SpinelKit consolidates the pure-Ruby "stdlib substitute" shims that every Spinel-compiled project would otherwise hand-roll. Spinel (the Ruby->native AOT compiler) cannot lower the json gem's C-ext fast path / metaprogrammed fallback, stdlib Logger, or C-ext git bindings -- and the spinelgems compatibility catalog confirms no verified gem exists to reuse. So this gem ships a JSON encoder+decoder+builder, .git/HEAD provenance, and a minimal levelled logger. Pure Ruby, no native extension, no runtime dependencies -- it vendors cleanly via bundler-spinel. Pre-alpha.