trace_tc (tasks/tracer.py's TracerTask wired to a generic Tracer instance) was logging to tc_trace.mat, but its var_list was empty, so it only ever wrote a bare tick counter - no actual tc data, despite the name. Drop the dead plumbing and the now-unused tracer.py module entirely; the real, populated brewpi.mat logging (sensor/heater/tc data, built directly inside TracerTask) is untouched. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01DkkuG48uHFCGKe6dPSERFk