Keynote: going from idea to working demo in an afternoon

Kiran Desai started with the maths of a buildathon. The judges see about three minutes; teams spend four hours. So most of what gets built, nobody sees. His plan was to work backwards from those three minutes.

He framed every good demo as a story with one twist: a moment where something happens that the audience didn't expect. Build the twist, he said, and fake the rest.

Before opening an editor, Kiran writes the ninety-second script for the demo: who the user is, what they try, and the moment it works. Anything that isn't in the script doesn't get built, which is how he keeps a four-hour build from turning into a half-finished product.

He then built a working prototype live on stage in about twenty-five minutes, narrating as he went. An AI coding tool generated the scaffolding, the forms and the settings page; Kiran said he let the agent write the whole settings page and has never read it.

The room's reaction was strongest when he skipped things on purpose: no login, hard-coded sample data, and one screen nobody would ever click on.

Afterwards he took the build apart. Most of his own time went on a single interaction, the twist, while everything around it was generated, stubbed or hard-coded. His advice was to hard-code the happy path, because judges forgive fake data but they don't forgive a spinner.

He finished with the last hour. Stop coding at 4:15, rehearse the demo twice out loud, record a backup video in case the Wi-Fi fails, and charge your laptop. Every team he's seen ship at 4:59 ends up demoing a bug.