diff --git a/tools/server/webui/src/lib/utils/branching.ts b/tools/server/webui/src/lib/utils/branching.ts
index ee3a505eed..07bd0c8988 100644
--- a/tools/server/webui/src/lib/utils/branching.ts
+++ b/tools/server/webui/src/lib/utils/branching.ts
@@ -69,8 +69,8 @@ export function filterByLeafNodeId(
 
 	// Sort: system messages first, then by timestamp
 	result.sort((a, b) => {
-		if (a.role === MessageRole.SYSTEM && b.role !== MessageRole.SYSTEM) return -1;
-		if (a.role !== MessageRole.SYSTEM && b.role === MessageRole.SYSTEM) return 1;
+		if (a.role === 'system' && b.role !== 'system') return -1;
+		if (a.role !== 'system' && b.role === 'system') return 1;
 
 		return a.timestamp - b.timestamp;
 	});