What it is

Gatecrash runs an entire event off one Raspberry Pi with no internet.

That is the whole idea, and everything else in these docs follows from it. Ticket validation at as many gates as you have phones, the control-room dashboard, every attendee's wallet, and Bluetooth mesh chat between phones — all of it from a single static binary on a machine that costs less than a night's bar takings.

The problem it exists for

Ticketing platforms charge a convenience fee per ticket and stop working when the venue's Wi-Fi does. For a stadium with fibre and a contract, that is fine. For a college fest in a basketball hall, an indie gig above a bar, a comedy room, a wedding, or a farm party where the nearest tower is a kilometre away, it is useless — and those are most events, and all of the ones where the fee hurts most.

Nothing gatecrash does during an event touches the internet, because during an event there usually isn't one.

The shape of it

                        ┌──────────────────────────────────┐
   scanner phones  ───▶ │           the box                │ ◀───  wall display
   (QR, offline-ok)     │  Raspberry Pi · one binary        │       (dashboard)
                        │  SQLite · own CA · own Wi-Fi      │
   attendee phones ───▶ │  DNS · DHCP · captive portal      │
   (wallet PWA)         └──────────────────────────────────┘
                                       │
                              no uplink required
                                       │
   attendee phones ◀───── BLE mesh ─────┴──▶ attendee phones
   (Backstage chat, works with the box switched off)

The box is gatecrash serve. One binary, one config file, one data directory. It holds the tickets, decides every scan, serves the three web apps, and — in AP mode — is the network: its own Wi-Fi, DHCP, DNS and captive portal.

The scanner is a web app a guard opens on a phone. It works offline, queues what it cannot send, and shows a verdict you can read from across a queue.

The wallet is a web app an attendee opens once. After that it works with the network off: the ticket is cached and rotating codes are generated on the phone.

The dashboard is the back room: who is inside, which door is struggling, what the gates are refusing, and who has picked up the alarm somebody just raised.

Backstage is the mesh: chat between phones over Bluetooth when there is no network at all, with the boxes joining in to bridge groups of people who cannot hear each other.

What you keep and what the box gets

The organizer's private key never touches the box. You mint keys and issue tickets on your own machine; the box gets a signed manifest and can verify tickets without being able to invent one. That separation is what makes it safe to hand a box to a venue.

Where to go next

• Try it in one command — a whole event, no hardware
• Running an event — the actual workflow, start to finish
• When the box is unreachable — the one honest trade in the system
• Correctness — how any of these claims are checked