Fix BackendsAPIClient.config_info

AGENTS.md

@@ -35,10 +35,13 @@ Before touching a subsystem, read the relevant notes in `contributing/`: `ARCHIT
 
 ## Testing Guidelines
 - Default to `uv run pytest`. Use markers from `tests/conftest.py` like `--runpostgres` if need to include specific tests.
+- Scope the run to the change: for trivial or localized edits, run only the affected test modules, `Test*` classes, or `-k` selection instead of the whole suite. Reserve the full suite for broad or cross-cutting changes.
+- Speed up large runs with `-n auto` (pytest-xdist), e.g. `uv run pytest -n auto`.
 - Group tests for the same unit (function/class) using `Test*` classes that mirror unit's name.
 - Keep tests hermetic (network disabled except localhost per `pytest.ini`); stub cloud calls with mocks.
 
 ## Commit & Pull Request Guidelines
+- Name branches `issue_{issue_num}_{title}` when the work tracks an issue (e.g. `issue_3959_replicated_alb_gateways`), and `pr_{title}` otherwise.
 - Commit messages follow the existing style: short, imperative summaries (e.g., “Fix exclude_not_available ignored”); include rationale in the body if needed.
 - For PRs, describe behavior changes and link related issues.
 - Include screenshots or terminal output when touching UX/CLI messages or frontend flows.

src/dstack/api/server/_backends.py

@@ -46,5 +46,7 @@ def delete(self, project_name: str, backends_names: List[BackendType]):
     def config_info(
         self, project_name: str, backend_name: BackendType
     ) -> AnyBackendConfigWithCreds:
-        resp = self._request(f"/api/project/{project_name}/backends/{backend_name}/config_info")
+        resp = self._request(
+            f"/api/project/{project_name}/backends/{backend_name.value}/config_info"
+        )
         return validate_extra_ignore(AnyBackendConfigWithCredsTagged, resp.json())

src/tests/api/test_backends.py

@@ -0,0 +1,22 @@
+import logging
+
+from dstack._internal.core.models.backends.base import BackendType
+from dstack.api.server._backends import BackendsAPIClient
+from tests.api.common import RequestRecorder
+
+AWS_CONFIG_PAYLOAD = {
+    "type": "aws",
+    "regions": ["eu-west-1"],
+    "creds": {"type": "access_key", "access_key": "key", "secret_key": "secret"},
+}
+
+
+class TestBackendsAPIClientConfigInfo:
+    def test_renders_backend_type_value_in_path(self):
+        recorder = RequestRecorder(AWS_CONFIG_PAYLOAD)
+        client = BackendsAPIClient(_request=recorder, _logger=logging.getLogger("test"))
+
+        result = client.config_info("main", BackendType.AWS)
+
+        assert recorder.last_path == "/api/project/main/backends/aws/config_info"
+        assert result.type == "aws"