feat(cli): place self-hosted deployments on a listener (#9056)

Follow-up to #8482. `langgraph deploy --push-to` can now create a
deployment in a workspace that
deploys through a listener in the customer's own cluster, which is the
hybrid case. Before this,
creation in such a workspace was impossible from the CLI: the control
plane rejected it and the CLI
told the user to go and create the deployment in the UI first.

## Changes
- Smart Auto-Placement: The CLI now proactively checks your workspace.
If you only have one listener and one Kubernetes namespace configured
(and are using the managed cloud control plane), it automatically routes
your deployment there. No extra flags needed.
- New Disambiguation Flags: If your workspace has multiple listeners or
namespaces, the CLI will ask you to choose. You can now pass
--listener-id and --k8s-namespace to tell it exactly where to deploy.
- Failing Fast: The CLI now validates your listener and namespace
choices before it starts building and pushing the heavy Docker image. If
you provide an invalid ID, it stops immediately instead of wasting your
time and bandwidth.
- Fixed a Duplication Bug: Previously, if you had many deployments with
similar names, a pagination issue could hide your existing deployment
from the CLI, causing it to accidentally create a duplicate. The CLI now
queries the server for the exact deployment name to guarantee this
doesn't happen.
- Cleaner Errors: Error messages from the control plane are now stripped
of their clunky HTTP envelopes so you get clear, readable sentences when
something goes wrong.

## Testing

Deployment on 3 paths, hybrid, self-hosted, nominal

libs/cli/tests/unit_tests/test_host_backend.py

@@ -79,19 +79,6 @@ def test_request_transport_error_raises():
         c._request("GET", "/test")
 
 
-def test_list_deployments_sends_query_params():
-    def handler(req: httpx.Request) -> httpx.Response:
-        assert req.url.path == "/v2/deployments"
-        assert req.url.params["name_contains"] == "my app"
-        return httpx.Response(200, json={"ok": True})
-
-    c = HostBackendClient(
-        "https://api.example.com", "test-key", transport=httpx.MockTransport(handler)
-    )
-    result = c.list_deployments("my app")
-    assert result == {"ok": True}
-
-
 def _capturing_client(captured: dict) -> HostBackendClient:
     def handler(req: httpx.Request) -> httpx.Response:
         captured["body"] = req.read()
@@ -421,7 +408,7 @@ def test_injected_transport_receives_requests_under_the_prefixed_base_url():
         transport=httpx.MockTransport(handler),
     )
 
-    assert c.list_revisions("dep-1", limit=2) == {"ok": True}
+    assert c.list_revisions("dep-1", limit=2) == []
     assert seen == {
         "url": "https://smith.example.com/api-host/v2/deployments/dep-1/revisions?limit=2",
         "api_key": "key",
@@ -546,3 +533,144 @@ def test_control_plane_endpoints_resolve(host_url, langsmith_endpoint, expected)
     endpoints = ControlPlaneEndpoints.resolve(host_url, langsmith_endpoint)
 
