feat: mark fully checked collapsed diff folders

TODO.md

@@ -8,7 +8,7 @@
 - [x] diff view: show the function/class context that a change hunk belongs to.
     - inline scope labels with sticky continuation, chosen before implementation
     - each side uses its own syntax tree; scope changes within a hunk get separate labels
-- [ ] diff view: annotate folder with checkmark if all items under given folder has been checked AND the folder is collapsed.
+- [x] diff view: annotate folder with checkmark if all items under given folder has been checked AND the folder is collapsed.
 - [ ] diff view: automatically detect changes and update the view when relevant bookmarks move change ids (regards bookmark-based diff view; i.e., user selected at least one bookmark in the before/after picker)
 - [ ] diff view: github integration (code review) - add comments on a pr, add review comments at specific lines of files, request changes, approve pr, etc.
 - [ ] diff view: local review comments (same features as for github reviews) that allows review of local changes to deliver specific reviews to ai agents used for coding.

docs/editing.md

@@ -432,7 +432,9 @@ Use the ordinary **file-picker/file-explorer actions and bindings**: Space `o` o
 
 File rows show colored **A** (added, green), **M** (modified, yellow), **D** (removed, red), or **R** (renamed, cyan) markers in Tree and List views, including filtered results. Rename rows show `R old/path -> new/path`; directories have no file-status marker.
 
-Mark or unmark a diff file with **`c` while browsing the changed-file tree**, **`:diff.review.toggle`**, or the command-palette action. With the changed-file explorer focused, it toggles the highlighted file without opening it; from a text pane, the command toggles the displayed file. Reviewed files show a green **`✓` immediately left of A/M/D/R, separated by one blank column**, in Tree and List views. The modification indicator keeps its existing indentation; the review marker uses the preceding gutter space instead of adding padding. Diff rows use the selection background and cursor rather than a `>` prefix. Directories and ordinary filesystem pickers cannot be marked. While filtering, including List view, `c` remains query text; use the palette or a control-key binding there. Explicit bindings take precedence over the default browsing shortcut.
+Mark or unmark a diff file with **`c` while browsing the changed-file tree**, **`:diff.review.toggle`**, or the command-palette action. With the changed-file explorer focused, it toggles the highlighted file without opening it; from a text pane, the command toggles the displayed file. Reviewed files show a green **`✓` immediately left of A/M/D/R, separated by one blank column**, in Tree and List views. The modification indicator keeps its existing indentation; the review marker uses the preceding gutter space instead of adding padding. Diff rows use the selection background and cursor rather than a `>` prefix. Directory review marks cannot be toggled directly, and ordinary filesystem pickers have no review marks. While filtering, including List view, `c` remains query text; use the palette or a control-key binding there. Explicit bindings take precedence over the default browsing shortcut.
+
+Collapsed folders show a green **`✓`** when every changed file beneath them is reviewed, including nested files and descendants hidden by filtering. Expanded folders stay unmarked. Folder marks update automatically when a descendant's review mark or the changed-file catalog changes.
 
 Review marks belong only to the open comparison and survive filtering, file navigation, lazy loading, tabs, split/unified/orientation changes, and pinned checkout-only transitions. A new or recomputed comparison clears them. Editing a writable After file clears only that file's mark; unchanged refreshes and saves preserve it. Marks do not change document text, undo history, or repository state, and are not persisted after closing the comparison.
 

src/files.rs

@@ -370,6 +370,20 @@ impl FilePicker {
         })
     }
 
+    /// Full catalog descendants, independent of filtering and folder expansion.
+    pub(crate) fn descendant_catalog_indices<'a>(
+        &'a self,
+        path: &'a Path,
+    ) -> impl Iterator<Item = usize> + 'a {
+        let start = self
+            .nodes
+            .partition_point(|node| node.path.as_path() <= path);
+        self.nodes[start..]
+            .iter()
+            .take_while(move |node| node.path.starts_with(path))
+            .filter_map(|node| node.catalog_index)
+    }
+
     fn selected_node(&self) -> Option<usize> {
         self.rows.get(self.selected).map(|row| row.node)
     }

