Notes from the team

German fiscal law requires every till transaction to be signed and kept for ten years. There is no delete. That one sentence decided more of the database than any product requirement did.

Which obligations bind you today, which bind you only if you take cash, and which one is still a draft bill whose start date has already moved twice this summer.

A duty that sat unenforceable for five years because nobody had built the letterbox. The letterbox opened in January, and the queue closes at the end of this month.

Five lessons from a platform built for a moment that has now passed — including the awkward one about knowing when a product has finished its job.

Sixteen CSV files nobody looks at, produced on the one morning somebody from the Finanzamt is standing at your counter waiting for them.

A PDF in an inbox is a poor entry ticket: it gets lost, it is trivial to fake, and whoever is on the door cannot check it. A signed certificate in an app is none of those things.

A clinic that has to open in a fortnight, in a converted nightclub, staffed by people who have never run one. Most are attempting it with a spreadsheet and a group chat.

A card in a slot, or a signature from a data centre. Which one is right depends on how many tills you have and how good your internet is — and after 1 April, not choosing is itself an answer.

It can warn you that you stood near someone who later tested positive, without any server ever learning that you stood near anyone. Here is the architecture that allows both, and why the code is public.

Five things to do in the next month, in the order that keeps a business trading. None of them takes longer than a week to put in place.

Three obligations arrived together on 1 January, and only one of them has a deadline you can safely leave until September.