add timeline

lib/components/calculator/calculator.dart

@@ -97,10 +97,16 @@ class _StationAutocompleteState extends State<StationAutocomplete> {
 }
 
 class RouteCalculator extends StatefulWidget {
-  const RouteCalculator({super.key, this.onDistanceComputed, this.onApplyRoute});
+  const RouteCalculator({
+    super.key,
+    this.onDistanceComputed,
+    this.onApplyRoute,
+    this.initialStations,
+  });
 
   final ValueChanged<double>? onDistanceComputed;
   final ValueChanged<RouteResult>? onApplyRoute;
+  final List<String>? initialStations;
 
   @override
   State<RouteCalculator> createState() => _RouteCalculatorState();
@@ -122,6 +128,9 @@ class _RouteCalculatorState extends State<RouteCalculator> {
     super.didChangeDependencies();
     if (!_fetched) {
       _fetched = true;
+      if (widget.initialStations != null && widget.initialStations!.isNotEmpty) {
+        context.read<DataService>().stations = List.from(widget.initialStations!);
+      }
       WidgetsBinding.instance.addPostFrameCallback((_) async {
         final data = context.read<DataService>();
         final result = await data.fetchStations();

lib/components/pages/legs.dart

@@ -1,6 +1,7 @@
 import 'dart:convert';
 
 import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
 import 'package:mileograph_flutter/objects/objects.dart';
 import 'package:mileograph_flutter/services/dataService.dart';
 import 'package:provider/provider.dart';
@@ -279,6 +280,11 @@ class _LegsPageState extends State<LegsPage> {
         trailing: Column(
           mainAxisAlignment: MainAxisAlignment.center,
           children: [
+            IconButton(
+              tooltip: 'Edit entry',
+              icon: const Icon(Icons.edit),
+              onPressed: () => context.push('/legs/edit/${leg.id}'),
+            ),
             Text(
               '${leg.mileage.toStringAsFixed(1)} mi',
               style:

