Analysis code for: From algorithmic fragility to measurement inequity in wearable-based digital population health

Analysis-only code release for the manuscript \"From algorithmic fragility to measurement inequity in wearable-based digital population health\". Includes the core wearable_algo processing/harmonisation library and the numbered, re-runnable analysis pipeline a1-a24: algorithmic-fragility metrics with survey-weighted bootstrap uncertainty, threshold-equivalence and rank-based targeting, subgroup and adjusted models, camera (CAPTURE-24) and polysomnography (MESA) reference validation, out-of-sample calibration with placebo and leave-one-group-out tests, and the consequence/inequity extension (NHANES-linked all-cause mortality and sensitivity analyses, national-surveillance recomputation, a disparity-instability index, a peak-cadence mechanism, decision-rule robustness, and an ADEPT implementation-verification check). Contains no raw or participant-level data; reported results are reproduced once the public datasets are downloaded and the controlled-access datasets obtained from their original custodians under the applicable data-use agreements.