# Paint by Habits 🎨

A whimsical habit tracker where consistency paints a picture. You define your
daily habits and pick a pixel-art image; every habit you check off reveals a few
pixels. Over days and weeks the artwork emerges — finish it, celebrate, pick the
next one.

## What it is

- **One self-contained file:** `index.html`. Vanilla JS + CSS, no build step,
  no frameworks, zero network requests. Works from `file://` or any static host.
- **Local-only:** all data lives in your browser's `localStorage`. No server,
  no accounts, no tracking.
- **Portable:** export your full state as a JSON backup and import it on
  another device.

## How it works

Each artwork is a pixel grid. On start, a seeded PRNG (mulberry32 +
Fisher–Yates) fixes a random reveal order that stays stable across sessions.
Checking off habits reveals pixels, and **the more you do in a single day, the
bigger the reward** — the first habit each day is worth 1 unit, the second 2,
the third 3, and so on (so a 4-habit day earns 1 + 2 + 3 + 4 = 10 units).
**Streaks multiply everything:** each day's units are scaled by the length of
your active streak, so on a 3-day streak the first check is worth 3 units and
the second 6, and on a 5-day streak they're worth 5 and 10. The per-image
reveal rate is sized so a "perfect month" of doing everything daily just fills
the picture. Pixels never un-reveal across days; missing a day just pauses
progress. Includes 8 built-in pixel artworks, or upload any image to pixelate
it into a 16–48 cell grid.

Dark/light theme follows your OS by default, with a manual override. Streaks
count any day you checked at least one habit; days where you did everything get
a ✨ perfect-day sparkle.

## Run it

Open `index.html` in a browser. That's it. To host it, copy the file to any
static host.

## Test it

There is no test harness checked in (single-file app). Validation performed:
`node --check` on the extracted script, a grep proving zero external
references, and scripted jsdom flow tests covering onboarding, check/uncheck
persistence, day rollover, uncheck floor clamping, corrupt-state recovery,
storage-unavailable mode, import validation, and the completion/celebration
flow. See `docs/DESIGN.md` §9 for the edge-case checklist.

## License

Dual-licensed under [Apache-2.0](../LICENSE-APACHE) and [MIT](../LICENSE-MIT),
following Rust ecosystem convention for this repository.

## Disclaimer

This software was written with Claude Code. Design by **Claude Fable 5**
(`claude-fable-5`), implementation by **Claude Sonnet 5** (`claude-sonnet-5`),
review and verification by **Claude Opus 4.8** (`claude-opus-4-8`).