What are common StreamTransformer patterns, such as debounce and throttle, and how do they help control the actual rate at which a stream's events are processed, particularly for something like a rapidly typed search query?

A debounce transformation delays processing a stream's most recently emitted value until a specified pause in new incoming events has genuinely occurred, meaning it effectively waits until a user has actually stopped typing for a brief moment before triggering an actual search, while a throttle transformation instead limits event processing to occurring at most once within a given fixed time window regardless of how many individual events actually occur during that window, and both of these patterns help meaningfully reduce unnecessary, wasteful work, such as avoiding firing off a brand new network request on every single individual keystroke a user types.

searchController.stream
  .debounceTime(Duration(milliseconds: 300))
  .listen((query) => performSearch(query));