implemented comprehensive accessibility (A11y) support across the app

lib/view/pages/talk/widgets/chat_bubble.dart

@@ -9,6 +9,7 @@ import '../../../../share_intent/remote_file_ref.dart';
 import '../../../../state/app/modules/chat/bloc/chat_bloc.dart';
 import '../../../../utils/downloads/download_job.dart';
 import '../../../../utils/haptics.dart';
+import '../../../../widget/a11y/a11y_labels.dart';
 import '../../../../widget/demo_restricted.dart';
 import '../../../../widget/downloads/download_trigger.dart';
 import '../data/chat_bubble_styles.dart';
@@ -120,9 +121,7 @@ class _ChatBubbleState extends State<ChatBubble>
     if (!_rendersAsCommentBubble) {
       base = styles.getSystemStyle();
     } else {
-      base = widget.isSender
-          ? styles.getSelfStyle()
-          : styles.getRemoteStyle();
+      base = widget.isSender ? styles.getSelfStyle() : styles.getRemoteStyle();
     }
     switch (widget.matchHighlight) {
       case SearchHighlight.none:
@@ -130,7 +129,9 @@ class _ChatBubbleState extends State<ChatBubble>
       case SearchHighlight.secondary:
         return base.copyWith(
           borderWidth: 1.5,
-          borderColor: Theme.of(context).colorScheme.primary.withValues(alpha: 0.45),
+          borderColor: Theme.of(
+            context,
+          ).colorScheme.primary.withValues(alpha: 0.45),
         );
       case SearchHighlight.active:
         return base.copyWith(
@@ -342,68 +343,72 @@ class _BubbleContent extends StatelessWidget {
   });
 
   @override
-  Widget build(BuildContext context) => Container(
-    constraints: BoxConstraints(
-      maxWidth: MediaQuery.of(context).size.width * 0.9,
-      minWidth: showActorDisplayName
-          ? actorText.size.width
-          : timeText.size.width + (isSender ? spacing + timeIconSize : 0) + 3,
-    ),
-    child: Stack(
-      children: [
-        if (showActorDisplayName) Positioned(top: 0, left: 0, child: actorWidget),
-        Padding(
-          padding: EdgeInsets.only(
-            bottom: showBubbleTime ? 18 : 0,
-            top: showActorDisplayName ? 18 : 0,
-          ),
-          child: Column(
-            crossAxisAlignment: CrossAxisAlignment.start,
-            children: [
-              if (parent != null &&
-                  bubbleData.messageType ==
-                      GetRoomResponseObjectMessageType.comment) ...[
-                AnswerReference(
-                  referenceMessage: parent!,
-                  selfId: selfId,
-                ),
-                const SizedBox(height: 5),
-              ],
-              messageWidget,
-            ],
-          ),
-        ),
-        if (showBubbleTime)
-          Positioned(
-            bottom: 0,
-            right: 0,
-            child: Row(
+  Widget build(BuildContext context) => MergeSemantics(
+    child: Container(
+      constraints: BoxConstraints(
+        maxWidth: MediaQuery.of(context).size.width * 0.9,
+        minWidth: showActorDisplayName
+            ? actorText.size.width
+            : timeText.size.width + (isSender ? spacing + timeIconSize : 0) + 3,
+      ),
+      child: Stack(
+        children: [
+          if (showActorDisplayName)
+            Positioned(top: 0, left: 0, child: actorWidget),
+          Padding(
+            padding: EdgeInsets.only(
+              bottom: showBubbleTime ? 18 : 0,
+              top: showActorDisplayName ? 18 : 0,
+            ),
+            child: Column(
+              crossAxisAlignment: CrossAxisAlignment.start,
               children: [
-                timeText,
-                if (isSender) ...[
-                  SizedBox(width: spacing),
-                  Icon(
-                    isRead ? Icons.done_all_outlined : Icons.done_outlined,
-                    size: timeIconSize,
-                    color: timeIconColor,
-                  ),
+                if (parent != null &&
+                    bubbleData.messageType ==
+                        GetRoomResponseObjectMessageType.comment) ...[
+                  AnswerReference(referenceMessage: parent!, selfId: selfId),
+                  const SizedBox(height: 5),
                 ],
+                messageWidget,
               ],
             ),
           ),
-        if (downloadJob?.status.value is DownloadInProgress)
-          Positioned(
-            bottom: 0,
-            right: 0,
-            left: 0,
-            child: LinearProgressIndicator(
-              value: () {
-                final s = downloadJob!.status.value as DownloadInProgress;
-                return s.percent <= 0 ? null : s.percent / 100;
-              }(),
+          if (showBubbleTime)
+            Positioned(
+              bottom: 0,
+              right: 0,
+              child: Row(
+                children: [
+                  timeText,
+                  if (isSender) ...[
+                    SizedBox(width: spacing),
+                    Icon(
+                      isRead ? Icons.done_all_outlined : Icons.done_outlined,
+                      size: timeIconSize,
+                      color: timeIconColor,
+                      semanticLabel: isRead
+                          ? A11yLabels.messageRead
+                          : A11yLabels.messageSent,
+                    ),
+                  ],
+                ],
+              ),
             ),
-          ),
-      ],
+          if (downloadJob?.status.value is DownloadInProgress)
+            Positioned(
+              bottom: 0,
+              right: 0,
+              left: 0,
+              child: LinearProgressIndicator(
+                semanticsLabel: A11yLabels.downloadingFile,
+                value: () {
+                  final s = downloadJob!.status.value as DownloadInProgress;
+                  return s.percent <= 0 ? null : s.percent / 100;
+                }(),
+              ),
+            ),
+        ],
+      ),
     ),
   );
 }