I wanted a quick image editor that just opened and worked — no download, no account, no upload. But the real motivation was to learn what actually sits behind a tool like Photoshop: layer compositing, flood fill, perceptual colour matching, snapshot history. So I set the rule that I'd build every piece by hand, with no image-editing libraries.

State lives in two Zustand stores — one for the canvas (layers, selection model, transforms, 30-step snapshot history) and one for the workspace (active tool and settings). Each pixel layer is backed by its own off-DOM canvas in a small registry, and the visible canvas re-composites them every frame. Editing follows a buffer-and-composite pattern: a stroke is drawn into a scratch buffer, then composited over a base snapshot at the layer's opacity and clipped to the active selection mask. The magic wand and bucket fill share a flood-fill that compares colours with a perceptual 'redmean' distance for natural-looking edges. Everything is local — nothing leaves the device.

Doing combat math mid-game kills the pace, and online calculators tend to drift out of date because someone has to hand-enter every datasheet. I wanted two things: instant, accurate matchup math without rolling a calculator by hand, and a unit database that stays faithful to the rules by being derived from the open BSData catalogues rather than retyped.

A single parse script treats the raw BSData .cat catalogues as the lossless source of truth and turns them into a typed factions.json with fast-xml-parser — stats, weapons, abilities and keywords, never hand-edited. The calculator runs in expected values (average dice, no RNG), auto-applying each weapon's own keywords — Lethal and Sustained Hits, Devastating Wounds, Anti-X, Blast, Rapid Fire, Melta — and modelling armour vs AP, cover, invulnerable saves and Feel No Pain. Toggleable detachment/army rules and a game-state conditions bar (½ range, stationary, charged) merge their modifiers into the result live, and legal-loadout rules (the pistol rule, pick-one weapon profiles) are enforced so no illegal combination is ever counted.