Preregister a paid eval (bars, arms, decoys, stop rules), dry-run it at zero cost, then run a three-item priced pilot whose spend table gates approval. (gstack)
Install
npx skills add garrytan/gstack --skill eval-plannpx skills add garrytan/gstack --skill eval-plan -a claude-code -gnpx skills add garrytan/gstack --skill eval-plan -a codex -ggemini skills install https://github.com/garrytan/gstack.git --path eval-plangh skill install garrytan/gstack eval-plangit clone --depth 1 https://github.com/garrytan/gstack /tmp/garrytan__gstack
mkdir -p ~/.claude/skills ~/.agents/skills
cp -R /tmp/garrytan__gstack/eval-plan ~/.claude/skills/eval-plan # Claude Code
cp -R /tmp/garrytan__gstack/eval-plan ~/.agents/skills/eval-plan # Codex, Cursor, Gemini CLI, Copilot, OpenCode