Extracting cube names from query

[altonzheng]

Is your feature request related to a problem? Please describe.
We are following the pattern described in https://cube.dev/docs/product/auth/context#enforcing-column-based-access to parse cube names and inject filters scoped to the authorized user in the queryRewrite hook.

One thing we noticed when enabling the Cube SQL API was that the query object passed to the hook has a different format for members -- eg. measures and dimensions can be appear as JS objects representing parsed SQL expressions, eg. { cubeName, alias, expr... } instead of a string as seen via the standard API and the linked docs.

We've updated our cube name parsing logic to handle this:

 const parseCubeName = (member) => {
    // Case 1: string member
    if (typeof member === 'string') {
      if (!CUBE_MEMBER_REGEX.test(member)) {
        throw new Error(`Invalid member string shape: ${member}`);
      }

      return member.split('.')[0];
    }

    // Case 2: parsed member expression object (must include cubeName)
    if (typeof member === 'object') {
      const cubeName = typeof member.cubeName === 'string' ? member.cubeName : '';
      if (!cubeName) {
        throw new Error(`Member object missing cubeName: ${JSON.stringify(member)}`);
      }
      return cubeName;
    }

    throw new Error(`Unsupported member type: ${member}`);
  };

Describe the solution you'd like
We want to confirm this behavior is expected/stable, and if it would be possible to include this in the documentation?

Also wondering if it makes sense to expose something like a getAllCubeNamesFromQuery method that could abstract this logic?

Thank you in advance!