FIP: Introducing Ordering

Farcaster's engineering team proposes "Account Ordering," a partially ordered sequence-number scheme for user data, as a fix for hubs drifting out of sync. The article says sync has slowed as the network passed 500M messages, and that per-hub rate limits, missing onchain state, gossip failures and pruning all compound the drift. Under account ordering, each user's app key gets its own sequence chain, which the article estimates would make sync 10x to 100x faster and reduce rate-limit collisions. The article also describes a Global Ordering alternative using a sequencer and blocks, which it calls cleaner but with a single point of failure and a harder rewrite. Commenters suggested per-signer ordering, and one proposed Rate-Limiting Nullifiers as a way to move rate-limit enforcement to clients.