CookieChangeEvent behaviour for `cookieStore.delete()`s of non-existing cookies is under specified

[IdanHo]

What is the issue with the Cookie Store API Standard?

The cookieStore does not fire change events for non-existing expired cookies subtest of WPT test https://github.com/web-platform-tests/wpt/blob/master/cookiestore/cookieStore_event_delete.https.window.js verifies that CookieChangeEvent deleted events are not fired for delete()s of non-existing cookies.
I could not find spec language that explicitly specifies that, and moreover the current definition is:

- A cookie which is removed due to an insertion of another cookie with the same name, domain, and path is ignored.
- A newly-created cookie which is not immediately evicted is considered changed.
- A newly-created cookie which is immediately evicted is considered deleted.
- A cookie which is otherwise evicted or removed is considered deleted

I read that as the delete('non-existent') falling into the third case.

[annevk]

Yeah, we need to redo the integration with the cookie specification. In particular we want to use the algorithms in https://httpwg.org/http-extensions/draft-ietf-httpbis-layered-cookies.html, probably with some indirection through Fetch. That will then give us back actual change records that we can then use to queue events. And ensure deduplication is done consistently and such.