with

          steps: { type: array, items: { type: string } }

  execute:
    with:
      # BOTH bindings, on purpose. The plan is a summary of the goal, never a
      # substitute for it: measured on five real seats, a prompt that carried
      # only the plan produced three GREEN runs with an invented or an empty
      # answer — the agent was asked to compute over data it never received,
      # and the assert below only proves non-emptiness. The goal rides in.
      goal: ${{ inputs.goal }}