From 3ddfde59cfbe30ab73d486f2c7113f451a478ba2 Mon Sep 17 00:00:00 2001
From: Simon Farshid <simon.farshid@outlook.com>
Date: Fri, 2 Aug 2024 13:25:28 -0700
Subject: [PATCH] feat(ai-sdk/useChat): assistant message append support (#627)

---
 .changeset/stupid-rice-tell.md                             | 5 +++++
 .../src/ui/use-chat/VercelUseChatThreadRuntime.tsx         | 7 +------
 2 files changed, 6 insertions(+), 6 deletions(-)
 create mode 100644 .changeset/stupid-rice-tell.md

diff --git a/.changeset/stupid-rice-tell.md b/.changeset/stupid-rice-tell.md
new file mode 100644
index 000000000..d069baf7c
--- /dev/null
+++ b/.changeset/stupid-rice-tell.md
@@ -0,0 +1,5 @@
+---
+"@assistant-ui/react-ai-sdk": patch
+---
+
+feat: assistant message append support
diff --git a/packages/react-ai-sdk/src/ui/use-chat/VercelUseChatThreadRuntime.tsx b/packages/react-ai-sdk/src/ui/use-chat/VercelUseChatThreadRuntime.tsx
index 1d9862384..faa922402 100644
--- a/packages/react-ai-sdk/src/ui/use-chat/VercelUseChatThreadRuntime.tsx
+++ b/packages/react-ai-sdk/src/ui/use-chat/VercelUseChatThreadRuntime.tsx
@@ -63,11 +63,6 @@ export class VercelUseChatThreadRuntime implements ReactThreadRuntime {
 
   public async append(message: AppendMessage): Promise<void> {
     // add user message
-    if (message.role !== "user")
-      throw new Error(
-        "Only appending user messages are supported in VercelUseChatRuntime. This is likely an internal bug in assistant-ui.",
-      );
-
     if (message.content.length !== 1 || message.content[0]?.type !== "text")
       throw new Error(
         "Only text content is supported by VercelUseChatRuntime. Use the Edge runtime for image support.",
@@ -80,7 +75,7 @@ export class VercelUseChatThreadRuntime implements ReactThreadRuntime {
     this.vercel.setMessages(newMessages);
 
     await this.vercel.append({
-      role: "user",
+      role: message.role,
       content: message.content[0].text,
     });
   }