refactor: introduce typed host runtime

app/api/context.py

@@ -0,0 +1,48 @@
+"""从 FastAPI AppState 读取类型化宿主能力。"""
+
+from collections.abc import AsyncGenerator
+from typing import cast
+
+from fastapi import Depends, Request
+
+from app.application.messaging.chat import AsyncAgentChatRepository, AsyncUnitOfWork
+from app.startup.context import AgentChatRuntime, HostRuntime
+
+
+def get_host_runtime(request: Request) -> HostRuntime:
+    """返回当前 lifespan 挂载的宿主运行时。"""
+    runtime = getattr(request.app.state, "host_runtime", None)
+    if not isinstance(runtime, HostRuntime):
+        raise RuntimeError("HostRuntime 尚未由启动组合根装配")
+    return runtime
+
+
+def get_agent_chat_runtime(
+    runtime: HostRuntime = Depends(get_host_runtime),
+) -> AgentChatRuntime:
+    """从完整宿主运行时收窄到 Agent 会话能力。"""
+    return runtime.agent_chat
+
+
+async def get_agent_chat_session(
+    runtime: AgentChatRuntime = Depends(get_agent_chat_runtime),
+) -> AsyncGenerator[object, None]:
+    """从类型化 Agent 会话运行时生成请求独占会话。"""
+    async for session in runtime.async_session():
+        yield session
+
+
+def get_agent_chat_repository(
+    session: object = Depends(get_agent_chat_session),
+    runtime: AgentChatRuntime = Depends(get_agent_chat_runtime),
+) -> AsyncAgentChatRepository:
+    """构造绑定当前请求会话的 Agent 会话仓储。"""
+    return cast(AsyncAgentChatRepository, runtime.repository(session))
+
+
+def get_agent_chat_transaction(
+    session: object = Depends(get_agent_chat_session),
+    runtime: AgentChatRuntime = Depends(get_agent_chat_runtime),
+) -> AsyncUnitOfWork:
+    """构造绑定当前请求会话的 Agent 会话事务端口。"""
+    return cast(AsyncUnitOfWork, runtime.transaction(session))