How do you tell a getter to only invalidate if the _value_ changes, rather than the tracked references accessed invalidate (for any reason)

[NullVoxPopuli]

Something that comes close to this is @dedupeTracked from tracked-toolbox: https://github.com/tracked-tools/tracked-toolbox/tree/master#dedupetracked

but it only works by intercepting the setting of a what-would-be-@tracked property.

The situation I have is related to the URL, but the source of the data could be anything.

get localData() {
  // currentURL will invalidate for *any* URL change, 
  // including QP-only transitions
  // but I want a way to discard the invalidations where the returned value
  // would be the same.
  return this.routerService.currentURL.split('?')[0];
}

or generically,

get localData() {
  let [dataYouCareAbout, dataYouDont] = this.upstreamDataYouDontControl;

  return dataYouCareAbout;
}

for rendering performance reasons (like, maybe something downstream, depending on localData causes other things to happen, you want those other things to execute as few times as possible -- in this case, based on value-equality rather than reference-dirtiness.

@cached is a reference-based cache, and the references do change, so it doesn't work.

What we need is something like @dedupeTracked, but for getters, and absorbing upstream changes.

@dedupeTracked  // @cached + value equality checking
get localData() {
  // ...
}

I don't think ember has a way to handle this.

Starbeam does, tho. So maybe the answer is to wait for better reactivity primitives.
https://www.starbeamjs.com/guides/advanced/equivalence.html