refactor: extract shared turn queue runtime (#991)

src/queue/turnQueueRuntime.ts

@@ -0,0 +1,61 @@
+import type { MessageCreate } from "@letta-ai/letta-client/resources/agents/agents";
+
+type MessageContentParts = Exclude<MessageCreate["content"], string>;
+
+export type QueuedTurnInput<TUserContent> =
+  | {
+      kind: "user";
+      content: TUserContent;
+    }
+  | {
+      kind: "task_notification";
+      text: string;
+    };
+
+type MergeQueuedTurnInputOptions<TUserContent> = {
+  normalizeUserContent: (content: TUserContent) => MessageCreate["content"];
+  separatorText?: string;
+};
+
+function appendContentParts(
+  target: MessageContentParts,
+  content: MessageCreate["content"],
+): void {
+  if (typeof content === "string") {
+    target.push({ type: "text", text: content });
+    return;
+  }
+  target.push(...content);
+}
+
+export function mergeQueuedTurnInput<TUserContent>(
+  queued: QueuedTurnInput<TUserContent>[],
+  options: MergeQueuedTurnInputOptions<TUserContent>,
+): MessageCreate["content"] | null {
+  if (queued.length === 0) {
+    return null;
+  }
+
+  const separatorText = options.separatorText ?? "\n";
+
+  const mergedParts: MessageContentParts = [];
+  let isFirst = true;
+
+  for (const item of queued) {
+    if (!isFirst) {
+      mergedParts.push({ type: "text", text: separatorText });
+    }
+    isFirst = false;
+
+    if (item.kind === "task_notification") {
+      mergedParts.push({ type: "text", text: item.text });
+      continue;
+    }
+
+    appendContentParts(mergedParts, options.normalizeUserContent(item.content));
+  }
+
+  return mergedParts.length > 0
+    ? (mergedParts as MessageCreate["content"])
+    : null;
+}