fix: detect forum service messages by field presence, not text absence

Stickers, voice notes, and captionless photos from the bot also lack
text and caption fields, so the previous check incorrectly classified
them as system messages and suppressed implicitMention.

Switch to checking for Telegram's forum_topic_* / general_forum_topic_*
service-message fields which only appear on actual service messages.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/telegram/bot-message-context.implicit-mention.test.ts

@@ -1,18 +1,20 @@
 import { describe, expect, it } from "vitest";
 import { buildTelegramMessageContextForTest } from "./bot-message-context.test-harness.js";
 
-describe("buildTelegramMessageContext implicitMention forum system messages", () => {
+describe("buildTelegramMessageContext implicitMention forum service messages", () => {
   /**
    * Build a group message context where the user sends a message inside a
    * forum topic that has `reply_to_message` pointing to a message from the
-   * bot.  Callers control whether the reply target looks like a system
-   * message (empty text) or a real bot reply (non-empty text).
+   * bot.  Callers control whether the reply target looks like a forum service
+   * message (carries `forum_topic_created` etc.) or a real bot reply.
    */
   async function buildGroupReplyCtx(params: {
     replyToMessageText?: string;
     replyToMessageCaption?: string;
     replyFromIsBot?: boolean;
     replyFromId?: number;
+    /** Extra fields on reply_to_message (e.g. forum_topic_created). */
+    replyToMessageExtra?: Record<string, unknown>;
   }) {
     const BOT_ID = 7; // matches test harness primaryCtx.me.id
     return await buildTelegramMessageContextForTest({
@@ -33,6 +35,7 @@ describe("buildTelegramMessageContext implicitMention forum system messages", ()
             first_name: "OpenClaw",
             is_bot: params.replyFromIsBot ?? true,
           },
+          ...params.replyToMessageExtra,
         },
       },
       resolveGroupActivation: () => true,
@@ -44,11 +47,14 @@ describe("buildTelegramMessageContext implicitMention forum system messages", ()
     });
   }
 
-  it("does NOT trigger implicitMention for forum topic system messages (empty-text bot message)", async () => {
-    // System message: bot created the topic → text is empty, from.is_bot = true
+  it("does NOT trigger implicitMention for forum_topic_created service message", async () => {
+    // Bot auto-generated "Topic created" message carries forum_topic_created.
     const ctx = await buildGroupReplyCtx({
       replyToMessageText: undefined,
       replyFromIsBot: true,
+      replyToMessageExtra: {
+        forum_topic_created: { name: "New Topic", icon_color: 0x6fb9f0 },
+      },
     });
 
     // With requireMention and no explicit @mention, the message should be
@@ -56,10 +62,21 @@ describe("buildTelegramMessageContext implicitMention forum system messages", ()
     expect(ctx).toBeNull();
   });
 
-  it("does NOT trigger implicitMention for empty-string text system messages", async () => {
+  it("does NOT trigger implicitMention for forum_topic_closed service message", async () => {
     const ctx = await buildGroupReplyCtx({
-      replyToMessageText: "",
+      replyToMessageText: undefined,
       replyFromIsBot: true,
+      replyToMessageExtra: { forum_topic_closed: {} },
+    });
+
+    expect(ctx).toBeNull();
+  });
+
+  it("does NOT trigger implicitMention for general_forum_topic_hidden service message", async () => {
+    const ctx = await buildGroupReplyCtx({
+      replyToMessageText: undefined,
+      replyFromIsBot: true,
+      replyToMessageExtra: { general_forum_topic_hidden: {} },
     });
 
     expect(ctx).toBeNull();
@@ -76,12 +93,12 @@ describe("buildTelegramMessageContext implicitMention forum system messages", ()
     expect(ctx?.ctxPayload?.WasMentioned).toBe(true);
   });
 
-  it("DOES trigger implicitMention for bot reply with whitespace-only text", async () => {
-    // A bot message that has actual whitespace text is NOT a system message,
-    // so it should still count as an implicit mention.  (Telegram's forum
-    // system messages have undefined / empty text, not whitespace.)
+  it("DOES trigger implicitMention for bot media messages with caption", async () => {
+    // Media messages from the bot have caption but no text — they should
+    // still count as real bot replies, not service messages.
     const ctx = await buildGroupReplyCtx({
-      replyToMessageText: " ",
+      replyToMessageText: undefined,
+      replyToMessageCaption: "Check out this image",
       replyFromIsBot: true,
     });
 
