Fix namespace_manager import guard and pin requirements to specific SHA

Agent-Logs-Url: https://github.com/weaviate/weaviate-cli/sessions/885f6e27-f122-407c-8e0b-e5228dacd9fc

Co-authored-by: jfrancoa <23482278+jfrancoa@users.noreply.github.com>

Author: Copilot

requirements-dev.txt

@@ -1,4 +1,6 @@
-weaviate-client @ git+https://github.com/weaviate/weaviate-python-client.git@jose/namespaces
+# TODO: revert to a released version pin (e.g. weaviate-client>=4.x.x) once
+# weaviate-python-client PR #2033 merges and a release is cut.
+weaviate-client @ git+https://github.com/weaviate/weaviate-python-client.git@f2babd27670729677c7784a0e30a27d4f8ec7328
 click==8.1.7
 twine
 pytest

weaviate_cli/managers/namespace_manager.py

@@ -3,11 +3,23 @@
 
 import click
 from weaviate.client import WeaviateClient
-from weaviate.namespaces.models import Namespace
+
+try:
+    from weaviate.namespaces.models import Namespace
+
+    _NAMESPACE_SUPPORT = True
+except ImportError:
+    Namespace = None  # type: ignore[assignment,misc]
+    _NAMESPACE_SUPPORT = False
 
 
 class NamespaceManager:
     def __init__(self, client: WeaviateClient):
+        if not _NAMESPACE_SUPPORT:
+            raise RuntimeError(
+                "Namespace support requires a weaviate-client version that includes "
+                "the namespaces module. Please upgrade your weaviate-client package."
+            )
         self.client = client
 
     def create_namespace(self, name: str, json_output: bool = False) -> Namespace: