fix(zulip): detect BAD_EVENT_QUEUE_ID instead of silently swallowing it

Root cause of Tanko not responding to DMs after initial connection:
Zulip event queues expire after ~10min of dont_block polling. When the
queue expired, _api_call() returned None for all 400-level errors, which
_fetch_events() treated as 'no events' and returned []. The poll loop
never knew the queue died, so it never reconnected.

Fix:
1. _api_call() now returns (Optional[Dict], status_code) tuple
2. _fetch_events() explicitly checks for 400 status and raises
   RuntimeError('BAD_EVENT_QUEUE_ID') for the poll loop to catch
3. All callers updated to unpack the tuple

Now when a queue expires, the poll loop catches the error and
calls _reconnect() to register a fresh queue.

plugins/platforms/zulip/adapter.py

@@ -242,7 +242,7 @@ class ZulipAdapter(BasePlatformAdapter):
             self._health_stats["started_at"] = datetime.now(timezone.utc).isoformat()
 
             # Register event queue
-            queue_resp = await self._api_call(
+            queue_resp, _ = await self._api_call(
                 "POST", "/api/v1/register",
                 data={
                     "event_types": '["message"]',
@@ -381,11 +381,15 @@ class ZulipAdapter(BasePlatformAdapter):
             await asyncio.sleep(self._poll_interval)
 
     async def _fetch_events(self) -> List[Dict[str, Any]]:
-        """Fetch events from the Zulip event queue."""
+        """Fetch events from the Zulip event queue.
+
+        Raises RuntimeError with BAD_EVENT_QUEUE_ID when the queue
+        expires, so _poll_forever can reconnect.
+        """
         if not self._queue_id:
             return []
 
-        resp = await self._api_call(
+        resp, raw_status = await self._api_call(
             "GET", "/api/v1/events",
             params={
                 "queue_id": self._queue_id,
@@ -393,6 +397,9 @@ class ZulipAdapter(BasePlatformAdapter):
                 "dont_block": "true",
             },
         )
+        # Detect queue expiry from HTTP response
+        if raw_status == 400:
+            raise RuntimeError("BAD_EVENT_QUEUE_ID: queue expired")
         if not resp:
             return []
 
@@ -409,7 +416,7 @@ class ZulipAdapter(BasePlatformAdapter):
         """Re-register the event queue."""
         self._queue_id = None
         try:
-            resp = await self._api_call(
+            resp, _ = await self._api_call(
                 "POST", "/api/v1/register",
                 data={
                     "event_types": '["message"]',
@@ -506,7 +513,7 @@ class ZulipAdapter(BasePlatformAdapter):
         Falls back to the configured or default value if resolution fails.
         """
         try:
-            resp = await self._api_call("GET", "/api/v1/users")
+            resp, _ = await self._api_call("GET", "/api/v1/users")
             if not resp:
                 return
             members = resp.get("members", [])
@@ -766,7 +773,7 @@ class ZulipAdapter(BasePlatformAdapter):
             "content": truncated,
         }
         try:
-            resp = await self._api_call("PATCH", "/api/v1/messages", data=payload)
+            resp, _ = await self._api_call("PATCH", "/api/v1/messages", data=payload)
             return resp is not None
         except Exception as e:
             logger.warning("[%s] Edit message %s error: %s", self.name, message_id, e)
@@ -782,6 +789,7 @@ class ZulipAdapter(BasePlatformAdapter):
                 "POST", "/api/v1/typing",
                 data={"to": user_ids, "op": "start"},
             )
+            # typing indicator failure is non-critical
         except Exception:
             pass  # Non-critical
 
@@ -795,6 +803,7 @@ class ZulipAdapter(BasePlatformAdapter):
                 "POST", "/api/v1/typing",
                 data={"to": user_ids, "op": "stop"},
             )
+            # typing indicator failure is non-critical
         except Exception:
             pass  # Non-critical
 
@@ -1009,10 +1018,15 @@ class ZulipAdapter(BasePlatformAdapter):
         path: str,
         data: Optional[Dict] = None,
         params: Optional[Dict] = None,
-    ) -> Optional[Dict]:
-        """Make an API call to Zulip."""
+    ) -> Tuple[Optional[Dict], int]:
+        """Make an API call to Zulip.
+
+        Returns (response_json, status_code). status_code is useful for
+        callers that need to detect specific HTTP errors like 400
+        (BAD_EVENT_QUEUE_ID). Returns (None, 0) on transport errors.
+        """
         if not self._http_client:
-            return None
+            return None, 0
 
         url = f"{self._site}{path}"
         headers = {
@@ -1033,7 +1047,7 @@ class ZulipAdapter(BasePlatformAdapter):
                     url, data=data, headers=headers,
                 )
             else:
-                return None
+                return None, 0
 
             if response.status_code >= 400:
                 logger.warning(
@@ -1041,20 +1055,21 @@ class ZulipAdapter(BasePlatformAdapter):
                     self.name, method, path,
                     response.status_code, response.text[:200],
                 )
-                return None
+                return None, response.status_code
 
-            return response.json()
+            return response.json(), response.status_code
 
         except httpx.TimeoutException:
             logger.debug("[%s] Timeout on %s %s", self.name, method, path)
-            return None
+            return None, 0
         except Exception as e:
             logger.warning("[%s] API error %s %s: %s", self.name, method, path, e)
-            return None
+            return None, 0
 
     async def _send_api_call(self, payload: Dict) -> Optional[Dict]:
         """Send a message to Zulip."""
-        return await self._api_call("POST", "/api/v1/messages", data=payload)
+        result, _ = await self._api_call("POST", "/api/v1/messages", data=payload)
+        return result
 
     # ------------------------------------------------------------------
     # Utilities