diff --git a/apps/api/main.py b/apps/api/main.py
index 242694e..2e17dad 100644
--- a/apps/api/main.py
+++ b/apps/api/main.py
@@ -2,6 +2,7 @@
 
 import asyncio
 import json
+import logging
 import os
 from pathlib import Path
 from typing import Any, AsyncGenerator
@@ -16,6 +17,8 @@ from pydantic import BaseModel, ValidationError
 
 from packages.home_capabilities import CAP_VERSION, LightState
 
+logger = logging.getLogger(__name__)
+
 app = FastAPI(
     title="Home Automation API",
     description="API for home automation system",
@@ -71,6 +74,7 @@ class DeviceInfo(BaseModel):
     device_id: str
     type: str
     name: str
+    features: dict[str, Any] = {}
 
 
 # Configuration helpers
@@ -145,19 +149,57 @@ async def get_devices() -> list[DeviceInfo]:
     """Get list of available devices.
     
     Returns:
-        list: List of device information
+        list: List of device information including features
     """
     devices = load_devices()
     return [
         DeviceInfo(
             device_id=device["device_id"],
             type=device["type"],
-            name=device.get("name", device["device_id"])
+            name=device.get("name", device["device_id"]),
+            features=device.get("features", {})
         )
         for device in devices
     ]
 
 
+@app.get("/layout")
+async def get_layout() -> dict[str, Any]:
+    """Get UI layout configuration.
+    
+    Returns:
+        dict: Layout configuration with rooms and device tiles
+    """
+    from packages.home_capabilities import load_layout
+    
+    try:
+        layout = load_layout()
+        
+        # Convert Pydantic models to dict
+        rooms = []
+        for room in layout.rooms:
+            devices = []
+            for tile in room.devices:
+                devices.append({
+                    "device_id": tile.device_id,
+                    "title": tile.title,
+                    "icon": tile.icon,
+                    "rank": tile.rank
+                })
+            
+            rooms.append({
+                "name": room.name,
+                "devices": devices
+            })
+        
+        return {"rooms": rooms}
+        
+    except Exception as e:
+        logger.error(f"Error loading layout: {e}")
+        # Return empty layout on error
+        return {"rooms": []}
+
+
 @app.post("/devices/{device_id}/set", status_code=status.HTTP_202_ACCEPTED)
 async def set_device(device_id: str, request: SetDeviceRequest) -> dict[str, str]:
     """Set device state.
diff --git a/apps/ui/api_client.py b/apps/ui/api_client.py
new file mode 100644
index 0000000..17bec53
--- /dev/null
+++ b/apps/ui/api_client.py
@@ -0,0 +1,116 @@
+"""
+HTTP Client for fetching devices from the API Gateway.
+"""
+import logging
+from typing import Optional
+import httpx
+
+logger = logging.getLogger(__name__)
+
+
+def fetch_devices(api_base: str = "http://localhost:8001") -> list[dict]:
+    """
+    Fetch devices from the API Gateway.
+    
+    Args:
+        api_base: Base URL of the API Gateway (default: http://localhost:8001)
+        
+    Returns:
+        List of device dictionaries. Each device contains at least:
+        - device_id (str): Unique device identifier
+        - type (str): Device type (e.g., "light")
+        - name (str): Human-readable device name
+        
+        Returns empty list on error.
+    """
+    url = f"{api_base}/devices"
+    
+    try:
+        response = httpx.get(url, timeout=3.0)
+        response.raise_for_status()
+        
+        devices = response.json()
+        
+        # API returns a list directly
+        if not isinstance(devices, list):
+            logger.warning(f"Unexpected response format from {url}: expected list, got {type(devices)}")
+            return []
+        
+        logger.info(f"Fetched {len(devices)} devices from API Gateway")
+        return devices
+        
+    except httpx.TimeoutException:
+        logger.warning(f"Timeout while fetching devices from {url}")
+        return []
+        
+    except httpx.HTTPStatusError as e:
+        logger.warning(f"HTTP error {e.response.status_code} while fetching devices from {url}")
+        return []
+        
+    except httpx.RequestError as e:
+        logger.warning(f"Request error while fetching devices from {url}: {e}")
+        return []
+        
+    except Exception as e:
+        logger.warning(f"Unexpected error while fetching devices from {url}: {e}")
+        return []
+
+
+def fetch_layout(api_base: str = "http://localhost:8001") -> dict:
+    """
+    Fetch UI layout from the API Gateway.
+    
+    Args:
+        api_base: Base URL of the API Gateway (default: http://localhost:8001)
+        
+    Returns:
+        Layout dictionary with structure:
+        {
+            "rooms": [
+                {
+                    "name": str,
+                    "devices": [
+                        {
+                            "device_id": str,
+                            "title": str,
+                            "icon": str,
+                            "rank": int
+                        }
+                    ]
+                }
+            ]
+        }
+        
+        Returns empty layout on error.
+    """
+    url = f"{api_base}/layout"
+    
+    try:
+        response = httpx.get(url, timeout=3.0)
+        response.raise_for_status()
+        
+        layout = response.json()
+        
+        # API returns a dict with "rooms" key
+        if not isinstance(layout, dict) or "rooms" not in layout:
+            logger.warning(f"Unexpected response format from {url}: expected dict with 'rooms', got {type(layout)}")
+            return {"rooms": []}
+        
+        logger.info(f"Fetched layout with {len(layout['rooms'])} rooms from API Gateway")
+        return layout
+        
+    except httpx.TimeoutException:
+        logger.warning(f"Timeout while fetching layout from {url}")
+        return {"rooms": []}
+        
+    except httpx.HTTPStatusError as e:
+        logger.warning(f"HTTP error {e.response.status_code} while fetching layout from {url}")
+        return {"rooms": []}
+        
+    except httpx.RequestError as e:
+        logger.warning(f"Request error while fetching layout from {url}: {e}")
+        return {"rooms": []}
+        
+    except Exception as e:
+        logger.warning(f"Unexpected error while fetching layout from {url}: {e}")
+        return {"rooms": []}
diff --git a/apps/ui/main.py b/apps/ui/main.py
index c6127df..1b01b65 100644
--- a/apps/ui/main.py
+++ b/apps/ui/main.py
@@ -1,11 +1,17 @@
 """UI main entry point."""
 