@@ -89,13 +106,14 @@ describe("buildTelegramMessageContext implicitMention forum system messages", ()
     expect(ctx?.ctxPayload?.WasMentioned).toBe(true);
   });
 
-  it("DOES trigger implicitMention for bot media messages with caption (not a system message)", async () => {
-    // Media messages from the bot have caption but no text — they should
-    // still count as real bot replies, not system messages.
+  it("DOES trigger implicitMention for bot sticker/voice (no text, no caption, no service field)", async () => {
+    // Stickers, voice notes, and captionless photos have neither text nor
+    // caption, but they are NOT service messages — they are legitimate bot
+    // replies that should trigger implicitMention.
     const ctx = await buildGroupReplyCtx({
       replyToMessageText: undefined,
-      replyToMessageCaption: "Check out this image",
       replyFromIsBot: true,
+      // No forum_topic_* fields → not a service message
     });
 
     expect(ctx).not.toBeNull();

src/telegram/bot-message-context.ts

@@ -471,18 +471,18 @@ export const buildTelegramMessageContext = async ({
     return null;
   }
   // Reply-chain detection: replying to a bot message acts like an implicit mention.
-  // Exclude forum-topic system messages (auto-generated "Topic created" messages by the
-  // bot that have empty text) so that every message inside a bot-created topic does not
-  // incorrectly bypass requireMention (#32256).
+  // Exclude forum-topic service messages (auto-generated "Topic created" etc. messages
+  // by the bot) so that every message inside a bot-created topic does not incorrectly
+  // bypass requireMention (#32256).
+  // We detect service messages by the presence of Telegram's forum_topic_* fields
+  // rather than by the absence of text/caption, because legitimate bot media messages
+  // (stickers, voice notes, captionless photos) also lack text/caption.
   const botId = primaryCtx.me?.id;
   const replyFromId = msg.reply_to_message?.from?.id;
   const replyToBotMessage = botId != null && replyFromId === botId;
-  const isReplyToSystemMessage =
-    replyToBotMessage &&
-    msg.reply_to_message?.from?.is_bot === true &&
-    !msg.reply_to_message?.text &&
-    !msg.reply_to_message?.caption;
-  const implicitMention = replyToBotMessage && !isReplyToSystemMessage;
+  const isReplyToServiceMessage =
+    replyToBotMessage && isTelegramForumServiceMessage(msg.reply_to_message);
+  const implicitMention = replyToBotMessage && !isReplyToServiceMessage;
   const canDetectMention = Boolean(botUsername) || mentionRegexes.length > 0;
   const mentionGate = resolveMentionGatingWithBypass({
     isGroup,
@@ -867,3 +867,30 @@ export const buildTelegramMessageContext = async ({
 export type TelegramMessageContext = NonNullable<
   Awaited<ReturnType<typeof buildTelegramMessageContext>>
 >;
+
+// ---------------------------------------------------------------------------
+// Helpers
+// ---------------------------------------------------------------------------
+
+/** Telegram forum-topic service-message fields (Bot API). */
+const FORUM_SERVICE_FIELDS = [
+  "forum_topic_created",
+  "forum_topic_edited",
+  "forum_topic_closed",
+  "forum_topic_reopened",
+  "general_forum_topic_hidden",
+  "general_forum_topic_unhidden",
+] as const;
+
+/**
+ * Returns `true` when the message is a Telegram forum service message (e.g.
+ * "Topic created").  These auto-generated messages carry one of the
+ * `forum_topic_*` / `general_forum_topic_*` fields and should not count as
+ * regular bot replies for implicit-mention purposes.
+ */
+function isTelegramForumServiceMessage(msg: Record<string, unknown> | undefined | null): boolean {
+  if (!msg) {
+    return false;
+  }
+  return FORUM_SERVICE_FIELDS.some((f) => msg[f] != null);
+}