So we replaced it with a market maker's book, running as an on-chain program.
Three layers, split by what each one actually needs:
1/ Oracle layer - off-chain
A high-frequency price engine reads equity venues, tokenized markets and crypto pairs, and holds a running fair value for every listed asset. Sub-second refresh, cross-venue consolidation, volatility-adjusted confidence bands.
2/ Quoting engine - closed source
Fair value plus current inventory becomes a two-sided quote. Per-asset spread models, inventory skew priced in rather than left for the next trader to find, and flow classification so uninformed flow gets a tighter quote than latency arbitrage does.
It stays closed source, and we'd rather say why than pretend it's an oversight: publishing the pricing logic publishes how to trade against it.
3/ Settlement - on-chain
Fills execute against our on-chain program and settle to Ethereum through Robinhood Chain's Orbit rollup. 100ms blocks, gas in ETH, balances stay in the contract.