+import logging
 from pathlib import Path
 
 from fastapi import FastAPI, Request
 from fastapi.responses import HTMLResponse
+from fastapi.staticfiles import StaticFiles
 from fastapi.templating import Jinja2Templates
 
+from apps.ui.api_client import fetch_devices, fetch_layout
+
+logger = logging.getLogger(__name__)
+
 # Initialize FastAPI app
 app = FastAPI(
     title="Home Automation UI",
@@ -17,18 +23,91 @@ app = FastAPI(
 templates_dir = Path(__file__).parent / "templates"
 templates = Jinja2Templates(directory=str(templates_dir))
 
+# Setup static files
+static_dir = Path(__file__).parent / "static"
+static_dir.mkdir(exist_ok=True)
+app.mount("/static", StaticFiles(directory=str(static_dir)), name="static")
+
 
 @app.get("/", response_class=HTMLResponse)
 async def index(request: Request) -> HTMLResponse:
-    """Render the main UI page.
+    """Redirect to dashboard.
     
     Args:
         request: The FastAPI request object
         
     Returns:
-        HTMLResponse: Rendered HTML template
+        HTMLResponse: Rendered dashboard
     """
-    return templates.TemplateResponse("index.html", {"request": request})
+    return await dashboard(request)
+
+
+@app.get("/dashboard", response_class=HTMLResponse)
+async def dashboard(request: Request) -> HTMLResponse:
+    """Render the dashboard with rooms and devices.
+    
+    Args:
+        request: The FastAPI request object
+        
+    Returns:
+        HTMLResponse: Rendered dashboard template
+    """
+    try:
+        # Load layout from API
+        layout_data = fetch_layout()
+        
+        # Fetch devices from API (now includes features)
+        api_devices = fetch_devices()
+        
+        # Create device lookup by device_id
+        device_map = {d["device_id"]: d for d in api_devices}
+        
+        # Build rooms with merged device data
+        rooms = []
+        for room in layout_data.get("rooms", []):
+            devices = []
+            for tile in room.get("devices", []):
+                # Merge tile data with API device data
+                device_data = {
+                    "device_id": tile["device_id"],
+                    "title": tile["title"],
+                    "icon": tile["icon"],
+                    "rank": tile["rank"],
+                }
+                
+                # Add type, name, and features from API if available
+                if tile["device_id"] in device_map:
+                    api_device = device_map[tile["device_id"]]
+                    device_data["type"] = api_device.get("type")
+                    device_data["name"] = api_device.get("name")
+                    device_data["features"] = api_device.get("features", {})
+                else:
+                    device_data["features"] = {}
+                
+                devices.append(device_data)
+            
+            # Sort devices by rank (ascending)
+            devices.sort(key=lambda d: d["rank"])
+            
+            rooms.append({
+                "name": room["name"],
+                "devices": devices
+            })
+        
+        logger.info(f"Rendering dashboard with {len(rooms)} rooms")
+        
+        return templates.TemplateResponse("dashboard.html", {
+            "request": request,
+            "rooms": rooms
+        })
+        
+    except Exception as e:
+        logger.error(f"Error rendering dashboard: {e}", exc_info=True)
+        # Fallback to empty dashboard
+        return templates.TemplateResponse("dashboard.html", {
+            "request": request,
+            "rooms": []
+        })
 
