diff --git a/plugins/teams_pipeline/runtime.py b/plugins/teams_pipeline/runtime.py
index 0163ccaaae..e8d3ada710 100644
--- a/plugins/teams_pipeline/runtime.py
+++ b/plugins/teams_pipeline/runtime.py
@@ -111,9 +111,19 @@ def bind_gateway_runtime(gateway: Any) -> bool:
         error_message = str(exc)
         gateway._teams_pipeline_runtime_error = error_message
         logger.warning(
-            "Teams pipeline runtime unavailable; leaving webhook scheduler unchanged: %s",
+            "Teams pipeline runtime unavailable: %s. Installing a drop-scheduler "
+            "so Graph notifications ack cleanly without piling up unbound.",
             error_message,
         )
+
+        async def _drop(notification: dict[str, Any], event: Any) -> None:
+            logger.debug(
+                "Dropping Graph notification because runtime is unavailable: id=%s resource=%s",
+                notification.get("id"),
+                notification.get("resource"),
+            )
+
+        adapter.set_notification_scheduler(_drop)
         return False
 
     async def _schedule(notification: dict[str, Any], event: Any) -> None:
diff --git a/tests/gateway/test_teams_pipeline_runtime_wiring.py b/tests/gateway/test_teams_pipeline_runtime_wiring.py
index d1f95b51ba..5a62033d00 100644
--- a/tests/gateway/test_teams_pipeline_runtime_wiring.py
+++ b/tests/gateway/test_teams_pipeline_runtime_wiring.py
@@ -28,6 +28,10 @@ def test_gateway_runner_wires_teams_pipeline_runtime(monkeypatch):
         return True
 
     monkeypatch.setattr("plugins.teams_pipeline.runtime.bind_gateway_runtime", _bind)
+    monkeypatch.setattr(
+        "gateway.run._load_gateway_config",
+        lambda: {"plugins": {"enabled": ["teams_pipeline"]}},
+    )
 
     GatewayRunner._wire_teams_pipeline_runtime(runner)
 
@@ -47,6 +51,10 @@ def test_gateway_runner_skips_wiring_without_msgraph_adapter(monkeypatch):
         return True
 
     monkeypatch.setattr("plugins.teams_pipeline.runtime.bind_gateway_runtime", _bind)
+    monkeypatch.setattr(
+        "gateway.run._load_gateway_config",
+        lambda: {"plugins": {"enabled": ["teams_pipeline"]}},
+    )
 
     GatewayRunner._wire_teams_pipeline_runtime(runner)
 
@@ -154,7 +162,11 @@ def test_build_pipeline_runtime_skips_sender_when_adapter_layer_is_unavailable(m
     assert runtime.teams_sender is None
 
 
-def test_bind_gateway_runtime_leaves_scheduler_unchanged_on_failure(monkeypatch):
+def test_bind_gateway_runtime_installs_drop_scheduler_on_failure(monkeypatch):
+    """When the runtime can't build, install a drop-scheduler so Graph
+    notifications still ack cleanly rather than leaving the adapter's
+    scheduler unbound.
+    """
     class FakeAdapter:
         def __init__(self):
             self.scheduler = None
@@ -181,5 +193,5 @@ def test_bind_gateway_runtime_leaves_scheduler_unchanged_on_failure(monkeypatch)
     bound = bind_gateway_runtime(gateway)
 
     assert bound is False
-    assert gateway.adapters[Platform.MSGRAPH_WEBHOOK].scheduler is None
+    assert callable(gateway.adapters[Platform.MSGRAPH_WEBHOOK].scheduler)
     assert gateway._teams_pipeline_runtime_error == "boom"