Release contract

starter-websocket releases are ordinary Go module tags plus a small, independently verifiable artifact set. The repository owns the complete build. No external release build service, mutable workspace snapshot, or network-resolved package list participates in artifact construction.

For v1.2.3, the release builder produces:

Artifact	Contract
starter-websocket_1.2.3_source.tar.gz	Exact tagged Git commit, under one versioned directory
starter-websocket_1.2.3_sbom.spdx.json	SPDX 2.3 packages from the consistent committed go.mod, go.sum, and vendor/modules.txt graph
checksums.txt	SHA-256 of the source archive and SBOM, sorted by filename
checksums.txt.sig	Raw Ed25519 signature of the exact checksum bytes
checksums.txt.pem	X.509 SubjectPublicKeyInfo PEM for signature verification

The source archive is reconstructed from the full commit’s git ls-tree identity and exact object bytes read through git cat-file --batch. It never uses checkout filters or git archive, so core.autocrlf and host line-ending settings cannot alter an artifact. Every tar and gzip timestamp is the source commit epoch; paths are relative, ownership is zeroed, executable modes and validated symlinks are preserved, and gzip output is deterministic. Gitlinks and unsupported modes fail closed. Dirty or untracked workspace files cannot enter the archive. The SBOM creation time uses the same epoch and contains no absolute checkout path. Construction fails when committed module selection, checksums, and vendored versions or replacements disagree; the builder does not rely on an earlier verifier to detect a stale dependency graph.

Protected production ceremony

The pinned central workflow validates the exact canonical tag and commit, repeats make verify-release without credentials, renders deterministic artifacts, signs them, and passes them to a separate verifier before publishing. No repository-local release builder exists. The immutable central renderer is the sole production implementation.

This repository’s reviewed public Ed25519 trust anchor is committed at security/release/ed25519-public.pem. Its SHA-256 fingerprint over the DER SubjectPublicKeyInfo bytes is 58d664089f3cb42262e491ed1a9e0c30b0f5d3722571f8f74c144afee55882b0. Store only the matching private key as the repository Actions secret SPICE_LIBRARY_RELEASE_SIGNING_KEY. Configure protected release-signing and release-publish environments for the signing approval and write-capable final job. Both environments should require the repository’s designated reviewers.

Do not create or push a release tag until the matching private signing secret and both protected environments are configured. Committing the public anchor does not assert that those controls, a tag, or a release exist. The caller forwards exactly one explicitly named signing secret; broad secrets: inherit forwarding is forbidden. The reusable workflow references that secret only in its protected release-signing job. Validation, planning, independent verification, and publishing cannot read it. The workflow fails closed on a missing key, an anchor mismatch, a moved tag, or independent verification failure.

Unsigned deterministic rehearsal

The library module authorizes an exact central renderer through its go.mod tool directive. make release-rehearsal asks that fully qualified tool for one read-only plan, then renders the same plan twice with GOWORK=off, GOPROXY=off, GOTOOLCHAIN=local, and GOFLAGS=-mod=vendor:

make release-rehearsal

Both renders are unsigned and always archive HEAD, never working-tree contents. Every artifact must be byte-identical, the checksum file must canonically authenticate its archive and SBOM, the SPDX document must carry the renderer/v1 provenance, and neither output may contain a signature or public key. The gate fails closed on an extra artifact, dependency drift, malformed checksum, provenance drift, or nondeterministic output.

make verify-release executes this deterministic rehearsal after the complete repository verification contract.

Consumer verification

With OpenSSL 3 and GNU-compatible checksum tooling:

sha256sum -c checksums.txt
openssl pkeyutl -verify -pubin -inkey checksums.txt.pem \
  -rawin -in checksums.txt -sigfile checksums.txt.sig

Consumers must authenticate the signature with the reviewed committed security/release/ed25519-public.pem, not an untrusted key downloaded beside the release. The central signer refuses a private key that does not match that anchor, and the independent verifier authenticates the complete artifact set before the protected publish job receives it.