docs(apps): 添加 Home 首页消息加载与滚动规则

apps/AGENTS.md

@@ -152,3 +152,29 @@ Auth is a global module. All auth/session behavior MUST follow a single state ma
   - session invalidation -> unauthenticated redirect path
 
 If a new auth-related requirement cannot fit this model, update this section first, then implement code.
+
+## 10) Home Message Loading & Scroll Rules (MUST)
+
+Home 首页历史消息加载与滚动策略属于高回归模块，必须遵循以下约束：
+
+- **MUST** use event-driven viewport decisions for Home message list behavior.
+  - Use `HomeMessageViewportController` as the decision engine.
+  - **MUST NOT** drive auto-scroll directly from `items.length` diffs or ad-hoc boolean combinations.
+- **MUST** distinguish semantic events at minimum:
+  - initial history loaded
+  - history prepend start/finish
+  - new message appended
+  - sub-route resume
+  - refresh completed
+  - user scroll state changed
+- **MUST** preserve reading position when user is away from bottom.
+  - New messages while reading history should show unread indicator instead of forcing bottom jump.
+- **MUST** preserve viewport anchor during history prepend.
+  - **MUST NOT** mix prepend restore with unconditional bottom auto-scroll.
+- **MUST** use `returnToHomePreserveState` for business-subroute returns to Home (calendar/todo/message-related flows).
+  - **MUST NOT** introduce new direct business-route `go('/home')` shortcuts.
+  - Auth entry flows (login/register success) are allowed to navigate to Home directly.
+- **MUST** add or update tests when touching Home message loading/scroll behavior:
+  - controller-level state transition tests
+  - widget-level unread indicator and scroll behavior tests
+  - route-return stability tests when navigation behavior changes