Engineering
How the models are built, tested, and kept current
Written for engineers and operators evaluating us. Every claim in these pieces traces to something you can open — a spec, the Concordance harness, the facts registry, or our public telemetry.
2026-08-16
Two Implementations or It Doesn't Ship
How we Concordance-test 47 financial models: an independent Python implementation rebuilt from the spec alone, 11,750 deterministic cases diffed at one part in a billion, and a CI gate that stops any release where the two disagree.
2026-08-16
Your Fintech Copilot Has No Answer Key
LLM eval stacks grade tone, safety, and retrieval. Nothing in them knows whether the refinance break-even your copilot just quoted is numerically right. Wiring in a computational answer key takes an afternoon.
2026-08-16
TY2026 Retirement and Estate Numbers, With Receipts
Every IRS and SSA constant our models consume for tax year 2026 — the value, the period it applies to, the primary source, and the date a human last checked it. The registry is the source of truth; this post is its narration.
Product and integration guides live under /writing; the method itself is defined at /proof.