ui(motion): make Fluid spring honest (#481)

CONTRIBUTING.md

@@ -81,10 +81,11 @@ version locally to avoid "works on my machine" drift. When bumping the pin, run
 
 For animated UI, **do not invent magic `Duration(...)` / raw curves** in widgets.
 
-- Use `QueryaMotion` tokens (`fast` / `standard` / `slow`) via
+- Use `QueryaMotion` tokens (`fast` / `standard` / `slow` / `treeExpand`) via
   `context.motionDuration` / `context.motionCurve` (or `QueryaMotion.effective*`).
-- Interactive Fluid motion: `QueryaSpring` / `QueryaSpringController` when
-  `QueryaSpring.springsEnabled` (Full motion only).
+- **Real springs only:** `QueryaSpring` / `QueryaSpringController` when
+  `QueryaSpring.springsEnabled` (Full motion) — tab indicator, drag settle, etc.
+  Do not use `springsEnabled` just to pick an emphasized cubic for fades/dialogs.
 - Honor Preferences Motion Full / Reduced / Off and OS `disableAnimations`.
 - Mid-drag layout (split panes) stays 1:1; spring settle only on drag-end.
 - Do not animate virtualized grid rows on scroll.

docs/motion-and-high-refresh.md

@@ -112,6 +112,16 @@ Introduce `lib/core/motion/` with a single source of truth for durations and cur
 - **Theme switch**: enable a tasteful `emphasized` cross-fade and consider making it on-by-default.
 - **List/grid item insertion** (results, history): subtle staggered fade-in for first paint only (no per-scroll cost).
 
+### 4.5 Springs vs duration-token cubics (#481)
+
+`QueryaSpring.springsEnabled` (Full motion only) means **real** `SpringSimulation` /
+`QueryaSpringController` — tab strip indicator, split drag settle, and similar
+interruptible physics.
+
+Shell morphs (`QueryaFadeSlide`, `QueryaSwitchingBody`, `showAppDialog`) always use
+duration tokens (`standard` + `enter`/`exit`). Do **not** treat `emphasized` cubic
+as a stand-in for “Fluid spring.”
+
 ---
 
 ## 5. Implementation plan (proposed issues)
@@ -156,6 +166,11 @@ When reviewing PRs that touch animation:
 5. Tree expand: chevron `AnimatedRotation` and `QueryaAnimatedExpand` **must** use
    `QueryaMotion.treeExpand` + `treeExpandCurve` (not `fast`/`standardCurve` mixed
    with `standard`/`enter`).
+6. **Springs vs cubics (#481):** `QueryaSpring.springsEnabled` gates **real**
+   `SpringSimulation` / `QueryaSpringController` only (tab strip indicator, split
+   drag settle). Shell morphs (`QueryaFadeSlide`, `QueryaSwitchingBody`,
+   `showAppDialog`) use duration-token cubics (`standard`/`enter`/`exit`) — do not
+   brand emphasized ease as “spring”.
 
 **Allowed named non-token durations** (named + documented — not magic literals at call sites):
 

lib/core/motion/querya_fade_slide.dart

@@ -2,12 +2,12 @@ import 'package:flutter/material.dart';
 
 import 'querya_motion.dart';
 import 'querya_motion_context.dart';
-import 'querya_spring.dart';
 
 /// Fades and optionally slides [child] when the keyed child changes.
 ///
-/// Uses a short spring-like curve when [QueryaSpring.springsEnabled], otherwise
-/// duration tokens. Prefer wrapping content with a stable [Key] on [child].
+/// Uses duration-token cubic curves ([QueryaMotion.standard] / [QueryaMotion.enter]),
+/// not [QueryaSpring] — reserve springs for interruptible physics (tab indicator,
+/// drag settle). Prefer wrapping content with a stable [Key] on [child].
 class QueryaFadeSlide extends StatelessWidget {
   const QueryaFadeSlide({
     super.key,
@@ -24,13 +24,8 @@ class QueryaFadeSlide extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    final useSpring = QueryaSpring.springsEnabled(context);
-    final duration = context.motionDuration(
-      useSpring ? QueryaMotion.standard : QueryaMotion.fast,
-    );
-    final curve = context.motionCurve(
-      useSpring ? QueryaMotion.emphasized : QueryaMotion.enter,
-    );
+    final duration = context.motionDuration(QueryaMotion.standard);
+    final curve = context.motionCurve(QueryaMotion.enter);
 
     return AnimatedSwitcher(
       duration: duration,

lib/core/motion/querya_spring.dart

@@ -6,8 +6,12 @@ import 'querya_motion_scope.dart';
 /// Spring presets for Fluid UI (interruptible / redirectable motion).
 ///
 /// Tuned toward critically damped motion (~Apple Response 0.3–0.5s feel).
-/// Use with [SpringSimulation] / [AnimationController.animateWith], not fixed
-/// [Duration] curves, when [springsEnabled] is true.
+/// Use **only** with [SpringSimulation] / [AnimationController.animateWith]
+/// when [springsEnabled] is true (tab indicator, drag settle, etc.).
+///
+/// Do **not** branch on [springsEnabled] merely to pick an emphasized cubic
+/// curve for [AnimatedOpacity] / [AnimatedSwitcher] / dialogs — those use
+/// [QueryaMotion] duration tokens instead (#481).
 abstract final class QueryaSpring {
   /// Snappy panels / dialogs / tab indicator (~0.3s Response feel).
   static const SpringDescription snappy = SpringDescription(

lib/core/motion/querya_switching_body.dart

@@ -2,12 +2,14 @@ import 'package:flutter/material.dart';
 
 import 'querya_motion.dart';
 import 'querya_motion_context.dart';
-import 'querya_spring.dart';
 
