A fast, browser-only diagram tool (think a tiny Figma/Excalidraw). Draw shapes, connect them with auto-snapping lines, drop in icons, and everything auto-saves locally. No backend — boards live in IndexedDB and are shareable via a single URL.

• Rendering: PixiJS v8 (WebGL) — GPU-accelerated, render-on-demand.
• State: nanostores — tiny reactive atoms. No React.
• Persistence: IndexedDB via idb-keyval.
• Sharing: board JSON → lz-string compression → query string.
• Build: Vite + TypeScript. Ships as static files (served by nginx in the Dockerfile).

npm install
npm run dev       # local dev server (http://localhost:5173)
npm run build     # type-check + production build to dist/
npm run preview   # serve the production build

• Dirty-set updates, not full diffs. Actions mutate the nanostore and tell the renderer exactly which node/edge ids changed (scene.updateNode(id)). Dragging one of thousands of shapes touches only that node + its incident edges.
• Render-on-demand. The Pixi ticker is stopped; app.render() is scheduled once per animation frame only when something is dirty.
• Per-view redraw guards. A shape's Graphics is only re-tessellated when its geometry/style actually changes; moving it just sets a container transform.
• All hit-testing in world space (not Pixi's event tree), so selection/marquee/ connect/resize are O(changed), and the camera is a single container transform.

src/
  state/        types, nanostore atoms (store.ts), mutation actions (actions.ts)
  render/       Pixi scene singleton (scene.ts), shape/edge view builders,
                geometry/snapping math, vector icon registry
  interaction/  controller.ts (pointer/keyboard state machine), camera, viewport,
                text-editor overlay, "/" icon palette
  persistence/  IndexedDB (db.ts), autosave, URL share encode/decode
  ui/           dashboard, editor chrome (toolbar/colors/zoom), DOM helpers, router
  main.ts       hash router: dashboard (#/) ↔ editor (#/board/:id), ?b= shared import

V select · T text · R rectangle · O circle · L connector line · A arrow (directed edge) · M move / pan · / icon palette (~80 architecture icons) · ⌫/Delete delete selection · ⌘/Ctrl+C/X/V copy / cut / paste · ⌘/Ctrl+Z undo · ⌘/Ctrl+Shift+Z (or Ctrl+Y) redo · scroll to pan · ⌘/Ctrl+scroll to zoom · space-drag to pan.

Double-click empty canvas to drop a text object · double-click a shape/line to edit its text/label · drop an image file onto the canvas to add it · drag a selected line's center handle to bend it · resize handles keep a locked aspect ratio (square for shapes, natural ratio for images).