lib/components/pages/loco_timeline.dart

@@ -0,0 +1,544 @@
+import 'package:flutter/material.dart';
+import 'package:intl/intl.dart';
+import 'package:mileograph_flutter/objects/objects.dart';
+import 'package:mileograph_flutter/services/dataService.dart';
+import 'package:provider/provider.dart';
+
+class LocoTimelinePage extends StatefulWidget {
+  const LocoTimelinePage({
+    super.key,
+    required this.locoId,
+    required this.locoLabel,
+  });
+
+  final int locoId;
+  final String locoLabel;
+
+  @override
+  State<LocoTimelinePage> createState() => _LocoTimelinePageState();
+}
+
+class _LocoTimelinePageState extends State<LocoTimelinePage> {
+  @override
+  void initState() {
+    super.initState();
+    WidgetsBinding.instance.addPostFrameCallback((_) => _load());
+  }
+
+  Future<void> _load() {
+    return context.read<DataService>().fetchLocoTimeline(widget.locoId);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final data = context.watch<DataService>();
+    final timeline = data.timelineForLoco(widget.locoId);
+    final isLoading = data.isLocoTimelineLoading(widget.locoId);
+
+    return Scaffold(
+      appBar: AppBar(
+        leading: IconButton(
+          icon: const Icon(Icons.arrow_back),
+          onPressed: () => Navigator.of(context).maybePop(),
+        ),
+        title: Text('Timeline · ${widget.locoLabel}'),
+      ),
+      body: RefreshIndicator(
+        onRefresh: _load,
+        child: ListView(
+          padding: const EdgeInsets.all(16),
+          physics: const AlwaysScrollableScrollPhysics(),
+          children: [
+            Text(
+              'Attribute timeline',
+              style: Theme.of(context).textTheme.titleLarge?.copyWith(
+                    fontWeight: FontWeight.w800,
+                  ),
+            ),
+            const SizedBox(height: 6),
+            Text(
+              'Each row is an attribute. Blocks stretch between change dates; scroll sideways for history.',
+              style: Theme.of(context).textTheme.bodyMedium,
+            ),
+            const SizedBox(height: 16),
+            if (isLoading && timeline.isEmpty)
+              const Padding(
+                padding: EdgeInsets.symmetric(vertical: 32.0),
+                child: Center(child: CircularProgressIndicator()),
+              )
+            else if (timeline.isEmpty)
+              Card(
+                child: Padding(
+                  padding: const EdgeInsets.all(16.0),
+                  child: Column(
+                    crossAxisAlignment: CrossAxisAlignment.start,
+                    children: [
+                      Text(
+                        'No timeline data yet',
+                        style: Theme.of(context).textTheme.titleMedium?.copyWith(
+                              fontWeight: FontWeight.w700,
+                            ),
+                      ),
+                      const SizedBox(height: 8),
+                      const Text(
+                        'This locomotive does not have any attribute history to show right now.',
+                      ),
+                      const SizedBox(height: 12),
+                      OutlinedButton.icon(
+                        onPressed: _load,
+                        icon: const Icon(Icons.refresh),
+                        label: const Text('Try again'),
+                      ),
+                    ],
+                  ),
+                ),
+              )
+            else
+              _TimelineGrid(entries: timeline),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+class _TimelineGrid extends StatelessWidget {
+  const _TimelineGrid({required this.entries});
+
+  final List<LocoAttrVersion> entries;
+
+  @override
+  Widget build(BuildContext context) {
+    final model = _TimelineModel.fromEntries(entries);
+    final axisSegments = model.axisSegments;
+    const labelWidth = 150.0;
+    const rowHeight = 52.0;
+
+    return Column(
+      crossAxisAlignment: CrossAxisAlignment.start,
+      mainAxisSize: MainAxisSize.min,
+      children: [
+        Scrollbar(
+          thumbVisibility: true,
+          child: SingleChildScrollView(
+            scrollDirection: Axis.horizontal,
+            child: IntrinsicWidth(
+              child: Column(
+                crossAxisAlignment: CrossAxisAlignment.start,
+                mainAxisSize: MainAxisSize.min,
+                children: [
+                  _AxisRow(
+                    labelWidth: labelWidth,
+                    segments: axisSegments,
+                    endLabel: model.endLabel,
+                  ),
+                  const SizedBox(height: 8),
+                  ...model.attrRows.entries.map(
+                    (entry) => Padding(
+                      padding: const EdgeInsets.symmetric(vertical: 2.0),
+                      child: _AttrRow(
+                        labelWidth: labelWidth,
+                        rowHeight: rowHeight,
+                        attrLabel: _formatAttrLabel(entry.key),
+                        cells: entry.value,
+                        segments: axisSegments,
+                      ),
+                    ),
+                  ),
+                ],
+              ),
+            ),
+          ),
+        ),
+        const SizedBox(height: 14),
+        Text(
+          'Dates mark when a value changed. The right edge of the last block is “Now” if no end date is present.',
+          style: Theme.of(context).textTheme.labelMedium,
+        ),
+      ],
+    );
+  }
+}
+
+class _AxisRow extends StatelessWidget {
