Update solver.py

solver.py

@@ -286,6 +286,13 @@ def solve_vrp(
 # Visualization
 # ---------------------------
 
+# ---------------------------
+# Visualization
+# ---------------------------
+
+from PIL import Image
+import io
+
 def plot_solution(
     df: pd.DataFrame,
     sol: Dict,
@@ -297,7 +304,9 @@ def plot_solution(
     ax.scatter([depot[0]], [depot[1]], s=120, marker="s", label="Depot", zorder=5)
 
     # color cycle
-    colors = plt.rcParams["axes.prop_cycle"].by_key().get("color", ["C0","C1","C2","C3","C4","C5"])
+    colors = plt.rcParams["axes.prop_cycle"].by_key().get(
+        "color", ["C0","C1","C2","C3","C4","C5"]
+    )
 
     for v, route in enumerate(routes):
         if not route:
@@ -327,4 +336,11 @@ def plot_solution(
     ax.grid(True, alpha=0.25)
     ax.legend(loc="best", fontsize=8, framealpha=0.9)
     ax.set_aspect("equal", adjustable="box")
-    return fig
+
+    # ✅ Convert Matplotlib figure → PIL.Image for Gradio
+    buf = io.BytesIO()
+    fig.savefig(buf, format="png", bbox_inches="tight")
+    plt.close(fig)
+    buf.seek(0)
+    return Image.open(buf)
+