ElyMark: clear the recent list from the sidebar

A Clear Recent Files button under the list writes an empty recent.json
(ely_files::recent::clear); a failure is shown, not swallowed.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

apps/ely-mark/src/desk/tests.rs

@@ -82,6 +82,26 @@ fn a_file_opens_with_its_outline_and_joins_the_recent_list(cx: &mut TestAppConte
     assert!(!kept.contains(r"\\\\?\\"), "plain paths only: {kept}");
 }
 
+#[gpui::test]
+fn the_recent_list_clears_from_its_button(cx: &mut TestAppContext) {
+    let (data, files) = (
+        tempfile::tempdir().expect("data"),
+        tempfile::tempdir().expect("files"),
+    );
+    let path = files.path().join("a.md");
+    std::fs::write(&path, "Text.\n").expect("a file");
+    let (desk, cx) = start(cx, data.path());
+    open(&desk, &path, cx);
+    assert!(desk.read_with(cx, |desk, _| !desk.recent.is_empty()));
+    let button = cx.debug_bounds("mark-clear-recent").expect("the button");
+    cx.simulate_click(button.center(), gpui::Modifiers::none());
+    cx.run_until_parked();
+    assert!(desk.read_with(cx, |desk, _| desk.recent.is_empty()));
+    let kept = std::fs::read_to_string(data.path().join("recent.json")).expect("the list");
+    assert_eq!(kept, "[]");
+    assert!(cx.debug_bounds("mark-clear-recent").is_none(), "nothing left to clear");
+}
+
 #[gpui::test]
 fn the_outline_follows_typing(cx: &mut TestAppContext) {
     let (data, files) = (

apps/ely-mark/src/places.rs

@@ -108,6 +108,22 @@ impl Desk {
         }
     }
 
+    /// Empties the recent list.
+    pub fn clear_recent(&mut self, cx: &mut Context<Self>) {
+        match ely_files::recent::clear(&self.recent_file) {
+            Ok(()) => {
+                log::info!("mark: the recent list is cleared");
+                self.recent.clear();
+                cx.notify();
+            }
+            Err(error) => {
+                log::error!("mark: the recent list did not clear: {error}");
+                let said = text(cx, "office.error.engine", &[("error", &error.to_string())]);
+                self.toast(said, Severity::Danger, cx);
+            }
+        }
+    }
+
     /// Line and column `at` in a tab or file.
     pub fn open_at(
         &mut self,

apps/ely-mark/src/side.rs

@@ -200,7 +200,7 @@ impl Side {
             .action(open)
             .into_any_element();
         }
-        let opener = desk.downgrade();
+        let (opener, clearer) = (desk.downgrade(), desk.downgrade());
         let rows = read.recent.iter().map(|path| {
             let name = path
                 .file_name()
@@ -214,15 +214,32 @@ impl Side {
             );
             (key, item)
         });
-        rows.fold(
-            SelectableList::new("mark-recent").label(text(cx, "mark.recent", &[])),
-            |list, (key, item)| list.row(key, item),
-        )
-        .on_activate(move |key, _, cx| {
-            let path = PathBuf::from(key.as_ref());
-            opener.update(cx, |desk, cx| desk.open_path(path, cx)).ok();
-        })
-        .into_any_element()
+        let list = rows
+            .fold(
+                SelectableList::new("mark-recent").label(text(cx, "mark.recent", &[])),
+                |list, (key, item)| list.row(key, item),
+            )
+            .on_activate(move |key, _, cx| {
+                let path = PathBuf::from(key.as_ref());
+                opener.update(cx, |desk, cx| desk.open_path(path, cx)).ok();
+            });
+        let clear = Button::new("mark-clear-recent", text(cx, "mark.recent.clear", &[]))
+            .size(ControlSize::Sm)
+            .on_click(move |_, _, cx| {
+                clearer.update(cx, |desk, cx| desk.clear_recent(cx)).ok();
+            });
+        div()
+            .flex()
+            .flex_col()
+            .gap_2()
+            .size_full()
+            .child(div().flex_1().min_h_0().child(list))
+            .child(
+                div()
+                    .debug_selector(|| "mark-clear-recent".into())
+                    .child(clear),
+            )
+            .into_any_element()
     }
 
     fn outline(&self, desk: &Entity<Desk>, cx: &mut Context<Self>) -> AnyElement {