An undecoded member in an ambiguous exact-signature group stays unpaired,
like a one-sided member, but the counterpart check considered only
one-sided members. A decoded member with the same declared type and name
on the other side was therefore reported as removed or added. Ambiguous
candidates now count as possible changed counterparts too.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>