Things built to be checked.
Side projects with the same rule as everything else: publish the number and the way to check it. No estimates where an exact answer exists, no dashboards without a trail back to the source.
A probability engine that refuses to estimate.
Every deck-building tool answers "what are the odds I draw this by turn three?" with a simulation: run it ten thousand times and call the average an answer. Deck Odds computes the exact probability instead. Same question, a true number.
The refusal is the feature. An estimate is a number you argue with; an exact answer moves the argument to the decision, which is where it belongs. It's the KPI rule wearing a card sleeve, and it's why the engine exists at all.
The ledger the store was already keeping.
Every event in the store, whether a sale, a fee or a box of envelopes, was already flowing through the tools. Books just stopped throwing that information away: each event lands in a proper ledger the moment it happens.
The result is accounting with no month-end: the books are always closed, because they were never open. Tax season is a report, not a project. It's what bookkeeping looks like when it's a byproduct instead of a chore.