A shop that answers at two in the morning

I had never done a hackathon. Five years of shipping software, and somehow never twenty-four hours in a room with strangers, a deadline and a projector. In September 2026 Remo Litoral organized one in Santa Fe, with v0 among the sponsors, and I signed up with the only teammate I did not have to interview: my brother, Franco Galfré .

We arrived with a problem instead of an idea. My father sells things. A couch that no longer fits, tools, a bicycle, whatever is in the way. He photographs it against the kitchen window, writes two lines, picks a price that feels right and posts it on Marketplace. Then he calls me: nobody is buying. Or the opposite: forty people asking “is it still available” at any hour, one offering half at two in the morning, and him, who has no patience for the phone, answering nobody and selling nothing.

So we built him tulocal .

What we built

You photograph the thing. The pipeline identifies what it is, its brand, its model and its condition, produces clean product shots that never change the item itself, writes the title and the description, and searches Mercado Libre for what the same thing sells for in Argentina today. You get a price range, a shop with its own URL and a QR code.

Then the part my father actually needed. Every shop has an employee, an agent with a name the seller chooses, that answers buyers’ questions from what it knows about the product, negotiates without ever going below a floor price the seller sets and the buyer never sees, and only when someone is serious opens a WhatsApp conversation with the owner, message already written. He does not talk to anyone until there is a sale to close.

Where the hours went

A hackathon is a scope exercise disguised as a coding exercise. We wrote down what the demo had to show, one path from photo to WhatsApp message, and everything that did not sit on that path lost. No payments, no shipping, no marketplace, no accounts for buyers. The product got better every time we said no.

The last five hours were not engineering, and they decided whether the engineering got seen. We warmed the price search cache with the exact product we would show, kept a fallback listing already processed in case the pipeline hung on stage, mirrored a phone on the projector so the room could watch the buyer haggle, and rehearsed the three minutes with a clock.

The employee that stops at the floor

The agent was the part I cared most about getting right, because it is the part that can embarrass you in front of a room. It has to concede, or nobody believes it is negotiating. It has to stop, or the seller loses money. And it has to do both without the number ever appearing in a prompt, because a model that knows the floor will eventually say it.

The other thing it needed was permission to not know. An agent that can say “let me ask the owner” is worth more than one that always has an answer. We gave it a tool for exactly that, the question goes to the seller, and the answer is saved to the product forever, so he answers once.

Working with my brother

Franco is shy and I am not, so the split was easy. I took the seller side and the pipeline; he took the buyer side and the metrics. On stage he played the buyer, scanned the QR with his own phone, lowballed the agent the way everyone lowballs, and read the replies out loud. It was the best part of the demo and I did not write a word of it.

There is something about building with someone who has known you your whole life. No onboarding, no politeness tax, a shorthand that took twenty-four years to develop and paid off in twenty-four hours.

What I am taking home

A product I want to keep working on, because my father is going to use it whether I finish it or not. A few new friends from teams I had not met before. A very specific kind of tired that only comes from a night mostly spent making something with people you like.

Valentin Galfré @galfrevn Se terminó la primer hackathon de @remolitoral 💙 así que un hilo rápido de lo que pasó:24 horas seguidas con @francogalfredev, mucho café, cero sueño y una idea que arrancó pensando en mi viejo y sus publicaciones de Marketplace 🌉Salió tulocal.site: le sacás una foto a algo y tenés un local online con un empleado con IA que atiende por vos creado en menos de 1 minuto!Pero lo mejor no fue el producto. Fue la gente, el ambiente y ver a un montón de equipos de Santa Fe y Paraná construyendo cosas en serio en un día 🫂 17 Sept 2026 Open on X ↗

And the wish that it happens again. Whoever runs the next one: tell us, we are going.

Twenty-four hours is not enough to build a product. It is enough to find out whether you want to.