The brief was one sentence: “£300 to £500, from London, social, a bit of sightseeing, Friday to Sunday.” The goal was an app that turns that sentence into one complete trip, with its reasoning, instead of an evening of tabs. We gave ourselves a day, and the result is Weekend Atlas.
Decide early what the model is allowed to do
The most useful decision came first: what the language model does, and what it doesn’t.
The model handles judgement. Which city fits “social, a bit of sightseeing” on this budget? Why that one and not the obvious alternative? That kind of soft matching is something models are genuinely good at, and the explanation is half the value.
Plain code handles numbers. Costs, dates and checking the budget are ordinary services with ordinary tests. A model can sound completely sure about a hostel price it made up, so prices never come from the model.
Between the two sit a handful of small services: one each for the itinerary, costs, weather, events and booking links. Each does one thing, which is a big part of what made a day possible.
Rank hostels for the trip you’re actually taking
Hostel ratings mostly tell you about cleanliness and location. On this kind of weekend, what matters just as much is whether you’ll meet people. So Weekend Atlas treats how social a hostel is as a ranking factor in its own right, alongside price and location.
What a day doesn’t get you
A day gets you a convincing skeleton. The hostel and flight data behind it was seeded by hand rather than live, there are no accounts, and nothing is set up to earn money. Those aren’t small gaps. Live travel data is most of the product, and it depends on other companies agreeing to give it to you.
That dependency is also what stopped FlightWatch, and it’s why Weekend Atlas is in the drawer for now. The idea we keep coming back to is combining the two: an app that notices a cheap fare and hands you a whole weekend built around it.