Create backward-compatibility-0-0-39.ts

Author: mme

sdks/typescript/packages/client/src/middleware/backward-compatibility-0-0-39.ts

@@ -0,0 +1,54 @@
+import { Middleware } from "./middleware";
+import { AbstractAgent } from "@/agent";
+import type { RunAgentInput, BaseEvent } from "@ag-ui/core";
+import type { Observable } from "rxjs";
+
+type InputMessage = RunAgentInput["messages"][number];
+
+function sanitizeMessageContent(message: InputMessage): InputMessage {
+  const rawContent = (message as { content?: unknown }).content;
+
+  if (Array.isArray(rawContent)) {
+    const concatenatedContent = rawContent
+      .filter(
+        (part): part is { type: "text"; text: string } =>
+          typeof part === "object" &&
+          part !== null &&
+          "type" in part &&
+          (part as { type: unknown }).type === "text" &&
+          typeof (part as { text?: unknown }).text === "string",
+      )
+      .map((part) => part.text)
+      .join("");
+
+    return {
+      ...message,
+      content: concatenatedContent,
+    } as InputMessage;
+  }
+
+  if (typeof rawContent === "string") {
+    return message;
+  }
+
+  return {
+    ...message,
+    content: "",
+  } as InputMessage;
+}
+
+/**
+ * Middleware placeholder that maintains compatibility with AG-UI 0.0.39 flows.
+ * Currently it simply forwards all events to the next middleware/agent.
+ */
+export class BackwardCompatibility_0_0_39 extends Middleware {
+  override run(input: RunAgentInput, next: AbstractAgent): Observable<BaseEvent> {
+    const { parentRunId: _parentRunId, ...rest } = input;
+    const sanitizedInput: RunAgentInput = {
+      ...rest,
+      messages: rest.messages.map(sanitizeMessageContent),
+    } as RunAgentInput;
+
+    return this.runNext(sanitizedInput, next);
+  }
+}