Currently, ACM lacks a native concept of universal namespaces, a feature present in several other multi-cluster management technologies. This absence leads to complexities in managing resources across ManagedClusterSets, particularly when namespaces are inconsistently named or require manual discovery on remote clusters.

This proposal aims to explore and implement a mechanism for universal namespace provisioning. We need to decide between two primary approaches:

Creating truly universal namespaces for ManagedClusterSets: This would involve the cluster manager automatically creating and managing a consistent namespace across all clusters within a ManagedClusterSet, based on a single definition.

Extending existing binding logic to ManagedClusters: If a namespace (e.g., "joshua") is bound to a ManagedClusterSet, the cluster manager would ensure that this namespace is automatically provisioned on all member ManagedClusters within that set.

Implementing universal namespaces offers several benefits:

Improved Alignment with Virtual Concepts: This aligns better with the conceptual idea of "virtual folders" or logical groupings of resources across clusters.

Reduced Discovery Overhead: Eliminates the need for manual discovery of namespaces on remote clusters, especially when names differ.

Enhanced Permission Management: Consistent with our current approach of pushing down permissions, extending this to namespaces would streamline access control.

Industry Best Practice Alignment: Adopts a pattern observed in other mature multi-cluster technologies, improving usability and familiarity for users migrating from other platforms.

Acceptance Criteria:

A clear decision is made on whether to implement a new "universal namespace" concept or extend existing binding logic.

Users can define a namespace at the ManagedClusterSet level.

When a namespace is defined/bound to a ManagedClusterSet, it is automatically provisioned on all member ManagedClusters within that set.

The system handles conflicts or existing namespaces gracefully (e.g., ensures idempotency, provides clear error messages for unresolvable conflicts).

Documentation is updated to reflect the new universal namespace functionality.

Permissions associated with the universal namespace are correctly propagated and enforced on the member ManagedClusters.

(Optional, depending on scope) A migration strategy or guidance is provided for existing multi-cluster deployments.