Location Service now ensures that the 0,0 location exists

microservices/LocationsApi/Services/LocationStore.cs

@@ -23,6 +23,8 @@ public class LocationStore
             .Ascending(l => l.Coord.Y);
         var coordIndexOptions = new CreateIndexOptions { Unique = true };
         _col.Indexes.CreateOne(new CreateIndexModel<Location>(coordIndex, coordIndexOptions));
+
+        EnsureOriginLocation();
     }
 
     private static void EnsureLocationSchema(IMongoDatabase db, string collectionName)
@@ -100,4 +102,31 @@ public class LocationStore
         var result = await _col.UpdateOneAsync(filter, update);
         return result.ModifiedCount > 0;
     }
+
+    private void EnsureOriginLocation()
+    {
+        var filter = Builders<Location>.Filter.And(
+            Builders<Location>.Filter.Eq(l => l.Coord.X, 0),
+            Builders<Location>.Filter.Eq(l => l.Coord.Y, 0)
+        );
+        var existing = _col.Find(filter).FirstOrDefault();
+        if (existing is not null)
+            return;
+
+        var origin = new Location
+        {
+            Name = "Origin",
+            Coord = new Coord { X = 0, Y = 0 },
+            CreatedUtc = DateTime.UtcNow
+        };
+
+        try
+        {
+            _col.InsertOne(origin);
+        }
+        catch (MongoWriteException ex) when (ex.WriteError.Category == ServerErrorCategory.DuplicateKey)
+        {
+            // Another instance seeded it first.
+        }
+    }
 }