feat: support SSE write_file(0

frontend/src/components/workspace/messages/context.ts

@@ -0,0 +1,21 @@
+import type { UseStream } from "@langchain/langgraph-sdk/react";
+import { createContext, useContext } from "react";
+
+import type { AgentThreadState } from "@/core/threads";
+
+export interface ThreadContextType {
+  threadId: string;
+  thread: UseStream<AgentThreadState>;
+}
+
+export const ThreadContext = createContext<ThreadContextType | undefined>(
+  undefined,
+);
+
+export function useThread() {
+  const context = useContext(ThreadContext);
+  if (context === undefined) {
+    throw new Error("useThread must be used within a ThreadContext");
+  }
+  return context;
+}