fix(bot): drop removed groups during sync

Previously syncGroupsForAccount only upserted, so groups removed from
WhatsApp (deleted, bot was kicked, etc.) lingered in the DB.

Now compute the diff: any whatsapp_groups row for this account whose
wa_group_jid is not in the live fetch result is deleted. Skip the delete
sweep when the fetch returns empty — that's more likely transient than
a genuine "every group gone" signal, and we don't want to nuke valid
data on a hiccup.

Return shape gains a `removed` count alongside `synced`.

apps/bot/src/whatsapp/group-sync.ts

@@ -1,4 +1,4 @@
-import { sql } from "drizzle-orm";
+import { and, eq, notInArray, sql } from "drizzle-orm";
 import type { WASocket } from "@whiskeysockets/baileys";
 import { whatsappGroups } from "@cmbot/db";
 import { db } from "../db.js";
@@ -7,13 +7,35 @@ import { logger } from "../logger.js";
 export async function syncGroupsForAccount(
   accountId: string,
   socket: WASocket,
-): Promise<{ synced: number }> {
+): Promise<{ synced: number; removed: number }> {
   const meta = await socket.groupFetchAllParticipating();
   const entries = Object.values(meta);
+  const liveJids = entries.map((g) => g.id);
+
+  // Remove DB rows for groups that are no longer in the live participant list
+  // (group was deleted, bot was removed, etc.). Only run the delete when we
+  // got at least one live group back — an empty result is more likely a
+  // transient WA fetch failure than a genuine "all groups gone" signal, and
+  // we don't want to nuke valid data on a hiccup.
+  let removed: { id: string }[] = [];
+  if (liveJids.length > 0) {
+    removed = await db
+      .delete(whatsappGroups)
+      .where(
+        and(
+          eq(whatsappGroups.accountId, accountId),
+          notInArray(whatsappGroups.waGroupJid, liveJids),
+        ),
+      )
+      .returning({ id: whatsappGroups.id });
+  }
 
   if (entries.length === 0) {
-    logger.info({ accountId }, "group-sync: no groups");
+    logger.info(
-    return { synced: 0 };
+      { accountId },
+      "group-sync: empty fetch — skipping delete sweep (treating as transient)",
+    );
+    return { synced: 0, removed: 0 };
   }
 
   const rows = entries.map((g) => ({
@@ -37,6 +59,9 @@ export async function syncGroupsForAccount(
       },
     });
 
-  logger.info({ accountId, count: rows.length }, "group-sync: synced");
+  logger.info(
-  return { synced: rows.length };
+    { accountId, count: rows.length, removed: removed.length },
+    "group-sync: synced",
+  );
+  return { synced: rows.length, removed: removed.length };
 }