Randori

I built this for me, on the mat, after class

I do jiu-jitsu. Most nights end the same way: sitting on the edge of the mat, trying to remember what actually happened in the last hour — which rolls emptied the tank, which armbar I walked into twice, what my coach said in the thirty seconds I could still hear him.

The apps I tried wanted me to be a runner. The notebooks got soaked. So I built the thing I kept reaching for and not finding: a log that speaks jiu-jitsu — effort, positions, submissions, notes in my own words — and turns tonight's mistakes into tomorrow's study plan.

That's the whole product brief. Everything in the app answers one of my three after-class questions, and anything that didn't got cut.

The physical truth of a night of training

Start a session and the Watch (or a paired chest strap) streams heart rate live while you roll. Effort is logged per round, in the seconds between rolls — one thumb, gloves-off honest. When class ends you have the real shape of the night: how hard, how long, how much was left in the tank.

Stop getting caught by the same thing

This is the feature I built the app to get. You write what happened in your own words — a note, not a dropdown — and Randori matches it to film-backed lessons from instructors worth learning from. Get caught in an armbar, see the defense. Then the counters to the counters.

The matching happens on your iPhone — your notes never leave your device to be understood. The library runs white belt through black, so the answer meets you at your level.

The belt, made honest

Jiu-jitsu progress is famously opaque — years between belts, promotions that arrive when they arrive. Randori counts what you can control: sessions accumulate into an honest forecast of where your training is heading, so the long road has mile markers.

A gym is people. So is the app.

You don't train alone, and the log shouldn't pretend you do. Connect with the people you actually roll with and share sessions — a social layer that runs on CloudKit's public database. No accounts, no server of mine holding your data.

Community features carry community responsibilities: user reporting shipped in 1.0, wired into the studio's own moderation tooling, so a report filed from the mat reaches a human the same day — not a backlog.

Small, honest machinery

SwiftUI on iPhone and Watch. Sessions sync through your private iCloud and write to Apple Health as real workouts. Even the anonymous usage telemetry defines a session the way a training log would — a burst of activity, ended by half an hour of quiet:

enum SessionTracker {
    static func noteActivity(now: Date = .now) {
        if let last, now.timeIntervalSince(last) >= quietGap {
            rotate(at: now)   // ≥30 quiet minutes = a new session
        }
        last = now
    }
}

Twelve languages at launch, from Japanese to Arabic — because the sport's vocabulary is already global, and the app should meet it there.