fix: address assistant capability review

apps/nextjs/src/app/api/assistant/chat/assistant-chat-input.ts

@@ -0,0 +1,32 @@
+export type AssistantMentionReference = {
+  type: "app" | "integration" | "board" | "widget";
+  id: string;
+};
+
+const mentionPattern = /:(app|integration|board|widget)\[([^\]\n]{1,1024})\](?:\{name=[^}\n]{1,1024}\})?/gu;
+
+const getMessageText = (message: { parts: unknown[] }) =>
+  message.parts
+    .flatMap((part) => {
+      if (!part || typeof part !== "object" || Array.isArray(part)) return [];
+      const value = part as Record<string, unknown>;
+      return value.type === "text" && typeof value.text === "string" ? [value.text] : [];
+    })
+    .join("\n");
+
+export const getRequestedMentionIds = (messages: { role: "user" | "assistant"; parts: unknown[] }[]) => {
+  const mentions = new Map<string, AssistantMentionReference>();
+  for (const message of messages) {
+    if (message.role !== "user") continue;
+    for (const match of getMessageText(message).matchAll(mentionPattern)) {
+      const type = match[1] as AssistantMentionReference["type"];
+      const id = match[2];
+      if (id) mentions.set(`${type}:${id}`, { type, id });
+      if (mentions.size >= 30) return [...mentions.values()];
+    }
+  }
+  return [...mentions.values()];
+};
+
+export const sanitizeAttachmentFilename = (filename: string | undefined) =>
+  (filename ?? "document").replaceAll(/[\n"<>]/gu, "_");