diff --git a/Doc/IM_App_架构设计.html b/Doc/IM_App_架构设计.html
index 2793eac..8d9dde1 100644
--- a/Doc/IM_App_架构设计.html
+++ b/Doc/IM_App_架构设计.html
@@ -3205,7 +3205,13 @@ flowchart LR
 <p><strong>两大核心逻辑</strong>：</p>
 <p>1. <strong>MVVM 分层职责</strong>：View（view/）只负责渲染和用户交互，ViewModel（presentation/）持有状态并处理业务逻辑，Model（model/ + entities/）定义数据结构 —— 三者通过 Riverpod Provider 连接，职责严格分离。</p>
 <p>2. <strong>Riverpod 单向数据流</strong>：用户操作 → <code>ref.read(vm.notifier).action()</code> → ViewModel 处理逻辑 → <code>state = newState</code> → <code>ref.watch(vm)</code> 检测变化 → View 自动 rebuild。数据永远单向流动，UI 永远是状态的函数。</p>
-<p>3. <strong>Widget 纯展示原则</strong>：View（Widget）层对业务数据严格只读。所有逻辑（导航、CRUD、状态变更、条件判断）必须在 ViewModel 中完成，View 只调用 ViewModel 方法并渲染返回的 State。包括 demo/测试页面也不例外。</p>
+<p>3. <strong>Widget 纯展示原则</strong>：<code>build()</code> 只做一件事——把 State 属性映射成 Widget 树，不允许出现任何计算或逻辑。</p>
+<ul>
+<li><strong>派生显示值必须是 State getter</strong>：凡是需要从 State 字段推导出另一个值（文本、颜色、样式等），一律写成 State 的 getter，Widget 只读取结果。例如：<code>String get buttonLabel =&gt; testStarted ? '结束' : '开始';</code>，Widget 写 <code>state.buttonLabel</code>，不在 <code>build()</code> 里写三元。</li>
+<li><strong>禁止 <code>build()</code> 内定义局部计算变量</strong>：<code>final isSelected = current == mode</code> 这类从构造参数/state 派生值的局部变量，不属于 <code>build()</code>。组件应接受已算好的 <code>bool isSelected</code> 参数，由父级或 State getter 负责计算。</li>
+<li><strong>导航、CRUD、状态变更全部在 ViewModel 中完成</strong>，Widget 只转发事件：<code>onTap: () =&gt; ref.read(vm.notifier).doAction()</code>。</li>
+<li><strong>demo/测试页面同样适用</strong>：demo 代码是示范，别人会照着模仿，写法必须与正式页面完全一致。</li>
+</ul>
 </blockquote>
 
 <hr>
diff --git a/apps/im_app/lib/features/chat/presentation/.gitkeep b/apps/im_app/lib/features/chat/presentation/.gitkeep
deleted file mode 100644
index e69de29..0000000
diff --git a/apps/im_app/lib/features/chat/presentation/chat_db_test_state.dart b/apps/im_app/lib/features/chat/presentation/chat_db_test_state.dart
new file mode 100644
index 0000000..c37e5ba
--- /dev/null
+++ b/apps/im_app/lib/features/chat/presentation/chat_db_test_state.dart
@@ -0,0 +1,39 @@
+// 数据库测试页状态（Demo，正式开发后随页面一并删除）
+
+/// 单条测试结果记录
+class TestResult {
+  final String title;
+  final String subtitle;
+  final String duration;
+
+  TestResult({
+    required this.title,
+    required this.subtitle,
+    required this.duration,
+  });
+}
+
+class ChatDbTestState {
+  final bool testStarted;
+  final List<TestResult> testResults;
+  final String currentState;
+
+  const ChatDbTestState({
+    this.testStarted = false,
+    this.testResults = const [],
+    this.currentState = '',
+  });
+
+  /// 按钮文案（Widget 直接读，不在 View 层做判断）
+  String get buttonLabel => testStarted ? '结束' : '开始';
+
+  ChatDbTestState copyWith({
+    bool? testStarted,
+    List<TestResult>? testResults,
+    String? currentState,
+  }) => ChatDbTestState(
+    testStarted: testStarted ?? this.testStarted,
+    testResults: testResults ?? this.testResults,
+    currentState: currentState ?? this.currentState,
+  );
+}
diff --git a/apps/im_app/lib/features/chat/presentation/chat_db_test_view_model.dart b/apps/im_app/lib/features/chat/presentation/chat_db_test_view_model.dart
index 1abaa52..4386f91 100644
--- a/apps/im_app/lib/features/chat/presentation/chat_db_test_view_model.dart
+++ b/apps/im_app/lib/features/chat/presentation/chat_db_test_view_model.dart
@@ -6,42 +6,12 @@ import 'package:im_app/app/di/db_provider.dart';
 import 'package:im_app/data/local/drift/app_database.dart';
 import 'package:riverpod_annotation/riverpod_annotation.dart';
 
+import 'chat_db_test_state.dart';
+
+export 'chat_db_test_state.dart';
+
 part 'chat_db_test_view_model.g.dart';
 
