{
  "id": "washtally-gutter-example-v1", "status": "illustrative arithmetic, not market rates",
  "original_scenario_date": "2026-10-13", "verified": "2026-10-14",
  "verification_scope": "Reproduction of saved prototype arithmetic; no trade reviewer, field testing or price research",
  "currency": "GBP", "length_unit": "metres",
  "inputs": {"length":40,"rate":3,"height_factor":0.25,"debris_factor":0.10,"downspout_count":2,"downspout_rate":5,"customer_travel":15,"minimum":100,"guard_charge":0,"elapsed_hours":2.5,"workers":1,"labour_cost_per_worker_hour":25,"consumables":10,"vehicle":15,"equipment":12,"overhead":20},
  "rules": ["Base = length * rate", "Height = base * height factor", "Debris = (base + height) * debris factor", "Extras added after adjustments", "Charge = max(subtotal, minimum)", "Costs = labour + other costs", "Profit = charge - included costs", "Margin = profit / charge * 100"],
  "outputs": {"base":120,"height":30,"debris":15,"downspouts":10,"customer_travel":15,"charge":190,"labour":62.5,"other_costs":57,"included_costs":119.5,"profit":70.5,"margin_percent_rounded":37.11,"revenue_per_elapsed_hour":76},
  "exclusions": ["fees", "taxes", "unentered costs", "safe-access assessment", "regional rate recommendations"]
}