Federated Community Discovery in Explore

Fluxer's planned federation will allow users to join communities hosted on other instances using their existing account. However, there is currently no announced way to discover these remote communities through the existing Explore page. For example, someone using a small self-hosted Fluxer instance might only see two public communities in Explore, even though hundreds or thousands of public communities could exist across the federated network. Without cross-instance discovery, users would need to find remote communities through external links, recommendations, or by already knowing where they are hosted. This could make smaller self-hosted instances feel isolated, despite being part of a much larger federated network.

Extend Fluxer's existing Explore page to support federated community discovery. Ideally, users should be able to:

• Browse and search public communities hosted across participating federated Fluxer instances.
• Discover remote communities alongside locally hosted ones in the same Explore interface.
• See which instance hosts each community.
• Join remote communities directly using their existing Fluxer account, without creating another account.
• Optionally filter between local communities and communities from other instances.

Instance operators and community administrators should be able to opt in or out of federated discovery, so participation remains voluntary. The goal is to make discovering and joining communities across the federated network feel just as simple and seamless as discovering communities on a single Fluxer instance.

I originally suggested this in the Federation Design Plan (#1093), but wanted to submit it separately since cross-instance community discovery is an important part of the overall federation experience. I believe federation should not only make it technically possible to join remote communities, but also make those communities easy to find. The exact implementation could involve a shared directory, opt-in discovery hubs, instance-to-instance discovery, or another solution that fits Fluxer's federation architecture. A centralized browsing experience does not necessarily require centralized community hosting. Communities could remain hosted and managed by their respective instances while still being discoverable through a unified Explore page. This would be especially valuable for smaller self-hosted instances, allowing their users to experience Fluxer as one connected network rather than a collection of isolated servers.