Address Copilot/CodeRabbit review feedback on the persistence PR.
1. SoftwareOperation: replace requireNotNull(keyPair) in SIGN/VERIFY/AGREE_KEY
branches with ServiceSpecificException(invalidArgument). The original
requireNotNull throws IllegalArgumentException, which the binder layer
wraps as KEYMINT_UNKNOWN_ERROR, defeating the goal of surfacing a
clean keystore-style error. Aligns with how ENCRYPT/DECRYPT already
handle missing key material in the same when block.
2. loadPersistedKeys: when a symmetric record has empty metadataBytes (e.g.
a save where Parcel.marshall() was empty for any reason), rebuild a
minimal KeyMetadata from PersistedKeyData primitive fields instead of
skipping the record. Skipping silently dropped the AES key, which is
the same 'logged out after reboot' behavior the PR is trying to fix.
The rebuilt metadata is structurally minimal but preserves the secret
material, which is the dominant correctness concern.
3. Comment fix: rebuildResponseFromRecord docs referred to 'v2 metadata
snapshot', the format in this PR is v3.
Andrea-lyz
5803039309