feat: add list_namespaces method to document index

Task: IL-174

src/intelligence_layer/connectors/document_index/document_index.py

@@ -288,6 +288,18 @@ def _raise_for_status(self, response: requests.Response) -> None:
             )
             raise exception_factory(response.text, HTTPStatus(response.status_code))
 
+    def list_namespaces(self) -> Sequence[str]:
+        """Lists all available namespaces.
+
+        Returns:
+            List of all available namespaces.
+        """
+
+        url = f"{self._base_document_index_url}/namespaces"
+        response = requests.get(url, headers=self.headers)
+        self._raise_for_status(response)
+        return [str(namespace) for namespace in response.json()]
+
     def create_collection(self, collection_path: CollectionPath) -> None:
         """Creates a collection at the path.
 

tests/connectors/document_index/test_document_index.py

@@ -48,6 +48,13 @@ def document_contents() -> DocumentContents:
     return DocumentContents(contents=[text], metadata={"Some": "Metadata"})
 
 
+@pytest.mark.internal
+def test_document_index_lists_namespaces(document_index: DocumentIndexClient) -> None:
+    namespaces = document_index.list_namespaces()
+
+    assert "aleph-alpha" in namespaces
+
+
 @pytest.mark.internal
 def test_document_index_creates_collection(
     document_index: DocumentIndexClient, collection_path: CollectionPath