fix(app): pass Reflex app instance to lifespan task app parameter

reflex/app_mixins/lifespan.py

@@ -85,7 +85,7 @@ def get_lifespan_tasks(self) -> tuple[asyncio.Task | Callable, ...]:
         return tuple(self._lifespan_tasks)
 
     @contextlib.asynccontextmanager
-    async def _run_lifespan_tasks(self, app: Starlette):
+    async def _run_lifespan_tasks(self, starlette_app: Starlette):
         self._lifespan_tasks_started = True
         running_tasks = []
         try:
@@ -98,7 +98,11 @@ async def _run_lifespan_tasks(self, app: Starlette):
                     else:
                         signature = inspect.signature(task)
                         if "app" in signature.parameters:
-                            task = functools.partial(task, app=app)
+                            task = functools.partial(task, app=self)
+                        if "starlette_app" in signature.parameters:
+                            task = functools.partial(
+                                task, starlette_app=starlette_app
+                            )
                         t_ = task()
                         if isinstance(t_, contextlib._AsyncGeneratorContextManager):
                             await stack.enter_async_context(t_)

tests/units/app_mixins/test_lifespan.py

@@ -0,0 +1,36 @@
+"""Unit tests for lifespan mixin behavior."""
+
+from __future__ import annotations
+
+import asyncio
+
+import pytest
+from starlette.applications import Starlette
+
+from reflex.app_mixins.lifespan import LifespanMixin
+
+
+@pytest.mark.asyncio
+async def test_lifespan_task_app_param_receives_reflex_app_instance():
+    """Lifespan tasks should receive the Reflex app instance, not Starlette."""
+
+    class DummyApp(LifespanMixin):
+        """Minimal test app based on the lifespan mixin."""
+
+    app = DummyApp()
+    received: dict[str, object] = {}
+
+    def lifespan_task(app):
+        """Record the app argument injected by the lifespan runner.
+
+        Args:
+            app: App object injected by the lifespan runner.
+        """
+        received["app"] = app
+
+    app.register_lifespan_task(lifespan_task)
+
+    async with app._run_lifespan_tasks(Starlette()):
+        await asyncio.sleep(0)
+
+    assert received["app"] is app