bgclock/public_html/README.md

# Backgammon Clock

A two-player match clock with **simple delay you can actually see**. Reserve time
plus a fixed number of free seconds each turn that never carry over — the
Backgammon Galaxy control. Defaults to 3:00 + 15s.

Plain HTML, CSS and JavaScript. No frameworks, no fonts, no images, no network.

## Getting it onto your phone

Chrome will only offer a real install over HTTPS, so the file needs a host.
GitHub Pages is free and takes about two minutes:

1. Create a new public repository, e.g. `bgclock`.
2. Upload all six files to the root: `index.html`, `manifest.webmanifest`,
   `sw.js`, `icon-192.png`, `icon-512.png`, `icon-maskable-512.png`.
3. **Settings → Pages → Source: Deploy from a branch → `main` / `(root)` → Save.**
4. Wait a minute, then open `https://<you>.github.io/bgclock/` in Chrome on Android.
5. Chrome menu (⋮) → **Add to Home screen** → **Install**.

Open it from the home-screen icon and it runs fullscreen with no browser
chrome, offline, with the screen kept awake while a game is on.

If you're using a different path than `/bgclock/`, edit the `"id"` field in
`manifest.webmanifest` to match, or just delete that line.

To try it before hosting, open `index.html` in any browser — everything works
except installation and the service worker.

## Using it

- **Tap your own half** to end your turn and start your opponent's clock.
  At the start, whoever taps first sets the *other* player going.
- The waiting player's taps are ignored, so a stray hand won't stop the clock.
- The bar under the big time is the delay draining. When it empties you get a
  soft tick and your reserve starts moving. That's the moment worth hearing.
- **Reset** returns to the starting position. It takes two taps: the first arms
  the button — it lights up and a ring unwinds around it — and a second tap
  within those two seconds does it. One stray thumb can't wipe a live game.
- **Pause** freezes mid-turn and resumes exactly where it stopped, delay
  included. Opening settings pauses automatically, and leaves it paused so the
  clock only restarts when both players are ready.

Backgammon clocks pause between games, and after a cocked die the delay is
normally restarted — use pause and reset for those.

## Settings

At the top of the sheet are two presets — **2m / 12s** and **3m / 15s**. Tapping
one jumps both timers there and lights it up. Change the time or delay by hand
and the highlight goes out; land back on a preset's numbers and it comes back on.

| Setting | Range | Default |
| --- | --- | --- |
| Time | 0:15 – 99:00 | 3:00 |
| Delay | 0 – 60 s | 15 s |
| Colour | Sage, Brass, Slate, Teal, Plum | Sage |
| Sound | on / off | on |

Brass is the colour in the chess.com app, if you want the exact original look.
Changing time or delay resets the clock. Settings are kept in `localStorage`, so
they survive closing the tab, force-quitting the installed app and rebooting the
phone — the app also asks for persistent storage so they aren't evicted when the
device runs low on space. Only the settings are stored; a game in progress isn't.

## Sounds

All three are generated with the Web Audio API, so there are no audio files to
download and nothing to attribute.

- **Turn change** — a soft rising fifth with an octave partial, marimba-like.
- **Delay expiry** — a single quiet 300 Hz tick, deliberately easy to miss unless
  you're listening for it.
- **Time out** — a falling triad, loud and unambiguous.

## Licence

Do whatever you like with it.