The invitee input had no combobox semantics: assistive
technology could not tell that the widget owns a listbox with
suggestions. Mark the input as role="combobox" with
aria-autocomplete="list" and an initial aria-expanded="false",
point aria-controls at the list and give the JS-built list a
matching id so the reference resolves.
The server splits the attendee input on whitespace, commas and
semicolons, but the search widget only treated commas and
semicolons as separators. Typing "a@x.com b" therefore sent the
whole string as the search query instead of "b", and picking a
contact dropped the whitespace-separated entry.
Split on /[\s;,]+/ in both fragment() and commit() so the
widget agrees with parseAttendees() on what an entry is.
hide() did not invalidate in-flight search requests. Clearing
the input or picking a contact while a request was pending let
the old response re-render and pop the suggestion list back
open. Bump requestSeq in hide() so every dismissal retires
pending responses.
Add a Vitest + jsdom harness with black-box tests for the
invitee widget, covering the stale-response race both on
field clear and on contact pick.
stefan.tollkuehn