Instruction file imported from d8ahazard/glimmr (.cursor/rules/web-ui.mdc). Copyright stays with the author.

Glimmr.Web Conventions

• This is Preact (with @preact/signals), not React. Use preact/hooks, class= (not className), and signals for global state (lib/store.ts).
• Backend contract: SignalR hub at /socket pushes camelCase JSON (olo = full store); actions invoke hub methods with REST fallback to POST /api/Glimmr/{method}. Types in src/types.ts must mirror the C# models (camelCase).
• Build output goes to ../Glimmr/wwwroot/app (base /app/); dotnet publish runs npm ci && npm run build automatically (skip with -p:SkipGlimmrWeb=true).
• Form inputs that write to SystemData must commit on blur/Enter or debounce (see CountCell/TextField in components/ui.tsx) - never per keystroke, every commit is a hub round-trip.

Mapping conventions

• LED master grid: 0-based, starts bottom-right corner, walks counter-clockwise (right side up, top right-to-left, left down, bottom left-to-right). Geometry in lib/maps.ts mirrors FrameSplitter.DrawGrid - keep them in sync.
• Sectors: 1-based, start bottom-right, counter-clockwise (DrawSectors).
• Device brightness sliders are 0-100. Hue V1 per-light override brightness is 0-255 (mappedLights), Hue V2 uses groups[].services.