go.mod specifies 'go 1.26' (no patch), making the download URL go1.26.linux-amd64.tar.gz which 404s. Use actions/setup-go on the runner and bind-mount GOROOT into the rockylinux container read-only, removing the curl+tar download entirely. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>