Publish the Go reference implementation through pkg.go.dev #135

Parent: #129

Publish reference-implementations/go as module tomlschema.org/go version v1.0.0-rc.2, distributed by the public Go module proxy and documented on pkg.go.dev. Go publication is tag- and domain-driven; there is no registry upload credential.

Maintainer setup — required before release

• Restore reliable public DNS, HTTPS, and hosting for tomlschema.org; the domain was not reachable during planning on 2026-08-19.
• Confirm who owns DNS and web deployment and record a backup maintainer.
• Use the agreed vanity module path tomlschema.org/go and keep the implementation in the monorepo subdirectory reference-implementations/go.
• Serve ?go-get=1 metadata for tomlschema.org/go that maps to https://github.com/brunoborges/toml-schema and identifies reference-implementations/go as the module subdirectory using the Go version supported by this project. Add go-source metadata if needed for pkg.go.dev source links.
• If the hosting platform cannot express the monorepo subdirectory mapping, choose one explicit alternative before implementation: change the public module path to a directly discoverable GitHub subdirectory path, move/split the module, or use a supported module-proxy mapping. Do not tag until go list -m succeeds through the vanity URL.

Repository and site implementation — after the path decision

• Add the vanity metadata endpoint and an automated check that fetches https://tomlschema.org/go?go-get=1 and validates the module prefix, VCS/repository, and subdirectory fields.
• Keep module tomlschema.org/go in go.mod if the approved vanity configuration resolves correctly.
• Verify the package comment in doc.go is suitable as the pkg.go.dev synopsis; add canonical documentation/repository links if pkg.go.dev cannot infer them.
• Add a release check/workflow for the exact monorepo tag form reference-implementations/go/v1.0.0-rc.2. The workflow must reject tags whose version or prefix is malformed, run tests, and execute a pre-publication module-resolution check without credentials.
• Document that Go module versions are immutable, cannot be overwritten, and must be retracted through a later go.mod version if defective.
• Update the Go README and REFERENCE_IMPLEMENTATIONS.md with go get tomlschema.org/go@v1.0.0-rc.2, pkg.go.dev link, tag format, and artifact-vs-language version explanation.

Execution plan

1. Verify the live vanity endpoint from outside the project and run GOPROXY=direct go list -m -json tomlschema.org/go@<reviewed-commit> or an equivalent non-tagged discovery probe.
2. Run go -C reference-implementations/go test ./... and go vet ./... if the repository adopts that check.
3. Create the annotated tag reference-implementations/go/v1.0.0-rc.2 on the reviewed commit; do not use repository-wide v1.0.0-rc.2.
4. Request the version through https://proxy.golang.org/tomlschema.org/go/@v/v1.0.0-rc.2.info or GOPROXY=https://proxy.golang.org go mod download tomlschema.org/go@v1.0.0-rc.2 to seed indexing.
5. Verify the version appears on pkg.go.dev, with source/documentation links and the redistributable MIT license recognized.
6. In a clean temporary module with an empty module cache, run go get tomlschema.org/go@v1.0.0-rc.2, compile a minimal validation example, and inspect go list -m -json to confirm the expected version and origin.

Acceptance criteria

• tomlschema.org/go?go-get=1 is reachable over valid HTTPS and correctly maps the monorepo module.
• The exact reference-implementations/go/v1.0.0-rc.2 tag resolves through proxy.golang.org.
• pkg.go.dev renders package docs, source links, and license status.
• A clean consumer imports tomlschema.org/go without replace, direct filesystem access, or a private proxy.

References: Go module paths, module directories in repositories, adding a package to pkg.go.dev.