diff --git a/plugins/platforms/zulip/adapter.py b/plugins/platforms/zulip/adapter.py
index 13e50a6..66b5a29 100644
--- a/plugins/platforms/zulip/adapter.py
+++ b/plugins/platforms/zulip/adapter.py
@@ -259,6 +259,11 @@ class ZulipAdapter(BasePlatformAdapter):
             self._last_event_id = data.get("last_event_id", -1)
             self._bot_user_id = data.get("user_id")
 
+            # Resolve bot user_id if register endpoint didn't provide it
+            # (common on some Zulip versions)
+            if self._bot_user_id is None:
+                await self._resolve_bot_user_id()
+
             # Gen 2: Try to resolve @all-bots user ID dynamically
             await self._resolve_all_bots_user_id()
 
@@ -503,6 +508,32 @@ class ZulipAdapter(BasePlatformAdapter):
                     "[%s] @all-bots refresh error (non-fatal)", self.name
                 )
 
+    # ------------------------------------------------------------------
+    # Gen 5: Bot user ID resolution
+    # ------------------------------------------------------------------
+
+    async def _resolve_bot_user_id(self) -> None:
+        """Fetch the bot's own user ID from /api/v1/users/me.
+
+        The /register endpoint does not always return user_id on
+        all Zulip server versions. This ensures @mention detection
+        works by resolving it from the identity endpoint.
+        """
+        try:
+            resp, _ = await self._api_call("GET", "/api/v1/users/me")
+            if resp:
+                uid = resp.get("user_id")
+                if uid is not None:
+                    self._bot_user_id = int(uid)
+                    logger.info(
+                        "[%s] Resolved bot user_id=%s from /users/me",
+                        self.name, uid,
+                    )
+        except Exception as e:
+            logger.debug(
+                "[%s] Could not resolve bot user_id: %s", self.name, e
+            )
+
     # ------------------------------------------------------------------
     # Gen 2: Dynamic @all-bots resolution
     # ------------------------------------------------------------------