Update app.py

app.py

@@ -140,15 +140,29 @@ def call_llm_for_order(role: str, local_state: dict, info_sharing_visible: bool,
     # build prompt (concise)
     prompt = (
         f"You are the {role.title()} in a 4-player Beer Game (Retailer -> Wholesaler -> Distributor -> Factory).\n"
-        f"Week: {local_state.get('week')} / {local_state.get('weeks_total')}\n"
-        f"- Inventory: {inventory}\n"
-        f"- Backlog: {backlog}\n"
+        f"Your objective is to minimize the **total weekly cost**, defined as:\n"
+        f"- Holding cost: $0.50 per unit of positive inventory per week.\n"
+        f"- Shortage cost: $1.00 per unit of backlog (unfilled orders) per week.\n\n"
+        f"Current state:\n"
+        f"- Week: {local_state.get('week')} / {local_state.get('weeks_total')}\n"
+        f"- Inventory on hand: {inventory}\n"
+        f"- Backlog (unfilled demand): {backlog}\n"
         f"- Incoming shipment next week: {pipeline_next}\n"
         f"- Incoming order this week: {incoming_order}\n"
     )
     if visible_history:
-        prompt += f"- Customer demand history (visible): {visible_history}\n"
-    prompt += "\nDecide a **non-negative integer** order quantity to place to your upstream supplier this week. Reply with an integer only."
+        prompt += (
+            f"- Recent customer demand history (visible): {visible_history}\n"
+        )
+
+    prompt += (
+        "\nWhen deciding your order, consider that orders take time to arrive "
+        "(1 week to reach upstream supplier + 2 weeks shipping + 2 weeks production for factory). "
+        "Avoid blindly following last week's demand. Try to balance the trade-off between "
+        "avoiding stockouts (backlog cost) and avoiding overstock (inventory cost).\n\n"
+        "Decide one **non-negative integer** order quantity to place to your upstream supplier "
+        "this week to minimize expected total cost. Reply with an integer only."
+    )
 
     try:
         resp = openai.ChatCompletion.create(