fix(rakefile): skip release:source_control_push on GitHub Actions

Rakefile

@@ -8,3 +8,29 @@ RSpec::Core::RakeTask.new(:spec)
 RuboCop::RakeTask.new
 
 task default: %i[rubocop spec]
+
+# ── CI release fix ────────────────────────────────────────────────────────────
+# `bundle exec rake release` (invoked by rubygems/release-gem@v1) runs
+# `release:source_control_push` which does:
+#   git push origin refs/heads/<current_branch>
+#   git push origin refs/tags/v<version>
+# On tag-triggered CI:
+#   1. HEAD is detached (checked out at the tag SHA, not a branch), so
+#      `refs/heads/HEAD` doesn't exist → `error: src refspec refs/heads/HEAD
+#      does not match any` and rake aborts.
+#   2. The tag was already pushed by the developer — that's what triggered
+#      the workflow. Re-pushing it is redundant.
+#
+# Neutralize the sub-task on GitHub Actions so rake release proceeds to
+# `release:rubygem_push`, which is the step that actually publishes to
+# rubygems.org via OIDC. Local `bundle exec rake release` behavior is
+# unchanged.
+if ENV['GITHUB_ACTIONS'] == 'true'
+  Rake::Task['release:source_control_push'].clear if Rake::Task.task_defined?('release:source_control_push')
+  namespace :release do
+    task :source_control_push do
+      puts '[release:source_control_push] SKIP on GitHub Actions ' \
+           '(HEAD detached at tag; tag already pushed by developer).'
+    end
+  end
+end