refactor: introduce typed host runtime

app/startup/context.py

@@ -0,0 +1,78 @@
+"""宿主启动阶段构建的类型化运行时上下文。"""
+
+from collections.abc import AsyncGenerator, Generator
+from dataclasses import dataclass
+from typing import Protocol
+
+from app.application.messaging.chat import (
+    AsyncAgentChatRepository,
+    AsyncUnitOfWork,
+)
+
+
+class AgentChatRepositoryFactory(Protocol):
+    """由请求会话构造 Agent 会话仓储的工厂端口。"""
+
+    def __call__(self, session: object) -> AsyncAgentChatRepository:
+        """绑定请求会话并返回 Agent 会话仓储。"""
+        ...
+
+
+class AsyncUnitOfWorkFactory(Protocol):
+    """由请求会话构造异步事务端口的工厂。"""
+
+    def __call__(self, session: object) -> AsyncUnitOfWork:
+        """绑定请求会话并返回异步事务端口。"""
+        ...
+
+
+class AsyncSessionProvider(Protocol):
+    """FastAPI 请求级异步会话提供器。"""
+
+    def __call__(self) -> AsyncGenerator[object, None]:
+        """生成一个请求独占的异步数据库会话。"""
+        ...
+
+
+class SyncSessionProvider(Protocol):
+    """兼容 API Facade 使用的同步会话提供器。"""
+
+    def __call__(self) -> Generator[object, None, None]:
+        """生成一个请求独占的同步数据库会话。"""
+        ...
+
+
+class CompatibilityApiData(Protocol):
+    """未迁移 API 领域继续使用的结构化兼容 Facade。"""
+
+    sync_session: SyncSessionProvider
+    async_session: AsyncSessionProvider
+
+    def repository(self, name: str, session: object) -> object:
+        """按旧能力名构造请求级仓储。"""
+        ...
+
+    def standalone_repository(self, name: str) -> object:
+        """按旧能力名构造独立仓储。"""
+        ...
+
+    def transaction(self, name: str, session: object) -> object:
+        """按旧能力名构造事务端口。"""
+        ...
+
+
+@dataclass(frozen=True, slots=True)
+class AgentChatRuntime:
+    """Agent 会话 API 可见的最小数据运行时。"""
+
+    async_session: AsyncSessionProvider
+    repository: AgentChatRepositoryFactory
+    transaction: AsyncUnitOfWorkFactory
+
+
+@dataclass(frozen=True, slots=True)
+class HostRuntime:
+    """宿主组合根构建且在一个 FastAPI lifespan 内共享的运行时对象。"""
+
+    agent_chat: AgentChatRuntime
+    compatibility_api_data: CompatibilityApiData