Telling people where the van is today

What this actually looks like

A pitch that changes every day is a business that has to be found every day. One channel, one line each morning — the street, the hours, and what has already run out — and the queue arrives with you instead of after you.

How you would set it up

1. Create a channel on the van’s name and put its QR code on the hatch, the cups and the board.
2. Post the pitch each morning, or schedule the week on Sunday when the route is fixed.
3. Add a circle around today’s pitch when only the people near it should be interrupted.

Draw a circle without knowing who is inside it

You place a centre and a radius on a map, and the circle travels attached to the alert. Every subscriber’s phone receives it and compares its own position locally, then decides whether to show it. No subscriber position is ever sent to us, which is why this is a design fact rather than a promise: there is no column anywhere that could hold one. Two consequences follow deliberately. A geofence only ever narrows — it cannot add somebody who did not subscribe. And it fails open: a phone that cannot work out where it is shows the alert rather than hiding it, because missing an evacuation is worse than seeing one meant for the next street.

Draft, schedule, send — and what cancelling cannot undo

Composing and sending are deliberately different permissions, so the person or script that writes an alert can be forbidden from publishing it. A scheduled alert becomes visible at its time without anything having to run at that minute, which means a server that was briefly down delivers late rather than never. Cancelling is honest about its limits: it stops an alert reaching phones that have not fetched it yet and does nothing at all to the phones that already have it. An alert cannot be unsent.

One handle, printed once, permanent

A channel lives at drop.top followed by its handle, and that address never changes. It cannot be edited after creation, because it ends up on a poster in a school entrance, on a festival gate and inside a QR code somebody has already laminated. The page behind it explains what the channel is, what it asks a phone for, and how to subscribe — so a stranger reading a poster can decide before installing anything. We generate the QR code for you, server-side, and it is never sent to a third-party image service.