Reading the body's dashboard — HRV, pupil, sleep, gut as a within-person slope

The framework reads four gauges as the body's dashboard: HRV/RSA (vagal brake), pupillometry (LC-NE proxy), sleep metrics (allostatic recovery), and GI signals (interoceptive load). The red-team's warning, carried on the card: EVERY one of these is a CONFOUNDED proxy. HRV moves with breathing, fitness, age, posture, caffeine, medication, and anxiety; pupil size moves with ambient light and cognitive load; the thresholds (HOMA-IR>2, hsCRP>3 mg/L, RMSSD<20 ms) are clinical conventions never validated for "which layer failed." A single absolute reading names nothing. So the discipline — and it is the framework's strongest, most honest move — is WITHIN-PERSON TRAJECTORY, not group average and not a snapshot: baseline → perturbation → recovery, measured under controlled conditions (paced 6-breath/min, fixed posture, caffeine washout), and the SIGNAL IS THE SLOPE of the recovery curve, not the baseline value. Within-person design removes between-person confounds by construction — each person is their own control. This is why the dashboard, read correctly, is a feedback SIGNAL (like every control system's sensor loop) rather than a diagnosis. One un-runnable falsifier was also fixed: "no interoception-GI link after controlling for anxiety" is unrunnable, because anxiety and autonomic dysregulation are the same thing from two angles — you would control away the phenomenon. Replaced with a RUNNABLE test: temporal precedence — does the interoceptive-error marker CHANGE before the GI/autonomic symptom, within-person (lead-lag)? Precedence is observable where statistical partialling is not. SAFETY BOUNDARY — this is a research framework, NOT medical advice, NOT a diagnosis, NOT a treatment plan. It is adjunctive to, never a replacement for, a licensed physician. STOP and seek urgent care for red flags: chest pain, sudden neurological deficit, fainting, severe or rapidly worsening symptoms. The engine seals the LOGIC of this framework; it does NOT and CANNOT seal that any mechanism here is medically true — that awaits the trials named below.