+  const _AxisRow({
+    required this.labelWidth,
+    required this.segments,
+    required this.endLabel,
+  });
+
+  final double labelWidth;
+  final List<_AxisSegment> segments;
+  final String endLabel;
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    return Row(
+      crossAxisAlignment: CrossAxisAlignment.start,
+      mainAxisSize: MainAxisSize.min,
+      children: [
+        SizedBox(
+          width: labelWidth,
+          height: 36,
+          child: Align(
+            alignment: Alignment.centerLeft,
+            child: Text(
+              'Date',
+              style: theme.textTheme.labelLarge?.copyWith(
+                fontWeight: FontWeight.w700,
+              ),
+            ),
+          ),
+        ),
+        ...segments.asMap().entries.map(
+          (entry) {
+            final i = entry.key;
+            final seg = entry.value;
+            final isLast = i == segments.length - 1;
+            return SizedBox(
+              width: seg.width,
+              height: 36,
+              child: Stack(
+                children: [
+                  Align(
+                    alignment: Alignment.centerLeft,
+                    child: Text(
+                      seg.label,
+                      style: theme.textTheme.labelSmall,
+                    ),
+                  ),
+                  if (isLast)
+                    Align(
+                      alignment: Alignment.centerRight,
+                      child: Text(
+                        endLabel,
+                        style: theme.textTheme.labelSmall,
+                      ),
+                    ),
+                ],
+              ),
+            );
+          },
+        ),
+      ],
+    );
+  }
+}
+
+class _AttrRow extends StatelessWidget {
+  const _AttrRow({
+    required this.labelWidth,
+    required this.rowHeight,
+    required this.attrLabel,
+    required this.cells,
+    required this.segments,
+  });
+
+  final double labelWidth;
+  final double rowHeight;
+  final String attrLabel;
+  final List<_RowCell> cells;
+  final List<_AxisSegment> segments;
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    return Row(
+      crossAxisAlignment: CrossAxisAlignment.center,
+      mainAxisSize: MainAxisSize.min,
+      children: [
+        Container(
+          width: labelWidth,
+          height: rowHeight,
+          padding: const EdgeInsets.symmetric(horizontal: 10),
+          alignment: Alignment.centerLeft,
+          decoration: BoxDecoration(
+            color: theme.colorScheme.surfaceContainerHighest,
+            borderRadius: BorderRadius.circular(10),
+          ),
+          child: Text(
+            attrLabel,
+            style: theme.textTheme.labelLarge?.copyWith(
+              fontWeight: FontWeight.w700,
+            ),
+          ),
+        ),
+        ...segments.asMap().entries.map((entry) {
+          final idx = entry.key;
+          final seg = entry.value;
+          final cell = cells[idx];
+          final hasValue = cell.value.isNotEmpty;
+          final textColor = ThemeData.estimateBrightnessForColor(
+                    cell.color.withOpacity(0.9),
+                  ) ==
+                  Brightness.dark
+              ? Colors.white
+              : Colors.black87;
+          return Container(
+            width: seg.width,
+            height: rowHeight,
+            padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 8),
+            decoration: BoxDecoration(
+              color: hasValue
+                  ? cell.color.withOpacity(0.9)
+                  : theme.colorScheme.surfaceContainerHighest,
+              borderRadius: BorderRadius.circular(12),
+              border: Border.all(
+                color: theme.colorScheme.outlineVariant,
+              ),
+            ),
+            child: hasValue
+                ? Column(
+                    crossAxisAlignment: CrossAxisAlignment.start,
+                    mainAxisAlignment: MainAxisAlignment.center,
+                    children: [
+                      Text(
+                        cell.value,
+                        maxLines: 1,
+                        overflow: TextOverflow.ellipsis,
+                        style: theme.textTheme.bodyMedium?.copyWith(
+                              fontWeight: FontWeight.w700,
+                              color: textColor,
+                            ) ??
+                            TextStyle(
+                              fontWeight: FontWeight.w700,
+                              color: textColor,
+                            ),
+                      ),
+                      const SizedBox(height: 4),
+                      Text(
+                        cell.rangeLabel,
+                        maxLines: 1,
+                        overflow: TextOverflow.ellipsis,
+                        style: theme.textTheme.labelSmall?.copyWith(
+                              color: textColor.withOpacity(0.9),
+                            ) ??
+                            TextStyle(color: textColor.withOpacity(0.9)),
+                      ),
+                    ],
+                  )
+                : const SizedBox.shrink(),
+          );
+        }),
+      ],
+    );
+  }
+}
+
+final DateFormat _dateFormat = DateFormat('yyyy-MM-dd');
+
+String? _formatDate(DateTime? date) {
+  if (date == null) return null;
+  return _dateFormat.format(date);
+}
+
+String _formatAttrLabel(String code) {
+  if (code.isEmpty) return 'Attribute';
+  final parts = code.split('_').where((p) => p.isNotEmpty).toList();