 
 def main() -> None:
diff --git a/apps/ui/static/style.css b/apps/ui/static/style.css
new file mode 100644
index 0000000..d06b227
--- /dev/null
+++ b/apps/ui/static/style.css
@@ -0,0 +1,257 @@
+/* Home Automation Dashboard Styles */
+
+:root {
+    --primary-color: #3b82f6;
+    --primary-hover: #2563eb;
+    --bg-color: #f8fafc;
+    --card-bg: #ffffff;
+    --text-primary: #1e293b;
+    --text-secondary: #64748b;
+    --border-color: #e2e8f0;
+    --shadow: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
+    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
+}
+
+* {
+    margin: 0;
+    padding: 0;
+    box-sizing: border-box;
+}
+
+body {
+    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
+    background-color: var(--bg-color);
+    color: var(--text-primary);
+    line-height: 1.6;
+}
+
+.container {
+    max-width: 1200px;
+    margin: 0 auto;
+    padding: 1rem;
+}
+
+/* Header */
+header {
+    background-color: var(--card-bg);
+    border-radius: 0.5rem;
+    padding: 1.5rem;
+    margin-bottom: 2rem;
+    box-shadow: var(--shadow);
+}
+
+header h1 {
+    font-size: 2rem;
+    font-weight: 700;
+    color: var(--text-primary);
+}
+
+/* Main Content */
+main {
+    margin-bottom: 2rem;
+}
+
+/* Room Section */
+.room {
+    background-color: var(--card-bg);
+    border-radius: 0.5rem;
+    padding: 1.5rem;
+    margin-bottom: 1.5rem;
+    box-shadow: var(--shadow);
+}
+
+.room-title {
+    font-size: 1.5rem;
+    font-weight: 600;
+    margin-bottom: 1rem;
+    color: var(--text-primary);
+    border-bottom: 2px solid var(--border-color);
+    padding-bottom: 0.5rem;
+}
+
+/* Device Grid */
+.devices-grid {
+    display: grid;
+    grid-template-columns: repeat(4, 1fr);
+    gap: 1rem;
+}
+
+/* Tablet: 2 columns */
+@media (max-width: 1024px) {
+    .devices-grid {
+        grid-template-columns: repeat(2, 1fr);
+    }
+}
+
+/* Mobile: 1 column */
+@media (max-width: 640px) {
+    .devices-grid {
+        grid-template-columns: 1fr;
+    }
+}
+
+/* Device Tile */
+.device-tile {
+    background-color: var(--bg-color);
+    border: 1px solid var(--border-color);
+    border-radius: 0.5rem;
+    padding: 1rem;
+    display: flex;
+    flex-direction: column;
+    gap: 0.75rem;
+    transition: all 0.2s;
+}
+
+.device-tile:hover {
+    box-shadow: var(--shadow-lg);
+    transform: translateY(-2px);
+}
+
+.device-header {
+    display: flex;
+    align-items: flex-start;
+    gap: 0.75rem;
+}
+
+.device-icon {
+    font-size: 2.5rem;
+    flex-shrink: 0;
+    line-height: 1;
+}
+
+.device-info {
+    flex: 1;
+    min-width: 0;
+}
+
+.device-title {
+    font-size: 1rem;
+    font-weight: 600;
+    color: var(--text-primary);
+    margin-bottom: 0.25rem;
+    white-space: nowrap;
+    overflow: hidden;
+    text-overflow: ellipsis;
+}
+
+.device-id {
+    font-size: 0.75rem;
+    color: var(--text-secondary);
+    font-family: 'Monaco', 'Courier New', monospace;
+}
+
+/* Device State */
+.device-state {
+    padding: 0.5rem;
+    background-color: var(--card-bg);
+    border-radius: 0.375rem;
+    text-align: center;
+}
+
+.state-text {
+    font-size: 0.875rem;
+    font-weight: 500;
+    color: var(--text-secondary);
+}
+
+/* Device Controls */
+.device-controls {
+    display: flex;
+    gap: 0.5rem;
+}
+
+/* Buttons */
+.btn {
+    flex: 1;
+    padding: 0.625rem 1rem;
+    border: none;
+    border-radius: 0.375rem;
+    font-size: 0.875rem;
+    font-weight: 600;
+    cursor: pointer;
+    transition: all 0.2s;
+    text-transform: uppercase;
+    letter-spacing: 0.025em;
+}
+
+.btn-on {
+    background-color: #10b981;
+    color: white;
+}
+
+.btn-on:hover {
+    background-color: #059669;
+}
+
+.btn-off {
+    background-color: #ef4444;
+    color: white;
+}
+
+.btn-off:hover {
+    background-color: #dc2626;
+}
+
+.btn:active {
+    transform: scale(0.98);
+}
+
+.btn-primary {
+    background-color: var(--primary-color);
+    color: white;
+}
+
+.btn-primary:hover {
+    background-color: var(--primary-hover);
+}
+
+.btn-primary:active {
+    transform: scale(0.98);
+}
+
+/* Empty State */
+.empty-state {
+    background-color: var(--card-bg);
+    border-radius: 0.5rem;
+    padding: 3rem 1.5rem;
+    text-align: center;
+    box-shadow: var(--shadow);
+}
+
+.empty-state p {
+    font-size: 1.125rem;
+    color: var(--text-secondary);
+    margin-bottom: 0.5rem;
+}
+
+.empty-state .hint {
+    font-size: 0.875rem;
+    color: var(--text-secondary);
+}
+
+/* Footer */
+footer {
+    text-align: center;
+    padding: 1rem;
+    color: var(--text-secondary);
+    font-size: 0.875rem;
+}
+
+/* Responsive */
+@media (max-width: 768px) {
+    header h1 {
+        font-size: 1.5rem;
+    }
+    
+    .room-title {
+        font-size: 1.25rem;
+    }
+    
+    .container {
+        padding: 0.75rem;
+    }
+    
+    .room {
+        padding: 1rem;
+    }
+}
diff --git a/apps/ui/templates/dashboard.html b/apps/ui/templates/dashboard.html
new file mode 100644
index 0000000..c5d3cbd
--- /dev/null
+++ b/apps/ui/templates/dashboard.html
@@ -0,0 +1,111 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Home Automation Dashboard</title>
+    <link rel="stylesheet" href="/static/style.css">
+</head>
+<body>
+    <div class="container">
+        <header>
+            <h1>🏠 Home Automation</h1>
+        </header>
+
+        <main>
+            {% if rooms %}
+                {% for room in rooms %}
+                <section class="room">
+                    <h2 class="room-title">{{ room.name }}</h2>
+                    
+                    <div class="devices-grid">
+                        {% for device in room.devices %}
+                        <div class="device-tile" data-device-id="{{ device.device_id }}">
+                            <div class="device-header">
+                                <div class="device-icon">{{ device.icon }}</div>
+                                <div class="device-info">
+                                    <h3 class="device-title">{{ device.title }}</h3>
+                                    <p class="device-id">{{ device.device_id }}</p>
+                                </div>
+                            </div>
+                            
+                            <div class="device-state">
+                                <span id="state-{{ device.device_id }}" class="state-text">—</span>
+                            </div>
+                            
+                            {% if device.type == "light" and device.features.power %}
+                            <div class="device-controls">
+                                <button class="btn btn-on" onclick="setDeviceState('{{ device.device_id }}', 'on')">
+                                    AN
+                                </button>
+                                <button class="btn btn-off" onclick="setDeviceState('{{ device.device_id }}', 'off')">
+                                    AUS
+                                </button>
+                            </div>
+                            {% endif %}
+                        </div>
+                        {% endfor %}
+                    </div>
+                </section>
+                {% endfor %}
+            {% else %}
+                <div class="empty-state">
+                    <p>Keine Räume oder Geräte konfiguriert.</p>
+                    <p class="hint">Prüfe config/layout.yaml und das API-Gateway.</p>
+                </div>
+            {% endif %}
+        </main>
+
+        <footer>
+            <p>Home Automation System v0.1.0</p>
+        </footer>
+    </div>
+
+    <script>
+        // Set device state via API
+        async function setDeviceState(deviceId, power) {
+            const stateSpan = document.getElementById(`state-${deviceId}`);
+            
+            try {
+                stateSpan.textContent = `⏳ ${power}...`;
+                
+                const response = await fetch(`http://localhost:8001/devices/${deviceId}/set`, {
+                    method: 'POST',
+                    headers: {
+                        'Content-Type': 'application/json',
+                    },
+                    body: JSON.stringify({
+                        type: 'light',
+                        payload: {
+                            power: power
+                        }
+                    })
+                });
+                
+                if (!response.ok) {
+                    throw new Error(`HTTP ${response.status}: ${response.statusText}`);
+                }
+                
+                const result = await response.json();
+                console.log('Device state set:', deviceId, power, result);
+                
+                stateSpan.textContent = `✓ ${power}`;
+                
+                // Reset to "—" after 2 seconds
+                setTimeout(() => {
+                    stateSpan.textContent = '—';
+                }, 2000);
+                
+            } catch (error) {
+                console.error('Error setting device state:', error);
+                stateSpan.textContent = `✗ Error`;
+                
+                // Reset after 3 seconds
+                setTimeout(() => {
+                    stateSpan.textContent = '—';
+                }, 3000);
+            }
+        }
+    </script>
+</body>
+</html>
diff --git a/config/devices.yaml b/config/devices.yaml
index 723ee7f..9ffb8fb 100644
--- a/config/devices.yaml
+++ b/config/devices.yaml
@@ -32,3 +32,12 @@ devices:
     topics:
       set: "vendor/test_lampe_2/set"
       state: "vendor/test_lampe_2/state"
+  - device_id: test_lampe_3
+    type: light
+    cap_version: "light@1.2.0"
+    technology: zigbee2mqtt
+    features:
+      power: true
+    topics:
+      set: "vendor/test_lampe_3/set"
+      state: "vendor/test_lampe_3/state"
diff --git a/config/layout.yaml b/config/layout.yaml
new file mode 100644
index 0000000..72c2292
--- /dev/null
+++ b/config/layout.yaml
@@ -0,0 +1,25 @@
+# UI Layout Configuration
+# Defines rooms and device tiles for the home automation UI
+
+rooms:
+  - name: Wohnzimmer
+    devices:
+      - device_id: test_lampe_2
+        title: Deckenlampe
+        icon: "💡"
+        rank: 5
+      - device_id: test_lampe_1
+        title: Stehlampe
+        icon: "�"
+        rank: 10
+        
+  - name: Schlafzimmer
+    devices:
+      - device_id: test_lampe_3
+        title: Nachttischlampe
+        icon: "🛏️"
+        rank: 10
+      
+
+
+
diff --git a/packages/home_capabilities/__init__.py b/packages/home_capabilities/__init__.py
index d186d13..9ad36cc 100644
--- a/packages/home_capabilities/__init__.py
+++ b/packages/home_capabilities/__init__.py
@@ -1,5 +1,6 @@
 """Home capabilities package."""
 
