diff --git a/src/evidently/legacy/calculations/stattests/chisquare_stattest.py b/src/evidently/legacy/calculations/stattests/chisquare_stattest.py
index be2117251c..a8d5f6abb1 100644
--- a/src/evidently/legacy/calculations/stattests/chisquare_stattest.py
+++ b/src/evidently/legacy/calculations/stattests/chisquare_stattest.py
@@ -41,8 +41,9 @@ def _chi_stat_test(
     ref_feature_dict = {**dict.fromkeys(keys, 0), **dict(reference_data.value_counts())}
     current_feature_dict = {**dict.fromkeys(keys, 0), **dict(current_data.value_counts())}
     k_norm = current_data.shape[0] / reference_data.shape[0]
-    f_exp = [ref_feature_dict[key] * k_norm for key in keys]
     f_obs = [current_feature_dict[key] for key in keys]
+    f_exp = [max(ref_feature_dict[key] * k_norm, 1e-6) for key in keys]
+    f_exp = [f / sum(f_exp) * sum(f_obs) for f in f_exp]
     p_value = chisquare(f_obs, f_exp)[1]
     return p_value, p_value < threshold
 
diff --git a/src/evidently/legacy/tests/utils.py b/src/evidently/legacy/tests/utils.py
index 697826f566..1b5093d12d 100644
--- a/src/evidently/legacy/tests/utils.py
+++ b/src/evidently/legacy/tests/utils.py
@@ -180,7 +180,10 @@ def dict(self, *args, **kwargs):
 
 
 # some monkeing for np asserts to work with ApproxValue
-np.core.numeric.ScalarType = np.core.numeric.ScalarType + (ApproxValue, ApproxValueNoDict)  # type: ignore[attr-defined]
+if hasattr(np, "_core"):
+    np._core.numeric.ScalarType = np._core.numeric.ScalarType + (ApproxValue, ApproxValueNoDict)  # type: ignore[attr-defined]
+else:
+    np.core.numeric.ScalarType = np.core.numeric.ScalarType + (ApproxValue, ApproxValueNoDict)  # type: ignore[attr-defined]
 
 
 def approx_result(value, relative=None, absolute=None):
diff --git a/src/evidently/ui/workspace.py b/src/evidently/ui/workspace.py
index ca7b1dadae..4f727b4a83 100644
--- a/src/evidently/ui/workspace.py
+++ b/src/evidently/ui/workspace.py
@@ -1198,7 +1198,10 @@ def delete_run(self, project_id: STR_UUID, snapshot_id: STR_UUID):
         Raises:
         * NotImplementedError (snapshot API not yet implemented)
         """
-        raise NotImplementedError  # todo: snapshot api
+        raise NotImplementedError(
+            "The Snapshot API is not yet implemented for RemoteWorkspace. "
+            "Please use a local Workspace instead."
+        )  # todo: snapshot api
 
     def get_run(self, project_id: STR_UUID, snapshot_id: STR_UUID) -> Optional[SnapshotModel]:
         """Get a snapshot (run) by ID.
@@ -1213,7 +1216,10 @@ def get_run(self, project_id: STR_UUID, snapshot_id: STR_UUID) -> Optional[Snaps
         Raises:
         * NotImplementedError (snapshot API not yet implemented)
         """
-        raise NotImplementedError  # todo: snapshot api
+        raise NotImplementedError(
+            "The Snapshot API is not yet implemented for RemoteWorkspace. "
+            "Please use a local Workspace instead."
+        )  # todo: snapshot api
 
     def list_runs(self, project_id: STR_UUID) -> Sequence[SnapshotID]:
         """List all snapshots (runs) for a project.
@@ -1227,7 +1233,10 @@ def list_runs(self, project_id: STR_UUID) -> Sequence[SnapshotID]:
         Raises:
         * NotImplementedError (snapshot API not yet implemented)
         """
-        raise NotImplementedError  # todo: snapshot api
+        raise NotImplementedError(
+            "The Snapshot API is not yet implemented for RemoteWorkspace. "
+            "Please use a local Workspace instead."
+        )  # todo: snapshot api
 
     def search_project(self, project_name: str, org_id: Optional[OrgID] = None) -> Sequence[Project]:
         """Search for projects by name.
diff --git a/tests/conftest.py b/tests/conftest.py
index cf527aeea9..bf54349bd5 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -9,7 +9,10 @@
 from evidently.pydantic_utils import PolymorphicModel
 
 # for np.testing.assert_equal to work with ApproxValue
-np.core.numeric.ScalarType = np.core.numeric.ScalarType + (ApproxValue,)  # type: ignore[attr-defined]
+if hasattr(np, "_core"):
+    np._core.numeric.ScalarType = np._core.numeric.ScalarType + (ApproxValue,)  # type: ignore[attr-defined]
+else:
+    np.core.numeric.ScalarType = np.core.numeric.ScalarType + (ApproxValue,)  # type: ignore[attr-defined]
 
 
 def smart_assert_equal(actual, expected, path=""):
diff --git a/tests/ui/test_workspace.py b/tests/ui/test_workspace.py
new file mode 100644
index 0000000000..ade972c972
--- /dev/null
+++ b/tests/ui/test_workspace.py
@@ -0,0 +1,32 @@
+import re
+import uuid
+
+import pytest
+
+from evidently.ui.workspace import RemoteWorkspace
+
+# Shared expected message — kept as a constant so the test fails loudly
+# if anyone silently removes or waters-down the user-facing guidance.
+_EXPECTED_MSG = "The Snapshot API is not yet implemented for RemoteWorkspace. Please use a local Workspace instead."
+
+
+@pytest.fixture()
+def remote_workspace():
+    """Return a RemoteWorkspace that skips the server-health check."""
+    return RemoteWorkspace(base_url="http://localhost:0", verify=False)
+
+
+class RemoteWorkspaceSnapshotAPITest:
+    """Verify that unimplemented snapshot methods raise an actionable error."""
+
+    def test_list_runs_raises_not_implemented(self, remote_workspace):
+        with pytest.raises(NotImplementedError, match=re.escape(_EXPECTED_MSG)):
+            remote_workspace.list_runs(str(uuid.uuid4()))
+
+    def test_get_run_raises_not_implemented(self, remote_workspace):
+        with pytest.raises(NotImplementedError, match=re.escape(_EXPECTED_MSG)):
+            remote_workspace.get_run(str(uuid.uuid4()), str(uuid.uuid4()))
+
+    def test_delete_run_raises_not_implemented(self, remote_workspace):
+        with pytest.raises(NotImplementedError, match=re.escape(_EXPECTED_MSG)):
+            remote_workspace.delete_run(str(uuid.uuid4()), str(uuid.uuid4()))