src/tui.rs

@@ -5692,10 +5692,22 @@ fn draw_file_list(
                     .and_then(|file| file.old_path.as_deref())
                     .or(entry.old_path);
                 let mut spans = Vec::with_capacity(8);
-                let reviewed = changed.is_some()
-                    && entry.catalog_index.is_some_and(|index| {
-                        changed_files.is_some_and(|(_, reviewed)| reviewed.contains(&index))
-                    });
+                let reviewed = changed_files.is_some_and(|(_, reviewed)| {
+                    if entry.is_dir {
+                        if entry.expanded {
+                            return false;
+                        }
+                        let mut descendants =
+                            picker.descendant_catalog_indices(entry.path).peekable();
+                        descendants.peek().is_some()
+                            && descendants.all(|index| reviewed.contains(&index))
+                    } else {
+                        changed.is_some()
+                            && entry
+                                .catalog_index
+                                .is_some_and(|index| reviewed.contains(&index))
+                    }
+                });
                 if changed_files.is_none() {
                     spans.push(Span::raw(if selected { ">" } else { " " }));
                     spans.push(Span::raw(" "));
@@ -9541,6 +9553,94 @@ mod tests {
         assert!(!screen_text(&terminal).contains('✓'));
     }
 
+    #[test]
+    fn collapsed_diff_folders_reflect_all_catalog_descendants() {
+        let files: Vec<_> = [
+            "src/top.rs",
+            "src/deep/leaf.rs",
+            "src/deep/other.rs",
+            "srcish/unreviewed.rs",
+            "src",
+            "compact/a/b/only.rs",
+        ]
+        .into_iter()
+        .map(|path| {
+            let mut file = deletion_file();
+            file.path = path.into();
+            file
+        })
+        .collect();
+        let paths = || {
+            files
+                .iter()
+                .enumerate()
+                .map(|(index, file)| (index, file.path.clone()))
+        };
+        let mut picker = FilePicker::from_paths(PathBuf::new(), paths());
+        let mut terminal = Terminal::new(ratatui::backend::TestBackend::new(100, 18)).unwrap();
+        let mut check = |picker: &FilePicker, reviewed: &BTreeSet<usize>, label: &str, marked| {
+            terminal
+                .draw(|frame| {
+                    draw_file_list(
+                        frame,
+                        picker,
+                        frame.area(),
+                        "",
+                        &mut WheelPanels::default(),
+                        Some((&files, reviewed)),
+                    );
+                })
+                .unwrap();
+            let text = screen_text(&terminal);
+            let row = text.lines().find(|row| row.contains(label)).unwrap();
+            assert_eq!(row.contains('✓'), marked, "{row}");
+            if marked {
+                let buffer = terminal.backend().buffer();
+                let y = text.lines().position(|row| row.contains(label)).unwrap() as u16;
+                let x = (0..100).find(|&x| buffer[(x, y)].symbol() == "✓").unwrap();
+                assert_eq!(buffer[(x, y)].fg, Color::Green);
+            }
+        };
+        let mut reviewed = BTreeSet::from([0, 1]);
+        check(&picker, &reviewed, "src/", false);
+        reviewed.insert(2);
+        check(&picker, &reviewed, "src/", true);
+        check(&picker, &reviewed, "srcish/", false);
+        check(&picker, &reviewed, "compact/a/b/", false);
+        reviewed.insert(5);
+        check(&picker, &reviewed, "compact/a/b/", true);
+
+        let selected = picker
+            .entries()
+            .position(|row| row.is_dir && row.path == std::path::Path::new("src"))
+            .unwrap();
+        picker.selected = selected;
+        picker.right();
+        check(&picker, &reviewed, "src/", false);
+        check(&picker, &reviewed, "deep/", true);
+
+        reviewed.remove(&2);
+        picker.query = "leaf.rs".into();
+        picker.refilter();
+        let selected = picker
+            .entries()
+            .position(|row| row.is_dir && row.path == std::path::Path::new("src/deep"))
+            .unwrap();
+        picker.selected = selected;
+        picker.accept();
+        check(&picker, &reviewed, "deep/", false);
+        reviewed.insert(2);
+        check(&picker, &reviewed, "deep/", true);
+        reviewed.remove(&2);
+        check(&picker, &reviewed, "deep/", false);
+
+        // A reverted file no longer in the picker must not block its folder's mark.
+        picker.replace_paths(paths().filter(|(index, _)| *index != 2));
+        check(&picker, &reviewed, "deep/", true);
+        picker.accept();
+        check(&picker, &reviewed, "deep/", false);
+    }
+
     #[test]
     fn normal_file_markers_keep_clean_rows_and_match_diff_colors_in_every_view() {
         use crate::repository::WorkingFileChange;