving its raw
 //! endpoints can therefore save an empty range for a visibly selected word/line.
-//! Capture only after navigation admission and destination validation succeed,
-//! immediately before replacing/leaving the live editor. Never use this to inspect
-//! pending queries, failed/no-op navigation, or restore focus to the same editor.
+//! Departure capture requires navigation admission and destination validation,
+//! immediately before replacing/leaving the live editor. Edit capture requires
+//! an admitted edit with a nonempty patch plan. Neither is a passive query:
+//! never use these to inspect pending queries, failed/no-op navigation, or restore
+//! focus to the same editor.
 use iced::advanced::{graphics, text};
 use iced::widget::text_editor::{Action, Content, Cursor, Motion, Position};
 
@@ -21,6 +23,23 @@ use iced::widget::text_editor::{Action, Content, Cursor, Motion, Position};
 /// selection joins editor lines with LF regardless of physical CRLF/LF endings.
 /// Only the selected text is temporarily copied; retained state is one Cursor.
 pub fn capture<R>(content: &mut Content<R>) -> Cursor
+where
+    R: text::Renderer<Editor = graphics::text::Editor>,
+{
+    effective_range(content)
+}
+
+/// Capture immediately before a committed indentation edit. Like departure,
+/// this converts Word/Line selections to their effective directional byte range.
+/// The caller restores the transformed range after editing the same Content.
+pub fn capture_for_edit<R>(content: &mut Content<R>) -> Cursor
+where
+    R: text::Renderer<Editor = graphics::text::Editor>,
+{
+    effective_range(content)
+}
+
+fn effective_range<R>(content: &mut Content<R>) -> Cursor
 where
     R: text::Renderer<Editor = graphics::text::Editor>,
 {