diff --git a/backend/internal/service/composite_platform.go b/backend/internal/service/composite_platform.go
index e3b5f9fd99..b5def4ff54 100644
--- a/backend/internal/service/composite_platform.go
+++ b/backend/internal/service/composite_platform.go
@@ -177,16 +177,6 @@ func (s *GatewayService) resolveCompositeRouteDecision(ctx context.Context, grou
 	return decision, decision.Matched, nil
 }
 
-func resolveCompositeTargetPlatform(ctx context.Context, group *Group, requestedModel string) (string, bool) {
-	if platform, ok := ResolvedTargetPlatformFromContext(ctx); ok {
-		return platform, true
-	}
-	if group == nil || group.Platform != PlatformComposite {
-		return "", false
-	}
-	return DetectModelPlatform(requestedModel)
-}
-
 func isConcreteRequestPlatform(platform string) bool {
 	switch platform {
 	case PlatformAnthropic, PlatformOpenAI, PlatformGemini, PlatformAntigravity, PlatformGrok:
diff --git a/backend/internal/service/gateway_scheduling.go b/backend/internal/service/gateway_scheduling.go
index bda206f5e2..99cfd02c4e 100644
--- a/backend/internal/service/gateway_scheduling.go
+++ b/backend/internal/service/gateway_scheduling.go
@@ -42,10 +42,13 @@ func (s *GatewayService) SelectAccountForModelWithExclusions(ctx context.Context
 		if err != nil {
 			return nil, err
 		}
+		if group == nil {
+			return nil, ErrGroupNotFound
+		}
 		groupID = resolvedGroupID
 		ctx = s.withGroupContext(ctx, group)
 		platform = group.Platform
-		if group != nil && group.Platform == PlatformComposite {
+		if group.Platform == PlatformComposite {
 			decision, ok, err := s.resolveCompositeRouteDecision(ctx, group, requestedModel, CompositeRouteEndpointAny)
 			if err != nil {
 				return nil, err