Writes up IConnectionFilter for content authors: the accept-path contract
(allocation-free, non-blocking, side effects owned by the filter), registration
order and short-circuiting, the unregister-on-throw policy, and why this must
not be routed through EventSink.InvokeSocketConnect.
Also records the IPAddress <-> UInt128 normalization quirk. Addresses are
normalized to IPv6 form, so a v4 address round-tripped through UInt128 can come
back as InterNetworkV6 with IsIPv4MappedToIPv6 set. That is what the seemingly
redundant clause in ToUInt128 is defending, not a stray condition. Noted as a
follow-up rather than churned mid-feature: the normalization would read better
as an explicit "to canonical v6 bits" step that never needs the family check.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2be79d054a