 from packages.home_capabilities.light import CAP_VERSION, LightState
+from packages.home_capabilities.layout import DeviceTile, Room, UiLayout, load_layout
 
-__all__ = ["LightState", "CAP_VERSION"]
+__all__ = ["LightState", "CAP_VERSION", "DeviceTile", "Room", "UiLayout", "load_layout"]
diff --git a/packages/home_capabilities/layout.py b/packages/home_capabilities/layout.py
new file mode 100644
index 0000000..49c49ac
--- /dev/null
+++ b/packages/home_capabilities/layout.py
@@ -0,0 +1,158 @@
+"""UI Layout models and loader for config/layout.yaml."""
+
+import logging
+from pathlib import Path
+from typing import Optional
+
+import yaml
+from pydantic import BaseModel, Field, field_validator
+
+logger = logging.getLogger(__name__)
+
+
+class DeviceTile(BaseModel):
+    """Represents a device tile in the UI.
+    
+    Attributes:
+        device_id: Unique identifier of the device
+        title: Display title for the device
+        icon: Icon name or emoji for the device
+        rank: Sort order within the room (lower = first)
+    """
+    
+    device_id: str = Field(
+        ...,
+        description="Unique device identifier"
+    )
+    
+    title: str = Field(
+        ...,
+        description="Display title for the device"
+    )
+    
+    icon: str = Field(
+        ...,
+        description="Icon name or emoji"
+    )
+    
+    rank: int = Field(
+        ...,
+        ge=0,
+        description="Sort order (lower values appear first)"
+    )
+
+
+class Room(BaseModel):
+    """Represents a room containing devices.
+    
+    Attributes:
+        name: Room name (e.g., "Wohnzimmer", "Küche")
+        devices: List of device tiles in this room
+    """
+    
+    name: str = Field(
+        ...,
+        description="Room name"
+    )
+    
+    devices: list[DeviceTile] = Field(
+        default_factory=list,
+        description="Device tiles in this room"
+    )
+    
+    @field_validator('devices')
+    @classmethod
+    def validate_devices(cls, v: list[DeviceTile]) -> list[DeviceTile]:
+        """Validate that devices list is not empty if provided."""
+        if v is not None and len(v) == 0:
+            logger.warning("Room has empty devices list")
+        return v
+
+
+class UiLayout(BaseModel):
+    """Represents the complete UI layout configuration.
+    
+    Attributes:
+        rooms: List of rooms in the layout
+    """
+    
+    rooms: list[Room] = Field(
+        default_factory=list,
+        description="Rooms in the layout"
+    )
+    
+    @field_validator('rooms')
+    @classmethod
+    def validate_rooms(cls, v: list[Room]) -> list[Room]:
+        """Validate that rooms list is not empty."""
+        if not v or len(v) == 0:
+            raise ValueError("Layout must contain at least one room")
+        return v
+    
+    def total_devices(self) -> int:
+        """Calculate total number of devices across all rooms.
+        
+        Returns:
+            int: Total device count
+        """
+        return sum(len(room.devices) for room in self.rooms)
+
+
+def load_layout(path: Optional[str] = None) -> UiLayout:
+    """Load UI layout from YAML configuration file.
+    
+    Args:
+        path: Optional path to layout.yaml. If None, uses default path
+              (apps/ui/config/layout.yaml relative to workspace root)
+    
+    Returns:
+        UiLayout: Parsed and validated layout configuration
+        
+    Raises:
+        FileNotFoundError: If layout file doesn't exist
+        ValueError: If layout validation fails
+        yaml.YAMLError: If YAML parsing fails
+    """
+    # Determine config path
+    if path is None:
+        # Default: config/layout.yaml at workspace root
+        # This file is assumed to be in packages/home_capabilities/
+        workspace_root = Path(__file__).parent.parent.parent
+        config_path = workspace_root / "config" / "layout.yaml"
+    else:
+        config_path = Path(path)
+    
+    # Check if file exists
+    if not config_path.exists():
+        raise FileNotFoundError(
+            f"Layout configuration not found: {config_path}. "
+            f"Please create a layout.yaml file with room and device definitions."
+        )
+    
+    # Load YAML
+    try:
+        with open(config_path, "r", encoding="utf-8") as f:
+            data = yaml.safe_load(f)
+    except yaml.YAMLError as e:
+        raise yaml.YAMLError(f"Failed to parse YAML in {config_path}: {e}")
+    
+    if data is None:
+        raise ValueError(f"Layout file is empty: {config_path}")
+    
+    # Validate and parse with Pydantic
+    try:
+        layout = UiLayout(**data)
+    except Exception as e:
+        raise ValueError(
+            f"Invalid layout configuration in {config_path}: {e}"
+        )
+    
+    # Log summary
+    total_devices = layout.total_devices()
+    room_names = [room.name for room in layout.rooms]
+    logger.info(
+        f"Loaded layout: {len(layout.rooms)} rooms, "
+        f"{total_devices} total devices (Rooms: {', '.join(room_names)})"
+    )
+    
+    return layout
diff --git a/pyproject.toml b/pyproject.toml
index 8c2b3db..b6fc3fb 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -21,6 +21,8 @@ jinja2 = "^3.1.6"
 apscheduler = "^3.11.0"
 redis = "^7.0.1"
 paho-mqtt = "^2.1.0"
+httpx = "^0.28.1"
+beautifulsoup4 = "^4.14.2"
 
 [tool.poetry.group.dev.dependencies]
 ruff = "^0.6.0"
diff --git a/tools/sim_test_lampe.py b/tools/sim_test_lampe.py
index db65543..4b8d4b6 100644
--- a/tools/sim_test_lampe.py
+++ b/tools/sim_test_lampe.py
@@ -28,7 +28,7 @@ BROKER_HOST = os.environ.get("MQTT_HOST", "172.16.2.16")
 BROKER_PORT = int(os.environ.get("MQTT_PORT", "1883"))
 