+  if (parts.isEmpty) return code;
+  return parts
+      .map((part) => part.length == 1
+          ? part.toUpperCase()
+          : part[0].toUpperCase() + part.substring(1))
+      .join(' ');
+}
+
+DateTime? _parseDateString(String? value) {
+  if (value == null || value.isEmpty) return null;
+  return DateTime.tryParse(value);
+}
+
+DateTime? _effectiveStart(LocoAttrVersion entry) {
+  return entry.validFrom ??
+      _parseDateString(entry.maskedValidFrom) ??
+      entry.txnFrom;
+}
+
+DateTime _safeEnd(DateTime start, DateTime? end) {
+  if (end == null || !end.isAfter(start)) {
+    return start.add(const Duration(days: 1));
+  }
+  return end;
+}
+
+class _TimelineModel {
+  final List<_AxisSegment> axisSegments;
+  final Map<String, List<_RowCell>> attrRows;
+  final String endLabel;
+
+  _TimelineModel({
+    required this.axisSegments,
+    required this.attrRows,
+    required this.endLabel,
+  });
+
+  factory _TimelineModel.fromEntries(List<LocoAttrVersion> entries) {
+    final grouped = <String, List<LocoAttrVersion>>{};
+    for (final entry in entries) {
+      grouped.putIfAbsent(entry.attrCode, () => []).add(entry);
+    }
+    final now = DateTime.now();
+    DateTime? minStart;
+    DateTime? maxEnd;
+    final attrSegments = <String, List<_ValueSegment>>{};
+
+    grouped.forEach((attr, items) {
+      items.sort(
+        (a, b) => (_effectiveStart(a) ?? now)
+            .compareTo(_effectiveStart(b) ?? now),
+      );
+      final segments = <_ValueSegment>[];
+      for (int i = 0; i < items.length; i++) {
+        final entry = items[i];
+        final start = _effectiveStart(entry) ?? now;
+        final nextStart = i < items.length - 1
+            ? _effectiveStart(items[i + 1])
+            : null;
+        final rawEnd = entry.validTo ?? nextStart ?? now;
+        final end = _safeEnd(start, rawEnd);
+        segments.add(
+          _ValueSegment(
+            start: start,
+            end: end,
+            value: entry.valueLabel,
+            entry: entry,
+          ),
+        );
+        minStart = minStart == null || start.isBefore(minStart!)
+            ? start
+            : minStart;
+        maxEnd = maxEnd == null || end.isAfter(maxEnd!) ? end : maxEnd;
+      }
+      attrSegments[attr] = segments;
+    });
+
+    minStart ??= now.subtract(const Duration(days: 1));
+    maxEnd ??= now;
+
+    final boundaryDates = <DateTime>{};
+    for (final segments in attrSegments.values) {
+      for (final seg in segments) {
+        boundaryDates.add(seg.start);
+      }
+    }
+    boundaryDates.add(maxEnd);
+    var boundaries = boundaryDates.toList()..sort();
+    if (boundaries.length < 2) {
+      boundaries = [minStart!, maxEnd];
+    }
+
+    final axisSegments = <_AxisSegment>[];
+    const pxPerDay = 4.0;
+    for (int i = 0; i < boundaries.length - 1; i++) {
+      final start = boundaries[i];
+      final end = boundaries[i + 1];
+      final days = (end.difference(start).inDays).clamp(1, 365);
+      final width = (days * pxPerDay) + 30;
+      axisSegments.add(
+        _AxisSegment(
+          start: start,
+          end: end,
+          width: width,
+          label: _formatDate(start) ?? '',
+        ),
+      );
+    }
+
+    final attrRows = <String, List<_RowCell>>{};
+    for (final entry in attrSegments.entries) {
+      final cells = <_RowCell>[];
+      for (final axis in axisSegments) {
+        final seg = entry.value
+            .firstWhere(
+              (s) => s.overlaps(axis.start, axis.end),
+              orElse: () => _ValueSegment.empty(axis.start, axis.end),
+            );
+        cells.add(_RowCell.fromSegment(seg));
+      }
+      attrRows[entry.key] = cells;
+    }
+
+    final endLabel = _formatDate(maxEnd) ?? 'Now';
+    return _TimelineModel(
+      axisSegments: axisSegments,
+      attrRows: attrRows,
+      endLabel: endLabel,
+    );
+  }
+}
+
+class _AxisSegment {
+  final DateTime start;
+  final DateTime end;
+  final double width;
+  final String label;
+
+  _AxisSegment({
+    required this.start,
+    required this.end,
+    required this.width,
+    required this.label,
+  });
+}
+
+class _ValueSegment {
+  final DateTime start;
+  final DateTime end;
+  final String value;
+  final LocoAttrVersion? entry;
+
+  _ValueSegment({
+    required this.start,
+    required this.end,
+    required this.value,
+    this.entry,
+  });
+
+  factory _ValueSegment.empty(DateTime start, DateTime end) => _ValueSegment(
+        start: start,
+        end: end,
+        value: '',
+        entry: null,
+      );
+
+  bool overlaps(DateTime s, DateTime e) {
+    return start.isBefore(e) && end.isAfter(s);
+  }
+}
+
+class _RowCell {
+  final String value;
+  final String rangeLabel;
+  final Color color;
+
+  const _RowCell({
+    required this.value,
+    required this.rangeLabel,
+    required this.color,
+  });
+
+  factory _RowCell.fromSegment(_ValueSegment seg) {
+    if (seg.value.isEmpty) {
+      return const _RowCell(
+        value: '',
+        rangeLabel: '',
+        color: Colors.transparent,
+      );
+    }
+    final displayStart = _formatDate(seg.start) ?? '';
+    final displayEnd = _formatDate(seg.entry?.validTo ?? seg.end) ?? 'Now';
+    final range = '$displayStart → $displayEnd';
+    return _RowCell(
+      value: seg.value,
+      rangeLabel: range,
+      color: _colorForValue(seg.value),
+    );
+  }
+}
+
+Color _colorForValue(String value) {
+  final hue = (value.hashCode % 360).toDouble();
+  final hsl = HSLColor.fromAHSL(1, hue, 0.55, 0.55);
+  return hsl.toColor();
+}