     assert (endpoints.control_plane_url, endpoints.dashboard_url) == expected
+
+
+@pytest.mark.parametrize(
+    ("payload", "expected"),
+    [
+        pytest.param(
+            {"resources": [{"id": "a"}, {"id": "b"}]},
+            [{"id": "a"}, {"id": "b"}],
+            id="list_returns_the_resources",
+        ),
+        pytest.param({"resources": []}, [], id="empty_list"),
+        pytest.param({}, [], id="missing_key"),
+        pytest.param({"resources": None}, [], id="null_resources"),
+        pytest.param(
+            {"resources": ["nope", {"id": "a"}]}, [{"id": "a"}], id="skips_non_objects"
+        ),
+        pytest.param([], [], id="unexpected_envelope"),
+    ],
+)
+def test_list_endpoints_return_resource_objects(payload, expected):
+    def handler(req: httpx.Request) -> httpx.Response:
+        return httpx.Response(200, json=payload)
+
+    c = HostBackendClient(
+        "https://api.example.com", "key", transport=httpx.MockTransport(handler)
+    )
+
+    assert c.list_deployments() == expected
+
+
+def test_list_listeners_asks_for_a_full_page():
+    seen: dict = {}
+
+    def handler(req: httpx.Request) -> httpx.Response:
+        seen["url"] = str(req.url)
+        return httpx.Response(200, json={"resources": [{"id": "listener-1"}]})
+
+    c = HostBackendClient(
+        "https://api.example.com", "key", transport=httpx.MockTransport(handler)
+    )
+
+    assert c.list_listeners() == [{"id": "listener-1"}]
+    assert seen["url"] == "https://api.example.com/v2/listeners?limit=100"
+
+
+@pytest.mark.parametrize(
+    ("control_plane_url", "expected"),
+    [
+        pytest.param("https://api.host.langchain.com", True, id="cloud"),
+        pytest.param("https://eu.api.host.langchain.com", True, id="cloud_region"),
+        pytest.param("https://dev.api.host.langchain.com", True, id="cloud_dev"),
+        pytest.param("https://smith.example.com/api-host", False, id="self_hosted"),
+        pytest.param(
+            "https://corp.example.com/langsmith/api-host",
+            False,
+            id="self_hosted_prefix",
+        ),
+        pytest.param("http://localhost:8080/api-host", False, id="local"),
+        pytest.param(
+            "https://evil-api.host.langchain.com", False, id="lookalike_needs_a_dot"
+        ),
+    ],
+)
+def test_is_cloud_recognises_the_managed_control_plane(control_plane_url, expected):
+    endpoints = ControlPlaneEndpoints.from_control_plane_url(control_plane_url)
+
+    assert endpoints.is_cloud is expected
+
+
+@pytest.mark.parametrize(
+    ("call", "expected_params"),
+    [
+        pytest.param(
+            lambda c: c.list_deployments(name="agent"),
+            {"name": "agent"},
+            id="exact_name_filters_server_side",
+        ),
+        pytest.param(
+            lambda c: c.list_deployments(name_contains="age"),
+            {"name_contains": "age"},
+            id="substring_search_keeps_its_own_parameter",
+        ),
+        pytest.param(
+            lambda c: c.list_deployments(),
+            {},
+            id="no_filter_sends_no_parameters",
+        ),
+        pytest.param(
+            lambda c: c.list_deployments(
+                name="agent", name_contains="agent", limit=100
+            ),
+            {"name": "agent", "name_contains": "agent", "limit": "100"},
+            id="both_filters_travel_together_for_older_servers",
+        ),
+    ],
+)
+def test_list_deployments_sends_one_name_filter(call, expected_params):
+    seen: dict = {}
+
+    def handler(req: httpx.Request) -> httpx.Response:
+        seen.update(dict(req.url.params))
+        return httpx.Response(200, json={"resources": []})
+
+    call(
+        HostBackendClient(
+            "https://api.example.com", "key", transport=httpx.MockTransport(handler)
+        )
+    )
+
+    assert seen == expected_params
+
+
+@pytest.mark.parametrize(
+    ("body", "expected"),
+    [
+        pytest.param(
+            {"detail": "Source configuration error: bad listener"},
+            "Source configuration error: bad listener",
+            id="fastapi_detail_is_unwrapped",
+        ),
+        pytest.param(
+            {"detail": {"loc": ["body"], "msg": "nope"}},
+            None,
+            id="a_structured_detail_is_left_alone",
+        ),
+        pytest.param({"other": "shape"}, None, id="an_unknown_shape_is_left_alone"),
+    ],
+)
+def test_error_detail_is_readable(body, expected):
+    c = HostBackendClient(
+        "https://api.example.com",
+        "key",
+        transport=httpx.MockTransport(lambda req: httpx.Response(400, json=body)),
+    )
+
+    with pytest.raises(HostBackendError) as error:
+        c.get_deployment("dep-1")
+
+    assert error.value.detail == expected
+    if expected is not None:
+        assert error.value.message.endswith(expected)