 # Devices to simulate
-DEVICES = ["test_lampe_1", "test_lampe_2"]
+DEVICES = ["test_lampe_1", "test_lampe_2", "test_lampe_3"]
 
 # Device states (one per device)
 device_states = {
@@ -39,6 +39,10 @@ device_states = {
     "test_lampe_2": {
         "power": "off",
         "brightness": 50
+    },
+    "test_lampe_3": {
+        "power": "off",
+        "brightness": 50
     }
 }
 
diff --git a/tools/test_api_client.py b/tools/test_api_client.py
new file mode 100644
index 0000000..87a9816
--- /dev/null
+++ b/tools/test_api_client.py
@@ -0,0 +1,169 @@
+"""
+Acceptance tests for API Client (fetch_devices).
+
+Tests:
+1. API running: fetch_devices() returns list with test_lampe_1, test_lampe_2
+2. API down: fetch_devices() returns empty list without crash
+"""
+import sys
+import time
+import subprocess
+from apps.ui.api_client import fetch_devices
+
+
+def test_api_running():
+    """Test 1: API is running -> fetch_devices() returns devices."""
+    print("Test 1: API running")
+    print("-" * 60)
+    
+    devices = fetch_devices("http://localhost:8001")
+    
+    if not devices:
+        print("  ✗ FAILED: Expected devices, got empty list")
+        return False
+    
+    print(f"  ✓ Received {len(devices)} devices")
+    
+    # Check structure
+    for device in devices:
+        device_id = device.get("device_id")
+        device_type = device.get("type")
+        name = device.get("name")
+        
+        if not device_id:
+            print(f"  ✗ FAILED: Device missing 'device_id': {device}")
+            return False
+        
+        if not device_type:
+            print(f"  ✗ FAILED: Device missing 'type': {device}")
+            return False
+        
+        if not name:
+            print(f"  ✗ FAILED: Device missing 'name': {device}")
+            return False
+        
+        print(f"    • {device_id} (type={device_type}, name={name})")
+    
+    # Check for expected devices
+    device_ids = {d["device_id"] for d in devices}
+    expected = {"test_lampe_1", "test_lampe_2"}
+    
+    if not expected.issubset(device_ids):
+        missing = expected - device_ids
+        print(f"  ✗ FAILED: Missing devices: {missing}")
+        return False
+    
+    print("  ✓ All expected devices present")
+    print()
+    return True
+
+
+def test_api_down():
+    """Test 2: API is down -> fetch_devices() returns empty list without crash."""
+    print("Test 2: API down (invalid port)")
+    print("-" * 60)
+    
+    try:
+        devices = fetch_devices("http://localhost:9999")
+        
+        if devices != []:
+            print(f"  ✗ FAILED: Expected empty list, got {len(devices)} devices")
+            return False
+        
+        print("  ✓ Returns empty list without crash")
+        print()
+        return True
+        
+    except Exception as e:
+        print(f"  ✗ FAILED: Exception raised: {e}")
+        print()
+        return False
+
+
+def test_api_timeout():
+    """Test 3: API timeout -> fetch_devices() returns empty list."""
+    print("Test 3: API timeout")
+    print("-" * 60)
+    
+    # Use httpbin.org delay endpoint to simulate slow API
+    try:
+        start = time.time()
+        devices = fetch_devices("https://httpbin.org/delay/5")  # 5s delay, but 3s timeout
+        elapsed = time.time() - start
+        
+        if devices != []:
+            print(f"  ✗ FAILED: Expected empty list, got {len(devices)} devices")
+            return False
+        
+        if elapsed >= 4.0:
+            print(f"  ✗ FAILED: Timeout not enforced (took {elapsed:.1f}s)")
+            return False
+        
+        print(f"  ✓ Returns empty list after timeout ({elapsed:.1f}s)")
+        print()
+        return True
+        
+    except Exception as e:
+        print(f"  ✗ FAILED: Exception raised: {e}")
+        print()
+        return False
+
+
+def main():
+    """Run all acceptance tests."""
+    print("=" * 60)
+    print("Testing API Client (fetch_devices)")
+    print("=" * 60)
+    print()
+    
+    # Check if API is running
+    print("Prerequisites: Checking if API is running on port 8001...")
+    try:
+        devices = fetch_devices("http://localhost:8001")
+        if devices:
+            print(f"✓ API is running ({len(devices)} devices found)")
+            print()
+        else:
+            print("⚠ API might not be running (no devices returned)")
+            print("  Start API with: poetry run uvicorn apps.api.main:app --port 8001")
+            print()
+    except Exception as e:
+        print(f"✗ Cannot reach API: {e}")
+        print("  Start API with: poetry run uvicorn apps.api.main:app --port 8001")
+        print()
+        sys.exit(1)
+    
+    results = []
+    
+    # Test 1: API running
+    results.append(("API running", test_api_running()))
+    
+    # Test 2: API down
+    results.append(("API down", test_api_down()))
+    
+    # Test 3: Timeout
+    results.append(("API timeout", test_api_timeout()))
+    
+    # Summary
+    print("=" * 60)
+    passed = sum(1 for _, result in results if result)
+    total = len(results)
+    print(f"Results: {passed}/{total} tests passed")
+    print("=" * 60)
+    
+    for name, result in results:
+        status = "✓" if result else "✗"
+        print(f"  {status} {name}")
+    
+    if passed == total:
+        print()
+        print("All tests passed!")
+        sys.exit(0)
+    else:
+        print()
+        print("Some tests failed.")
+        sys.exit(1)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/tools/test_dashboard.py b/tools/test_dashboard.py
new file mode 100644
index 0000000..93c3f22
--- /dev/null
+++ b/tools/test_dashboard.py
@@ -0,0 +1,210 @@
+"""
+Acceptance tests for Dashboard Route.
+
+Tests:
+1. GET /dashboard loads without errors
+2. Rooms are shown in layout.yaml order
+3. Devices within each room are sorted by rank (ascending)
+4. GET / redirects to dashboard
+"""
+import sys
+import httpx
+
+
+def test_dashboard_loads():
+    """Test 1: Dashboard loads without errors."""
+    print("Test 1: Dashboard loads")
+    print("-" * 60)
+    
+    try:
+        response = httpx.get("http://localhost:8002/dashboard", timeout=5.0)
+        response.raise_for_status()
+        
+        html = response.text
+        
+        # Check for essential elements
+        if "Home Automation" not in html:
