Owns gem metadata, building, and artifact verification independently of the publication destination. Commands use argument arrays rather than shell interpolation. Registry operations belong to Destination.
RubyGem.new(gemspec: 'example.gemspec') selects an explicit specification; otherwise it uses GEMSPEC_PATH or the only root gemspec. Missing or ambiguous selections fail. The standard workflow uses this package during capture and resolution, exporting its absolute gemspec path.
The optional directory: defaults to a nonempty RELEASE_DATA_DIR or a new temporary directory. The standard workflow supplies the execution provider's directory explicitly; Actions capture also exports it for manual callbacks and subsequent processes. directory returns this location. Keep it outside the working tree so build artifacts do not enter release commits.
version reads the gemspec version in a fresh Ruby process so callback edits are visible even if the specification was previously loaded.
build!(release) overwrites release.gem, checks its version, and records its name, version, and checksum in release.json. It returns the package filename. Call it after the release commit and before tagging; Git#tag! rejects build mutations in the checkout.
Builds use SOURCE_DATE_EPOCH for the gemspec date and archive timestamps. Workflow capture supplies the committer timestamp of the original source commit, not the generated release commit; an explicit value takes precedence. Direct builds without capture or an override retain RubyGems' fixed default 1980-01-02T00:00:00Z.
Reproduce a release from the same source commit: equivalent files in another commit can have a different timestamp. Toolchains, generated files, gemspecs, and signing inputs must also remain stable. No previous archive is needed; partial output is overwritten. built?(release) verifies an existing archive and manifest without building.
The standard Actions workflow builds at checkpoint and again during publication. Each build writes the same reproducible archive and digest manifest; direct builds overwrite prior output.
artifact(release) verifies the built name, version, and digest and returns a copy named NAME-VERSION.gem. Registry destinations and hosted releases use those exact bytes.
Verification checks the retained archive against the manifest and validates its gem metadata before publication. artifact(release) copies the verified canonical archive to its name-and-version path.
Build failures, version mismatches, and changed artifacts raise. The package does not contact a registry or upload files; see Destination::RubyGems for publication and duplicate-version safeguards.