Remote sync of webdav

lib/models/fuel_entry.dart

@@ -1,6 +1,10 @@
 class FuelEntry {
   final String id;
+
+  /// References [Vehicle.id] (the hidden, immutable identifier) — not the
+  /// VIN, which is user-editable and so unsuitable as a foreign key.
   final String vehicleId;
+
   final DateTime date;
   final double gallons;
   final double pricePerGallon;
@@ -26,16 +30,21 @@ class FuelEntry {
     this.deletedAt,
   });
 
-  /// True once the receipt photo has been uploaded to Drive and the local
-  /// copy removed. Viewing it then requires downloading it on demand.
-  bool get isReceiptUploadedToDrive =>
-      receiptImagePath == null && receiptDriveFileId != null;
+  /// True once the receipt photo has been uploaded to Drive, regardless of
+  /// whether a local copy is also being kept (see the "keep photos on this
+  /// phone" setting). Viewing it locally is preferred when a local copy
+  /// exists; otherwise it requires downloading from Drive on demand.
+  bool get isReceiptUploadedToDrive => receiptDriveFileId != null;
 
-  /// True while a receipt photo exists only locally and still needs to be
-  /// uploaded next sync. A row in this state is never pushed to Drive as-is
-  /// (a local file path is meaningless on another device) — sync uploads
-  /// the image first, which clears this.
-  bool get hasPendingLocalReceipt => receiptImagePath != null;
+  /// True while a receipt photo still needs to be uploaded to Drive: a
+  /// local file exists but hasn't made it there yet. Once
+  /// [receiptDriveFileId] is set this is false — even if a local copy is
+  /// also being kept — since that field alone is what marks "no longer
+  /// needs uploading", independent of local retention. A row in this state
+  /// is never pushed to Drive as data (a local file path is meaningless on
+  /// another device) — sync uploads the image first, which sets
+  /// [receiptDriveFileId] and clears this.
+  bool get needsReceiptUpload => receiptImagePath != null && receiptDriveFileId == null;
 
   FuelEntry copyWith({
     String? receiptImagePath,

lib/models/vehicle.dart

@@ -1,9 +1,19 @@
 class Vehicle {
+  /// Hidden, immutable, generated primary key — never shown in the UI and
+  /// never editable. This is what fuel entries actually reference and what
+  /// sync merges on, so that [vin] itself is free to be edited without
+  /// breaking those references or losing sync history.
   final String id;
-  final String make;
-  final String model;
-  final String color;
-  final String licensePlate;
+
+  /// The vehicle's identification number. Required and must be unique
+  /// among active (non-deleted) vehicles, but — unlike [id] — the user can
+  /// edit it later (e.g. to fix a typo from a misread VIN scan).
+  final String vin;
+
+  /// User-chosen label, e.g. "Mom's Car" or "Red Ford F-150". Optional —
+  /// when absent, screens fall back to other identifying info instead.
+  final String? nickname;
+
   final DateTime updatedAt;
 
   /// Soft-delete tombstone: null means active. Deleting sets this instead
@@ -15,30 +25,35 @@ class Vehicle {
 
   Vehicle({
     required this.id,
-    required this.make,
-    required this.model,
-    required this.color,
-    required this.licensePlate,
+    required this.vin,
     required this.updatedAt,
+    this.nickname,
     this.deletedAt,
   });
 
-  String get displayName => '$color $make $model ($licensePlate)';
+  /// What screens should show as the vehicle's primary label: the nickname
+  /// if one was given, otherwise the VIN itself.
+  String get displayLabel {
+    final trimmedNickname = nickname?.trim();
+    if (trimmedNickname != null && trimmedNickname.isNotEmpty) {
+      return trimmedNickname;
+    }
+    return vin;
+  }
 
+  /// Note: [id] is intentionally not overridable here — it's the hidden
+  /// identifier, not an editable field.
   Vehicle copyWith({
-    String? make,
-    String? model,
-    String? color,
-    String? licensePlate,
+    String? vin,
+    String? nickname,
+    bool clearNickname = false,
     DateTime? updatedAt,
     DateTime? deletedAt,
   }) {
     return Vehicle(
       id: id,
-      make: make ?? this.make,
-      model: model ?? this.model,
-      color: color ?? this.color,
-      licensePlate: licensePlate ?? this.licensePlate,
+      vin: vin ?? this.vin,
+      nickname: clearNickname ? null : (nickname ?? this.nickname),
       updatedAt: updatedAt ?? this.updatedAt,
       deletedAt: deletedAt ?? this.deletedAt,
     );
@@ -46,20 +61,16 @@ class Vehicle {
 
   Map<String, Object?> toMap() => {
         'id': id,
-        'make': make,
-        'model': model,
-        'color': color,
-        'license_plate': licensePlate,
+        'vin': vin,
+        'nickname': nickname,
         'updated_at': updatedAt.millisecondsSinceEpoch,
         'deleted_at': deletedAt?.millisecondsSinceEpoch,
       };
 
   factory Vehicle.fromMap(Map<String, Object?> map) => Vehicle(
         id: map['id'] as String,
-        make: map['make'] as String,
-        model: map['model'] as String,
-        color: map['color'] as String,
-        licensePlate: map['license_plate'] as String,
+        vin: map['vin'] as String,
+        nickname: map['nickname'] as String?,
         updatedAt: DateTime.fromMillisecondsSinceEpoch(map['updated_at'] as int, isUtc: true),
         deletedAt: map['deleted_at'] != null
             ? DateTime.fromMillisecondsSinceEpoch(map['deleted_at'] as int, isUtc: true)