+            print("  ✗ FAILED: Missing title 'Home Automation'")
+            return False
+        
+        if "Wohnzimmer" not in html:
+            print("  ✗ FAILED: Missing room 'Wohnzimmer'")
+            return False
+        
+        if "Schlafzimmer" not in html:
+            print("  ✗ FAILED: Missing room 'Schlafzimmer'")
+            return False
+        
+        print("  ✓ Dashboard loads successfully")
+        print("  ✓ Contains expected rooms")
+        print()
+        return True
+        
+    except Exception as e:
+        print(f"  ✗ FAILED: {e}")
+        print()
+        return False
+
+
+def test_room_order():
+    """Test 2: Rooms appear in layout.yaml order."""
+    print("Test 2: Room order matches layout.yaml")
+    print("-" * 60)
+    
+    try:
+        response = httpx.get("http://localhost:8002/dashboard", timeout=5.0)
+        response.raise_for_status()
+        
+        html = response.text
+        
+        # Find positions of room titles
+        wohnzimmer_pos = html.find('class="room-title">Wohnzimmer<')
+        schlafzimmer_pos = html.find('class="room-title">Schlafzimmer<')
+        
+        if wohnzimmer_pos == -1:
+            print("  ✗ FAILED: Room 'Wohnzimmer' not found")
+            return False
+        
+        if schlafzimmer_pos == -1:
+            print("  ✗ FAILED: Room 'Schlafzimmer' not found")
+            return False
+        
+        # Wohnzimmer should appear before Schlafzimmer
+        if wohnzimmer_pos > schlafzimmer_pos:
+            print("  ✗ FAILED: Room order incorrect")
+            print(f"    Wohnzimmer at position {wohnzimmer_pos}")
+            print(f"    Schlafzimmer at position {schlafzimmer_pos}")
+            return False
+        
+        print("  ✓ Rooms appear in correct order:")
+        print("    1. Wohnzimmer")
+        print("    2. Schlafzimmer")
+        print()
+        return True
+        
+    except Exception as e:
+        print(f"  ✗ FAILED: {e}")
+        print()
+        return False
+
+
+def test_device_rank_sorting():
+    """Test 3: Devices are sorted by rank (ascending)."""
+    print("Test 3: Devices sorted by rank")
+    print("-" * 60)
+    
+    try:
+        response = httpx.get("http://localhost:8002/dashboard", timeout=5.0)
+        response.raise_for_status()
+        
+        html = response.text
+        
+        # In Wohnzimmer: Deckenlampe (rank=5) should come before Stehlampe (rank=10)
+        deckenlampe_pos = html.find('device-title">Deckenlampe<')
+        stehlampe_pos = html.find('device-title">Stehlampe<')
+        
+        if deckenlampe_pos == -1:
+            print("  ✗ FAILED: Device 'Deckenlampe' not found")
+            return False
+        
+        if stehlampe_pos == -1:
+            print("  ✗ FAILED: Device 'Stehlampe' not found")
+            return False
+        
+        if deckenlampe_pos > stehlampe_pos:
+            print("  ✗ FAILED: Devices not sorted by rank")
+            print(f"    Deckenlampe (rank=5) at position {deckenlampe_pos}")
+            print(f"    Stehlampe (rank=10) at position {stehlampe_pos}")
+            return False
+        
+        print("  ✓ Devices sorted by rank (ascending):")
+        print("    Wohnzimmer: Deckenlampe (rank=5) → Stehlampe (rank=10)")
+        print()
+        return True
+        
+    except Exception as e:
+        print(f"  ✗ FAILED: {e}")
+        print()
+        return False
+
+
+def test_root_redirect():
+    """Test 4: GET / shows dashboard."""
+    print("Test 4: Root path (/) shows dashboard")
+    print("-" * 60)
+    
+    try:
+        response = httpx.get("http://localhost:8002/", timeout=5.0, follow_redirects=True)
+        response.raise_for_status()
+        
+        html = response.text
+        
+        # Should contain dashboard elements
+        if "Home Automation" not in html:
+            print("  ✗ FAILED: Root path doesn't show dashboard")
+            return False
+        
+        if "Wohnzimmer" not in html:
+            print("  ✗ FAILED: Root path missing rooms")
+            return False
+        
+        print("  ✓ Root path shows dashboard")
+        print()
+        return True
+        
+    except Exception as e:
+        print(f"  ✗ FAILED: {e}")
+        print()
+        return False
+
+
+def main():
+    """Run all acceptance tests."""
+    print("=" * 60)
+    print("Testing Dashboard Route")
+    print("=" * 60)
+    print()
+    
+    # Check if UI is running
+    print("Prerequisites: Checking if UI is running on port 8002...")
+    try:
+        response = httpx.get("http://localhost:8002/dashboard", timeout=3.0)
+        print("✓ UI is running")
+        print()
+    except Exception as e:
+        print(f"✗ Cannot reach UI: {e}")
+        print("  Start UI with: poetry run uvicorn apps.ui.main:app --port 8002")
+        print()
+        sys.exit(1)
+    
+    results = []
+    
+    # Run tests
+    results.append(("Dashboard loads", test_dashboard_loads()))
+    results.append(("Room order", test_room_order()))
+    results.append(("Device rank sorting", test_device_rank_sorting()))
+    results.append(("Root redirect", test_root_redirect()))
+    
+    # Summary
+    print("=" * 60)
+    passed = sum(1 for _, result in results if result)
+    total = len(results)
+    print(f"Results: {passed}/{total} tests passed")
+    print("=" * 60)
+    
+    for name, result in results:
+        status = "✓" if result else "✗"
+        print(f"  {status} {name}")
+    
+    if passed == total:
+        print()
+        print("All tests passed!")
+        sys.exit(0)
+    else:
+        print()
+        print("Some tests failed.")
+        sys.exit(1)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/tools/test_layout_loader.py b/tools/test_layout_loader.py
new file mode 100644
index 0000000..baa1832
--- /dev/null
+++ b/tools/test_layout_loader.py
@@ -0,0 +1,288 @@
+#!/usr/bin/env python3
+"""Test layout loader and models."""
+
+import sys
+import tempfile
+from pathlib import Path
+
+# Add parent directory to path
+sys.path.insert(0, str(Path(__file__).parent.parent))
+
+from packages.home_capabilities.layout import DeviceTile, Room, UiLayout, load_layout
+
+
+def test_device_tile_creation():
+    """Test DeviceTile model creation."""
+    print("Test 1: DeviceTile Creation")
+    
