Adding a higher-priority RSA provider leaves both kids in JWKS, so tokens signed before and after the rotation both validate. Deleting the old provider makes its tokens 401 immediately, and the resource server's JWKS cache does not buy a grace period because an unknown kid triggers a refetch.
The encryption key Q3 asks about does not exist yet, since B-2 showed the tokens are stored as plaintext JWTs, so the measured signing-key rotation is what its design has to copy: write with one key, read with several, and keep the overlap longer than the lifetime of anything signed with the old one.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
