minor page tweaks

lib/components/calculator/calculator.dart

@@ -133,6 +133,7 @@ class _RouteCalculatorState extends State<RouteCalculator> {
   bool _loadingStations = false;
 
   RouteResult? _routeResult;
+  List<String>? _calculatedStations;
   RouteResult? get result => _routeResult;
   String? _errorMessage;
 
@@ -178,6 +179,7 @@ class _RouteCalculatorState extends State<RouteCalculator> {
     if (cleaned.length < 2) {
       setState(() {
         _routeResult = null;
+        _calculatedStations = null;
         _errorMessage = 'Add at least two stations before calculating.';
       });
       return;
@@ -185,6 +187,7 @@ class _RouteCalculatorState extends State<RouteCalculator> {
     setState(() {
       _errorMessage = null;
       _routeResult = null;
+      _calculatedStations = null;
     });
     final api = context.read<ApiService>(); // context is valid here
     try {
@@ -195,6 +198,7 @@ class _RouteCalculatorState extends State<RouteCalculator> {
       if (res is Map && res['error'] == false) {
         setState(() {
           _routeResult = RouteResult.fromJson(Map<String, dynamic>.from(res));
+          _calculatedStations = List.from(cleaned);
         });
         final distance = (_routeResult?.distance ?? 0);
         widget.onDistanceComputed?.call(distance);
@@ -205,17 +209,30 @@ class _RouteCalculatorState extends State<RouteCalculator> {
           ).msg;
         });
       } else {
-        setState(() => _errorMessage = 'Failed to calculate route.');
+        setState(() {
+          _errorMessage = 'Failed to calculate route.';
+          _calculatedStations = null;
+        });
       }
     } catch (e) {
-      setState(() => _errorMessage = 'Failed to calculate route: $e');
+      setState(() {
+        _errorMessage = 'Failed to calculate route: $e';
+        _calculatedStations = null;
+      });
     }
   }
 
+  void _markRouteDirty() {
+    _routeResult = null;
+    _calculatedStations = null;
+    _errorMessage = null;
+  }
+
   void _addStation() {
     final data = context.read<DataService>();
     setState(() {
       data.stations.add('');
+      _markRouteDirty();
     });
   }
 
@@ -223,6 +240,7 @@ class _RouteCalculatorState extends State<RouteCalculator> {
     final data = context.read<DataService>();
     setState(() {
       data.stations.removeAt(index);
+      _markRouteDirty();
     });
   }
 
@@ -230,6 +248,7 @@ class _RouteCalculatorState extends State<RouteCalculator> {
     final data = context.read<DataService>();
     setState(() {
       data.stations[index] = value;
+      _markRouteDirty();
     });
   }
 
@@ -237,14 +256,91 @@ class _RouteCalculatorState extends State<RouteCalculator> {
     final data = context.read<DataService>();
     setState(() {
       data.stations = [''];
-      _routeResult = null;
-      _errorMessage = null;
+      _markRouteDirty();
     });
   }
 
