Roadmap to complete PDS

[snarfed]

Moved here from snarfed/bridgy-fed#381. Bluesky team still hasn't launched federation yet, so this is somewhat speculation, but their docs and blog posts and discussions and comments in chat have painted a pretty complete picture. Here's what we think we still need:

• XRPC: https://lexrpc.readthedocs.io/, https://github.com/snarfed/lexrpc
  • Validate data against lexicon schemas (optional)
• Data conversion to/from app.bsky lexicons in granary:
• [x] Bridgy Fed serves most app.bsky read XRPCs, eg https://fed.brid.gy/xrpc/app.bsky.feed.getAuthorFeed?author=snarfed.org
• Federation
  • MST
  • signed commit chain
  • [ ] blob serving
  • remaining com.atproto.sync methods
  • guarantee that commit chains we serve are immutable (except for rebases)
  • DID resolution
  • [ ] ingest/sync other PDSes' repos
  • [ ] did:web serving

[snarfed]

Done! Woo!