fix(cloudflare): Fix remaining AI SDK 6.x type compatibility issues

Additional fixes for UIMessage type changes in AI SDK 5+/6.x:

- Remove `content` property usage (UIMessage always uses `parts` array)
- Replace `data` with `metadata` for custom message metadata
- Remove `createdAt` property (no longer in UIMessage interface)
- Update tool part handling to support AI SDK 6 format where tool
  type is `tool-${toolName}` with properties directly on the part
- Remove legacy content fallback in processMessages

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: dcramer

packages/mcp-cloudflare/src/client/components/chat/chat-message.tsx

@@ -127,6 +127,13 @@ const ToolPart = memo(function ToolPart({
   );
 });
 
+// Helper to check if a part is a tool part (type starts with "tool-")
+const isToolPart = (part: { type: string }): part is {
+  type: `tool-${string}`;
+} & ChatToolInvocation => {
+  return part.type.startsWith("tool-") && part.type !== "tool-invocation";
+};
+
 // Main component for rendering individual message parts
 const MessagePart = memo(function MessagePart({
   part,
@@ -137,30 +144,43 @@ const MessagePart = memo(function MessagePart({
   messageData,
   onSlashCommand,
 }: MessagePartProps) {
-  switch (part.type) {
-    case "text":
-      return (
-        <TextPart
-          text={part.text}
-          role={messageRole}
-          messageId={messageId}
-          isStreaming={isStreaming}
-          messageData={messageData}
-          onSlashCommand={onSlashCommand}
-        />
-      );
-    case "tool-invocation":
-      return (
-        <ToolPart
-          toolInvocation={part.toolInvocation as ChatToolInvocation}
-          messageId={messageId}
-          partIndex={partIndex}
-        />
-      );
-    default:
-      // Fallback for unknown part types
-      return null;
+  // Handle text parts
+  if (part.type === "text") {
+    return (
+      <TextPart
+        text={part.text}
+        role={messageRole}
+        messageId={messageId}
+        isStreaming={isStreaming}
+        messageData={messageData}
+        onSlashCommand={onSlashCommand}
+      />
+    );
   }
+
+  // Handle tool parts (AI SDK 6 format: type is "tool-${toolName}")
+  if (isToolPart(part)) {
+    // Convert AI SDK 6 tool part to our ChatToolInvocation format
+    const toolInvocation: ChatToolInvocation = {
+      toolCallId: part.toolCallId,
+      toolName: part.type.replace(/^tool-/, ""),
+      args: (part as any).input ?? {},
+      state: (part as any).state === "result" ? "result" : "call",
+      result: (part as any).output
+        ? { content: [{ type: "text", text: String((part as any).output) }] }
+        : undefined,
+    };
+    return (
+      <ToolPart
+        toolInvocation={toolInvocation}
+        messageId={messageId}
+        partIndex={partIndex}
+      />
+    );
+  }
+
+  // Fallback for unknown part types
+  return null;
 });
 
 // Export the memoized components

packages/mcp-cloudflare/src/client/components/chat/chat-messages.tsx

@@ -10,9 +10,6 @@ import { useAuth } from "../../contexts/auth-context";
 // Import UIMessage from our types (re-exported as Message for compatibility)
 import type { UIMessage } from "@ai-sdk/react";
 
-// Cache for stable part objects to avoid recreating them
-const partCache = new WeakMap<UIMessage, { type: "text"; text: string }>();
-
 function processMessages(
   messages: UIMessage[],
   isChatLoading: boolean,
@@ -50,25 +47,6 @@ function processMessages(
           });
         },
       );
-    } else if (message.content) {
-      // Use cached part object to maintain stable references
-      let part = partCache.get(message);
-      if (!part) {
-        part = { type: "text", text: message.content };
-        partCache.set(message, part);
-      }
-
-      allParts.push({
-        part,
-        messageId: message.id,
-        messageRole: message.role,
-        partIndex: 0,
-        // Stream if it's AI response OR local streaming simulation
-        isStreaming:
-          (isLastMessage && isChatLoading) ||
-          isMessageStreaming?.(message.id) ||
-          false,
-      });
     }
   });
 
@@ -137,7 +115,7 @@ export function ChatMessages({
             const originalMessage = messages.find(
               (m) => m.id === item.messageId,
             );
-            const messageData = originalMessage?.data as any;
+            const messageData = originalMessage?.metadata as any;
             const hasToolActions =
               messageData?.type === "tools-list" &&
               messageData?.toolsDetailed &&
@@ -151,7 +129,7 @@ export function ChatMessages({
                   messageRole={item.messageRole}
                   partIndex={item.partIndex}
                   isStreaming={item.isStreaming}
-                  messageData={originalMessage?.data}
+                  messageData={originalMessage?.metadata}
                   onSlashCommand={onSlashCommand}
                 />
                 {/* Show tool actions list for tools-list messages */}

packages/mcp-cloudflare/src/client/components/chat/chat.tsx

@@ -256,13 +256,12 @@ Try asking me things like:
       id: string,
       role: "user" | "assistant" | "system",
       text: string,
-      data?: Record<string, unknown>,
+      metadata?: Record<string, unknown>,
     ): UIMessage => ({
       id,
       role,
       parts: [{ type: "text", text }],
-      createdAt: new Date(),
-      ...(data && { data }),
+      ...(metadata && { metadata }),
     }),
     [],
   );

packages/mcp-cloudflare/src/client/hooks/use-persisted-chat.ts

@@ -69,7 +69,7 @@ export function usePersistedChat(isAuthenticated: boolean) {
     }
 
     // UIMessage should always have parts, but check for empty
-    return msg.parts && msg.parts.length > 0;
+    return Boolean(msg.parts && msg.parts.length > 0);
   }, []);
 
   // Load initial messages from localStorage