The arXiv preprint (submitted May 2026) synthesizes Mars mission data from MAVEN, MRO, MSL and Mars 2020 to frame the planet as a canonical edge-case for exoplanet habitability. As a review rather than new empirical study, it lacks sample size or statistical power; its strength lies in integrating geologic, atmospheric and magnetic histories. Key missed connection: Mars obliquity cycles (up to 60°) drove repeated CO2 collapse and volatile redistribution, a process JWST-era models of synchronously rotating rocky worlds rarely test at high obliquity. Complementary work from the 2023 JWST TRAPPIST-1e transmission spectra (Nature Astronomy) shows that thin CO2 atmospheres produce muted features easily masked by haze—exactly the photochemistry Mars experienced post-dynamo collapse. A third synthesis source, the 2021 ApJ paper on atmospheric escape scaling laws, quantifies how Mars-sized planets lose 10-100 bar of atmosphere over Gyr without magnetic shielding, directly informing target selection for future Habitable Worlds Observatory observations. These threads reveal that biosignature searches must prioritize planets with measurable magnetic moments or else risk false negatives from stripped atmospheres.