fix: preserve telegram queue fifo during grace window

gateway/run.py

@@ -7902,12 +7902,15 @@ class GatewayRunner:
                 )
                 adapter = self.adapters.get(source.platform)
                 if adapter:
-                    merge_pending_message_event(
-                        adapter._pending_messages,
-                        _quick_key,
-                        event,
-                        merge_text=True,
-                    )
+                    if self._busy_input_mode == "queue":
+                        self._enqueue_fifo(_quick_key, event, adapter)
+                    else:
+                        merge_pending_message_event(
+                            adapter._pending_messages,
+                            _quick_key,
+                            event,
+                            merge_text=True,
+                        )
                 return None
 
             running_agent = self._running_agents.get(_quick_key)

tests/gateway/test_busy_session_ack.py

@@ -27,6 +27,7 @@ sys.modules.setdefault("telegram.ext", types.ModuleType("telegram.ext"))
 from gateway.platforms.base import (
     MessageEvent,
     MessageType,
+    Platform,
     SessionSource,
     build_session_key,
 )
@@ -66,6 +67,8 @@ def _make_runner():
     runner._busy_text_mode = "interrupt"
     runner.adapters = {}
     runner.config = MagicMock()
+    runner.config.group_sessions_per_user = True
+    runner.config.thread_sessions_per_user = False
     runner.session_store = None
     runner.hooks = MagicMock()
     runner.hooks.emit = AsyncMock()
@@ -119,6 +122,55 @@ class TestBusySessionAck:
         assert sk not in runner._pending_messages
         running_agent.interrupt.assert_not_called()
 
+    @pytest.mark.asyncio
+    async def test_telegram_grace_followups_respect_queue_fifo(self, monkeypatch):
+        """Rapid Telegram text follow-ups in queue mode must not merge."""
+        from gateway.run import GatewayRunner
+
+        monkeypatch.setenv("HERMES_TELEGRAM_FOLLOWUP_GRACE_SECONDS", "3.0")
+
+        runner, _sentinel = _make_runner()
+        runner._busy_input_mode = "queue"
+        runner._queued_events = {}
+        adapter = _make_adapter()
+
+        source = SessionSource(
+            platform=Platform.TELEGRAM,
+            chat_id="123",
+            chat_type="dm",
+            user_id="user1",
+        )
+        sk = build_session_key(source)
+        runner.adapters[source.platform] = adapter
+
+        agent = MagicMock()
+        agent.get_activity_summary.return_value = {
+            "seconds_since_activity": 0.0,
+        }
+        runner._running_agents[sk] = agent
+        runner._running_agents_ts[sk] = time.time()
+
+        events = [
+            MessageEvent(
+                text=text,
+                message_type=MessageType.TEXT,
+                source=source,
+                message_id=f"m-{idx}",
+            )
+            for idx, text in enumerate(("first", "second", "third"), start=1)
+        ]
+
+        for event in events:
+            result = await GatewayRunner._handle_message(runner, event)
+            assert result is None
+
+        assert adapter._pending_messages[sk].text == "first"
+        assert [event.text for event in runner._queued_events[sk]] == [
+            "second",
+            "third",
+        ]
+        agent.interrupt.assert_not_called()
+
     @pytest.mark.asyncio
     async def test_sends_ack_when_agent_running(self):
         """First message during busy session should get a status ack."""