Why: The runner cannot reach github.com, so cloning actions/checkout timed out before any test ran.
Evidence: mirrors.aliyun.com/golang/go1.27.1.linux-amd64.tar.gz returned HTTP 200. The workflow now fetches GITHUB_SHA with the job token and installs Go from that mirror.
Impact: Submodule checkout still requires SUBMODULE_TOKEN. A missing secret fails the job with that message.
Refs: feature/agent-stack-r0-r1
Co-authored-by: Cursor <cursoragent@cursor.com>
Why: The runner has no SSH key, so recursive checkout failed, and tests had no module proxy or race detector.
Evidence: Workflow matches PROJECT.md vet, test, and race commands, with setup-go 1.27 and GOPROXY=https://goproxy.cn,direct.
Impact: vet-and-test runs on ubuntu-latest. SUBMODULE_TOKEN must be set by the owner before checkout can succeed.
Refs: feature/agent-stack-r0-r1
Co-authored-by: Cursor <cursoragent@cursor.com>