MINIMALIST_STOPWATCH

# Minimalist Stopwatch

A stopwatch. Black screen, enormous digits, three transport buttons, an orientation lock and a
gear. Nothing else, ever.

By **Mantra Productions**, Zagreb. Built for reading across a room.

    play    toggle. Starts, resumes, and pauses a running clock
    pause   toggle. Freezes a running clock, resumes a paused one
    stop    back to zeros

Play and pause are one toggle wearing two glyphs, so there is no wrong one to hit. The symbols
never change; the highlight moves between them to say what the next press would do. While the
clock is not running the play glyph is white, and it is the only thing on the screen besides the
digits that ever is.

The corner button sets which way up the app sits: one press portrait, the next landscape. It does
not follow the phone.

A button that cannot act is dimmed and inert. No button is ever hidden, because a control that
disappears moves the layout, and a stopwatch whose buttons shuffle is worse than one with a dim
button.

The three sit along the bottom in **both** orientations, evenly spaced, well clear of the digits.
There is no ring drawn around them, and the touch target is the full circle's worth of space all
the same.

Hours, minutes and seconds, all six numbers, from the moment it opens. Nothing finer: the last
digit of a tenths display is the only thing on a screen moving at a speed the eye cannot rest on.
The width never changes, ever.

The gear opens a six by four swatch grid for the digit colour, and a choice of normal or bold.
Every press applies live, over the black below the digits, so you are looking at the thing you
are choosing.

## Install

The latest APK is on the [releases page](../../releases). Two builds are kept at a time.

## The part that is actually hard

A stopwatch is a clock, and clocks are where lazy code shows.

The elapsed figure is **never accumulated by adding ticks**. Two fields are kept, the instant the
current run segment began and the milliseconds banked before it, and the answer is arrived at by
subtraction every time it is asked for. The clock is `SystemClock.elapsedRealtime()`, which is
monotonic and does not move when a time server corrects the wall clock.

Both fields survive rotation, backgrounding, process death and reboot. A reboot mid-run returns
zeros rather than a number that is silently short, because a wrong answer delivered confidently
is worse than no answer.

## Checking it

    python3 scripts/verify.py            18 structural checks, one second
    ./gradlew :app:testReleaseUnitTest   39 cases, plain JVM, no emulator
    python3 scripts/sabotage.py          39 mutations, each rule broken on purpose

The last one is the important one. A test you have never seen fail is a rumour.

See [`HANDOFF.md`](HANDOFF.md) for the briefing, [`NEXT_DEFAULTS.md`](NEXT_DEFAULTS.md) for why
each decision was made, and [`DELIVERY_RECORD.md`](DELIVERY_RECORD.md) for what was proven about
the shipped artefact and, more usefully, what was not.