PORTRAIT

PORTRAIT turns population health data into a per-patient passport - calibrated position, honest uncertainty, and what genuinely stands out - and refuses when the data cannot support a description. Built and validated during the event on public NHANES. The describability-and-calibration gate holds per-slice coverage in [0.85–0.95] across all six age×sex groups on 2,247 held-out adults from unseen survey years, where a conventional split under-covers every group and abstention halves. A pre-registered confirmatory test found profile coherence adds mortality signal beyond twelve markers plus age and sex (ΔC≈+0.005, permutation p<0.001, survives frailty adjustment) - small, real, and against our stated null. Eight phase-gated sessions; every hypothesis git-tagged before running; every reported number traced to a manifest; a leakage guard separating an eligible target (AUC 0.48) from covert self-prediction (0.998). The interface is grounded in a 73-requirement specification drawn from UX systematic reviews and device standards (IEC 62366, WCAG 2.2 AA). What it means. A description tool that states its precondition and abstains when unmet is safer than one that always answers. PORTRAIT ships that behaviour with the negative results that earned it.