fix: restore tab and diff context through jump history

src/tui.rs

@@ -1057,6 +1057,7 @@ fn chrome_title(
     index: usize,
     path: Option<&std::path::Path>,
     dirty: bool,
+    is_diff: bool,
 ) -> String {
     let name = path
         .map(|path| {
@@ -1075,6 +1076,7 @@ fn chrome_title(
         };
         match field {
             "index" => write!(title, "{index}").unwrap(),
+            "view" if is_diff => title.push_str("Diff · "),
             "name" => title.push_str(&name),
             "path" => title.push_str(&path),
             "modified" if dirty => title.push_str(" [+]"),
@@ -1109,6 +1111,7 @@ fn chrome_items<'a>(
                         index + 1,
                         buffer.as_ref().and_then(|buffer| buffer.path),
                         buffer.is_some_and(|buffer| buffer.dirty),
+                        editor.tab_is_diff(index),
                     )),
                     config,
                     tab: Some(index),
@@ -1133,6 +1136,7 @@ fn chrome_items<'a>(
                 editor.tab_index() + 1,
                 editor.path(),
                 editor.dirty(),
+                editor.tab_is_diff(editor.tab_index()),
             )),
             "position" => Cow::Owned(format!(
                 "{}:{}",
@@ -1207,6 +1211,7 @@ fn chrome_items<'a>(
                 editor.tab_index() + 1,
                 editor.path(),
                 editor.dirty(),
+                editor.tab_is_diff(editor.tab_index()),
             ));
         } else if text.chars().any(char::is_control) {
             text = Cow::Owned(display_text(&text));
@@ -5574,7 +5579,7 @@ mod tests {
         let path = directory.file("λ\t{index}.rs", "source");
         let editor = Editor::open(Some(path.clone()), vec![]).unwrap();
         let groups = chrome_groups(&editor, editor.bottom_bar_config(), &SyntaxCache::new());
-        let title = chrome_title("{path}", 2, Some(&path), false);
+        let title = chrome_title("{path}", 2, Some(&path), false, false);
         assert_eq!(title, display_text(&display_path(&path)));
         assert!(groups.iter().flatten().any(|item| item.text == title));
         assert_eq!(editor.path(), Some(path.as_path()));
@@ -6129,6 +6134,105 @@ mod tests {
         }
     }
 
+    #[test]
+    fn comparison_titles_distinguish_same_named_tabs_and_follow_current_context() {
+        let directory = Directory::new();
+        let path = directory.file("source.rs", "fn main() {}");
+        for phase in ["loading", "before", "after", "view"] {
+            let mut editor = Editor::open(Some(path.clone()), vec![]).unwrap();
+            editor.execute("tab.new");
+            editor.execute("diff");
+            if phase != "loading" {
+                let (id, _) = editor.take_diff_request().unwrap();
+                editor.apply_diff_result(id, Ok(crate::diff::Outcome::Catalog(diff_catalog())));
+            }
+            if matches!(phase, "after" | "view") {
+                editor.handle(Input::Down);
+                editor.handle(Input::Enter);
+            }
+            if phase == "view" {
+                editor.handle(Input::Down);
+                editor.handle(Input::Enter);
+                let (id, _) = editor.take_diff_request().unwrap();
+                editor.apply_diff_result(
+                    id,
+                    Ok(crate::diff::Outcome::Comparison(crate::diff::Comparison {
+                        root: directory.0.clone(),
+                        editable_paths: Default::default(),
+                        before: "baseline".into(),
+                        after: "historic".into(),
+                        files: vec![syntax_diff_file("source.rs", "fn old() {}", "fn main() {}")],
+                    })),
+                );
+            }
+            let default_tabs = editor.top_bar_config().segment("tabs").clone();
+            for (template, ordinary, comparison, marker_count) in [
+                (None, "1 source.rs", "2 Diff · source.rs", 1),
+                (
+                    Some("{index} {name}{modified}"),
+                    "1 source.rs",
+                    "2 source.rs",
+                    0,
+                ),
+                (
+                    Some("T{index}:{view}{name}{modified}"),
+                    "T1:source.rs",
+                    "T2:Diff · source.rs",
+                    1,
+                ),
+            ] {
+                configure_chrome(&mut editor, |top, bottom| {
+                    top.segments.insert("tabs".into(), default_tabs.clone());
+                    if let Some(template) = template {
+                        top.segments.get_mut("tabs").unwrap().title = template.into();
+                    }
+                    bottom.left = vec!["mode".into()];
+                    bottom.center.clear();
+                    bottom.right.clear();
+                    bottom.segments.get_mut("mode").unwrap().title = "Current:{view}{name}".into();
+                });
+                for comparison_active in [true, false] {
+                    let mut terminal =
+                        Terminal::new(ratatui::backend::TestBackend::new(160, 2)).unwrap();
+                    terminal
+                        .draw(|frame| {
+                            for (line, y) in [
+                                (editor.top_bar_config(), 0),
+                                (editor.bottom_bar_config(), 1),
+                            ] {
+                                draw_chrome(
+                                    frame,
+                                    chrome_groups(&editor, line, &SyntaxCache::new()),
+                                    Rect::new(0, y, 160, 1),
+                                );
+                            }
+                        })
+                        .unwrap();
+                    let titles = pane_screen(&terminal, Rect::new(0, 0, 160, 1));
+                    assert!(titles.contains(ordinary), "{phase}: {titles}");
+                    assert!(titles.contains(comparison), "{phase}: {titles}");
+                    assert_eq!(
+                        titles.matches("Diff · ").count(),
+                        marker_count,
+                        "{phase}: {titles}"
+                    );
+                    let current = pane_screen(&terminal, Rect::new(0, 1, 160, 1));
+                    let expected = if comparison_active {
+                        "Current:Diff · source.rs"
+                    } else {
+                        "Current:source.rs"
+                    };
+                    assert!(current.contains(expected), "{phase}: {current}");
+                    editor.execute(if comparison_active {
+                        "tab.previous"
+                    } else {
+                        "tab.next"
+                    });
+                }
+            }
+        }
+    }
+
     #[test]
     fn tab_titles_update_templates_without_reinterpreting_file_names() {
         let directory = Directory::new();
@@ -6158,12 +6262,6 @@ mod tests {
         let titles = pane_screen(&terminal, Rect::new(0, 0, 160, 1));
         assert!(titles.contains("T1:λ{index}�.rs [+]"), "{titles}");
         assert!(titles.contains("T2:λ{index}�.rs [+]"), "{titles}");
-        let buffer = terminal.backend().buffer();
-        assert_eq!(buffer[(0, 0)].bg, Color::Reset);
-        let active = (0..159)
-            .find(|&x| buffer[(x, 0)].symbol() == "T" && buffer[(x + 1, 0)].symbol() == "2")
-            .unwrap();
-        assert_eq!(buffer[(active, 0)].bg, Color::Cyan);
 
         configure_chrome(&mut editor, |top, _| {
             top.segments.get_mut("tabs").unwrap().title = "{index}:{path}{modified}".into();