Prevent bare-id model picker revert when the provider hint is empty: an ambiguous bare id that collides across provider groups no longer snaps to the default group on re-render. Adds a revert-sensitive regression test and fixes three cross-file test-isolation leaks found while gating. Thanks @webtecnica.
Co-authored-by: webtecnica <webtecnica@users.noreply.github.com>
