Notes on credit infrastructure.

Occasional writing from the engineers behind Workspace and the Engine — on exact arithmetic, market rules, and records that hold up under audit.

07 Jul 20265 min read

The schedule is the product

Nobody repays a rate. They repay a schedule: twelve dates and twelve amounts. What an installment product actually promises, where its cost peaks, and why the rounding rule is part of the definition.

30 Jun 20264 min read

Product versions are evidence

Immutable versions, a recorded human signer, and a hash-chained audit log. Why a credit catalog should be built like evidence, and why every loan binds to the exact version it originated under.

23 Jun 20265 min read

The balance never stops moving

An installment loan is decided once. A revolving line is decided every day. Cycles, minimum due, interest on a balance that changes underneath you, and why revolving credit is the hardest thing to get exactly right.

09 Jun 20265 min read

CAT, explained for people who ship credit products

Mexico’s Costo Anual Total is the number a credit product is judged by. What it measures, how CONDUSEF’s method frames it, and why it belongs at definition time, not audit time.

02 Jun 20264 min read

Zero interest is not zero cost

In buy-now-pay-later the borrower rate is 0.00% and the credit is still expensive. Who actually funds it, why the ticket range is the real risk control, and why the late policy is a product decision.

26 May 20264 min read

A payday advance is mostly fee

One advance, one repayment, priced in days. Why the fee dominates the cost of short-dated credit, why the cap bites hardest at the smallest ticket, and why days are not a rounded-down month.

19 May 20264 min read

Why loan math should never touch floating point

Money in integer minor units, rates in basis points, and one rounding step defined by the market’s rule. How the Capcells engine keeps every loan computation exact — and provably reproducible.

Everything above ships in the product.

Exact arithmetic, official cost checks, signed versions, a tamper-evident history — Workspace is how a credit company gets them without building them. Bring a product and we’ll prove it on your numbers.

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