fix(llc): keep reaction group while its count stays positive

packages/stream_chat/CHANGELOG.md

@@ -22,6 +22,8 @@
 - Fixed `Channel.name`/`image`/`extraData` setters throwing after a *failed* initialization; they now only throw once the channel is successfully initialized.
 - Fixed `Channel.initialized` staying errored after a failed init; it now reflects a subsequent successful (re)initialization.
 - Fixed a `StateError` (`Cannot add new events after calling close`) thrown when the client is disposed while a reconnect recovery is still in flight.
+- Fixed `Message.deleteMyReaction` dropping an entire reaction group when its summed scores reached zero even though other users' reactions kept the count positive; the group is now retained as long as its count stays above zero.
+- Fixed reaction groups synthesized from legacy `reaction_counts`/`reaction_scores` payloads being discarded at parse time when their score total was zero or negative despite a positive count.
 
 ## 10.2.0
 

packages/stream_chat/lib/src/core/models/message.dart

@@ -172,7 +172,8 @@ class Message extends Equatable implements ComparableFieldProvider {
       final count = reactionCounts?[type] ?? 0;
       final sumScores = reactionScores?[type] ?? 0;
 
-      if (count == 0 || sumScores == 0) continue;
+      // Keep the group while count is positive; score may be zero or negative.
+      if (count <= 0) continue;
       final now = DateTime.timestamp();
       groups[type] = {
         'count': count,
@@ -1025,11 +1026,11 @@ extension MessageReactionHelper on Message {
       final group = reactionGroups.remove(type);
       if (group == null) continue;
 
-      // Update the reaction group.
+      // Keep the group while count is positive; score may be zero or negative.
       final updatedCount = group.count - 1;
       final updatedSumScores = group.sumScores - reaction.score;
 
-      if (updatedCount > 0 && updatedSumScores > 0) {
+      if (updatedCount > 0) {
         reactionGroups[type] = group.copyWith(
           count: updatedCount,
           sumScores: updatedSumScores,

packages/stream_chat/test/src/core/models/message_reaction_helper_test.dart

@@ -361,6 +361,51 @@ void main() {
         // Should have updated the reaction group counts
         expect(updatedMessage.reactionGroups, isEmpty);
       });
+
+      test('should keep reaction group with non-positive score sum while '
+          'count remains positive', () {
+        // A positively-scored own reaction and a negatively-scored reaction
+        // from another user net the group score to zero while count is 2.
+        final ownReaction = Reaction(
+          type: 'like',
+          score: 1,
+          user: testUser,
+          userId: testUser.id,
+          messageId: emptyMessage.id,
+        );
+
+        final otherUser = User(id: 'other-user-id');
+        final otherReaction = Reaction(
+          type: 'like',
+          score: -1,
+          user: otherUser,
+          userId: otherUser.id,
+          messageId: emptyMessage.id,
+        );
+
+        final messageWithReactions = emptyMessage.copyWith(
+          ownReactions: [ownReaction],
+          latestReactions: [ownReaction, otherReaction],
+          reactionGroups: {
+            'like': ReactionGroup(
+              count: 2,
+              sumScores: 0,
+              firstReactionAt: ownReaction.createdAt,
+              lastReactionAt: otherReaction.createdAt,
+            ),
+          },
+        );
+
+        final updatedMessage = messageWithReactions.deleteMyReaction();
+
+        // The group must survive because another user's reaction remains, even
+        // though the remaining summed score is negative.
+        expect(updatedMessage.reactionGroups!.length, 1);
+        expect(updatedMessage.reactionGroups!['like']!.count, 1);
+        expect(updatedMessage.reactionGroups!['like']!.sumScores, -1);
+        expect(updatedMessage.latestReactions!.length, 1);
+        expect(updatedMessage.latestReactions!.first.userId, otherUser.id);
+      });
     });
   });
 }

packages/stream_chat/test/src/core/models/message_test.dart

@@ -520,6 +520,25 @@ void main() {
           expect(message.reactionGroups!['love']!.sumScores, 5);
         },
       );
+
+      test(
+        'synthesizes groups from legacy reaction_counts/reaction_scores '
+        'even when the score total is zero or negative',
+        () {
+          final message = Message.fromJson(const {
+            'reaction_counts': {'like': 2, 'dislike': 3},
+            'reaction_scores': {'like': 0, 'dislike': -3},
+          });
+
+          // Both groups must be retained because their count is positive, even
+          // though the summed scores are zero and negative respectively.
+          expect(message.reactionGroups, isNotNull);
+          expect(message.reactionGroups!['like']!.count, 2);
+          expect(message.reactionGroups!['like']!.sumScores, 0);
+          expect(message.reactionGroups!['dislike']!.count, 3);
+          expect(message.reactionGroups!['dislike']!.sumScores, -3);
+        },
+      );
     });
   });