lib/components/pages/traction.dart

@@ -574,6 +574,12 @@ class _TractionPageState extends State<TractionPage> {
                   icon: const Icon(Icons.info_outline),
                   label: const Text('Details'),
                 ),
+                const SizedBox(width: 8),
+                TextButton.icon(
+                  onPressed: () => _openTimeline(loco),
+                  icon: const Icon(Icons.timeline),
+                  label: const Text('Timeline'),
+                ),
                 const Spacer(),
                 if (widget.selectionMode)
                   TextButton.icon(
@@ -692,6 +698,14 @@ class _TractionPageState extends State<TractionPage> {
     return (background, foreground);
   }
 
+  void _openTimeline(LocoSummary loco) {
+    final label = '${loco.locoClass} ${loco.number}'.trim();
+    context.push(
+      '/traction/${loco.id}/timeline',
+      extra: {'label': label},
+    );
+  }
+
   Future<void> _showLocoInfo(LocoSummary loco) async {
     await showModalBottomSheet(
       context: context,

lib/components/pages/trips.dart

@@ -301,6 +301,25 @@ class _TripsPageState extends State<TripsPage> {
                       ],
                     ),
                     const SizedBox(height: 8),
+                    if (!loading && items.isNotEmpty) ...[
+                      Wrap(
+                        spacing: 8,
+                        runSpacing: 8,
+                        children: [
+                          Chip(
+                            avatar: const Icon(Icons.train, size: 16),
+                            label: Text('Total had: ${items.length}'),
+                          ),
+                          Chip(
+                            avatar: const Icon(Icons.star, size: 16),
+                            label: Text(
+                              'Winners: ${items.where((e) => e.won == true).length}',
+                            ),
+                          ),
+                        ],
+                      ),
+                      const SizedBox(height: 8),
+                    ],
                     if (loading)
                       const Center(
                         child: Padding(

