Function renderActivity

packages/react-server/src/ReactFizzServer.js:2809–2850

(
  request: Request,
  task: Task,
  keyPath: KeyNode,
  props: ActivityProps,
)

}

function renderActivity(
  request: Request,
  task: Task,
  keyPath: KeyNode,
  props: ActivityProps,
): void {
  const segment = task.blockedSegment;
  if (segment === null) {
    // Replay
    const mode = props.mode;
    if (mode === 'hidden') {
      // A hidden Activity boundary is not server rendered. Prerendering happens
      // on the client.
    } else {
      // A visible Activity boundary has its children rendered inside the boundary.
      const prevKeyPath = task.keyPath;
      task.keyPath = keyPath;
      renderNode(request, task, props.children, -1);
      task.keyPath = prevKeyPath;
    }
  } else {
    // Render
    const mode = props.mode;
    if (mode === 'hidden') {
      // A hidden Activity boundary is not server rendered. Prerendering happens
      // on the client.
    } else {
      // An Activity boundary is delimited so that we can hydrate it separately.
      pushStartActivityBoundary(segment.chunks, request.renderState);
      segment.lastPushedText = false;
      // A visible Activity boundary has its children rendered inside the boundary.
      const prevKeyPath = task.keyPath;
      task.keyPath = keyPath;
      // We use the non-destructive form because if something suspends, we still
      // need to pop back up and finish the end comment.
      renderNode(request, task, props.children, -1);
      task.keyPath = prevKeyPath;
      pushEndActivityBoundary(segment.chunks, request.renderState);
      segment.lastPushedText = false;
    }
  }
}

function renderViewTransition(
  request: Request,