{
  "completed_step": "C419",
  "next_proposed_step": "C420",
  "question": "At each of the five established upper stations, hold that existing coordinate and apply E, E², P and J to its paired lower station. Test every exact output against the frozen regular source menu, keeping source membership, boundary identity and missing intermediate points explicit.",
  "reason_selected_after_current_result": "The fixed Mirror joins are now closed negatively. The next small test asks whether the new2K profile contributes sourced harmonic endpoints under the existing scalar operators, without searching for a new pivot.",
  "executed": false,
  "authorization_remaining": 4,
  "fixed_scope": "Mirror/529; regular Gears Noah/Shem/Flood only; SP companion local. Fixed source inputs, no canonical/graph changes."
}