temp_controller.py, temp_controller_smith.py, and kalman.py imported
matplotlib at module level just to support eyeballed-plot __main__
blocks, coupling the live server's import graph to a GUI plotting lib
it never uses at runtime. Relocate those demos (and kalman_eval.py) to
scripts/demos/pid/ and strip the now-unused imports/__main__ blocks
from the production files.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
