The control-connection abstraction (RFC v2 §5): object-safe Transport/
Listener/Conn over opaque pre-resolved addresses (resolution stays the c9
seam), with FramedConn as the single shared byte->Frame codec feeding
Frame::decode's incremental contract. Nothing forecloses additional
per-peer connections for the jarred bulk plane; the membrane is not a
transport (D2).
TCP parks the calling actor via scheduler fd readiness (MSG_NOSIGNAL
writes, EINPROGRESS dial resolved through SO_ERROR). Loopback is the
shipped in-memory test transport: OS-thread-blocking condvar pipes with
TCP-shaped close semantics, per-instance address registry.
Conformance suite runs the same codec over both impls: roundtrips both
directions, framing across split writes, coalesced frames, peer-close
mid-frame as TruncatedByPeer (not EOF), clean close as Ok(None). Plus
impl-specific establishment/error cases and a 4 MiB cross-buffer TCP
frame under real backpressure.
