Roadmap

go-ruby-time/time is grown test-first, each capability differential-tested against MRI rather than built in isolation. The deterministic, interpreter-independent slice of Ruby's Time extracted from rbgo's internals is complete.

Stage	What	Status
Constructors	Now, At / AtNsec / AtTime, UTC, Local, New, Parse, Strptime.	Done
Components & conversions	All civil accessors, sub-second (USec/NSec/Subsec), zone fields, weekday predicates, to_i/to_f/to_r/to_a.	Done
Zone shifts	UTCTime, GetLocal, ToLocal — same instant, different observed offset.	Done
Arithmetic & ordering	Add/Sub, Diff, Round/Floor/Ceil, Cmp, Before/After, Equal, Hash.	Done
Formatting	Full Strftime directive set, Inspect, ToS, CTime, ISO8601, RFC2822, HTTPDate — MRI's exact bytes.	Done
Differential oracle & coverage	Formatters, strftime corpus, accessors, arithmetic, Parse/Strptime checked against ruby (TZ=UTC, ≥ 4.0); 100% coverage, green across 6 arches and 3 OSes.	Done

Documented out-of-scope boundaries

These are deliberate, recorded so the module's surface is unambiguous:

• No interpreter. The library implements the deterministic algorithm; it never runs arbitrary Ruby. Anything that needs a live binding or evaluation is the consumer's job — that is why rbgo binds this module rather than the reverse.
• Reference is reference Ruby (MRI). Byte-for-byte conformance targets MRI's behaviour; differences across MRI releases are matched to the reference used by the differential oracle.
• Standalone & reusable. The module has no dependency on the Ruby runtime; the dependency runs the other way.

See Usage & API for the surface and Why pure Go for the deterministic/interpreter split.