M3 Overhaul

lib/theme/app_surfaces.dart

@@ -1,22 +1,34 @@
 import 'package:flutter/material.dart';
 
+/// M3 Expressive surface tokens.
+///
+/// Cards now use **tonal elevation** (color tints) instead of drop-shadows.
+/// Large containers adopt the M3 standard 28 dp corner radius; compact items
+/// use 16 dp; small chips/badges use 12 dp.
 @immutable
 class AppSurfaces extends ThemeExtension<AppSurfaces> {
   const AppSurfaces({
     required this.cardRadius,
     required this.compactCardRadius,
+    required this.containerRadius,
     required this.dialogRadius,
-    required this.cardElevation,
-    required this.cardShadowColor,
-    required this.compactShadowColor,
+    required this.chipRadius,
   });
 
+  /// Standard card radius – 16 dp (M3 medium shape).
   final double cardRadius;
+
+  /// Compact card radius for dense list tiles – 12 dp.
   final double compactCardRadius;
+
+  /// Large container radius – 28 dp (M3 Expressive).
+  final double containerRadius;
+
+  /// Dialog / bottom-sheet radius – 28 dp.
   final double dialogRadius;
-  final double cardElevation;
-  final Color cardShadowColor;
-  final Color compactShadowColor;
+
+  /// Chip / badge radius – 12 dp.
+  final double chipRadius;
 
   // convenience shapes
   RoundedRectangleBorder get standardShape =>
@@ -24,6 +36,9 @@ class AppSurfaces extends ThemeExtension<AppSurfaces> {
   RoundedRectangleBorder get compactShape => RoundedRectangleBorder(
     borderRadius: BorderRadius.circular(compactCardRadius),
   );
+  RoundedRectangleBorder get containerShape => RoundedRectangleBorder(
+    borderRadius: BorderRadius.circular(containerRadius),
+  );
   RoundedRectangleBorder get dialogShape =>
       RoundedRectangleBorder(borderRadius: BorderRadius.circular(dialogRadius));
 
@@ -33,10 +48,9 @@ class AppSurfaces extends ThemeExtension<AppSurfaces> {
         const AppSurfaces(
           cardRadius: 16,
           compactCardRadius: 12,
-          dialogRadius: 20,
-          cardElevation: 3,
-          cardShadowColor: Color.fromRGBO(0, 0, 0, 0.12),
-          compactShadowColor: Color.fromRGBO(0, 0, 0, 0.08),
+          containerRadius: 28,
+          dialogRadius: 28,
+          chipRadius: 12,
         );
   }
 
@@ -44,18 +58,16 @@ class AppSurfaces extends ThemeExtension<AppSurfaces> {
   AppSurfaces copyWith({
     double? cardRadius,
     double? compactCardRadius,
+    double? containerRadius,
     double? dialogRadius,
-    double? cardElevation,
-    Color? cardShadowColor,
-    Color? compactShadowColor,
+    double? chipRadius,
   }) {
     return AppSurfaces(
       cardRadius: cardRadius ?? this.cardRadius,
       compactCardRadius: compactCardRadius ?? this.compactCardRadius,
+      containerRadius: containerRadius ?? this.containerRadius,
       dialogRadius: dialogRadius ?? this.dialogRadius,
-      cardElevation: cardElevation ?? this.cardElevation,
-      cardShadowColor: cardShadowColor ?? this.cardShadowColor,
-      compactShadowColor: compactShadowColor ?? this.compactShadowColor,
+      chipRadius: chipRadius ?? this.chipRadius,
     );
   }
 
@@ -63,28 +75,17 @@ class AppSurfaces extends ThemeExtension<AppSurfaces> {
   AppSurfaces lerp(ThemeExtension<AppSurfaces>? other, double t) {
     if (other is! AppSurfaces) return this;
     return AppSurfaces(
-      cardRadius: lerpDouble(cardRadius, other.cardRadius, t) ?? cardRadius,
-      compactCardRadius:
-          lerpDouble(compactCardRadius, other.compactCardRadius, t) ??
-          compactCardRadius,
-      dialogRadius:
-          lerpDouble(dialogRadius, other.dialogRadius, t) ?? dialogRadius,
-      cardElevation:
-          lerpDouble(cardElevation, other.cardElevation, t) ?? cardElevation,
-      cardShadowColor:
-          Color.lerp(cardShadowColor, other.cardShadowColor, t) ??
-          cardShadowColor,
-      compactShadowColor:
-          Color.lerp(compactShadowColor, other.compactShadowColor, t) ??
-          compactShadowColor,
+      cardRadius: _lerpDouble(cardRadius, other.cardRadius, t),
+      compactCardRadius: _lerpDouble(
+        compactCardRadius,
+        other.compactCardRadius,
+        t,
+      ),
+      containerRadius: _lerpDouble(containerRadius, other.containerRadius, t),
+      dialogRadius: _lerpDouble(dialogRadius, other.dialogRadius, t),
+      chipRadius: _lerpDouble(chipRadius, other.chipRadius, t),
     );
   }
 }
 
-// Helper because dart:ui lerpDouble isn't exported here
-double? lerpDouble(num? a, num? b, double t) {
-  if (a == null && b == null) return null;
-  a = a ?? 0;
-  b = b ?? 0;
-  return a + (b - a) * t;
-}
+double _lerpDouble(double a, double b, double t) => a + (b - a) * t;