diff --git a/mobile/apps/photos/lib/models/similar_files.dart b/mobile/apps/photos/lib/models/similar_files.dart
index ee946c499a..eadbc34cb1 100644
--- a/mobile/apps/photos/lib/models/similar_files.dart
+++ b/mobile/apps/photos/lib/models/similar_files.dart
@@ -1,18 +1,21 @@
+import "dart:convert";
+
 import "package:photos/models/file/file.dart";
+import "package:photos/services/search_service.dart";
 
 class SimilarFiles {
   final List<EnteFile> files;
   final Set<int> fileIds;
-  final double furthestDistance;
+  double furthestDistance;
 
   SimilarFiles(
     this.files,
     this.furthestDistance,
-  )      : fileIds = files.map((file) => file.uploadedFileID!).toSet();
+  ) : fileIds = files.map((file) => file.uploadedFileID!).toSet();
 
-  int get totalSize =>
-      files.fold(0, (sum, file) => sum + (file.fileSize ?? 0));
+  int get totalSize => files.fold(0, (sum, file) => sum + (file.fileSize ?? 0));
 
+  // TODO: lau: check if we're not using this wrong
   bool get isEmpty => files.isEmpty;
 
   int get length => files.length;
@@ -26,7 +29,125 @@ class SimilarFiles {
     fileIds.remove(file.uploadedFileID);
   }
 
+  void addFile(EnteFile file) {
+    files.add(file);
+    fileIds.add(file.uploadedFileID!);
+  }
+
   bool containsFile(EnteFile file) {
     return fileIds.contains(file.uploadedFileID);
   }
+
+  Map<String, dynamic> toJson() {
+    return {
+      'fileIDs': fileIds.toList(),
+      'distance': furthestDistance,
+    };
+  }
+
+  String toJsonString() {
+    return jsonEncode(toJson());
+  }
+
+  factory SimilarFiles.fromJson(
+    Map<String, dynamic> json,
+    Map<int, EnteFile> fileMap,
+  ) {
+    final fileIds = List<int>.from(json['fileIDs']);
+    final furthestDistance = json['distance'].toDouble();
+
+    final files = <EnteFile>[];
+    for (final fileId in fileIds) {
+      final file = fileMap[fileId];
+      if (file == null) continue;
+      files.add(file);
+    }
+
+    return SimilarFiles(
+      files,
+      furthestDistance,
+    );
+  }
+
+  static SimilarFiles fromJsonString(
+    String jsonString,
+    Map<int, EnteFile> fileMap,
+  ) {
+    return SimilarFiles.fromJson(jsonDecode(jsonString), fileMap);
+  }
+}
+
+class SimilarFilesCache {
+  final List<String> similarFilesJsonStringList;
+  final Set<int> allCheckedFileIDs;
+  final double distanceThreshold;
+  final bool exact;
+
+  List<SimilarFiles>? _similarFilesList;
+
+  /// Milliseconds since epoch
+  final int cachedTime;
+
+  SimilarFilesCache({
+    required this.similarFilesJsonStringList,
+    required this.allCheckedFileIDs,
+    required this.distanceThreshold,
+    required this.exact,
+    required this.cachedTime,
+  });
+
+  Future<List<SimilarFiles>> similarFilesList() async {
+    final allFiles = await SearchService.instance.getAllFilesForSearch();
+    final fileMap = <int, EnteFile>{};
+    for (final file in allFiles) {
+      if (file.uploadedFileID == null) continue;
+      fileMap[file.uploadedFileID!] = file;
+    }
+    _similarFilesList ??= similarFilesJsonStringList.map((jsonString) {
+      return SimilarFiles.fromJson(jsonDecode(jsonString), fileMap);
+    }).toList();
+    return _similarFilesList!;
+  }
+
+  Future<Set<int>> getGroupedFileIDs() async {
+    final similarFiles = await similarFilesList();
+    final groupedFileIDs = <int>{};
+    for (final files in similarFiles) {
+      groupedFileIDs.addAll(files.fileIds);
+    }
+    return groupedFileIDs;
+  }
+
+  factory SimilarFilesCache.fromJson(
+    Map<String, dynamic> json,
+  ) {
+    return SimilarFilesCache(
+      similarFilesJsonStringList:
+          json['similarFilesJsonStringList'] as List<String>,
+      allCheckedFileIDs: Set.from(json['allCheckedFileIDs']),
+      distanceThreshold: json['distanceThreshold'] as double,
+      exact: json['exact'] as bool,
+      cachedTime: json['cachedTime'] as int,
+    );
+  }
+
+  Map<String, dynamic> toJson() {
+    return {
+      'similarFilesJsonStringList': similarFilesJsonStringList,
+      'allCheckedFileIDs': allCheckedFileIDs.toList(),
+      'distanceThreshold': distanceThreshold,
+      'exact': exact,
+      'cachedTime': cachedTime,
+    };
+  }
+
+  static String encodeToJsonString(SimilarFilesCache cache) {
+    return jsonEncode(cache.toJson());
+  }
+
+  static SimilarFilesCache decodeFromJsonString(
+    String jsonString,
+  ) {
+    return SimilarFilesCache.fromJson(jsonDecode(jsonString));
+  }
 }