fix(coding-teacher): restore context and read project files

src/pages/Chat/TeacherChatPanel.tsx

@@ -225,7 +225,7 @@ export function TeacherChatPanel({
         <div className="min-w-0 flex-1">
           <h2 className="truncate text-sm font-semibold">{definition?.name ?? '编程老师'}</h2>
           <p className="text-xs text-muted-foreground">
-            {draftRevision ? '运营草稿试聊' : '结合当前编程会话答疑'}
+            {draftRevision ? '运营草稿试聊' : '结合当前会话和项目文件答疑'}
           </p>
         </div>
         <button
@@ -298,6 +298,11 @@ export function TeacherChatPanel({
                 本轮上下文已省略 {request.omittedMessages} 条较早消息。
               </p>
             )}
+            {(request.truncatedMessages ?? 0) > 0 && (
+              <p className="text-xs text-muted-foreground">
+                {draftRevision ? '较长的上下文已节选。' : '较长的上下文已节选，老师可按需读取原文。'}
+              </p>
+            )}
             {request.error && <p className="text-xs text-destructive">{request.error}</p>}
             {request.response && (
               <div className="flex gap-3 text-xs text-muted-foreground">