+  bool _isResultCurrent(List<String> stations) {
+    if (_routeResult == null || _calculatedStations == null) return false;
+    final cleaned = stations.where((s) => s.trim().isNotEmpty).toList();
+    if (cleaned.length != _calculatedStations!.length) return false;
+    for (var i = 0; i < cleaned.length; i++) {
+      if (cleaned[i] != _calculatedStations![i]) return false;
+    }
+    return true;
+  }
+
   @override
   Widget build(BuildContext context) {
     final data = context.watch<DataService>();
+    final isCompact = MediaQuery.of(context).size.width < 600;
+    final showApply =
+        widget.onApplyRoute != null && _isResultCurrent(data.stations);
+    final primaryPadding = EdgeInsets.symmetric(
+      horizontal: isCompact ? 14 : 20,
+      vertical: isCompact ? 10 : 14,
+    );
+    final secondaryPadding = EdgeInsets.symmetric(
+      horizontal: isCompact ? 10 : 16,
+      vertical: isCompact ? 8 : 12,
+    );
+    final primaryStyle = FilledButton.styleFrom(
+      padding: primaryPadding,
+      minimumSize: Size(0, isCompact ? 38 : 46),
+    );
+    final secondaryStyle = OutlinedButton.styleFrom(
+      padding: secondaryPadding,
+      minimumSize: Size(0, isCompact ? 34 : 42),
+    );
+
+    Widget buildSecondaryButton({
+      required IconData icon,
+      required String label,
+      required VoidCallback onPressed,
+    }) {
+      if (isCompact) {
+        return Tooltip(
+          message: label,
+          child: OutlinedButton(
+            onPressed: onPressed,
+            style: secondaryStyle,
+            child: Icon(icon, size: 20),
+          ),
+        );
+      }
+      return OutlinedButton.icon(
+        onPressed: onPressed,
+        icon: Icon(icon, size: 20),
+        label: Text(label),
+        style: secondaryStyle,
+      );
+    }
+
+    Widget buildPrimaryAction({required bool fullWidth}) {
+      final button = showApply
+          ? FilledButton.icon(
+              onPressed: () => widget.onApplyRoute!(_routeResult!),
+              icon: const Icon(Icons.check),
+              label: const Text('Apply to entry'),
+              style: primaryStyle,
+            )
+          : FilledButton.icon(
+              onPressed: () async {
+                await _calculateRoute(data.stations);
+              },
+              icon: const Icon(Icons.route),
+              label: const Text('Calculate Route'),
+              style: primaryStyle,
+            );
+      final key =
+          ValueKey<String>(showApply ? 'apply-primary-action' : 'calc-primary-action');
+      if (!fullWidth) return KeyedSubtree(key: key, child: button);
+      return KeyedSubtree(
+        key: key,
+        child: SizedBox(width: double.infinity, child: button),
+      );
+    }
+
     return Column(
       children: [
         Align(
@@ -301,6 +397,7 @@ class _RouteCalculatorState extends State<RouteCalculator> {
               setState(() {
                 final moved = data.stations.removeAt(oldIndex);
                 data.stations.insert(newIndex, moved);
+                _markRouteDirty();
               });
             },
             children: List.generate(data.stations.length, (index) {
@@ -364,56 +461,94 @@ class _RouteCalculatorState extends State<RouteCalculator> {
               context.push('/calculator/details', extra: result);
             },
           ),
-          if (widget.onApplyRoute != null)
-            Padding(
-              padding: const EdgeInsets.symmetric(horizontal: 16.0),
-              child: ElevatedButton.icon(
-                onPressed: () => widget.onApplyRoute!(_routeResult!),
-                icon: const Icon(Icons.check),
-                label: const Text('Apply to entry'),
-              ),
-            ),
         ]
         else
           SizedBox.shrink(),
         const SizedBox(height: 10),
         Padding(
           padding: const EdgeInsets.symmetric(horizontal: 16.0),
-          child: Wrap(
-            alignment: WrapAlignment.center,
-            spacing: 12,
-            runSpacing: 8,
-            children: [
-              ...(() {
-                final reverseButton = ElevatedButton.icon(
-                  icon: const Icon(Icons.swap_horiz),
-                  label: const Text('Reverse route'),
-                  onPressed: () async {
-                    setState(() {
-                      data.stations = data.stations.reversed.toList();
-                    });
-                    await _calculateRoute(data.stations);
-                  },
-                );
-                final addButton = ElevatedButton.icon(
-                  icon: const Icon(Icons.add),
-                  label: const Text('Add Station'),
-                  onPressed: _addStation,
-                );
-                final calculateButton = ElevatedButton.icon(
-                  icon: const Icon(Icons.route),
-                  label: const Text('Calculate Route'),
-                  onPressed: () async {
-                    await _calculateRoute(data.stations);
-                  },
-                );
-                final isMobile = MediaQuery.of(context).size.width < 600;
-                return isMobile
-                    ? [addButton, reverseButton, calculateButton]
-                    : [reverseButton, addButton, calculateButton];
-              })(),
-            ],
-          ),
+          child: isCompact
+              ? Column(
+                  children: [
+                    Row(
+                      mainAxisAlignment: MainAxisAlignment.center,
+                      children: [
+                        buildSecondaryButton(
+                          icon: Icons.swap_horiz,
+                          label: 'Reverse route',
+                          onPressed: () async {
+                            setState(() {
+                              data.stations = data.stations.reversed.toList();
+                            });
+                            await _calculateRoute(data.stations);
+                          },
+                        ),
+                        const SizedBox(width: 12),
+                        buildSecondaryButton(
+                          icon: Icons.add,
+                          label: 'Add station',
+                          onPressed: _addStation,
+                        ),
+                      ],
+                    ),
+                    const SizedBox(height: 10),
+                    SizedBox(
+                      width: double.infinity,
+                      child: AnimatedSwitcher(
+                        duration: const Duration(milliseconds: 220),
+                        transitionBuilder: (child, animation) {
+                          final curved = CurvedAnimation(
+                            parent: animation,
+                            curve: Curves.easeOutBack,
+                          );
+                          return ScaleTransition(
+                            scale:
+                                Tween<double>(begin: 0.94, end: 1.0).animate(curved),
+                            child: FadeTransition(opacity: animation, child: child),
+                          );
+                        },
+                      child: buildPrimaryAction(fullWidth: true),
+                    ),
+                  ),
+                ],
+                )
+              : Wrap(
+                  alignment: WrapAlignment.center,
+                  spacing: 12,
+                  runSpacing: 8,
+                  children: [
+                    buildSecondaryButton(
+                      icon: Icons.swap_horiz,
+                      label: 'Reverse route',
+                      onPressed: () async {
+                        setState(() {
+                          data.stations = data.stations.reversed.toList();
+                        });
+                        await _calculateRoute(data.stations);
+                      },
+                    ),
+                    AnimatedSwitcher(
+                      duration: const Duration(milliseconds: 220),
+                      transitionBuilder: (child, animation) {
+                        final curved = CurvedAnimation(
+                          parent: animation,
+                          curve: Curves.easeOutBack,
+                        );
+                        return ScaleTransition(
+                          scale:
+                              Tween<double>(begin: 0.94, end: 1.0).animate(curved),
+                          child: FadeTransition(opacity: animation, child: child),
+                        );
+                      },
+                      child: buildPrimaryAction(fullWidth: false),
+                    ),
+                    buildSecondaryButton(
+                      icon: Icons.add,
+                      label: 'Add station',
+                      onPressed: _addStation,
+                    ),
+                  ],
+                ),
         ),
 
         const SizedBox(height: 16),