Reference implementation in Go, built from the implementation plan
(milestones M0 to M5): datekey, profile, provider, codec, agewrap,
extension, capsule, accesskey, the datekeys CLI, official vectors and
fixtures, the mutation corpus, fuzz targets, interop and live tests,
CI workflows, traceability and policy documents.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>