Optionalvalue?: Record<string, unknown>WebAuthn credential creation options.
The value field is present on iOS only, for MetadataCallback-backed FIDO registration
flows where the native iOS bridge aliases the MetadataCallback type to
"FidoRegistrationCallback" when _action is "webauthn_registration" and emits the
full WebAuthn credential creation options as value.
On Android, MetadataCallback-backed FIDO flows are not aliased — they surface as
type: "MetadataCallback" with value set directly on that callback. value is
therefore always undefined on Android for this type.
FidoRegistrationCallback payload with typed named fields.