diff --git a/backend/app/schemas/_types.py b/backend/app/schemas/_types.py
new file mode 100644
index 0000000..4db3fee
--- /dev/null
+++ b/backend/app/schemas/_types.py
@@ -0,0 +1,22 @@
+from datetime import datetime, timezone
+from typing import Annotated
+
+from pydantic import PlainSerializer
+
+
+def _to_utc_iso(v: datetime | None) -> str | None:
+    if v is None:
+        return None
+    if v.tzinfo is None:
+        v = v.replace(tzinfo=timezone.utc)
+    else:
+        v = v.astimezone(timezone.utc)
+    return v.isoformat().replace("+00:00", "Z")
+
+
+# 数据库里存的是 datetime.utcnow() 产出的 naive UTC。裸 ISO 字符串
+# 会被 JS new Date(...) 当本地时间解析, 少 8 小时。统一序列化为带 Z 的
+# UTC ISO, 前端/小程序拿到后 new Date(...) 会正确转成本地时区。
+UtcDatetime = Annotated[
+    datetime, PlainSerializer(_to_utc_iso, return_type=str, when_used="json")
+]
diff --git a/backend/app/schemas/audit.py b/backend/app/schemas/audit.py
index 1bb31ef..437fac8 100644
--- a/backend/app/schemas/audit.py
+++ b/backend/app/schemas/audit.py
@@ -1,7 +1,7 @@
-from datetime import datetime
-
 from pydantic import BaseModel
 
+from ._types import UtcDatetime
+
 
 class AuditLogResponse(BaseModel):
     id: int
@@ -10,7 +10,7 @@ class AuditLogResponse(BaseModel):
     target_type: str | None
     target_id: str | None
     detail_json: dict | None
-    created_at: datetime
+    created_at: UtcDatetime
 
 
 class StatsOverviewResponse(BaseModel):
diff --git a/backend/app/schemas/chat.py b/backend/app/schemas/chat.py
index 64e2f84..6cc12f3 100644
--- a/backend/app/schemas/chat.py
+++ b/backend/app/schemas/chat.py
@@ -1,7 +1,7 @@
-from datetime import datetime
-
 from pydantic import BaseModel, Field
 
+from ._types import UtcDatetime
+
 
 class ConversationCreate(BaseModel):
     title: str = "新会话"
@@ -10,8 +10,8 @@ class ConversationCreate(BaseModel):
 class ConversationResponse(BaseModel):
     id: int
     title: str
-    created_at: datetime
-    last_message_at: datetime | None
+    created_at: UtcDatetime
+    last_message_at: UtcDatetime | None
 
 
 class ChatStreamRequest(BaseModel):
@@ -42,7 +42,7 @@ class MessageResponse(BaseModel):
     status: str
     token_usage: int
     pu_usage: int
-    created_at: datetime
+    created_at: UtcDatetime
     references: list[ReferenceResponse]
     attachments: list[AttachmentResponse] = Field(default_factory=list)
 
diff --git a/backend/app/schemas/document.py b/backend/app/schemas/document.py
index 5008971..7537300 100644
--- a/backend/app/schemas/document.py
+++ b/backend/app/schemas/document.py
@@ -1,7 +1,7 @@
-from datetime import datetime
-
 from pydantic import BaseModel, Field
 
+from ._types import UtcDatetime
+
 
 class DocumentCreate(BaseModel):
     title: str = Field(min_length=1, max_length=255)
@@ -31,4 +31,4 @@ class DocumentResponse(BaseModel):
     status: str
     owner_dept: str | None
     tags: list[str]
-    created_at: datetime
+    created_at: UtcDatetime
diff --git a/backend/app/schemas/user.py b/backend/app/schemas/user.py
index 4f079a7..d08b005 100644
--- a/backend/app/schemas/user.py
+++ b/backend/app/schemas/user.py
@@ -1,7 +1,7 @@
-from datetime import datetime
-
 from pydantic import BaseModel, Field
 
+from ._types import UtcDatetime
+
 
 class UserCreate(BaseModel):
     phone: str = Field(min_length=6, max_length=32)
@@ -34,7 +34,7 @@ class UserResponse(BaseModel):
     status: str
     role_codes: list[str]
     is_superuser: bool
-    created_at: datetime | None = None
+    created_at: UtcDatetime | None = None
 
 
 class BulkImportResult(BaseModel):
diff --git a/frontend/src/styles/main.css b/frontend/src/styles/main.css
index 6d21878..60d7a70 100644
--- a/frontend/src/styles/main.css
+++ b/frontend/src/styles/main.css
@@ -835,16 +835,6 @@ button {
   white-space: nowrap;
 }
 
-/* 共享文档 (ref.source_url 存在) 时, 标题变成蓝色外链, 悬停加下划线 */
-.bubble-reference-item summary .ref-title-link {
-  color: #1a73e8;
-  text-decoration: none;
-  cursor: pointer;
-}
-.bubble-reference-item summary .ref-title-link:hover {
-  text-decoration: underline;
-}
-
 /* 展开区域内的链接地址行, 显示完整 URL, 蓝色字, 可换行 */
 .bubble-reference-item .ref-url-line {
   display: block;
diff --git a/frontend/src/views/ChatView.vue b/frontend/src/views/ChatView.vue
index abebd0e..b81961d 100644
--- a/frontend/src/views/ChatView.vue
+++ b/frontend/src/views/ChatView.vue
@@ -302,7 +302,7 @@ watch(messages, scrollToEnd, { deep: true })
                     @click="onBubbleClick"
                   />
                   <div v-if="msg.references && msg.references.length" class="bubble-references">
-                    <div class="bubble-references-title">参考知识片段</div>
+                    <div class="bubble-references-title">参考来源</div>
                     <div class="bubble-references-body">
                       <details
                         v-for="(ref, rIdx) in msg.references"
@@ -311,15 +311,7 @@ watch(messages, scrollToEnd, { deep: true })
                       >
                         <summary>
                           <span class="ref-icon">📄</span>
-                          <a
-                            v-if="ref.source_url"
-                            :href="ref.source_url"
-                            target="_blank"
-                            rel="noopener noreferrer"
-                            class="ref-title ref-title-link"
-                            @click.stop
-                          >{{ rIdx + 1 }}.{{ ref.source_title || '未知来源' }}</a>
-                          <span v-else class="ref-title">{{ rIdx + 1 }}.{{ ref.source_title || '未知来源' }}</span>
+                          <span class="ref-title">{{ rIdx + 1 }}.{{ ref.source_title || '未知来源' }}</span>
                           <small v-if="ref.page_no" class="ref-page">第 {{ ref.page_no }} 页</small>
                           <span class="ref-arrow">›</span>
                         </summary>