Block j/k while a page switch is in flight

README.md

@@ -35,7 +35,7 @@ Set `HN_REDUCED_MOTION=1` to disable visual animations; ANSI and monochrome pale
 
 ## Read a story
 
-Use `j/k` or the arrow keys to select a story. Press `1`, `2`, or `3` for Top, New, or Best; `4` opens Saved. Use `n/p` to change pages — or keep holding `j` past the last story to continue on the next page's first story, and `k` at the top to go back a page.
+Use `j/k` or the arrow keys to select a story. Press `1`, `2`, or `3` for Top, New, or Best; `4` opens Saved. Use `n/p` to change pages — or press `j` past the last story to continue on the next page's first story, and `k` at the top to go back a page (further `j/k` wait while the page loads).
 
 Press `o` or Enter to open the discussion and its article. Press `c` to read the discussion without opening a new article pane. If a companion pane is already open, it follows the selected story. `O` always opens the story in your default browser.
 

src/app.rs

@@ -209,14 +209,18 @@ impl App {
 
     /// Move to next story. At the last story of the page, continue on the next
     /// page instead (the first story once it loads). Returns true when the
-    /// page advanced and the caller should request the new page.
+    /// page advanced and the caller should request the new page. While a page
+    /// or feed switch is still in flight, j/k are ignored so repeated presses
+    /// cannot stack multiple page advances.
     pub fn next_story(&mut self) -> bool {
-        if self.stories.is_empty() {
+        if self.stories.is_empty() || self.showing_stale_stories() {
             return false;
         }
         if self.selected_index < self.stories.len() - 1 {
             self.move_selection(self.selected_index + 1);
             false
+        } else if self.is_loading() {
+            false
         } else {
             let page = self.current_page;
             self.next_page();
@@ -225,12 +229,17 @@ impl App {
     }
 
     /// Move to previous story. At the first story of the page, go back to the
-    /// previous page (restoring the position left there). Returns true when
-    /// the page changed and the caller should request it.
+    /// previous page. Returns true when the page changed and the caller should
+    /// request it. Blocked while a page/feed switch is in flight, like next_story.
     pub fn prev_story(&mut self) -> bool {
+        if self.showing_stale_stories() {
+            return false;
+        }
         if self.selected_index > 0 {
             self.move_selection(self.selected_index - 1);
             false
+        } else if self.is_loading() {
+            false
         } else {
             let page = self.current_page;
             self.prev_page();

src/ui/ui_tests.rs

@@ -819,3 +819,32 @@ fn j_mid_list_returns_false_and_keeps_selection_on_page() {
     assert_eq!(app.selected_index, 1);
     assert_eq!(app.current_page, 1);
 }
+
+#[test]
+fn jk_do_not_stack_while_a_page_switch_is_in_flight() {
+    let mut app = feed();
+    app.selected_index = app.stories.len() - 1;
+    assert!(app.next_story(), "first j advances to page 2");
+    assert_eq!(app.current_page, 2);
+    // Page 2 has not loaded: the displayed list is still page 1 (stale), so
+    // further j/k must be ignored instead of stacking another page advance.
+    assert!(app.showing_stale_stories());
+    assert!(!app.next_story(), "j while fetching must not advance to page 3");
+    assert_eq!(app.current_page, 2);
+    assert!(!app.prev_story(), "k while a switch is in flight must not move");
+    assert_eq!(app.current_page, 2);
+    assert_eq!(app.selected_index, app.stories.len() - 1);
+}
+
+#[test]
+fn page_advance_blocked_during_same_page_refresh_but_selection_still_moves() {
+    let mut app = feed();
+    app.selected_index = app.stories.len() - 1;
+    app.set_story_loading(true);
+    assert!(!app.next_story(), "j at the end during a refresh must not advance");
+    assert_eq!(app.current_page, 1);
+    let mut app = feed();
+    app.set_story_loading(true);
+    assert!(!app.next_story(), "mid-list j still works during a refresh");
+    assert_eq!(app.selected_index, 1);
+}