Carbonate reservoirs commonly show complex lithologic assemblages and strong heterogeneity, and their mechanical properties may change rapidly at the centimeter-to-millimeter scale. Conventional discrete sampling tests, limited by sparse sampling points, therefore tend to systematically miss the millimeter-scale weak zones that control fracture initiation as well as favorable stimulation zones. In this study, an approximately 40 m full-diameter continuous core from the Majiagou Formation in the Ordos Basin was investigated using continuous scratch testing with a minimum independent sampling interval of 0.1 mm. A high-resolution mechanical profile along the wellbore was established. Based on scratch energy, contact mechanics, and fracture mechanics models, continuous profiles of scratch-derived equivalent uniaxial compressive strength (UCSscr), Young’s modulus, hardness, and fracture toughness (KⅠC) were obtained and integrated with lithologic observations for fracability evaluation. The results show that limestone, dolostone, and gypsiferous rocks are frequently interbedded in the studied interval. UCSscr and KⅠC exhibit significant fluctuations at the millimeter-to-centimeter scale, revealing mechanical discontinuities and weak zones that are difficult to capture using conventional discrete tests. The indentation results show good consistency with the continuous scratch-derived profile, with a correlation coefficient of R² = 0.87, indicating that continuous scratch testing can reliably characterize the relative mechanical differences among different lithologic intervals. Furthermore, a fracability classification criterion jointly constrained by UCSscr and KⅠC was proposed. Fractured limestone, calcareous dolostone, and gypsiferous dolostone were classified as Class I sweet spots; massive limestone, gypsum rock, and nodular dolostone as Class II sweet spots; and argillaceous dolostone as Class III sweet spots. These results demonstrate that continuous scratch testing enables high-resolution mechanical profile analysis of carbonate rocks at the full-diameter core scale, supports continuous identification of millimeter-scale weak zones and fracability classification, and provides experimental evidence for mechanical zoning, fracturing interval selection, and stimulation-parameter optimization in strongly heterogeneous carbonate reservoirs.