Roadmap

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

Stage	What	Status
Option specification	The Spec model for an option: long and short names, whether it takes a required/optional argument, the --[no-] negation form, and the coercion type — built the way OptionParser#on describes one.	Done
argv matching	Matching an argv against the spec: long --opt, short -o, unambiguous abbreviations, bundled short flags -abc, --opt=val and -oval argument attachment — exactly MRI's rules.	Done
Dispatch modes	parse! (permute, consume), order! (stop at the first non-option), permute! and the getopts convenience mode — each leaving the residual argv as MRI does.	Done
Type coercion	Coercion of option arguments to Integer, Float, and the other built-in OptionParser accept-types, raising MRI's InvalidArgument on a bad value.	Done
Error taxonomy	MRI's full OptionParser::ParseError family — AmbiguousOption, InvalidOption, MissingArgument, NeedlessArgument, InvalidArgument — surfaced as typed Go errors.	Done
Differential oracle & coverage	A wide argv/spec corpus parsed both here and by the system ruby, compared against MRI's residual argv and error classes; 100% coverage, gofmt + go vet clean, green across all six 64-bit Go arches and three 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.