feat: enable native readonly diff interaction and synchronized pane cursors

tests/diff.rs

@@ -143,8 +143,7 @@ fn typed_diff_edits_unsaved_working_after_and_preserves_undo_on_explicit_close()
     }
     session.handle(Input::Escape);
     assert!(session.editor().diff().is_some());
-    assert_eq!(session.editor().context().text, "uafter\n");
-    assert_eq!(session.editor().cursor(), cursor);
+    assert_eq!(session.editor().context().text, "before\n");
     assert_eq!(fs::read_to_string(&source).unwrap(), "after\n");
 
     session.handle(Input::Char('\t'));
@@ -152,6 +151,8 @@ fn typed_diff_edits_unsaved_working_after_and_preserves_undo_on_explicit_close()
         session.editor().diff().unwrap().focus,
         vamp::diff::Focus::After
     );
+    assert_eq!(session.editor().context().text, "uafter\n");
+    assert_eq!(session.editor().cursor(), cursor);
     for input in [Input::Char('i'), Input::Char('x'), Input::Escape] {
         session.handle(input);
     }
@@ -320,3 +321,63 @@ fn editable_diff_navigation_skips_omitted_lines_without_expanding_excerpts() {
     type_query(&mut session, "]");
     assert_eq!(shown(&session), [16, 17, 18, 19, 20, 21, 22, 78, 79, 80]);
 }
+
+#[test]
+fn readonly_jump_history_restores_the_comparison_file_and_source_cursor() {
+    let fixture = Fixture::new();
+    fixture.git(&["init", "-q"]);
+    let root = fixture.0.join("repo");
+    for name in ["first", "second"] {
+        let mut lines = (1..=40)
+            .map(|row| format!("// {name}_stable_{row:03}"))
+            .collect::<Vec<_>>();
+        lines[19] = format!("// {name}_before");
+        fs::write(root.join(format!("{name}.rs")), lines.join("\n") + "\n").unwrap();
+    }
+    fixture.git(&["add", "."]);
+    fixture.git(&["commit", "-qm", "base"]);
+    for name in ["first", "second"] {
+        let path = root.join(format!("{name}.rs"));
+        let text = fs::read_to_string(&path).unwrap();
+        fs::write(path, text.replace("_before", "_after")).unwrap();
+    }
+    let mut session = EditorSession::open(Some(root.join("first.rs")), vec![], None).unwrap();
+    session.execute("diff");
+    wait_until(&mut session, |session| {
+        !session.editor().diff().unwrap().loading
+    });
+    for input in [Input::Down, Input::Enter, Input::Enter] {
+        session.handle(input);
+    }
+    wait_until(&mut session, |session| {
+        session.editor().diff().unwrap().phase == Phase::View
+    });
+    session.handle(Input::Char('\t'));
+    let first_origin = session.editor().cursor();
+    type_query(&mut session, "/first_before");
+    session.handle(Input::Enter);
+    for input in [
+        Input::Char(' '),
+        Input::Char('e'),
+        Input::Home,
+        Input::Down,
+        Input::Enter,
+    ] {
+        session.handle(input);
+    }
+    let second_origin = session.editor().cursor();
+    type_query(&mut session, "/second_before");
+    session.handle(Input::Enter);
+    session.handle(Input::Ctrl('o'));
+    assert_eq!(session.editor().cursor(), second_origin);
+    session.handle(Input::Ctrl('o'));
+    assert_eq!(session.editor().diff().unwrap().file, 0);
+    assert_eq!(session.editor().cursor(), first_origin);
+    assert!(session.editor().context().text.contains("first_before"));
+    assert!(!session.editor().context().text.contains("second_before"));
+    session.execute("diff.close");
+    assert_eq!(
+        session.editor().context().text,
+        fs::read_to_string(root.join("first.rs")).unwrap()
+    );
+}