Find traders
Nobody hands out a ranked list of wallets, and typing one out would mean inventing it. So Mirror reads the chain instead, in two passes. Scanning takes the tokens with money behind them right now, opens each one's pool, and pulls out the wallets trading it. Screening then reads each of those wallets' own history and keeps only the ones that actually made money — which is usually a small fraction of them.
Chain
Reading fine. Anything empty below is empty because no wallet is tracked yet, not because the chain is unreachable.
Scanning reads every token transfer in that block range, takes the busiest tokens, and returns the wallets behind them — contracts filtered out. That finds wallets that were active, which is not the same as good: most of a running market is bots, snipers and people losing money. Screening is the part that reads each one's own history and throws away everyone who cannot show a profit. Nothing is stored for a wallet that fails.