otbr installed socat from apt at every start, which the namespace egress baseline denies, so it crash-looped. otbr-agent now speaks spinel+hdlc+unix to a socket served by a native alpine/socat sidecar that bridges to slzb-thread:6638 (openthread/otbr image of 2026-11-07; Unix stream sockets landed in OpenThread #13785). otbr-egress allows only that TCP link (S28-48). Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>