refactor: 重构聊天模块支持 SSE 断线重连及用户上下文隔离

apps/lib/features/home/presentation/widgets/home_chat_item_renderer.dart

@@ -10,14 +10,15 @@ import '../../../../core/utils/tool_name_localizer.dart';
 import '../../../../shared/widgets/app_loading_indicator.dart';
 import '../../../../shared/widgets/ui_schema/ui_schema_renderer.dart';
 
-const _messagePaddingH = 13.0;
-const _messagePaddingV = 9.0;
-const _cornerRadius = 12.0;
-const _attachmentPreviewSize = 88.0;
-const _attachmentPreviewRadius = 10.0;
-const _attachmentPreviewGap = 8.0;
-const _toolResultWidthFactor = 0.9;
-const _iconSize = 24.0;
+const _messageMaxWidthFactor = 0.82;
+const _messagePaddingH = AppSpacing.md;
+const _messagePaddingV = AppSpacing.sm;
+const _cornerRadius = AppRadius.lg;
+const _attachmentPreviewSize = AppSpacing.xxl * 3 + AppSpacing.xs;
+const _attachmentPreviewRadius = AppRadius.md;
+const _attachmentPreviewGap = AppSpacing.sm;
+const _toolResultWidthFactor = 0.88;
+const _iconSize = AppSpacing.xxl;
 
 class HomeChatItemRenderer {
   static Widget build(BuildContext context, ChatListItem item) {
@@ -34,6 +35,8 @@ class HomeChatItemRenderer {
   static Widget _buildMessageItem(BuildContext context, TextMessageItem item) {
     final colorScheme = Theme.of(context).colorScheme;
     final isUser = item.sender == MessageSender.user;
+    final maxMessageWidth =
+        MediaQuery.sizeOf(context).width * _messageMaxWidthFactor;
     final imageAttachments = _collectRenderableImageAttachments(
       item.attachments,
     );
@@ -49,7 +52,8 @@ class HomeChatItemRenderer {
               : MainAxisAlignment.start,
           crossAxisAlignment: CrossAxisAlignment.start,
           children: [
-            Flexible(
+            ConstrainedBox(
+              constraints: BoxConstraints(maxWidth: maxMessageWidth),
               child: Container(
                 padding: const EdgeInsets.symmetric(
                   horizontal: _messagePaddingH,
@@ -58,21 +62,24 @@ class HomeChatItemRenderer {
                 decoration: BoxDecoration(
                   color: isUser
                       ? colorScheme.primaryContainer
-                      : colorScheme.surface,
+                      : colorScheme.surfaceContainerLow,
                   borderRadius: BorderRadius.only(
                     topLeft: const Radius.circular(_cornerRadius),
                     topRight: const Radius.circular(_cornerRadius),
                     bottomLeft: Radius.circular(isUser ? _cornerRadius : 0),
                     bottomRight: Radius.circular(isUser ? 0 : _cornerRadius),
                   ),
-                  border: isUser
-                      ? null
-                      : Border.all(color: colorScheme.outlineVariant),
+                  border: Border.all(
+                    color: isUser
+                        ? colorScheme.primary.withValues(alpha: 0.12)
+                        : colorScheme.outlineVariant,
+                  ),
                 ),
                 child: Text(
                   item.content,
                   style: TextStyle(
-                    fontSize: 14,
+                    fontSize: AppSpacing.md,
+                    height: 1.45,
                     color: isUser
                         ? colorScheme.onPrimaryContainer
                         : colorScheme.onSurface,
@@ -302,6 +309,7 @@ class HomeChatItemRenderer {
         : null;
     final needsOuterCard = appearance == null || appearance == 'plain';
     final schemaContent = UiSchemaRenderer(
+      context,
       colorScheme,
     ).renderSchema(item.uiSchema);
     final wrappedContent = needsOuterCard
@@ -309,9 +317,11 @@ class HomeChatItemRenderer {
             width: double.infinity,
             padding: const EdgeInsets.all(AppSpacing.md),
             decoration: BoxDecoration(
-              color: colorScheme.surface,
+              color: colorScheme.surfaceContainerLow.withValues(alpha: 0.65),
               borderRadius: BorderRadius.circular(AppRadius.lg),
-              border: Border.all(color: colorScheme.outlineVariant),
+              border: Border.all(
+                color: colorScheme.outlineVariant.withValues(alpha: 0.25),
+              ),
             ),
             child: schemaContent,
           )