hardened API decoding against server fields the models did not expect

The Talk room list crashed for a new account because the server omits
lastMessage for rooms without a visible message and the model required it.
Beyond that single field, a review of the Talk models against the OpenAPI
spec of the installed version (23.0.8) found the same crash class in several
places: closed enums over open server values (inCall bitmask, rich-object
types, actor and message types), a deleted parent sent as {id, deleted},
and the autocomplete status arriving as an object.

- json_serializable `checked: true`: decode errors now name class and field
- lists (rooms, messages, participants, autocomplete) decode per entry;
  a malformed entry is skipped and reported via ClientErrorReporter
- unknownEnumValue fallbacks for all response enums of Talk and breakers
- lastMessage nullable; inCall as bitmask; deleted parent placeholder;
  autocomplete status object/string; fixed shareWithDisplayNameUnique key
- GetRoomParams no longer sends null query parameters

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HrepDTL4qDe35TuS29sLW3

lib/api/marianumcloud/talk/chat/get_chat_response.dart

@@ -2,12 +2,14 @@ import 'package:json_annotation/json_annotation.dart';
 
 import '../../../../extensions/date_time.dart';
 import '../../../api_response.dart';
+import '../../../json_lenient.dart';
 import '../room/get_room_response.dart';
 
 part 'get_chat_response.g.dart';
 
 @JsonSerializable(explicitToJson: true)
 class GetChatResponse extends ApiResponse {
+  @JsonKey(fromJson: _messagesFromJson)
   Set<GetChatResponseObject> data;
 
   GetChatResponse(this.data);
@@ -23,15 +25,20 @@ class GetChatResponse extends ApiResponse {
   }
 }
 
+Set<GetChatResponseObject> _messagesFromJson(Object? raw) =>
+    decodeSetLenient(raw, GetChatResponseObject.fromJson, what: 'message');
+
 @JsonSerializable(explicitToJson: true)
 class GetChatResponseObject {
   int id;
   String token;
+  @JsonKey(unknownEnumValue: GetRoomResponseObjectMessageActorType.unknown)
   GetRoomResponseObjectMessageActorType actorType;
   String actorId;
   String actorDisplayName;
   int timestamp;
   String systemMessage;
+  @JsonKey(unknownEnumValue: GetRoomResponseObjectMessageType.unknown)
   GetRoomResponseObjectMessageType messageType;
   bool isReplyable;
   String referenceId;
@@ -40,6 +47,11 @@ class GetChatResponseObject {
   List<String>? reactionsSelf;
   @JsonKey(fromJson: _fromJson)
   Map<String, RichObjectString>? messageParameters;
+
+  /// The quoted message. When the original is no longer available (expired,
+  /// purged) the server only sends `{id, deleted: true}`; that becomes a
+  /// deleted-comment placeholder so the quote still renders.
+  @JsonKey(fromJson: _parentFromJson)
   GetChatResponseObject? parent;
 
   /// Whether the server flagged this message to be rendered as Markdown
@@ -73,11 +85,29 @@ class GetChatResponseObject {
   /// [timestamp] is in seconds.
   DateTime get sentAt => DateTime.fromMillisecondsSinceEpoch(timestamp * 1000);
 
-  static GetChatResponseObject getDateDummy(int timestamp) =>
-      getTextDummy(
-        DateTime.fromMillisecondsSinceEpoch(
-          timestamp * 1000,
-        ).formatDateRelativeShort(),
+  static GetChatResponseObject getDateDummy(int timestamp) => getTextDummy(
+    DateTime.fromMillisecondsSinceEpoch(
+      timestamp * 1000,
+    ).formatDateRelativeShort(),
+  );
+
+  static GetChatResponseObject deletedPlaceholder(int id) =>
+      GetChatResponseObject(
+        id,
+        '',
+        GetRoomResponseObjectMessageActorType.user,
+        '',
+        '',
+        0,
+        '',
+        GetRoomResponseObjectMessageType.deletedComment,
+        false,
+        '',
+        'Nachricht wurde gelöscht',
+        null,
+        null,
+        null,
+        null,
       );
 
   static GetChatResponseObject getTextDummy(String text) =>
@@ -100,14 +130,24 @@ class GetChatResponseObject {
       );
 }
 
+GetChatResponseObject? _parentFromJson(Object? json) {
+  if (json is! Map<String, dynamic>) return null;
+  if (json['deleted'] == true) {
+    return GetChatResponseObject.deletedPlaceholder(
+      (json['id'] as num?)?.toInt() ?? 0,
+    );
+  }
+  return GetChatResponseObject.fromJson(json);
+}
+
 Map<String, RichObjectString>? _fromJson(dynamic json) {
   if (json is Map<String, dynamic>) {
     final data = <String, RichObjectString>{};
-    for (final element in json.keys) {
-      data.putIfAbsent(
-        element,
-        () => RichObjectString.fromJson(json[element] as Map<String, dynamic>),
-      );
+    for (final entry in json.entries) {
+      final value = entry.value;
+      if (value is Map<String, dynamic>) {
+        data[entry.key] = RichObjectString.fromJson(value);
+      }
     }
     return data;
   }
@@ -117,6 +157,7 @@ Map<String, RichObjectString>? _fromJson(dynamic json) {
 
 @JsonSerializable(explicitToJson: true)
 class RichObjectString {
+  @JsonKey(unknownEnumValue: RichObjectStringObjectType.unknown)
   RichObjectStringObjectType type;
   String id;
   String name;
@@ -148,4 +189,14 @@ enum RichObjectStringObjectType {
   geoLocation,
   @JsonValue('call')
   call,
+  @JsonValue('user-group')
+  userGroup,
+  @JsonValue('circle')
+  circle,
+  @JsonValue('email')
+  email,
+
+  /// Anything else (deck cards, contacts, calendar events, ...); the
+  /// placeholder still resolves to the object's name.
+  unknown,
 }