implemented a customizable chat background system with support for patterns, solid colors, and gallery images; added a dedicated settings page with live preview and adjustable blur/dim effects, updated the image cropper to support flexible aspect ratios for wallpapers, and integrated file cleanup logic during account logout.

lib/storage/chat_background_settings.dart

@@ -0,0 +1,46 @@
+import 'package:json_annotation/json_annotation.dart';
+
+part 'chat_background_settings.g.dart';
+
+/// Source of the chat background.
+/// * [pattern] — the bundled tiled asset (legacy default, dark-mode inverted)
+/// * [image] — a user-picked image stored at [AppPaths.chatBackgroundImage]
+/// * [color] — a single solid colour ([ChatBackgroundSettings.colorValue])
+/// * [none] — plain theme surface colour
+enum ChatBackgroundType { pattern, image, color, none }
+
+/// How [ChatBackgroundType.pattern]/[ChatBackgroundType.image] fill the area.
+enum ChatBackgroundFit { cover, tile, center }
+
+@JsonSerializable()
+class ChatBackgroundSettings {
+  ChatBackgroundType type;
+  ChatBackgroundFit fit;
+
+  /// ARGB colour for [ChatBackgroundType.color]; null until the user picks one.
+  int? colorValue;
+
+  /// Monotonically increasing cache-buster. The image lives under a constant
+  /// filename, so Flutter's [ImageCache] can't tell a replacement apart — this
+  /// counter drives a [ValueKey] that forces a fresh subtree after a swap.
+  int imageVersion;
+
+  /// Strength of the black dim overlay drawn above the background (0..1).
+  double dim;
+
+  /// Gaussian blur sigma applied to the pattern/image layer (0..~25).
+  double blur;
+
+  ChatBackgroundSettings({
+    required this.type,
+    required this.fit,
+    required this.colorValue,
+    required this.imageVersion,
+    required this.dim,
+    required this.blur,
+  });
+
+  factory ChatBackgroundSettings.fromJson(Map<String, dynamic> json) =>
+      _$ChatBackgroundSettingsFromJson(json);
+  Map<String, dynamic> toJson() => _$ChatBackgroundSettingsToJson(this);
+}

lib/storage/chat_background_settings.g.dart

@@ -0,0 +1,42 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'chat_background_settings.dart';
+
+// **************************************************************************
+// JsonSerializableGenerator
+// **************************************************************************
+
+ChatBackgroundSettings _$ChatBackgroundSettingsFromJson(
+  Map<String, dynamic> json,
+) => ChatBackgroundSettings(
+  type: $enumDecode(_$ChatBackgroundTypeEnumMap, json['type']),
+  fit: $enumDecode(_$ChatBackgroundFitEnumMap, json['fit']),
+  colorValue: (json['colorValue'] as num?)?.toInt(),
+  imageVersion: (json['imageVersion'] as num).toInt(),
+  dim: (json['dim'] as num).toDouble(),
+  blur: (json['blur'] as num).toDouble(),
+);
+
+Map<String, dynamic> _$ChatBackgroundSettingsToJson(
+  ChatBackgroundSettings instance,
+) => <String, dynamic>{
+  'type': _$ChatBackgroundTypeEnumMap[instance.type]!,
+  'fit': _$ChatBackgroundFitEnumMap[instance.fit]!,
+  'colorValue': instance.colorValue,
+  'imageVersion': instance.imageVersion,
+  'dim': instance.dim,
+  'blur': instance.blur,
+};
+
+const _$ChatBackgroundTypeEnumMap = {
+  ChatBackgroundType.pattern: 'pattern',
+  ChatBackgroundType.image: 'image',
+  ChatBackgroundType.color: 'color',
+  ChatBackgroundType.none: 'none',
+};
+
+const _$ChatBackgroundFitEnumMap = {
+  ChatBackgroundFit.cover: 'cover',
+  ChatBackgroundFit.tile: 'tile',
+  ChatBackgroundFit.center: 'center',
+};

lib/storage/settings.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:json_annotation/json_annotation.dart';
 
+import 'chat_background_settings.dart';
 import 'dev_tools_settings.dart';
 import 'file_settings.dart';
 import 'file_view_settings.dart';
@@ -22,6 +23,7 @@ class Settings {
   ModulesSettings modulesSettings;
   TimetableSettings timetableSettings;
   TalkSettings talkSettings;
+  ChatBackgroundSettings chatBackgroundSettings;
   FileSettings fileSettings;
   HolidaysSettings holidaysSettings;
   FileViewSettings fileViewSettings;
@@ -35,6 +37,7 @@ class Settings {
     required this.modulesSettings,
     required this.timetableSettings,
     required this.talkSettings,
+    required this.chatBackgroundSettings,
     required this.fileSettings,
     required this.holidaysSettings,
     required this.fileViewSettings,

lib/storage/settings.g.dart

@@ -18,6 +18,9 @@ Settings _$SettingsFromJson(Map<String, dynamic> json) => Settings(
   talkSettings: TalkSettings.fromJson(
     json['talkSettings'] as Map<String, dynamic>,
   ),
+  chatBackgroundSettings: ChatBackgroundSettings.fromJson(
+    json['chatBackgroundSettings'] as Map<String, dynamic>,
+  ),
   fileSettings: FileSettings.fromJson(
     json['fileSettings'] as Map<String, dynamic>,
   ),
@@ -44,6 +47,7 @@ Map<String, dynamic> _$SettingsToJson(Settings instance) => <String, dynamic>{
   'modulesSettings': instance.modulesSettings.toJson(),
   'timetableSettings': instance.timetableSettings.toJson(),
   'talkSettings': instance.talkSettings.toJson(),
+  'chatBackgroundSettings': instance.chatBackgroundSettings.toJson(),
   'fileSettings': instance.fileSettings.toJson(),
   'holidaysSettings': instance.holidaysSettings.toJson(),
   'fileViewSettings': instance.fileViewSettings.toJson(),