- Decode embedded IPv4 from NAT64 well-known and local-use prefixes - Reapply private and reserved IPv4 policy to 6to4 destinations - Fail closed on malformed RFC 6052 local-use encodings
- Port PHP PRIVATE_V4_CIDRS and PRIVATE_V6_PREFIXES onto netip.Prefix - Fail closed on invalid addresses; Unmap remains the caller's job