Bug Report: update_activity_partial rejects visibility_tag even when provided

[drakhu]

When calling update_activity_partial in the Python SDK to update an activity’s visibility to "tag" and set a corresponding visibility_tag, the API responds with a validation error:

"visibility_tag is a required field when visibility is tag"

Even though visibility_tag is included in the set payload.
This suggests the Feeds v3 backend may not be correctly applying or detecting visibility_tag when sent via partial updates.

Steps to Reproduce

Code:

s.client.feeds.update_activity_partial(
    id="xxx",
    user_id="xxx",
    set={
        "visibility": "tag",
        "visibility_tag": "manager",
    },
)

API returns:

StreamAPIException: Stream error code 4: UpdateActivityPartial failed with error:
"visibility_tag is a required field when visibility is tag"