With restore: true and the answer cache on, alice's "write to
alice@example.com" and bob's "write to bob@example.com" redact to the
same request, and bob was given the answer kept for alice, her address put
back in it. A request with restore values is now never looked up in the
cache nor kept in it.
The similar-question cache compared the last message's text and blanked
its parts: two pictures asked about in the same words were one question.
A last message with any part that is not text is now reused only when the
request is the same.
Found in review; both tests fail without the fix.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>