[murdercode]

Summary

Whole-year chronological age causes Fitness Age to jump at birthdays and reference-band boundaries. SuperAgeCore 0.5.0 accepts fractional chronological age and interpolates complete adjacent integer-age results in every algorithm mode, preserving the 0.4.0 integer outputs, observed values, missing-data rules, weights and adult eligibility.

FitnessAgeProfile.chronologicalAge and FitnessAgeResult.chronologicalAge become Double. Integer initializer overloads and legacy integer JSON remain supported; callers that store the public properties in Int variables must convert explicitly. Methodology, independent golden fixtures, migration notes and the version constant ship together.

RFC issue: #7

Type

• Algorithm change with approved RFC

Validation

• swift build and swift test: 57 tests passed in Debug
• swift build -c release and swift test -c release: 57 tests passed
• Integer source/test baseline matches both public v0.4.0 and the app-pinned source
• 13 fractional golden cases, 26 exact integer anchors and 432 birthday boundary cases cover both reference sexes and every mapping mode
• Legacy/fractional Codable, adult eligibility, invalid ages, exclusions and confidence covered
• Optimized macOS benchmark: 10,000 calculations; median 0.017500 ms, p95 0.022167 ms
• Methodology and changelog updated; release date 2026-10-05
• DCO signoff included on the implementation commit
• git diff --check passed