Constant RESPONSE_BUFFER_SIZE 

pub(crate) const RESPONSE_BUFFER_SIZE: usize = 16;

The number of serialized responses each waiter buffers before drops occur. Only one valid response is needed and batched senders keep re-requesting, so extra responses are free to drop. Kept small because bodies (leaves, merkle trees, VID shares) can be large and every in-flight request pins its own buffer