diff --git a/packages/ui/src/components/chat/message/renderCompare.ts b/packages/ui/src/components/chat/message/renderCompare.ts
index e06064a1..057f15c4 100644
--- a/packages/ui/src/components/chat/message/renderCompare.ts
+++ b/packages/ui/src/components/chat/message/renderCompare.ts
@@ -80,6 +80,13 @@ export const areRenderRelevantPartsEqual = (left: Part[], right: Part[]): boolea
       if (leftTool !== rightTool) {
         return false;
       }
+      // Compare tool output so streaming updates (e.g., todo list progress)
+      // trigger re-renders when the output payload changes.
+      const leftOutput = (leftPart as { output?: unknown }).output;
+      const rightOutput = (rightPart as { output?: unknown }).output;
+      if (leftOutput !== rightOutput) {
+        return false;
+      }
       continue;
     }