{
  "completed_step": "C418",
  "next_proposed_step": "C419",
  "question": "Test the five established2K station pairs against the existing17K cumulative Shem/Flood joins and the already admitted Mirror corner exchanges, using only the frozen cumulative source register and no fitted new axis.",
  "reason_selected_after_current_result": "The source profile is now exact and boundary-qualified. The Mirror focus requires testing whether it actually rejoins the existing17K construction before pursuing further harmonic relations.",
  "executed": false,
  "authorization_remaining": 5,
  "fixed_scope": "Mirror/529; regular Gears Noah/Shem/Flood only; SP companion local. Fixed source inputs, no canonical/graph changes."
}