#551: Shift+Spacebar plays every frame by default

Shift+Spacebar set Skip to 1, so it played every other frame out of the box. It now plays every
frame, like Spacebar. Skip still works when it is set.

Co-Authored-By: Claude Haiku 5.5 <[email protected]>

crates/engine/src/preview.rs

@@ -205,9 +205,8 @@ impl PreviewPreset {
     pub fn default_for(s: PreviewShortcut) -> Self {
         let d = PreviewPreset::default();
         match s {
-            PreviewShortcut::Spacebar => d,
-            // A lighter preview: every other frame.
-            PreviewShortcut::ShiftSpacebar => PreviewPreset { skip: 1, ..d },
+            // Frame skipping is off by default; set Skip to play fewer frames.
+            PreviewShortcut::Spacebar | PreviewShortcut::ShiftSpacebar => d,
             PreviewShortcut::Numpad0 => PreviewPreset { range: PreviewRange::WorkArea, play_from: PlayFrom::RangeStart, ..d },
             PreviewShortcut::ShiftNumpad0 => {
                 PreviewPreset { range: PreviewRange::WorkArea, play_from: PlayFrom::RangeStart, skip: 1, resolution: PreviewResolution::Half, ..d }
@@ -509,6 +508,13 @@ mod tests {
         assert_eq!(pl.frame_after(237, 1), None);
     }
 
+    /// #551: Shift+Spacebar used to skip every other frame out of the box.
+    #[test]
+    fn shift_spacebar_plays_every_frame_by_default() {
+        assert_eq!(PreviewPreset::default_for(PreviewShortcut::ShiftSpacebar).skip, 0);
+        assert_eq!(PreviewPreset::default_for(PreviewShortcut::ShiftSpacebar), PreviewPreset::default_for(PreviewShortcut::Spacebar));
+    }
+
     #[test]
     fn settings_commands_round_trip() {
         let mut s = comp_session();

crates/ui-egui/tests/ui_preview_align.rs

@@ -118,7 +118,8 @@ fn playback_follows_the_shortcut_options() {
     h.step();
     assert!(h.state().playback.playing);
     assert_eq!(h.state().playback.shortcut, PreviewShortcut::ShiftSpacebar);
-    assert_eq!(h.state().playback.plan.unwrap().step, 2);
+    // Every frame by default (#551): Skip is 0 until the user sets it.
+    assert_eq!(h.state().playback.plan.unwrap().step, 1);
 }
 
 #[test]