HttpUrl baseUrl = server.url("/v1/chat/");

  // Exercise your application code, which should make those HTTP requests.
  // Responses are returned in the same order that they are enqueued.
  Chat chat = new Chat(baseUrl);

  chat.loadMore();
  assertEquals("hello, world!", chat.messages());

  chat.loadMore();
  chat.loadMore();
  assertEquals(""
      + "hello, world!\n"
      + "sup, bra?\n"

* Then check that the tests **pass** after the PR. ✅

* Many PRs don't have tests, you can **remind** them to add tests, or you can even **suggest** some tests yourself. That's one of the things that consume most time and you can help a lot with that.

* Then also comment what you tried, that way I'll know that you checked it. 🤓

## Create a Pull Request

    Use o chat apenas para outro tipo de assunto.

### Não faça perguntas no chat

    Nutzen Sie den Chat nur für andere allgemeine Gespräche.

### Den Chat nicht für Fragen verwenden

* Then close one of the tabs.

That will raise the `WebSocketDisconnect` exception, and all the other clients will receive a message like:

```
Client #1596980209979 left the chat
```

!!! tip
    The app above is a minimal and simple example to demonstrate how to handle and broadcast messages to several WebSocket connections.

    ```

尝试以下操作：

* 使用多个浏览器选项卡打开应用程序。
* 从这些选项卡中发送消息。
* 然后关闭其中一个选项卡。

这将引发 `WebSocketDisconnect` 异常，并且所有其他客户端都会收到类似以下的消息：

```
Client #1596980209979 left the chat
```

!!! tip
    上面的应用程序是一个最小和简单的示例，用于演示如何处理和向多个 WebSocket 连接广播消息。

    但请记住，由于所有内容都在内存中以单个列表的形式处理，因此它只能在进程运行时工作，并且只能使用单个进程。

* Schließen Sie dann einen der Tabs.

Das wird die Ausnahme `WebSocketDisconnect` auslösen und alle anderen Clients erhalten eine Nachricht wie:

```
Client #1596980209979 left the chat
```

!!! tip "Tipp"
    Die obige Anwendung ist ein minimales und einfaches Beispiel, das zeigt, wie Nachrichten verarbeitet und an mehrere WebSocket-Verbindungen gesendet werden.

    finally:
        some_cleanup()
```

...that way the `finally` block is run regardless of any exception that might happen.

### Features

* The same PR [#4575](https://github.com/tiangolo/fastapi/pull/4575) from above also fixes the `contextvars` context for the code before and after `yield`. This was the main objective of that PR.

/**
 * A set of worker threads that are shared among a set of task queues.
 *
 * Use [INSTANCE] for a task runner that uses daemon threads. There is not currently a shared
 * instance for non-daemon threads.
 *
 * The task runner is also responsible for releasing held threads when the library is unloaded.
 * This is for the benefit of container environments that implement code unloading.
 *

to make sure we have an independent value in the `ContextVar` for each request that uses the database, and that value will be used as the database state (connection, transactions, etc) for the whole request.

For that, we need to create another `async` dependency `reset_db_state()` that is used as a sub-dependency in `get_db()`. It will set the value for the context variable (with just a default `dict`) that will be used as the database state for the whole request. And then the dependency...