lib/main.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:dynamic_color/dynamic_color.dart';
 import 'package:mileograph_flutter/components/pages/calculator.dart';
+import 'package:mileograph_flutter/components/pages/loco_timeline.dart';
 import 'package:mileograph_flutter/components/pages/new_entry.dart';
 import 'package:mileograph_flutter/components/pages/new_traction.dart';
 import 'package:mileograph_flutter/components/pages/traction.dart';
@@ -11,6 +12,7 @@ import 'package:mileograph_flutter/components/pages/legs.dart';
 import 'package:mileograph_flutter/services/apiService.dart';
 import 'package:mileograph_flutter/services/authservice.dart';
 import 'package:mileograph_flutter/services/dataService.dart';
+import 'package:mileograph_flutter/services/navigation_guard.dart';
 
 import 'components/login/login.dart';
 import 'components/pages/dashboard.dart';
@@ -94,12 +96,41 @@ class MyApp extends StatelessWidget {
             ),
             GoRoute(path: '/legs', builder: (_, __) => LegsPage()),
             GoRoute(path: '/traction', builder: (_, __) => TractionPage()),
+            GoRoute(
+              path: '/traction/:id/timeline',
+              builder: (_, state) {
+                final idParam = state.pathParameters['id'];
+                final locoId = int.tryParse(idParam ?? '') ?? 0;
+                final extra = state.extra;
+                String label = state.uri.queryParameters['label'] ?? '';
+                if (extra is Map && extra['label'] is String) {
+                  label = extra['label'] as String;
+                } else if (extra is String && extra.isNotEmpty) {
+                  label = extra;
+                }
+                if (label.trim().isEmpty) {
+                  label = 'Loco $locoId';
+                }
+                return LocoTimelinePage(
+                  locoId: locoId,
+                  locoLabel: label,
+                );
+              },
+            ),
             GoRoute(
               path: '/traction/new',
               builder: (_, __) => const NewTractionPage(),
             ),
             GoRoute(path: '/trips', builder: (_, __) => TripsPage()),
             GoRoute(path: '/add', builder: (_, __) => NewEntryPage()),
+            GoRoute(
+              path: '/legs/edit/:id',
+              builder: (_, state) {
+                final idParam = state.pathParameters['id'];
+                final legId = idParam == null ? null : int.tryParse(idParam);
+                return NewEntryPage(editLegId: legId);
+              },
+            ),
           ],
         ),
         GoRoute(path: '/login', builder: (_, __) => const LoginScreen()),
@@ -180,12 +211,14 @@ class _MyHomePageState extends State<MyHomePage> {
     return newIndex;
   }
 
-  void _onItemTapped(int index, int currentIndex) {
+  Future<void> _onItemTapped(int index, int currentIndex) async {
     if (index < 0 || index >= contentPages.length || index == currentIndex) {
       return;
     }
-    context.push(contentPages[index]);
+    await NavigationGuard.attemptNavigation(() async {
-    _getIndexFromLocation(contentPages[index]);
+      if (!mounted) return;
+      context.go(contentPages[index]);
+    });
   }
 
   bool loggedIn = false;

lib/objects/objects.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import 'package:intl/intl.dart';
 
 class DestinationObject {
   const DestinationObject(
@@ -190,6 +191,143 @@ class LocoSummary extends Loco {
   );
 }
 
