v1.2 scaffold

backend/app/services/scenario_engine.py

@@ -0,0 +1,32 @@
+from sqlalchemy import delete, select
+from sqlalchemy.orm import Session
+
+from app.models.product import Product
+from app.models.scenario import CostingResult, Scenario
+from app.services.costing_engine import calculate_product_cost
+
+
+def run_scenario(db: Session, scenario: Scenario) -> list[dict]:
+    db.execute(delete(CostingResult).where(CostingResult.scenario_id == scenario.id))
+    products = db.scalars(select(Product).order_by(Product.name)).all()
+    results: list[dict] = []
+
+    for product in products:
+        breakdown = calculate_product_cost(db, product.id, overrides=scenario.overrides or {})
+        db.add(
+            CostingResult(
+                scenario_id=scenario.id,
+                product_id=product.id,
+                finished_product_delivered=breakdown["finished_product_delivered"],
+                distributor_price=breakdown["distributor_price"],
+                wholesale_price=breakdown["wholesale_price"],
+                warnings=breakdown["warnings"],
+                details=breakdown,
+            )
+        )
+        results.append(breakdown)
+
+    scenario.status = "reviewed"
+    db.commit()
+    return results
+