[codex] Bind release publishers to immutable tags (BUZZ-SEC-039) (#1914)

scripts/verify-release-ref.sh

@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+if [ "$#" -ne 2 ]; then
+  echo "usage: $0 <tag-prefix> <version>" >&2
+  exit 2
+fi
+
+tag_prefix=$1
+version=$2
+
+if [[ ! "$version" =~ ^[0-9]+\.[0-9]+\.[0-9]+(-[0-9A-Za-z.-]+)?$ ]]; then
+  echo "::error::Invalid release version '$version'" >&2
+  exit 1
+fi
+
+tag="${tag_prefix}${version}"
+expected_ref="refs/tags/${tag}"
+if [ "${GITHUB_REF:-}" != "$expected_ref" ]; then
+  echo "::error::Release must run at ${expected_ref}; got ${GITHUB_REF:-<unset>}" >&2
+  exit 1
+fi
+
+head_sha=$(git rev-parse 'HEAD^{commit}')
+if ! tag_sha=$(git rev-parse "refs/tags/${tag}^{commit}" 2>/dev/null); then
+  echo "::error::Release tag '${tag}' is missing from the checkout" >&2
+  exit 1
+fi
+
+if [ "$head_sha" != "$tag_sha" ]; then
+  echo "::error::HEAD ${head_sha} does not match ${tag} commit ${tag_sha}" >&2
+  exit 1
+fi
+
+echo "Verified ${expected_ref} at ${head_sha}"