diff --git a/backend/internal/devsandbox/bootstrap.go b/backend/internal/devsandbox/bootstrap.go
index 63eb6a2..30b2716 100644
--- a/backend/internal/devsandbox/bootstrap.go
+++ b/backend/internal/devsandbox/bootstrap.go
@@ -197,6 +197,10 @@ func ensureMembershipsAndDrive(ctx context.Context, svc *lobby.Service, game lob
 				return game, fmt.Errorf("dev_sandbox: insert membership %d: %w", i+1, err)
 			}
 		}
+		logger.Info("memberships ensured",
+			zap.Int("count", len(users)),
+			zap.String("game_id", game.GameID.String()),
+		)
 		next, err := svc.ReadyToStart(ctx, &caller, false, game.GameID)
 		if err != nil {
 			return game, fmt.Errorf("dev_sandbox: ready to start: %w", err)