We run a small automation studio where most first contact with clients happens
through an agent: it reads project feeds, drafts proposals, and sends them. A
human reviews the results later. That setup is cheap and fast — and last week it
produced the most expensive-looking quote we ever sent.
The proposal went out as R$ 60,000. The work was quoted at R$ 600.
What the dashboard showed
The proposal read: Oferta: R$ 60.000,00 · Oferta Final: R$ 75.000,00. One
zero too many, and then a 25% markup on top of it. The client received a system
message announcing a five-figure e-commerce fix.
What actually happened
Two independent defects, compounding:
- A typing error in the numeric field. 600 became 60000. No guard caught it, because the form accepted any positive number.
- The ×1.25 display anomaly we've documented before. Across five separate measurements — including our own dashboard — a value typed into the offer field renders to the client as 1.25× in a second, "final" field. 600 showed as 750. 900 showed as 1.125. So the error didn't just survive; it got dressed up.
Neither defect is exotic. That's the point.
The fix, in the order that mattered
- Correct in public, fast. The agent sent a follow-up message in the same thread: the number was a filling error, the real quote is R$ 600, apologies, offer to cancel and resubmit. A corrected quote costs one message. A client who discovered it themselves costs the project.
- Sanity-band the numeric fields. Any quote outside a plausible band for the project's budget range now blocks the send instead of warning.
- Compensate deliberately, not implicitly. For the 1.25 rendering, the agent now types value ÷ 1.25 when the target is a net number — and marks client-facing figures as measured, not assumed.
The general rule
An agent that can execute a transaction can execute your mistakes at the same
speed. Every numeric field that reaches a human being needs:
- a sanity band, not just a type check;
- a rendered-value preview (what the client will see, not what was typed);
- a human-readable number in the confirmation step — "six hundred reais", not "600".
The R$ 60,000 quote was never accepted. It didn't need to be. The lesson was
already fully delivered the moment the client saw it.
We build this stack in the open: x125-display-calculator — a free, single-file, in-browser calculator for the ×1.25 display-space problem, plus more write-ups on our blog.
