* successfully cancelled step will immediately start closing all objects captured for later closing
 * by it and by its input steps.
 *
 * <h3>Ending a pipeline</h3>
 *
 * Each {@code ClosingFuture} pipeline must be ended. To end a pipeline, decide whether you want to
 * close the captured objects automatically or manually.
 *
 * <h4>Automatically closing</h4>
 *

    val delegate = delegate
    if (delegate != null) {
      this.delegate = null
      delegate.onClosing(webSocket, code, reason)
    } else {
      events.add(Closing(code, reason))
    }
  }

  override fun onClosed(
    webSocket: WebSocket,
    code: Int,
    reason: String,
  ) {
    Platform.get().log("[WS $name] onClosed $code", Platform.INFO, null)

If there are compelling use cases for early closing in dependencies with `yield`, I would consider adding a new way to opt in to early closing.

### Dependencies with `yield` and `except`, Technical Details { #dependencies-with-yield-and-except-technical-details }

 *
 *  * **Open:** the web socket has been accepted by the remote peer and is fully operational.
 *    Messages in either direction are enqueued for immediate transmission.
 *
 *  * **Closing:** one of the peers on the web socket has initiated a graceful shutdown. The web
 *    socket will continue to transmit already-enqueued messages but will refuse to enqueue new
 *    ones.
 *

 *   <li><b>Convenience methods:</b> These are implementations of common operations that are
 *       typically implemented by opening a reader using one of the methods in the first category,
 *       doing something and finally closing the reader that was opened.
 * </ul>
 *
 * <p>Several methods in this class, such as {@link #readLines()}, break the contents of the source

  /**
   * Regression test for an edge case where closing response body in the HTTP engine doesn't release
   * the corresponding stream allocation. This test keeps those response bodies alive and reads
   * them after the redirect has completed. This forces a connection to not be reused where it would
   * be otherwise.
   *
   *
   * This test leaks a response body by not closing it.
   *

 *  6. Read from and close that source.
 *
 * Exchanges that do not have a request body may skip creating and closing the request body.
 * Exchanges that do not have a response body can call
 * [newFixedLengthSource(0)][newFixedLengthSource] and may skip reading and closing that source.
 */
class Http1ExchangeCodec(
  /** The client that configures this stream. May be null for HTTPS proxy tunnels. */

            saveInfo(messages -> messages.addSuccessStartedDataUpdate(GLOBAL));
        }
        return redirect(getClass());
    }

    /**
     * Reloads the document index by closing and reopening it.
     *
     * @param form the action form (validated but not used for configuration)
     * @return HTML response redirecting to the maintenance page
     */
    @Execute
    @Secured({ ROLE })

## Technical Details { #technical-details }

FastAPI implements some SSE best practices out of the box.

* Send a **"keep alive" `ping` comment** every 15 seconds when there hasn't been any message, to prevent some proxies from closing the connection, as suggested in the [HTML specification: Server-Sent Events](https://html.spec.whatwg.org/multipage/server-sent-events.html#authoring-notes).
* Set the `Cache-Control: no-cache` header to **prevent caching** of the stream.

    ```
    """

    def __init__(
        self,
        code: Annotated[
            int,
            Doc(
                """
                A closing code from the
                [valid codes defined in the specification](https://datatracker.ietf.org/doc/html/rfc6455#section-7.4.1).
                """
            ),
        ],
        reason: Annotated[