fix(slack): recognize bot-id-form mentions (<@B…>) everywhere

src/slack/events.ts

@@ -163,7 +163,7 @@ export function registerSlackEvents(
     if (m.channel_type === "channel" || m.channel_type === "group" || m.channel_type === "mpim") {
       if (m.channel_type === "mpim" && m.channel) syncForUnseenGroup(client, String(m.channel));
       const threadReply = isThreadReply(m);
-      const isMention = mentionsBot(m.text ?? "", ids.botUserId);
+      const isMention = mentionsBot(m.text ?? "", ids.botUserId, ids.ownBotId);
       const willDispatch = threadReply && !isMention && (await botHasStakeInThread(client, m.channel, m.thread_ts));
       await mirrorMessageEvent(m, client, willDispatch ? { handled: true } : {});
       if (!threadReply) return;

src/slack/message-gating.ts

@@ -1,7 +1,15 @@
 import { LRUCache } from "lru-cache";
 
-export function mentionsBot(text: string, botUserId: string): boolean {
-  return botUserId ? text.includes(`<@${botUserId}>`) : false;
+export function mentionsBot(text: string, botUserId: string, ownBotId = ""): boolean {
+  // Both id forms mention the bot: the bot USER id (`<@U…>`, the form
+  // Slack's autocomplete inserts) and the BOT id (`<@B…>`, which
+  // hand-typed mentions and some clients encode). A B-form mention is a
+  // legitimate mention of this bot — `bots.info` maps it to the same
+  // single-bot app — but Slack fires no `app_mention` for it, so without
+  // recognizing it here the message is dropped at top level and
+  // misdispatched as ambient in threads (#630).
+  if (botUserId && text.includes(`<@${botUserId}>`)) return true;
+  return Boolean(ownBotId) && text.includes(`<@${ownBotId}>`);
 }
 
 export function threadHasBotStake(
@@ -17,7 +25,7 @@ export function threadHasBotStake(
     return Boolean(
       (botUserId && user === botUserId) ||
       (ownBotId && bot === ownBotId) ||
-      (botUserId && mentionsBot(text, botUserId)),
+      mentionsBot(text, botUserId, ownBotId),
     );
   });
 }

src/slack/mirror.ts

@@ -117,7 +117,7 @@ export function createMirror(deps: {
         text,
         ...(Object.keys(mentions).length ? { mentions } : {}),
         ...(m.bot_id || m.bot_profile ? { bot: true } : {}),
-        ...(mentionsBot(raw, ids.botUserId) ? { mentionsSelf: true } : {}),
+        ...(mentionsBot(raw, ids.botUserId, ids.ownBotId) ? { mentionsSelf: true } : {}),
         ...(opts.editedAt ? { editedAt: opts.editedAt } : {}),
         ...(opts.handled ? { handled: true } : {}),
         ...(opts.containerName ? { containerName: opts.containerName } : {}),

src/slack/mrkdwn.ts

@@ -10,8 +10,15 @@ export function resolveMentionsInText(text: string, lookup: (id: string) => stri
   });
 }
 
-export function stripMention(text: string, botUserId: string): string {
-  const withoutMention = botUserId ? text.replace(new RegExp(`<@${botUserId}>`, "g"), "") : text;
+export function stripMention(text: string, botUserId: string, ownBotId = ""): string {
+  // Strip BOTH mention forms (bot user id and bot id — see
+  // mentionsBot) including the legacy `<@ID|label>` shape, so the core
+  // never receives a raw `<@B…>` token for an addressed turn (#630).
+  let withoutMention = text;
+  for (const id of [botUserId, ownBotId]) {
+    if (!id) continue;
+    withoutMention = withoutMention.replace(new RegExp(`<@${id}(?:\|[^>]*)?>`, "g"), "");
+  }
   return decodeSlackEntities(withoutMention).trim();
 }
 

src/slack/turn-handler.ts

@@ -202,7 +202,7 @@ export function createTurnHandler(deps: {
     else classified = await classifyUserCached(client, inc.userId);
     const actor = classified.actor;
     const timezone = classified.timezone;
-    const text = stripMention(inc.rawText, ids.botUserId);
+    const text = stripMention(inc.rawText, ids.botUserId, ids.ownBotId);
     if (!hasContent(text, inc.files)) return;
 
     let audience: ActorAssertion[] = [actor];

test/slack-message-gating.test.ts

@@ -90,6 +90,19 @@ test("dmThreadRef gives the DM main pane one continuous lane and each thread its
   assert.notEqual(dmThreadRef("D1", "1699999999.000100"), dmThreadRef("D1"));
 });
 
+test("mentionsBot recognizes the bot-id form (<@B…>) alongside the user-id form (#630)", () => {
+  // A hand-typed mention can arrive encoded against the bot id; Slack fires
+  // no app_mention for it, so message-gating recognition is the only thing
+  // that can dispatch it.
+  assert.equal(mentionsBot("hey <@BOTID> do this", "UBOT", "BOTID"), true);
+  assert.equal(mentionsBot("<@UBOT> classic form", "UBOT", "BOTID"), true);
+  assert.equal(mentionsBot("both <@UBOT> <@BOTID>", "UBOT", "BOTID"), true);
+  assert.equal(mentionsBot("<@OTHERBOT> not me", "UBOT", "BOTID"), false);
+  assert.equal(mentionsBot("no ids configured", "", ""), false);
+  // Back-compat: the two-arg form still works.
+  assert.equal(mentionsBot("hey <@BOT> do this", "BOT"), true);
+});
+
 test("mentionsBot detects the bot @mention so thread-follow leaves those to app_mention", () => {
   assert.equal(mentionsBot("hey <@BOT> do this", "BOT"), true);
   assert.equal(mentionsBot("just a follow-up", "BOT"), false);

test/slack-mrkdwn.test.ts

@@ -24,6 +24,15 @@ test("decodeSlackEntities / stripMention", () => {
   assert.equal(stripMention("<@BOT>", "BOT"), "");
 });
 
+test("stripMention strips the bot-id form and the legacy label shape (#630)", () => {
+  // The core must not receive a raw <@B…> token for an addressed turn.
+  assert.equal(stripMention("<@BOTID> run the tests", "UBOT", "BOTID"), "run the tests");
+  assert.equal(stripMention("<@BOTID|qm> run the tests", "UBOT", "BOTID"), "run the tests");
+  assert.equal(stripMention("<@UBOT> classic", "UBOT", "BOTID"), "classic");
+  assert.equal(stripMention("<@UBOT|qm> legacy label", "UBOT", "BOTID"), "legacy label");
+  assert.equal(stripMention("unrelated <@OTHER> stays", "UBOT", "BOTID"), "unrelated <@OTHER> stays");
+});
+
 test("toSlackMrkdwn: bold uses single * (the screenshot bug: **x** rendered literally)", () => {
   assert.equal(toSlackMrkdwn("**Git commands**"), "*Git commands*");
   assert.equal(toSlackMrkdwn("__also bold__"), "*also bold*");