+class LocoAttrVersion {
+  final String attrCode;
+  final int? versionId;
+  final int locoId;
+  final int? attrTypeId;
+  final String? valueStr;
+  final int? valueInt;
+  final DateTime? valueDate;
+  final bool? valueBool;
+  final String? valueEnum;
+  final DateTime? validFrom;
+  final DateTime? validTo;
+  final DateTime? txnFrom;
+  final DateTime? txnTo;
+  final String? suggestedBy;
+  final String? approvedBy;
+  final DateTime? approvedAt;
+  final int? sourceEventId;
+  final String? precisionLevel;
+  final String? maskedValidFrom;
+  final dynamic valueNorm;
+
+  const LocoAttrVersion({
+    required this.attrCode,
+    required this.locoId,
+    this.versionId,
+    this.attrTypeId,
+    this.valueStr,
+    this.valueInt,
+    this.valueDate,
+    this.valueBool,
+    this.valueEnum,
+    this.validFrom,
+    this.validTo,
+    this.txnFrom,
+    this.txnTo,
+    this.suggestedBy,
+    this.approvedBy,
+    this.approvedAt,
+    this.sourceEventId,
+    this.precisionLevel,
+    this.maskedValidFrom,
+    this.valueNorm,
+  });
+
+  factory LocoAttrVersion.fromJson(Map<String, dynamic> json) {
+    return LocoAttrVersion(
+      attrCode: json['attr_code']?.toString() ?? '',
+      locoId: (json['loco_id'] as num?)?.toInt() ?? 0,
+      versionId: (json['loco_attr_v_id'] as num?)?.toInt(),
+      attrTypeId: (json['attr_type_id'] as num?)?.toInt(),
+      valueStr: json['value_str']?.toString(),
+      valueInt: (json['value_int'] as num?)?.toInt(),
+      valueDate: _parseDate(json['value_date']),
+      valueBool: _parseBool(json['value_bool']),
+      valueEnum: json['value_enum']?.toString(),
+      validFrom: _parseDate(json['valid_from']),
+      validTo: _parseDate(json['valid_to']),
+      txnFrom: _parseDate(json['txn_from']),
+      txnTo: _parseDate(json['txn_to']),
+      suggestedBy: json['suggested_by']?.toString(),
+      approvedBy: json['approved_by']?.toString(),
+      approvedAt: _parseDate(json['approved_at']),
+      sourceEventId: (json['source_event_id'] as num?)?.toInt(),
+      precisionLevel: json['precision_level']?.toString(),
+      maskedValidFrom: json['masked_valid_from']?.toString(),
+      valueNorm: json['value_norm'],
+    );
+  }
+
+  static DateTime? _parseDate(dynamic value) {
+    if (value == null) return null;
+    if (value is DateTime) return value;
+    return DateTime.tryParse(value.toString());
+  }
+
+  static bool? _parseBool(dynamic value) {
+    if (value == null) return null;
+    if (value is bool) return value;
+    if (value is num) return value != 0;
+    final str = value.toString().toLowerCase();
+    if (['true', '1', 'yes'].contains(str)) return true;
+    if (['false', '0', 'no'].contains(str)) return false;
+    return null;
+  }
+
+  static List<LocoAttrVersion> fromGroupedJson(dynamic json) {
+    final List<LocoAttrVersion> items = [];
+    if (json is Map) {
+      json.forEach((key, value) {
+        if (value is List) {
+          for (final entry in value) {
+            if (entry is Map<String, dynamic>) {
+              final merged = Map<String, dynamic>.from(entry);
+              merged.putIfAbsent('attr_code', () => key);
+              items.add(LocoAttrVersion.fromJson(merged));
+            }
+          }
+        }
+      });
+    }
+    items.sort(
+      (a, b) {
+        final aDate = a.validFrom ?? a.txnFrom ?? DateTime.fromMillisecondsSinceEpoch(0);
+        final bDate = b.validFrom ?? b.txnFrom ?? DateTime.fromMillisecondsSinceEpoch(0);
+        final dateCompare = aDate.compareTo(bDate);
+        if (dateCompare != 0) return dateCompare;
+        return a.attrCode.compareTo(b.attrCode);
+      },
+    );
+    return items;
+  }
+
+  String get valueLabel {
+    if (valueStr != null && valueStr!.isNotEmpty) return valueStr!;
+    if (valueEnum != null && valueEnum!.isNotEmpty) return valueEnum!;
+    if (valueInt != null) return valueInt!.toString();
+    if (valueBool != null) return valueBool! ? 'Yes' : 'No';
+    if (valueDate != null) return DateFormat('yyyy-MM-dd').format(valueDate!);
+    if (valueNorm != null && valueNorm.toString().isNotEmpty) {
+      return valueNorm.toString();
+    }
+    return '—';
+  }
+
+  String get validityRange {
+    final start = maskedValidFrom ?? _formatDate(validFrom) ?? 'Unknown';
+    final end = _formatDate(validTo, fallback: 'Present') ?? 'Present';
+    return '$start → $end';
+  }
+
+  String? _formatDate(DateTime? value, {String? fallback}) {
+    if (value == null) return fallback;
+    return DateFormat('yyyy-MM-dd').format(value);
+  }
+}
+
 class LeaderboardEntry {
   final String userId, username, userFullName;
   final double mileage;

