brewpi.py passed a literal 20 as theta_amb to Pot, and temp_controller_smith.py's two internal Pot models (and every demo's Pot/TempController instantiation) silently relied on Pot's default of 20 instead. Add a top-level ambient_temperature key to config.json(.templ/.sim), thread it through brewpi.py into both the real plant and the Smith predictor's models via a new theta_amb param on TempController, and make the demos pass it explicitly too. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>