From 4ea2701a29c0b86ae9b710fd93e5da4b1f664c91 Mon Sep 17 00:00:00 2001
From: Hugo Durand <hugo.durand@langchain.dev>
Date: Tue, 22 Sep 2026 16:29:33 -0400
Subject: [PATCH] fix(cli): refuse a malformed listener instead of dropping it

---
 libs/cli/langgraph_cli/deploy.py              |  9 ++--
 .../unit_tests/cli/test_deploy_command.py     | 49 ++++++++++++-------
 .../tests/unit_tests/test_deploy_helpers.py   | 14 +++++-
 3 files changed, 48 insertions(+), 24 deletions(-)

diff --git a/libs/cli/langgraph_cli/deploy.py b/libs/cli/langgraph_cli/deploy.py
index 525f9d5de..f12dc8d68 100644
--- a/libs/cli/langgraph_cli/deploy.py
+++ b/libs/cli/langgraph_cli/deploy.py
@@ -157,10 +157,12 @@ class Listener:
     namespaces: tuple[str, ...]
 
     @classmethod
-    def from_resource(cls, resource: Mapping[str, object]) -> "Listener | None":
+    def from_resource(cls, resource: Mapping[str, object]) -> "Listener":
         identifier = str(resource.get("id") or "")
         if not identifier:
-            return None
+            raise HostBackendError(
+                "The control plane returned a listener without an id."
+            )
         compute_config = resource.get("compute_config")
         namespaces = (
             compute_config.get("k8s_namespaces")
@@ -1467,8 +1469,7 @@ def _available_listeners(client: HostBackendClient) -> tuple[Listener, ...]:
     resources = _call_host_backend_with_optional_tenant(
         client, lambda c: c.list_listeners()
     )
-    listeners = (Listener.from_resource(resource) for resource in resources)
-    return tuple(listener for listener in listeners if listener is not None)
+    return tuple(Listener.from_resource(resource) for resource in resources)
 
 
 def _ensure_customer_registry_source(existing: ExistingDeployment) -> None:
diff --git a/libs/cli/tests/unit_tests/cli/test_deploy_command.py b/libs/cli/tests/unit_tests/cli/test_deploy_command.py
index 9e08c7957..318177fbf 100644
--- a/libs/cli/tests/unit_tests/cli/test_deploy_command.py
+++ b/libs/cli/tests/unit_tests/cli/test_deploy_command.py
@@ -918,24 +918,6 @@ def test_a_truncated_listener_page_says_so(deploy_project: DeployProject) -> Non
     assert "first 100" in result.output
 
 
-def test_a_listener_without_an_id_is_ignored(deploy_project: DeployProject) -> None:
-    deploy_project.control_plane.listeners = [
-        {"compute_id": "broken", "compute_config": {"k8s_namespaces": ["agents"]}},
-        LISTENER,
-    ]
-
-    result = deploy_project.run(
-        "--push-to", PUSH_REPOSITORY, host_url=CLOUD_CONTROL_PLANE_URL
-    )
-
-    assert result.exit_code == 0, result.output
-    assert deploy_project.control_plane.bodies[CREATE_DEPLOYMENT]["source_config"] == {
-        "resource_spec": {},
-        "listener_id": "listener-1",
-        "listener_config": {"k8s_namespace": "agents"},
-    }
-
-
 def test_a_managed_build_in_a_listener_workspace_points_at_push_to(
     deploy_project: DeployProject,
 ) -> None:
@@ -949,3 +931,34 @@ def test_a_managed_build_in_a_listener_workspace_points_at_push_to(
     assert result.exit_code != 0
     assert "--push-to" in result.output
     assert deploy_project.docker.verbs() == []
+
+
+def test_a_managed_control_plane_without_listeners_creates_as_before(
+    deploy_project: DeployProject,
+) -> None:
+    result = deploy_project.run(
+        "--push-to", PUSH_REPOSITORY, host_url=CLOUD_CONTROL_PLANE_URL
+    )
+
+    assert result.exit_code == 0, result.output
+    assert deploy_project.control_plane.bodies[CREATE_DEPLOYMENT]["source_config"] == {
+        "resource_spec": {}
+    }
+    assert deploy_project.timeline.count(LIST_LISTENERS) == 1
+
+
+def test_a_listener_without_an_id_is_reported_rather_than_ignored(
+    deploy_project: DeployProject,
+) -> None:
+    deploy_project.control_plane.listeners = [
+        {"compute_id": "broken", "compute_config": {"k8s_namespaces": ["agents"]}},
+        LISTENER,
+    ]
+
+    result = deploy_project.run(
+        "--push-to", PUSH_REPOSITORY, host_url=CLOUD_CONTROL_PLANE_URL
+    )
+
+    assert result.exit_code != 0
+    assert "without an id" in result.output
+    assert deploy_project.docker.verbs() == []
diff --git a/libs/cli/tests/unit_tests/test_deploy_helpers.py b/libs/cli/tests/unit_tests/test_deploy_helpers.py
index 3ea3931a9..0da5eaef5 100644
--- a/libs/cli/tests/unit_tests/test_deploy_helpers.py
+++ b/libs/cli/tests/unit_tests/test_deploy_helpers.py
@@ -960,8 +960,6 @@ class TestListener:
                 Listener("listener-1", "", ()),
                 id="only_an_id",
             ),
-            pytest.param({"compute_id": "c"}, None, id="no_id_is_not_a_listener"),
-            pytest.param({"id": ""}, None, id="empty_id_is_not_a_listener"),
         ],
     )
     def test_from_resource_reads_the_control_plane_shape(self, resource, expected):
@@ -1179,3 +1177,15 @@ def test_a_partial_page_without_a_match_means_the_name_is_free():
     )
 
     assert find_deployment_by_name(client, "brand-new-agent") is None
+
+
+@pytest.mark.parametrize(
+    "resource",
+    [
+        pytest.param({"compute_id": "c"}, id="no_id"),
+        pytest.param({"id": ""}, id="empty_id"),
+    ],
+)
+def test_a_listener_without_an_id_is_refused(resource):
+    with pytest.raises(HostBackendError, match="without an id"):
+        Listener.from_resource(resource)