lib/services/dataService.dart

@@ -49,6 +49,12 @@ class DataService extends ChangeNotifier {
   bool get isTractionLoading => _isTractionLoading;
   bool _tractionHasMore = false;
   bool get tractionHasMore => _tractionHasMore;
+  final Map<int, List<LocoAttrVersion>> _locoTimelines = {};
+  final Map<int, bool> _isLocoTimelineLoading = {};
+  List<LocoAttrVersion> timelineForLoco(int locoId) =>
+      _locoTimelines[locoId] ?? [];
+  bool isLocoTimelineLoading(int locoId) =>
+      _isLocoTimelineLoading[locoId] ?? false;
 
   // Trips
   List<TripSummary> _trips = [];
@@ -235,6 +241,24 @@ class DataService extends ChangeNotifier {
     }
   }
 
+  Future<List<LocoAttrVersion>> fetchLocoTimeline(int locoId) async {
+    _isLocoTimelineLoading[locoId] = true;
+    _notifyAsync();
+    try {
+      final json = await api.get('/loco/get-timeline/$locoId');
+      final timeline = LocoAttrVersion.fromGroupedJson(json);
+      _locoTimelines[locoId] = timeline;
+      return timeline;
+    } catch (e) {
+      debugPrint('Failed to fetch loco timeline for $locoId: $e');
+      _locoTimelines[locoId] = [];
+      return [];
+    } finally {
+      _isLocoTimelineLoading[locoId] = false;
+      _notifyAsync();
+    }
+  }
+
   Future<dynamic> createLoco(Map<String, dynamic> payload) async {
     try {
       final response = await api.put('/loco/new', payload);
@@ -424,6 +448,8 @@ class DataService extends ChangeNotifier {
     _trips = [];
     _tripDetails = [];
     _eventFields = [];
+    _locoTimelines.clear();
+    _isLocoTimelineLoading.clear();
     _notifyAsync();
   }
 

lib/services/navigation_guard.dart

@@ -0,0 +1,40 @@
+typedef NavigationGuardCallback = Future<bool> Function();
+
+class NavigationGuard {
+  static NavigationGuardCallback? _callback;
+
+  static void register(NavigationGuardCallback callback) {
+    _callback = callback;
+  }
+
+  static void unregister(NavigationGuardCallback callback) {
+    if (_callback == callback) {
+      _callback = null;
+    }
+  }
+
+  static Future<void> attemptNavigation(
+    Future<void> Function() performNavigation,
+  ) async {
+    if (_promptActive) return;
+    final cb = _callback;
+    if (cb == null) {
+      await performNavigation();
+      return;
+    }
+    _promptActive = true;
+    bool allow = false;
+    try {
+      allow = await cb();
+    } catch (_) {
+      allow = false;
+    } finally {
+      _promptActive = false;
+    }
+    if (allow) {
+      await performNavigation();
+    }
+  }
+
+  static bool _promptActive = false;
+}

pubspec.yaml

@@ -16,7 +16,7 @@ publish_to: "none" # Remove this line if you wish to publish to pub.dev
 # https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
 # In Windows, build-name is used as the major, minor, and patch parts
 # of the product and file versions while build-number is used as the build suffix.
-version: 0.1.3+1
+version: 0.1.6+1
 
 environment:
   sdk: ^3.8.1