fix: keep dock drag springs live and add elastic leading-edge pull

mobile/lib/widgets/glass_dock.dart

@@ -3,6 +3,7 @@ import 'dart:ui' as ui;
 
 import 'package:flutter/material.dart';
 import 'package:flutter/physics.dart';
+import 'package:flutter/scheduler.dart';
 
 import 'glass_refraction.dart';
 
@@ -38,19 +39,91 @@ class _GlassDockState extends State<GlassDock> with TickerProviderStateMixin {
   late final AnimationController _sway = AnimationController.unbounded(
     vsync: this,
   );
+  late final AnimationController _ripple = AnimationController(
+    vsync: this,
+    duration: const Duration(milliseconds: 620),
+  );
+  void _wakeRipple() {
+    if (!_reduceMotion && !_ripple.isAnimating) _ripple.forward(from: 0);
+  }
+
+  double _swayTarget = 0, _swayVelocity = 0, _dragTarget = 0, _dragVelocity = 0;
+  Duration? _elasticLastTick;
+  late final Ticker _elasticTicker = createTicker(_tickElastic);
+  void _startElastic() {
+    if (!_elasticTicker.isActive) {
+      _elasticLastTick = null;
+      _elasticTicker.start();
+    }
+  }
+
+  // Keep one clock alive while input changes its targets. Restarting a spring
+  // on every pointer event repeatedly paints t=0 under continuous dragging.
+  void _tickElastic(Duration elapsed) {
+    final seconds = _elasticLastTick == null
+        ? 1 / 60
+        : ((elapsed - _elasticLastTick!).inMicroseconds / 1000000).clamp(
+            0.0,
+            0.25,
+          );
+    _elasticLastTick = elapsed;
+    final sway = _advanceSpring(
+      _sway.value,
+      _swayVelocity,
+      _swayTarget,
+      220,
+      18,
+      seconds,
+    );
+    final drag = _advanceSpring(
+      _dragFollow.value,
+      _dragVelocity,
+      _dragTarget,
+      680,
+      28,
+      seconds,
+    );
+    _swayVelocity = sway.$2;
+    _dragVelocity = drag.$2;
+    _sway.value = sway.$1;
+    _dragFollow.value = drag.$1;
+    if ((_sway.value - _swayTarget).abs() < 0.0005 &&
+        _swayVelocity.abs() < 0.005 &&
+        (_dragFollow.value - _dragTarget).abs() < 0.0005 &&
+        _dragVelocity.abs() < 0.005) {
+      _sway.value = _swayTarget;
+      _dragFollow.value = _dragTarget;
+      _swayVelocity = _dragVelocity = 0;
+      _elasticTicker.stop();
+      _elasticLastTick = null;
+    }
+  }
+
+  (double, double) _advanceSpring(
+    double value,
+    double velocity,
+    double target,
+    double stiffness,
+    double damping,
+    double seconds,
+  ) {
+    final steps = math.max(1, (seconds * 120).ceil());
+    final step = seconds / steps;
+    for (var i = 0; i < steps; i++) {
+      velocity += (stiffness * (target - value) - damping * velocity) * step;
+      value += velocity * step;
+    }
+    return (value, velocity);
+  }
+
   void _swayTo(double target) {
+    _swayTarget = _reduceMotion ? 0 : target;
     if (_reduceMotion) {
       _sway.value = 0;
+      _swayVelocity = 0;
       return;
     }
-    _sway.animateWith(
-      SpringSimulation(
-        const SpringDescription(mass: 1, stiffness: 220, damping: 18),
-        _sway.value,
-        target,
-        _sway.velocity.clamp(-12, 12),
-      ),
-    );
+    _startElastic();
   }
 
   bool _reduceMotion = false;
@@ -59,6 +132,7 @@ class _GlassDockState extends State<GlassDock> with TickerProviderStateMixin {
   void initState() {
     super.initState();
     _targetIndex = widget.selectedIndex;
+    _dragTarget = widget.selectedIndex.toDouble();
   }
 
   double get _pressure => _press.value.clamp(0.0, 1.18);
@@ -85,13 +159,34 @@ class _GlassDockState extends State<GlassDock> with TickerProviderStateMixin {
       _motion.value = widget.selectedIndex.toDouble();
       _press.value = 0;
       _tap.value = 0;
+      _ripple.value = 0;
+      _elasticTicker.stop();
+      _elasticLastTick = null;
+      _swayTarget = _swayVelocity = _dragVelocity = 0;
+      _dragTarget = _drag ?? widget.selectedIndex.toDouble();
+      _dragFollow.value = _drag ?? widget.selectedIndex.toDouble();
       _sway.value = 0;
     }
   }
 
