Error in Playground Single Agent

Using the current main branch and using the Playground Single Agent tap (process and multi agent without any issue):

**Error: Objects are not valid as a React child (found: object with keys {ai_model_id, metadata, content_type, role, name, items, encoding, finish_reason, status}). If you meant to render a collection of children, use an array instead.**

at throwOnInvalidObjectType (webpack-internal:///(app-pages-browser)/./node_modules/next/dist/compiled/react-dom/cjs/react-dom-client.development.js:6632:13)
at reconcileChildFibersImpl (webpack-internal:///(app-pages-browser)/./node_modules/next/dist/compiled/react-dom/cjs/react-dom-client.development.js:7567:11)
at eval (webpack-internal:///(app-pages-browser)/./node_modules/next/dist/compiled/react-dom/cjs/react-dom-client.development.js:7607:33)
at reconcileChildren (webpack-internal:///(app-pages-browser)/./node_modules/next/dist/compiled/react-dom/cjs/react-dom-client.development.js:8048:13)
at beginWork (webpack-internal:///(app-pages-browser)/./node_modules/next/dist/compiled/react-dom/cjs/react-dom-client.development.js:10216:13)
at runWithFiberInDEV (webpack-internal:///(app-pages-browser)/./node_modules/next/dist/compiled/react-dom/cjs/react-dom-client.development.js:1511:30)
at performUnitOfWork (webpack-internal:///(app-pages-browser)/./node_modules/next/dist/compiled/react-dom/cjs/react-dom-client.development.js:15120:22)
at workLoopSync (webpack-internal:///(app-pages-browser)/./node_modules/next/dist/compiled/react-dom/cjs/react-dom-client.development.js:14944:41)
at renderRootSync (webpack-internal:///(app-pages-browser)/./node_modules/next/dist/compiled/react-dom/cjs/react-dom-client.development.js:14924:11)
at performWorkOnRoot (webpack-internal:///(app-pages-browser)/./node_modules/next/dist/compiled/react-dom/cjs/react-dom-client.development.js:14454:44)
at performWorkOnRootViaSchedulerTask (webpack-internal:///(app-pages-browser)/./node_modules/next/dist/compiled/react-dom/cjs/react-dom-client.development.js:16275:7)
at MessagePort.performWorkUntilDeadline (webpack-internal:///(app-pages-browser)/./node_modules/next/dist/compiled/scheduler/cjs/scheduler.development.js:45:48)
at ClientPageRoot (webpack-internal:///(app-pages-browser)/./node_modules/next/dist/client/components/client-page.js:20:50)

現在の main ブランチで Playground Single Agent tap からエラーを再現し、そのレスポンスをレンダリングするフロントエンドのエントリーポイントを調査します。ai_model_id、metadata、content_type、role、name、items、encoding、finish_reason、status を含むオブジェクトを追跡し、それが React の子としてレンダリングされている箇所を特定します。Single Agent playground がこのエラーなしで正常にレンダリングされ、process と multi-agent のパスも引き続き動作すれば完了です。

索引モデルが issue の本文から書いたものです。