Supersedes the earlier flat yi_max clamp / FSM-gating ideas: same inner
PID instance switches its active param set (Inner.Heat vs Inner.Hold)
by state instead of freezing, giving bumpless transfer for free and a
tight yi_max that only applies while HOLD is driving it.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KefnwbGDM8CGrhb4sFhVq9
Records the root cause of the cold-water overshoot in docs/overshoot.png
(integral windup in pid_heat with no anti-windup engagement, since y never
saturated) and the refined fix plan: gate pid_heat by FSM state instead of
a flat yi_max clamp, which was rejected after the numbers showed it would
also cripple legitimate high-rate ramps.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KefnwbGDM8CGrhb4sFhVq9
jensandClaude Sonnet 5