fix: accelerate geometry animations

crates/ferese-animation/src/lib.rs

@@ -19,8 +19,8 @@ impl Default for SpringConfig {
     fn default() -> Self {
         Self {
             mass: 1.0,
-            stiffness: 320.0,
+            stiffness: 700.0,
-            damping: 36.0,
+            damping: 53.0,
             position_tolerance: 0.1,
             velocity_tolerance: 0.1,
         }
@@ -422,6 +422,27 @@ mod tests {
         assert_eq!(one_forty_four.current, target);
     }
 
+    #[test]
+    fn default_spring_completes_most_motion_within_two_hundred_milliseconds() {
+        let start = Rect::new(0.0, 0.0, 100.0, 100.0);
+        let target = Rect::new(500.0, 300.0, 900.0, 700.0);
+        let mut animated = AnimatedRect::new(start);
+        animated.set_target(target);
+
+        for _ in 0..12 {
+            animated.advance(Duration::from_secs_f64(1.0 / 60.0), SpringConfig::default());
+        }
+
+        assert!(animated.current.x >= 475.0);
+        assert!(animated.current.y >= 285.0);
+        assert!(animated.current.width >= 860.0);
+        assert!(animated.current.height >= 670.0);
+        assert!(animated.current.x <= target.x);
+        assert!(animated.current.y <= target.y);
+        assert!(animated.current.width <= target.width);
+        assert!(animated.current.height <= target.height);
+    }
+
     #[test]
     fn disabled_animation_snaps_to_target() {
         let mut geometry = WindowGeometry::new(Rect::new(0.0, 0.0, 100.0, 100.0), None);

docs/ferese-window-manager-spec.md

@@ -574,8 +574,8 @@ to `visual.target`. Geometry uses spring animation; opacity, dimming, blur
 intensity, and overlays use bounded easing. Updates MUST use presentation or
 monotonic frame timestamps and MUST NOT assume a fixed refresh rate.
 
-The default geometry spring uses mass `1.0`, stiffness `320.0`, and damping
+The default geometry spring uses mass `1.0`, stiffness `700.0`, and damping
-`36.0`, which is approximately critically damped. Geometry defaults MUST NOT
+`53.0`, which is approximately critically damped. Geometry defaults MUST NOT
 overshoot shared tile boundaries. User-configured underdamped geometry springs
 MAY overshoot numerically, but their rendered content remains clipped to the
 animated allocation and MUST NOT cover adjacent windows.
@@ -927,8 +927,8 @@ reduced_motion = false
 speed = 1.0
 
 [animations.spring]
-stiffness = 320.0
+stiffness = 700.0
-damping = 36.0
+damping = 53.0
 mass = 1.0
 
 [tiling]