Goal: execute the approved plan with visible checkpoints and gate-backed completion

flow:
  run: mkdir -p .prompt-language/runs/demo/logs
  prompt: Read the approved plan and carry it out in small verified steps. After each substantial step, append a short checkpoint to `.prompt-language/runs/demo/logs/checkpoints.md`.
  run: npm test
  if tests_fail
    prompt: Fix the failing tests shown above without abandoning the approved plan.
    run: npm test
  end
  run: npm run lint
  if lint_fail
    prompt: Fix the lint errors shown above.
    run: npm run lint
  end

done when:
  tests_pass
  lint_pass
