Builder's note, a few hours in — the surprising thing I learned shipping this:

I set out to prove my settlement engine needed heavy infrastructure. Postgres, multiple nodes, the works. So before I built all that, I benchmarked it against plain SQLite on my own hardware.

SQLite won. Not close.

Even after I did Postgres right — decoupled settlement from the audit log, deadlock-free concurrent writers, the whole thing scaling properly across cores — SQLite in-process still beat it by a wide margin on a single box. So I shipped the simpler engine and I'll move to Postgres the day I actually outgrow one machine. Not a day before.

The core that's real today is the ledger underneath: it's tamper-evident (any post-hoc edit to history or balances breaks a hash chain and gets caught on verify), it conserves value to the cent under load, and it proves its own integrity — you don't take my word for it, you run the check.

Multi-rail routing across cards/ACH/wire/crypto is where I'm driving. The audited settlement core that everything sits on is what's built and measured.

Happy to go deep on the integrity design with anyone who wants to poke holes in it — that's the fun part.