diff --git a/SVSim.Database/Services/Inventory/GrantSource.cs b/SVSim.Database/Services/Inventory/GrantSource.cs
index f3a383c..d721ef2 100644
--- a/SVSim.Database/Services/Inventory/GrantSource.cs
+++ b/SVSim.Database/Services/Inventory/GrantSource.cs
@@ -28,6 +28,7 @@ public enum GrantSource
     AchievementReward = 13,
     SerialCodeRedeem = 14,
     CardCosmeticCascade = 15,
+    // Reserved high to stay visually distinct from gameplay sources; 16–98 are intentionally unused.
     AdminGrant = 99,
 }
 
@@ -37,6 +38,7 @@ public enum GrantSource
 /// </summary>
 public static class GrantSourceMessages
 {
+    /// <exception cref="ArgumentOutOfRangeException">An unmapped <see cref="GrantSource"/> value was passed.</exception>
     public static string For(GrantSource source) => source switch
     {
         GrantSource.Unknown             => "Unknown",