-class TestResult {
-  final String title;
-  final String subtitle;
-  final String duration;
-
-  TestResult({
-    required this.title,
-    required this.subtitle,
-    required this.duration,
-  });
-}
-
-class ChatDbTestState {
-  final bool testStarted;
-  final List<TestResult> testResults;
-  final String currentState;
-
-  const ChatDbTestState({
-    this.testStarted = false,
-    this.testResults = const [],
-    this.currentState = '',
-  });
-
-  ChatDbTestState copyWith({
-    bool? testStarted,
-    List<TestResult>? testResults,
-    String? currentState,
-  }) => ChatDbTestState(
-    testStarted: testStarted ?? this.testStarted,
-    testResults: testResults ?? this.testResults,
-    currentState: currentState ?? this.currentState,
-  );
-}
-
 @riverpod
 class ChatDbTestViewModel extends _$ChatDbTestViewModel {
   @override
diff --git a/apps/im_app/lib/features/chat/view/chat_db_test_page.dart b/apps/im_app/lib/features/chat/view/chat_db_test_page.dart
index 95c1f01..3c8c025 100644
--- a/apps/im_app/lib/features/chat/view/chat_db_test_page.dart
+++ b/apps/im_app/lib/features/chat/view/chat_db_test_page.dart
@@ -30,7 +30,7 @@ class ChatDbTestPage extends ConsumerWidget {
               mainAxisAlignment: MainAxisAlignment.spaceBetween,
               children: [
                 AppButton.inverse(
-                  label: state.testStarted ? '结束' : '开始',
+                  label: state.buttonLabel,
                   onPressed: () => vm.toggleDBTest(),
                 ),
                 SizedBox(width: 8),
diff --git a/apps/im_app/lib/features/settings/view/theme_view.dart b/apps/im_app/lib/features/settings/view/theme_view.dart
index e3e96a9..3151cb9 100644
--- a/apps/im_app/lib/features/settings/view/theme_view.dart
+++ b/apps/im_app/lib/features/settings/view/theme_view.dart
@@ -16,32 +16,27 @@ class ThemeView extends ConsumerWidget {
     final current = ref.watch(themeViewModelProvider);
 
     return Scaffold(
-      appBar: AppBar(
-        title: const Text('主题'),
-      ),
+      appBar: AppBar(title: const Text('主题')),
       body: ListView(
         children: [
           const SettingsSectionHeader(title: '外观'),
           ThemeOptionTile(
             label: '跟随系统',
-            mode: ThemeMode.system,
-            current: current,
+            isSelected: current == ThemeMode.system,
             onTap: () => ref
                 .read(themeViewModelProvider.notifier)
                 .setMode(ThemeMode.system),
           ),
           ThemeOptionTile(
             label: '黑色模式',
-            mode: ThemeMode.dark,
-            current: current,
+            isSelected: current == ThemeMode.dark,
             onTap: () => ref
                 .read(themeViewModelProvider.notifier)
                 .setMode(ThemeMode.dark),
           ),
           ThemeOptionTile(
             label: '白色模式',
-            mode: ThemeMode.light,
-            current: current,
+            isSelected: current == ThemeMode.light,
             onTap: () => ref
                 .read(themeViewModelProvider.notifier)
                 .setMode(ThemeMode.light),
diff --git a/apps/im_app/lib/features/settings/view/widgets/theme_option_tile.dart b/apps/im_app/lib/features/settings/view/widgets/theme_option_tile.dart
index d270d9f..92b1df5 100644
--- a/apps/im_app/lib/features/settings/view/widgets/theme_option_tile.dart
+++ b/apps/im_app/lib/features/settings/view/widgets/theme_option_tile.dart
@@ -5,14 +5,13 @@ import '../../../../../core/ui/base/context_theme_ext.dart';
 /// 单个主题选项行
 ///
 /// 纯展示 + 事件透传，不感知任何 Provider。
-/// 由父级传入 [current] 判断选中状态，[onTap] 处理切换。
+/// 父级传入 [isSelected] 决定是否显示勾选图标，[onTap] 处理切换。
 ///
 /// 用法：
 /// ```dart
 /// ThemeOptionTile(
 ///   label: '黑色模式',
-///   mode: ThemeMode.dark,
-///   current: current,
+///   isSelected: current == ThemeMode.dark,
 ///   onTap: () => ref.read(themeViewModelProvider.notifier).setMode(ThemeMode.dark),
 /// )
 /// ```
@@ -20,20 +19,17 @@ class ThemeOptionTile extends StatelessWidget {
   const ThemeOptionTile({
     super.key,
     required this.label,
-    required this.mode,
-    required this.current,
+    required this.isSelected,
     required this.onTap,
   });
 
   final String label;
-  final ThemeMode mode;
-  final ThemeMode current;
+  final bool isSelected;
   final VoidCallback onTap;
 
   @override
   Widget build(BuildContext context) {
     final s = context.styles;
-    final isSelected = current == mode;
 
     return ListTile(
       title: Text(label),