Update solver.py

solver.py

@@ -9,6 +9,17 @@ from PIL import Image
 import io
 
 
+def convert_numpy(obj):
+    if isinstance(obj, dict):
+        return {k: convert_numpy(v) for k, v in obj.items()}
+    elif isinstance(obj, list):
+        return [convert_numpy(v) for v in obj]
+    elif isinstance(obj, (np.integer, np.floating)):
+        return obj.item()
+    else:
+        return obj
+
+
 # ---------------------------
 # Data utils
 # ---------------------------
@@ -378,14 +389,18 @@ def solve_vrp_tw(df, depot=(0.0, 0.0), n_vehicles=4,
     }
 
     metrics = {
-        "vehicles_used": int(sum(1 for r in routes if r)),
-        "total_distance": round(total_dist, 2),
-        "per_route_distance": [round(d, 2) for d in per_route_dist],
-        "per_route_load": [round(l, 2) for l in per_route_loads],
-        "capacity": capacity,
-        "time_window_report": time_window_report,
-        "note": "Enhanced heuristic (TW-aware clustering → insertion → 2-opt → Or-opt). Auto lateness scaling."
+    "vehicles_used": int(sum(1 for r in routes if r)),
+    "total_distance": round(total_dist, 2),
+    "per_route_distance": [round(d, 2) for d in per_route_dist],
+    "per_route_load": [round(l, 2) for l in per_route_loads],
+    "capacity": capacity,
+    "time_window_report": time_window_report,
+    "note": "Enhanced heuristic (TW-aware clustering → insertion → 2-opt → Or-opt). Auto lateness scaling."
     }
+    
+    # ✅ Convert NumPy values to native types
+    metrics = convert_numpy(metrics)
+
 
     return {
         "routes": routes,