+  late final AnimationController _dragFollow = AnimationController.unbounded(
+    vsync: this,
+    value: widget.selectedIndex.toDouble(),
+  );
+  void _followDragTo(double target) {
+    _dragTarget = target;
+    if (_reduceMotion) {
+      _dragFollow.value = target;
+      _dragVelocity = 0;
+      return;
+    }
+    _startElastic();
+  }
+
   double? _drag;
   double _dragSpeed = 0;
-  double get _position => _drag ?? _motion.value.clamp(-0.12, 2.12);
+  double get _position =>
+      (_drag != null ? _dragFollow.value : _motion.value).clamp(-0.12, 2.12);
   void _moveTo(int index, {double velocity = 0, bool springyTap = false}) {
     _targetIndex = index;
     if (_reduceMotion) {
@@ -140,10 +235,13 @@ class _GlassDockState extends State<GlassDock> with TickerProviderStateMixin {
 
   @override
   void dispose() {
+    _elasticTicker.dispose();
     _motion.dispose();
     _press.dispose();
     _tap.dispose();
     _sway.dispose();
+    _ripple.dispose();
+    _dragFollow.dispose();
     super.dispose();
   }
 
@@ -159,25 +257,25 @@ class _GlassDockState extends State<GlassDock> with TickerProviderStateMixin {
             colors: lens
                 ? [
                     Color.lerp(
-                      const Color(0xFFA1A4AA).withValues(alpha: 0.34),
+                      const Color(0xFFA1A4AA).withValues(alpha: 0.28),
                       const Color(0xFFD8DBE0).withValues(alpha: 0.0252),
                       pressure,
                     )!,
                     Color.lerp(
-                      const Color(0xFF8E939B).withValues(alpha: 0.26),
+                      const Color(0xFF8E939B).withValues(alpha: 0.21),
                       const Color(0xFFC3C7CE).withValues(alpha: 0.0144),
                       pressure,
                     )!,
                     Color.lerp(
-                      const Color(0xFFB4B7BC).withValues(alpha: 0.32),
+                      const Color(0xFFB4B7BC).withValues(alpha: 0.26),
                       const Color(0xFFE5E7EB).withValues(alpha: 0.0216),
                       pressure,
                     )!,
                   ]
                 : [
-                    Colors.white.withValues(alpha: 0.38),
-                    const Color(0xFFFDFEFF).withValues(alpha: 0.24),
-                    Colors.white.withValues(alpha: 0.30),
+                    Colors.white.withValues(alpha: 0.29),
+                    const Color(0xFFFDFEFF).withValues(alpha: 0.17),
+                    Colors.white.withValues(alpha: 0.23),
                   ],
           ),
         ),
@@ -187,7 +285,7 @@ class _GlassDockState extends State<GlassDock> with TickerProviderStateMixin {
     return ClipRRect(
       borderRadius: BorderRadius.circular(40),
       child: GlassRefraction(
-        strength: lens ? 0.78 + pressure * 0.70 : 1.14,
+        strength: lens ? 0.78 + pressure * 0.70 : 0.98,
         blurSigma: lens ? 1.6 - pressure * 0.6 : 1.5,
         child: content,
       ),
@@ -202,7 +300,14 @@ class _GlassDockState extends State<GlassDock> with TickerProviderStateMixin {
         MediaQuery.sizeOf(context).width >= 600 ? 300.0 : 264.0,
       );
       return AnimatedBuilder(
-        animation: Listenable.merge([_motion, _press, _tap, _sway]),
+        animation: Listenable.merge([
+          _motion,
+          _press,
+          _tap,
+          _sway,
+          _ripple,
+          _dragFollow,
+        ]),
         builder: (context, _) {
           final press = _pressure;
           final pulse = _reduceMotion ? 0.0 : math.sin(math.pi * _tap.value);
@@ -213,21 +318,34 @@ class _GlassDockState extends State<GlassDock> with TickerProviderStateMixin {
               : math.sin(2 * math.pi * _tap.value);
           final tapStretch = tapWave >= 0 ? tapWave * 0.24 : tapWave * 0.065;
           final tapRise = tapWave >= 0 ? -tapWave * 0.045 : -tapWave * 0.15;
+          // Pointer movement wakes a finite ripple; pauses do not start idle loops.
+          final dragWave = _reduceMotion
+              ? 0.0
+              : math.sin(2 * math.pi * _ripple.value) * press.clamp(0.0, 1.0);
+          final dragStretch = dragWave * (dragWave >= 0 ? 0.10 : 0.06);
           final speed = _reduceMotion
               ? 0.0
               : (_drag != null ? _dragSpeed : _motion.velocity).abs();
           final stretch =
-              (speed / 80).clamp(0.0, 0.08) + tapStretch + press * 0.30;
+              (speed / 80).clamp(0.0, 0.08) +
+              tapStretch +
+              press * 0.30 +
+              dragStretch;
           final lensWidth = _travel * (1 + stretch);
           final lensHeight =
               (_height - _inset * 2) *
-              (1 + press * 0.31 + tapRise - (speed / 180).clamp(0.0, 0.035));
+              (1 +
+                  press * 0.31 +
+                  tapRise -
+                  dragWave * 0.08 -
+                  (speed / 180).clamp(0.0, 0.035));
