feat: askai bot hints for followups (#10291)

services/ask-ai-bot/events/messageCreate.ts

@@ -9,6 +9,48 @@ import { answerQuestion } from "../utils/ai";
 import { buildServerContext } from "../utils/discord/server-context";
 import { logger } from "../utils/logger";
 
+async function shouldSendFollowUpHint(
+  message: OmitPartialGroupDMChannel<Message<boolean>>,
+): Promise<boolean> {
+  try {
+    const thread = message.channel;
+    if (!thread.isThread()) return false;
+
+    const botId = message.client.user?.id || "";
+    const starterMessage = await thread.fetchStarterMessage().catch(() => null);
+
+    const messages = await thread.messages.fetch({ limit: 20 });
+
+    let hasOtherHumanMessages = false;
+    let botWasPingedOrRepliedTo = false;
+
+    for (const msg of messages.values()) {
+      if (msg.author.bot) continue;
+      if (starterMessage && msg.id === starterMessage.id) continue;
+      if (msg.id === message.id) continue;
+
+      hasOtherHumanMessages = true;
+
+      if (msg.mentions.has(botId)) {
+        botWasPingedOrRepliedTo = true;
+      }
+
+      if (msg.reference?.messageId && !botWasPingedOrRepliedTo) {
+        const referenced = await thread.messages
+          .fetch(msg.reference.messageId)
+          .catch(() => null);
+        if (referenced?.author.bot) {
+          botWasPingedOrRepliedTo = true;
+        }
+      }
+    }
+
+    return !hasOtherHumanMessages && !botWasPingedOrRepliedTo;
+  } catch {
+    return false;
+  }
+}
+
 export default {
   event: Events.MessageCreate,
   handler: async (
@@ -56,6 +98,13 @@ export default {
           logger.verbose(
             `Ignoring thread message from ${message.author.username} (not mentioned or replied to)`,
           );
+
+          if (await shouldSendFollowUpHint(message)) {
+            await message.channel.send(
+              "To ask me a follow-up, please **reply to one of my messages** or **@mention me**. I won't see messages sent otherwise.",
+            );
+          }
+
           return;
         }