This dataset supports the manuscript “Measuring Governance Sustainability in Cross-Border Strategic Partnerships under Geopolitical Friction: A Composite-Indicator Analysis of China-Malaysia Relations, 2015–2024.” The uploaded workbook, SMTI_computation_package.xlsx, contains the machine-readable computation package for the Strategic Mutual Trust Index (SMTI). It includes the long-format indicator-level dataset, codebook, source log, raw values, computed dimension scores, final SMTI values, min-max normalization parameters, sensitivity intervals, plausibility correlations, normalization checks, and formula guide. The core analysis period is 2015–2024. Any 2025 observations included in the workbook are retained only as an exploratory extension and are excluded from baseline SMTI construction, normalization parameters, rank-order correlations, and sensitivity checks. The data were derived from publicly available statistical, official, survey, media, and policy sources documented in the Source_Log sheet of the workbook.