Tully is a music creation app. We designed two of its screens: the metronome you reach for mid-take, and the takes list that keeps every recording where you left it.
That single fact set every decision. You are holding a guitar, the phone is on a stand, and you have one free hand and no attention to spare. Anything requiring two taps and a read is a failure.
Drag the dial for a rough number, tap plus or minus to land it exactly. Both live in the same control.
48px, centred in the dial, legible from across a room at a music stand's distance.
One accent colour in the whole interface, spent entirely on state. If it glows, it is playing.
Green is never decoration. It marks what is active and nothing else.
Play and pause occupy the same pixel. Muscle memory beats animation.
Takes rise over the session so you never lose your place in it.
The dial went through two full explorations before it settled. Both are in the rail above, kept deliberately, because the reason the final one works is visible only next to the ones that did not.
Everything was specified against a 375pt frame with real values, so engineering never had to guess at a radius or a gap.
Running and stopped drawn as a pair, so the difference between them is the only thing that moves.
Rejected directions stayed in the file so the team could see what had been tried.
A single green across the whole section, reserved entirely for live state.
Tully is the client. Product names and trademarks belong to their owner. Screens above are rendered from the production design file and cover the metronome and takes section only, which is the part of the app we worked on.