zlay#

an AT Protocol relay in zig. subscribes to every PDS on the network, verifies commit signatures, and serves the merged event stream to downstream consumers.

live instance: zlay.waow.tech — metrics dashboard

design#

• direct PDS crawl — the bootstrap relay is called once at startup for the host list via listHosts, then all data flows directly from each PDS.

• optimistic signature validation — on signing key cache miss, the frame passes through immediately and the DID is queued for background resolution. all subsequent commits are verified against the cached key. the cache caps at a configurable size and evicts the oldest 10% by resolve time when full.

• inline collection index — indexes (DID, collection) pairs in the event processing pipeline using RocksDB. serves listReposByCollection from the relay process — no sidecar. the index design draws on fig's work on lightrail.

• reader thread per PDS + frame processing pool — each PDS gets a lightweight reader thread (cursor tracking, rate limiting, header decode). heavy work (full CBOR decode, validation, DB persist, broadcast) runs on a shared pool of frame workers (configurable, default 16).

spec compliance#

implements the AT Protocol sync spec — subscribeRepos, listRepos, getRepoStatus, getLatestCommit, listReposByCollection, listHosts, getHostStatus, and requestCrawl.

dependencies#

build#

requires zig 0.15 and a C/C++ toolchain (for RocksDB).

zig build                          # build (debug)
zig build test                     # run tests
zig build -Doptimize=ReleaseSafe   # release build (production default)

configuration#

see docs/deployment.md for production deployment and docs/backfill.md for collection index backfill.

license#

MIT