Pingback from subregistries with extension data

Use case

Anthropic will probably run a subregistry, where we do light security scanning and maybe mark some things as 'Verified' publishers etc. I also expect others will too (e.g. GitHub, Microsoft, ...).

I reckon it would be useful for the official registry UI to show some of these verifications from reputable subregistries i.e. checkmarks like '☑️ Security scanned by Anthropic and GitHub' or '☑️ Publisher name verified by Microsoft and Google'.

I also think other subregistries might benefit from these annotations. E.g. if I'm running a corporate MCP registry for my employees, it would be quite useful to have the data of security scans from the main registries available with one seed sync from the official registry (rather than having to set up syncs and deduplication from a bunch of registries myself). So it would be useful on the API.

Challenges

• Makes the data flow less of a beautiful DAG, as data now also flows back from subregistries
• May want to auth the annotations somehow, e.g. only Anthropic can write to the x-com.anthropic extension space in the official registry
• Almost certainly want to allowlist some subregistries to give them the permission to do this, rather than allowing any subregistry to do it, to avoid spam/clogging up official registry with lots of stuff.
  • Realistically I think this is probably the big names in AI, e.g. Anthropic, GitHub, Microsoft, OpenAI, Google, ..., and also perhaps some well maintained and trusted orgs that might run subregistries with value add annotations e.g. PulseMCP.
  • But we are effectively privileging some group of registries, so we probably want to come up with some fair and community-accepted set of criteria for entering this group.

Start by reviewing the current registry API, extension-data model, synchronization behavior, and official registry UI data flow. Define acceptance criteria for annotation permissions, trusted-subregistry allowlisting, propagation, and UI display; the issue currently presents these as open design challenges and names no files or tests.