           // Resize real glass bounds: sampling stays aligned without scaling text.
           final sway = _reduceMotion ? 0.0 : _sway.value.clamp(-1.2, 1.2);
           final bodyGrowth = press * 12 + pulse * 3 + sway.abs() * 4;
           final bodyHeight =
               _height + press * 5 + pulse * 1.5 - sway.abs() * 0.8;
           final dockShift = sway * 8;
+          final leadingPull = sway * 6;
           return SizedBox(
             width: _width,
             height: _height,
@@ -245,9 +363,9 @@ class _GlassDockState extends State<GlassDock> with TickerProviderStateMixin {
                       boxShadow: [
                         BoxShadow(
                           color: const Color(0xFF4C6078)
-                              .withValues(alpha: 0.075),
-                          blurRadius: 18,
-                          offset: const Offset(0, 6),
+                              .withValues(alpha: 0.05),
+                          blurRadius: 14,
+                          offset: const Offset(0, 4),
                         ),
                       ],
                     ),
@@ -255,9 +373,9 @@ class _GlassDockState extends State<GlassDock> with TickerProviderStateMixin {
                       clipBehavior: Clip.none,
                       children: [
                         Positioned(
-                          left: -bodyGrowth / 2,
+                          left: -bodyGrowth / 2 + math.min(leadingPull, 0),
                           top: (_height - bodyHeight) / 2,
-                          width: _width + bodyGrowth,
+                          width: _width + bodyGrowth + leadingPull.abs(),
                           height: bodyHeight,
                           child: _glass(child: const SizedBox.expand()),
                         ),
@@ -328,7 +446,11 @@ class _GlassDockState extends State<GlassDock> with TickerProviderStateMixin {
             onHorizontalDragStart: index == widget.selectedIndex
                 ? (_) {
                     final start = _position.clamp(0.0, 2.0);
+                    _dragFollow.value = start;
+                    _dragTarget = start;
+                    _dragVelocity = _motion.velocity;
                     _motion.stop();
+                    _wakeRipple();
                     _pressTo(_reduceMotion ? 0 : 1);
                     setState(() {
                       _drag = start;
@@ -339,18 +461,20 @@ class _GlassDockState extends State<GlassDock> with TickerProviderStateMixin {
             onHorizontalDragUpdate: index == widget.selectedIndex
                 ? (details) => setState(() {
                     _dragSpeed = details.delta.dx / _travel * 60;
+                    _wakeRipple();
                     _swayTo((_dragSpeed / 8).clamp(-1.0, 1.0));
-                    _drag = (_position + details.delta.dx / _travel).clamp(
+                    _drag = (_drag! + details.delta.dx / _travel).clamp(
                       0.0,
                       2.0,
                     );
+                    _followDragTo(_drag!);
                   })
                 : null,
             onHorizontalDragEnd: index == widget.selectedIndex
                 ? (details) => _select(
-                    _position.round().clamp(0, 2),
+                    (_drag ?? _position).round().clamp(0, 2),
                     elastic: true,
-                    velocity: details.velocity.pixelsPerSecond.dx / _travel,
+                    velocity: _dragVelocity,
                   )
                 : null,
             onHorizontalDragCancel: index == widget.selectedIndex
@@ -359,7 +483,7 @@ class _GlassDockState extends State<GlassDock> with TickerProviderStateMixin {
                     final position = _position;
                     setState(() => _drag = null);
                     _motion.value = position;
-                    _moveTo(widget.selectedIndex);
+                    _moveTo(widget.selectedIndex, velocity: _dragVelocity);
                     _pressTo(0);
                     _swayTo(0);
                   }
@@ -515,7 +639,7 @@ class _GlassRimPainter extends CustomPainter {
       outer,
       Paint()
         ..style = PaintingStyle.stroke
-        ..strokeWidth = lens ? 1.8 : 2.8
+        ..strokeWidth = lens ? 1.4 : 1.8
         ..maskFilter = MaskFilter.blur(BlurStyle.normal, lens ? 0.9 : 0.65)
         ..shader = ui.Gradient.linear(
           bounds.topLeft,
@@ -532,7 +656,7 @@ class _GlassRimPainter extends CustomPainter {
       outer,
       Paint()
         ..style = PaintingStyle.stroke
-        ..strokeWidth = lens ? 1.25 : 1.1
+        ..strokeWidth = lens ? 1.0 : 0.85
         ..shader = ui.Gradient.sweep(
           bounds.center,
           [
@@ -553,7 +677,7 @@ class _GlassRimPainter extends CustomPainter {
       inner,
       Paint()
         ..style = PaintingStyle.stroke
-        ..strokeWidth = 0.7
+        ..strokeWidth = 0.45
         ..shader = ui.Gradient.linear(
           bounds.topLeft,
           bounds.bottomRight,