refactor: govern background tasks and query ownership

app/api/context.py

@@ -22,6 +22,7 @@ from app.startup.context import (
     HostRuntime,
     SubscriptionRuntime,
 )
+from app.runtime.tasks import TaskRegistry, get_task_registry
 
 
 def get_host_runtime(request: Request) -> HostRuntime:
@@ -32,6 +33,20 @@ def get_host_runtime(request: Request) -> HostRuntime:
     return runtime
 
 
+def get_background_task_registry(
+    runtime: HostRuntime = Depends(get_host_runtime),
+) -> TaskRegistry:
+    """返回当前 lifespan 统一管理的后台任务登记器。"""
+    return runtime.tasks
+
+
+def resolve_background_task_registry(value: object) -> TaskRegistry:
+    """兼容直接调用 endpoint 的旧入口，并优先使用注入的任务登记器。"""
+    if isinstance(value, TaskRegistry):
+        return value
+    return get_task_registry()
+
+
 def get_api_runtime_config(
     runtime: HostRuntime = Depends(get_host_runtime),
 ) -> ApiRuntimeConfig: