- hbc_mini.c: move the probe-thread pthread_join to after the shutdown HTB send, so the clean-shutdown notification is no longer delayed behind (and possibly lost to a SIGKILL racing) a probe thread blocked in popen()/ping. - hbc_mini.c: log a LOGW when pthread_create() fails to start the probe thread, and when probe_v4/probe_v6 are not IP literals (probe_init), so both previously silent no-op failure modes are now diagnosable. Diagnostic only — no behavior change to the PROBE_UNKNOWN fallback path. - hbc_mini.py: remove the unused 'import struct' (F401). Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Uc9V1v7iXruubpoLiSE24M