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+# CLAUDE.md — AI Assistant Guide for `ferienhaus`
+
+## Project Overview
+
+**BarrierefRei Reisen** is a single-page React application for finding and comparing accessible vacation homes in Germany. The entire interface is in German. The app is frontend-only with no backend, API, or database — all data is static.
+
+**Stack:** React 19 · Vite 7 · Plain CSS · ESLint 9 · ES Modules
+
+---
+
+## Development Commands
+
+```bash
+npm run dev       # Start dev server with hot module replacement (http://localhost:5173)
+npm run build     # Production build (outputs to dist/)
+npm run preview   # Preview production build locally
+npm run lint      # Run ESLint checks
+```
+
+There are **no tests** configured. To add tests, install Vitest or Jest.
+
+---
+
+## Repository Structure
+
+```
+ferienhaus/
+├── index.html                  # HTML entry point, mounts #root
+├── vite.config.js              # Vite config with React plugin
+├── eslint.config.js            # ESLint flat config (v9 style)
+├── package.json                # Dependencies & scripts
+├── public/                     # Static assets served as-is
+└── src/
+    ├── main.jsx                # Renders <App /> into #root
+    ├── App.jsx                 # Root component — state, layout, filtering logic
+    ├── App.css                 # All application styles (~814 lines)
+    ├── index.css               # Global resets, CSS variables, base typography
+    ├── assets/                 # Static assets imported by components
+    ├── components/
+    │   ├── FilterPanel.jsx     # Sidebar: price/guests/type/accessibility filters
+    │   ├── HausCard.jsx        # Card for a single vacation home listing
+    │   └── CompareTable.jsx    # Modal overlay comparing up to 3 selected homes
+    └── data/
+        └── ferienhauser.js     # Static data: ACCESSIBILITY_FEATURES + ferienhauser array
+```
+
+---
+
+## Architecture & Data Flow
+
+### State (all in `App.jsx`)
+
+| State var     | Type       | Purpose                                         |
+|---------------|------------|-------------------------------------------------|
+| `filter`      | object     | Current filter: `{features[], maxPreis, minPersonen, typ}` |
+| `sortBy`      | string     | `"bewertung"` \| `"preis-asc"` \| `"preis-desc"` \| `"merkmale"` |
+| `compareIds`  | number[]   | IDs of homes selected for comparison (max 3)    |
+| `showCompare` | boolean    | Whether the comparison modal is visible         |
+| `sidebarOpen` | boolean    | Mobile sidebar toggle                           |
+
+Filtering and sorting are performed with `useMemo` in `App.jsx` — no external state library.
+
+### Data Shape
+
+Each vacation home object in `ferienhauser.js`:
+```js
+{
+  id: number,
+  name: string,
+  region: string,
+  bundesland: string,         // German federal state
+  typ: "Haus" | "Chalet" | "Bungalow" | "Villa" | "Cottage" | "Apartment",
+  personen: number,           // max guest capacity
+  schlafzimmer: number,       // bedroom count
+  preisProNacht: number,      // price per night in EUR
+  bewertung: number,          // star rating (1–5)
+  anzahlBewertungen: number,  // number of reviews
+  bild: string,               // emoji used as image placeholder
+  beschreibung: string,       // German description
+  accessibility: string[],    // keys from ACCESSIBILITY_FEATURES
+  adresse: string,
+}
+```
+
+Accessibility feature keys (defined in `ACCESSIBILITY_FEATURES`):
+- **mobility:** `rollstuhlgerecht`, `rampe`, `aufzug`, `breiteSchieren`, `erdgeschoss`
+- **bathroom:** `bodengleicheDusche`, `haltegriffe`
+- **kitchen:** `behindertengerechteKueche`
+- **outdoor:** `parkplatz`, `pool`, `strandnah`
+- **sensory:** `sehbehinderung`, `hoerbehinderung`
+- **general:** `haustiere`
+
+---
+
+## Key Conventions
+
+### Language
+All UI text, labels, and data are in **German**. Keep new UI text in German.
+
+### JavaScript / JSX
+- ES Modules (`"type": "module"` in package.json) — always use `import`/`export`
+- React function components with hooks only — no class components
+- No TypeScript (type declaration packages are present but not used)
+- `useMemo` for expensive derived state; `useState` for local UI state
+- ESLint flat config (v9): avoid unused imports and variables
+
+### CSS
+- All styles in `App.css` (component styles) and `index.css` (global resets)
+- CSS custom properties defined in `:root` in `index.css`:
+  - Colors: `--primary`, `--primary-dark`, `--primary-light`, `--accent`, `--danger`, gray scale
+  - Utilities: `--radius`, `--shadow-sm`, `--shadow-md`, `--shadow-lg`
+- Responsive breakpoints: `@media (max-width: 900px)` and `@media (max-width: 600px)`
+- No CSS preprocessor, no CSS Modules, no CSS-in-JS
+- Follow existing BEM-like class naming: `app-header`, `card-grid`, `filter-panel`, etc.
+
+### Component Props
+
+**`<FilterPanel filter onFilterChange />`**
+- `filter`: current filter object
+- `onFilterChange`: setter from `useState`
+
+**`<HausCard haus isSelected onToggleCompare compareCount />`**
+- `haus`: single vacation home object
+- `isSelected`: whether this home is in the comparison list
+- `onToggleCompare(id)`: callback to add/remove from comparison
+- `compareCount`: current comparison list length (to enforce 3-item max)
+
+**`<CompareTable hauser onRemove onClose />`**
+- `hauser`: array of vacation home objects (max 3)
+- `onRemove(id)`: removes a home from comparison (closes modal if last one removed)
+- `onClose()`: closes the modal without removing homes
+
+---
+
+## Filter Defaults
+
+```js
+const DEFAULT_FILTER = { features: [], maxPreis: 400, minPersonen: 1, typ: "Alle" };
+```
+
+The "reset filters" button in `FilterPanel` and the empty-state button both reset to this value.
+
+---
+
+## Adding New Data
+
+To add more vacation homes, append to the `ferienhauser` array in `src/data/ferienhauser.js`. Each entry must have a unique numeric `id`. The `accessibility` array should contain only keys present in `ACCESSIBILITY_FEATURES`.
+
+To add a new accessibility feature, add it to the `ACCESSIBILITY_FEATURES` object with `label`, `icon` (emoji), and `category` (`"mobility"` | `"bathroom"` | `"kitchen"` | `"outdoor"` | `"sensory"` | `"general"`). The `FilterPanel` groups and renders features by category automatically.
+
+---
+
+## What Is NOT Present (Yet)
+
+- No tests (no Vitest, Jest, or Testing Library)
+- No TypeScript (packages installed but unused)
+- No backend or API calls
+- No environment variables / `.env` files
+- No CI/CD pipeline
+- No routing (single-page, no React Router)
+- No state management library (no Redux, Zustand, etc.)
+- No Prettier or other formatter — only ESLint
+
+---
+
+## ESLint Rules of Note
+
+```js
+// Unused vars are errors, EXCEPT uppercase/underscore-prefixed names
+"no-unused-vars": ["error", { varsIgnorePattern: "^[A-Z_]" }]
+```
+
+Run `npm run lint` before committing. Lint errors will block the build in CI if one is added.