Writing on payment systems.

Three teardowns of systems that hold and move other people's money. Each is built the same way: a failure, what it looked like from outside, and what has to be true so it does not recur. Every claim carries the commit and the test behind it. If you are picking one, take the first: it opens from a symptom rather than from a thesis.

Teardown

Reconciliation Doesn't Break in the Arithmetic

Fourteen places where the balance in your dashboard stops matching the balance at your provider and the figure in your accountant's report. For each: the symptom, and what catches it.

14 failure modes · 13 of them checkable by a public Go library

Read the teardown → Safeguards

The Check That Never Failed

Fourteen safeguards that were present, reviewed and believed, and were not working. What each one looked like from outside, and what it took to make it prove itself.

14 safeguards · every one shipped, reviewed, and silently inert

Read it → Falsehoods

Falsehoods Engineers Believe About Moving Money

Ten sentences about holds, deposits, fees and reserves that read like axioms and are false. Each one cost real money; under each is a commit and a test.

10 falsehoods · a commit and a test under each

Read the ten →

Or skip the reading

Tell me what your system does with money.

A diagram, three sentences, or a list of the systems money moves between. I read it and reply in writing. Free, no call, usually within two days.

✉ jeffrey@jeffreyjorgensen.dev ↗ Telegram @JeffreyJorgensen