fix: async tasks could lose the app context

We set and unset the app context in various places, which can cause
an async task to run when the context is not set.
In the case of setting a reactive variable, this will cause it
to assume the global context, which does not lead to a rerender.

solara/server/app.py

@@ -472,11 +472,10 @@ def on_msg(msg):
             context = get_current_context()
             import ipyvuetify
 
-            with context:
-                container = ipyvuetify.Html(tag="div")
-                context.container = container
-                load_app_widget(None, app, path)
-                comm.send({"method": "finished", "widget_id": context.container._model_id})
+            container = ipyvuetify.Html(tag="div")
+            context.container = container
+            load_app_widget(None, app, path)
+            comm.send({"method": "finished", "widget_id": context.container._model_id})
         elif method == "check":
             context = get_current_context()
         elif method == "reload":

solara/server/server.py

@@ -125,12 +125,11 @@ async def app_loop(ws: websocket.WebsocketWrapper, session_id: str, connection_i
         run_context = contextlib.nullcontext()
 
     kernel = context.kernel
-    with run_context:
+    with run_context, context:
         if user:
-            with context:
-                from solara_enterprise.auth import user as solara_user
+            from solara_enterprise.auth import user as solara_user
 
-                solara_user.set(user)
+            solara_user.set(user)
 
         while True:
             try:
@@ -144,11 +143,10 @@ async def app_loop(ws: websocket.WebsocketWrapper, session_id: str, connection_i
             else:
                 msg = deserialize_binary_message(message)
             t1 = time.time()
-            with context:
-                process_kernel_messages(kernel, msg)
-                t2 = time.time()
-                if settings.main.timing:
-                    print(f"timing: total={t2-t0:.3f}s, deserialize={t1-t0:.3f}s, kernel={t2-t1:.3f}s")  # noqa: T201
+            process_kernel_messages(kernel, msg)
+            t2 = time.time()
+            if settings.main.timing:
+                print(f"timing: total={t2-t0:.3f}s, deserialize={t1-t0:.3f}s, kernel={t2-t1:.3f}s")  # noqa: T201
 
 
 def process_kernel_messages(kernel: Kernel, msg: Dict):

tests/integration/async_test.py

@@ -0,0 +1,29 @@
+import asyncio
+from pathlib import Path
+
+import playwright.sync_api
+
+import solara
+import solara.server.starlette
+
+HERE = Path(__file__).parent
+
+
+@solara.component
+def Page():
+    def run_async():
+        async def some_task():
+            await asyncio.sleep(0.01)
+            label.value = "asyncio run"
+
+        asyncio.create_task(some_task())
+
+    label = solara.use_reactive("initial")
+    solara.Button(label.value, on_click=run_async)
+
+
+def test_async_callback(page_session: playwright.sync_api.Page, solara_app, extra_include_path, solara_server):
+    with extra_include_path(HERE), solara_app("async_test"):
+        page_session.goto(solara_server.base_url + "/")
+        page_session.locator("text=initial").click()
+        page_session.locator("text=asyncio run").wait_for()