 /// Keep-alive indexed stack with opacity (+ optional slide) transitions.
 ///
 /// Off-screen children stay mounted (SQL editor state, etc.). Prefer this over
 /// hard `if` swaps for empty↔workspace and similar shell morphs.
+///
+/// Uses duration-token cubics ([QueryaMotion.standard] / enter / exit), not
+/// [QueryaSpring] — springs stay for interruptible physics only.
 class QueryaSwitchingBody extends StatelessWidget {
   const QueryaSwitchingBody({
     super.key,
@@ -26,13 +28,8 @@ class QueryaSwitchingBody extends StatelessWidget {
   Widget build(BuildContext context) {
     assert(children.isNotEmpty, 'QueryaSwitchingBody requires children');
     final safeIndex = index.clamp(0, children.length - 1);
-    final useSpring = QueryaSpring.springsEnabled(context);
-    final duration = context.motionDuration(
-      useSpring ? QueryaMotion.standard : QueryaMotion.fast,
-    );
-    final inCurve = context.motionCurve(
-      useSpring ? QueryaMotion.emphasized : QueryaMotion.enter,
-    );
+    final duration = context.motionDuration(QueryaMotion.standard);
+    final inCurve = context.motionCurve(QueryaMotion.enter);
     final outCurve = context.motionCurve(QueryaMotion.exit);
 
     return Stack(

lib/shared/widgets/app_dialog.dart

@@ -4,7 +4,6 @@ import 'package:flutter/material.dart';
 
 import 'package:querya_desktop/core/motion/querya_motion.dart';
 import 'package:querya_desktop/core/motion/querya_motion_context.dart';
-import 'package:querya_desktop/core/motion/querya_spring.dart';
 
 /// Shows a modal dialog with a frosted, dimmed backdrop over the app.
 ///
@@ -76,12 +75,9 @@ class _BlurredDialogScaffoldState extends State<_BlurredDialogScaffold> {
 
   void _rebuildCurved() {
     _curved?.dispose();
-    final useSpring = QueryaSpring.springsEnabled(context);
     _curved = CurvedAnimation(
       parent: widget.animation,
-      curve: context.motionCurve(
-        useSpring ? QueryaMotion.emphasized : QueryaMotion.enter,
-      ),
+      curve: context.motionCurve(QueryaMotion.enter),
       reverseCurve: context.motionCurve(QueryaMotion.exit),
     );
   }

test/core/motion/querya_fade_slide_test.dart

@@ -92,7 +92,7 @@ void main() {
     expect(find.text('a'), findsNothing);
   });
 
-  testWidgets('uses standard duration when springs enabled (full)',
+  testWidgets('uses standard/enter duration tokens (full motion)',
       (tester) async {
     await tester.pumpWidget(
       wrap(
@@ -104,10 +104,10 @@ void main() {
     final switcher =
         tester.widget<AnimatedSwitcher>(find.byType(AnimatedSwitcher));
     expect(switcher.duration, QueryaMotion.standard);
-    expect(switcher.switchInCurve, QueryaMotion.emphasized);
+    expect(switcher.switchInCurve, QueryaMotion.enter);
   });
 
-  testWidgets('uses fast duration when reduced (no springs)', (tester) async {
+  testWidgets('halves standard duration when reduced', (tester) async {
     await tester.pumpWidget(
       wrap(
         const QueryaFadeSlide(
@@ -122,7 +122,7 @@ void main() {
       switcher.duration,
       QueryaMotion.effectiveDuration(
         tester.element(find.byType(QueryaFadeSlide)),
-        QueryaMotion.fast,
+        QueryaMotion.standard,
       ),
     );
     expect(switcher.switchInCurve, QueryaMotion.enter);

test/core/motion/querya_switching_body_test.dart

@@ -228,8 +228,7 @@ void main() {
     expect(opacity.duration, QueryaMotion.instant);
   });
 
-  testWidgets('reduced motion disables springs path (fast halved)',
-      (tester) async {
+  testWidgets('halves standard duration when reduced', (tester) async {
     await tester.pumpWidget(
       wrap(
         const QueryaSwitchingBody(
@@ -246,7 +245,7 @@ void main() {
       opacity.duration,
       QueryaMotion.effectiveDuration(
         tester.element(find.byType(QueryaSwitchingBody)),
-        QueryaMotion.fast,
+        QueryaMotion.standard,
       ),
     );
   });