+    tile = DeviceTile(
+        device_id="test_lamp",
+        title="Test Lamp",
+        icon="💡",
+        rank=10
+    )
+    
+    assert tile.device_id == "test_lamp"
+    assert tile.title == "Test Lamp"
+    assert tile.icon == "💡"
+    assert tile.rank == 10
+    
+    print("  ✓ DeviceTile created successfully")
+    return True
+
+
+def test_room_creation():
+    """Test Room model creation."""
+    print("\nTest 2: Room Creation")
+    
+    tiles = [
+        DeviceTile(device_id="lamp1", title="Lamp 1", icon="💡", rank=1),
+        DeviceTile(device_id="lamp2", title="Lamp 2", icon="💡", rank=2)
+    ]
+    
+    room = Room(name="Living Room", devices=tiles)
+    
+    assert room.name == "Living Room"
+    assert len(room.devices) == 2
+    assert room.devices[0].rank == 1
+    
+    print("  ✓ Room with 2 devices created")
+    return True
+
+
+def test_ui_layout_creation():
+    """Test UiLayout model creation."""
+    print("\nTest 3: UiLayout Creation")
+    
+    rooms = [
+        Room(
+            name="Room 1",
+            devices=[DeviceTile(device_id="d1", title="D1", icon="💡", rank=1)]
+        ),
+        Room(
+            name="Room 2",
+            devices=[DeviceTile(device_id="d2", title="D2", icon="💡", rank=1)]
+        )
+    ]
+    
+    layout = UiLayout(rooms=rooms)
+    
+    assert len(layout.rooms) == 2
+    assert layout.total_devices() == 2
+    
+    print("  ✓ UiLayout with 2 rooms created")
+    print(f"  ✓ Total devices: {layout.total_devices()}")
+    return True
+
+
+def test_layout_validation_empty_rooms():
+    """Test that layout validation rejects empty rooms list."""
+    print("\nTest 4: Validation - Empty Rooms")
+    
+    try:
+        UiLayout(rooms=[])
+        print("  ✗ Should have raised ValueError")
+        return False
+    except ValueError as e:
+        if "at least one room" in str(e):
+            print(f"  ✓ Correct validation error: {e}")
+            return True
+        else:
+            print(f"  ✗ Wrong error message: {e}")
+            return False
+
+
+def test_load_layout_from_file():
+    """Test loading layout from YAML file."""
+    print("\nTest 5: Load Layout from YAML")
+    
+    yaml_content = """
+rooms:
+  - name: Wohnzimmer
+    devices:
+      - device_id: test_lampe_1
+        title: Stehlampe
+        icon: "💡"
+        rank: 10
+      - device_id: test_lampe_2
+        title: Tischlampe
+        icon: "💡"
+        rank: 20
+        
+  - name: Schlafzimmer
+    devices:
+      - device_id: test_lampe_3
+        title: Nachttischlampe
+        icon: "🛏️"
+        rank: 5
+"""
+    
+    with tempfile.NamedTemporaryFile(mode='w', suffix='.yaml', delete=False) as f:
+        f.write(yaml_content)
+        temp_path = Path(f.name)
+    
+    try:
+        layout = load_layout(str(temp_path))
+        
+        assert len(layout.rooms) == 2
+        assert layout.rooms[0].name == "Wohnzimmer"
+        assert len(layout.rooms[0].devices) == 2
+        assert layout.total_devices() == 3
+        
+        # Check device sorting by rank
+        wohnzimmer_devices = layout.rooms[0].devices
+        assert wohnzimmer_devices[0].rank == 10
+        assert wohnzimmer_devices[1].rank == 20
+        
+        print("  ✓ Layout loaded from YAML")
+        print(f"  ✓ Rooms: {len(layout.rooms)}")
+        print(f"  ✓ Total devices: {layout.total_devices()}")
+        print(f"  ✓ Room order preserved: {[r.name for r in layout.rooms]}")
+        
+        return True
+        
+    finally:
+        temp_path.unlink()
+
+
+def test_load_layout_missing_file():
+    """Test error handling for missing file."""
+    print("\nTest 6: Missing File Error")
+    
+    try:
+        load_layout("/nonexistent/path/layout.yaml")
+        print("  ✗ Should have raised FileNotFoundError")
+        return False
+    except FileNotFoundError as e:
+        if "not found" in str(e):
+            print(f"  ✓ Correct error for missing file")
+            return True
+        else:
+            print(f"  ✗ Wrong error message: {e}")
+            return False
+
+
+def test_load_layout_invalid_yaml():
+    """Test error handling for invalid YAML."""
+    print("\nTest 7: Invalid YAML Error")
+    
+    yaml_content = """
+rooms:
+  - name: Room1
+    devices: [invalid yaml structure
+"""
+    
+    with tempfile.NamedTemporaryFile(mode='w', suffix='.yaml', delete=False) as f:
+        f.write(yaml_content)
+        temp_path = Path(f.name)
+    
+    try:
+        load_layout(str(temp_path))
+        print("  ✗ Should have raised YAMLError")
+        temp_path.unlink()
+        return False
+    except Exception as e:
+        temp_path.unlink()
+        if "YAML" in str(type(e).__name__) or "parse" in str(e).lower():
+            print(f"  ✓ Correct YAML parsing error")
+            return True
+        else:
+            print(f"  ✗ Unexpected error: {type(e).__name__}: {e}")
+            return False
+
+
+def test_load_layout_missing_required_fields():
+    """Test validation for missing required fields."""
+    print("\nTest 8: Missing Required Fields")
+    
+    yaml_content = """
+rooms:
+  - name: Room1
+    devices:
+      - device_id: lamp1
+        title: Lamp
+        # Missing: icon, rank
+"""
+    
+    with tempfile.NamedTemporaryFile(mode='w', suffix='.yaml', delete=False) as f:
+        f.write(yaml_content)
+        temp_path = Path(f.name)
+    
+    try:
+        load_layout(str(temp_path))
+        print("  ✗ Should have raised ValueError")
+        temp_path.unlink()
+        return False
+    except ValueError as e:
+        temp_path.unlink()
+        if "icon" in str(e) or "rank" in str(e) or "required" in str(e).lower():
+            print(f"  ✓ Validation error for missing fields")
+            return True
+        else:
+            print(f"  ✗ Wrong error: {e}")
+            return False
+
+
+def test_load_default_layout():
+    """Test loading default layout from workspace."""
+    print("\nTest 9: Load Default Layout (config/layout.yaml)")
+    
+    try:
+        layout = load_layout()
+        
+        print(f"  ✓ Default layout loaded")
+        print(f"  ✓ Rooms: {len(layout.rooms)} ({', '.join(r.name for r in layout.rooms)})")
+        print(f"  ✓ Total devices: {layout.total_devices()}")
+        
+        for room in layout.rooms:
+            print(f"    - {room.name}: {len(room.devices)} devices")
+            for device in room.devices:
+                print(f"      • {device.title} (id={device.device_id}, rank={device.rank})")
+        
+        return True
+        
+    except FileNotFoundError:
+        print("  ⚠ Default layout.yaml not found (expected at config/layout.yaml)")
+        return True  # Not a failure if file doesn't exist yet
+    except Exception as e:
+        print(f"  ✗ Error loading default layout: {e}")
+        return False
+
+
+def main():
+    """Run all tests."""
+    print("=" * 60)
+    print("Testing Layout Loader and Models")
+    print("=" * 60)
+    
+    tests = [
+        test_device_tile_creation,
+        test_room_creation,
+        test_ui_layout_creation,
+        test_layout_validation_empty_rooms,
+        test_load_layout_from_file,
+        test_load_layout_missing_file,
+        test_load_layout_invalid_yaml,
+        test_load_layout_missing_required_fields,
+        test_load_default_layout,
+    ]
+    
+    results = []
+    for test in tests:
+        try:
+            results.append(test())
+        except Exception as e:
+            print(f"  ✗ Unexpected exception: {e}")
+            results.append(False)
+    
+    print("\n" + "=" * 60)
+    passed = sum(results)
+    total = len(results)
+    print(f"Results: {passed}/{total} tests passed")
+    print("=" * 60)
+    
+    return 0 if all(results) else 1
+
+
+if __name__ == "__main__":
+    sys.exit(main())
diff --git a/tools/test_responsive_dashboard.py b/tools/test_responsive_dashboard.py
new file mode 100644
index 0000000..919d2e6
--- /dev/null
+++ b/tools/test_responsive_dashboard.py
@@ -0,0 +1,296 @@
+"""
+Acceptance tests for Responsive Dashboard.
+
+Tests:
+1. Desktop: 4 columns grid
+2. Tablet: 2 columns grid
+3. Mobile: 1 column grid
+4. POST requests work (via API check)
+5. No horizontal scrolling on any viewport
+"""
+import sys
+import httpx
+from bs4 import BeautifulSoup
+
+
+def test_dashboard_html_structure():
+    """Test 1: Dashboard has correct HTML structure."""
+    print("Test 1: Dashboard HTML Structure")
+    print("-" * 60)
+    
+    try:
+        response = httpx.get("http://localhost:8002/dashboard", timeout=5.0)
+        response.raise_for_status()
+        
+        html = response.text
+        soup = BeautifulSoup(html, 'html.parser')
+        
+        # Check for grid container
+        grid = soup.find('div', class_='devices-grid')
+        if not grid:
+            print("  ✗ FAILED: Missing .devices-grid container")
+            return False
+        
+        # Check for device tiles
+        tiles = soup.find_all('div', class_='device-tile')
+        if len(tiles) < 2:
+            print(f"  ✗ FAILED: Expected at least 2 device tiles, found {len(tiles)}")
+            return False
+        
+        # Check for state spans
+        state_spans = soup.find_all('span', id=lambda x: x and x.startswith('state-'))
+        if len(state_spans) < 2:
+            print(f"  ✗ FAILED: Expected state spans, found {len(state_spans)}")
+            return False
+        
+        # Check for ON/OFF buttons
+        btn_on = soup.find_all('button', class_='btn-on')
+        btn_off = soup.find_all('button', class_='btn-off')
+        
+        if not btn_on or not btn_off:
+            print("  ✗ FAILED: Missing ON/OFF buttons")
+            return False
+        
+        print(f"  ✓ Found {len(tiles)} device tiles")
+        print(f"  ✓ Found {len(state_spans)} state indicators")
+        print(f"  ✓ Found {len(btn_on)} ON buttons and {len(btn_off)} OFF buttons")
+        print()
+        return True
+        
+    except Exception as e:
+        print(f"  ✗ FAILED: {e}")
+        print()
+        return False
+
+
+def test_responsive_css():
+    """Test 2: CSS has responsive grid rules."""
+    print("Test 2: Responsive CSS")
+    print("-" * 60)
+    
+    try:
+        response = httpx.get("http://localhost:8002/static/style.css", timeout=5.0)
+        response.raise_for_status()
+        
+        css = response.text
+        
+        # Check for desktop 4 columns
+        if 'grid-template-columns: repeat(4, 1fr)' not in css:
+            print("  ✗ FAILED: Missing desktop grid (4 columns)")
+            return False
+        
+        # Check for tablet media query (2 columns)
+        if 'max-width: 1024px' not in css or 'repeat(2, 1fr)' not in css:
+            print("  ✗ FAILED: Missing tablet media query (2 columns)")
+            return False
+        
+        # Check for mobile media query (1 column)
+        if 'max-width: 640px' not in css:
+            print("  ✗ FAILED: Missing mobile media query")
+            return False
+        
+        print("  ✓ Desktop: 4 columns (grid-template-columns: repeat(4, 1fr))")
+        print("  ✓ Tablet: 2 columns (@media max-width: 1024px)")
+        print("  ✓ Mobile: 1 column (@media max-width: 640px)")
+        print()
+        return True
+        
+    except Exception as e:
+        print(f"  ✗ FAILED: {e}")
+        print()
+        return False
+
+
+def test_javascript_functions():
+    """Test 3: JavaScript POST function exists."""
+    print("Test 3: JavaScript POST Function")
+    print("-" * 60)
+    
+    try:
+        response = httpx.get("http://localhost:8002/dashboard", timeout=5.0)
+        response.raise_for_status()
+        
+        html = response.text
+        
+        # Check for setDeviceState function
+        if 'function setDeviceState' not in html and 'async function setDeviceState' not in html:
+            print("  ✗ FAILED: Missing setDeviceState function")
+            return False
+        
+        # Check for fetch POST call
+        if 'fetch(' not in html or 'method: \'POST\'' not in html:
+            print("  ✗ FAILED: Missing fetch POST call")
+            return False
+        
+        # Check for correct API endpoint pattern
+        if '/devices/${deviceId}/set' not in html and '/devices/' not in html:
+            print("  ✗ FAILED: Missing correct API endpoint")
+            return False
+        
+        # Check for JSON payload
+        if 'type: \'light\'' not in html and '"type":"light"' not in html:
+            print("  ✗ FAILED: Missing correct JSON payload")
+            return False
+        
+        print("  ✓ setDeviceState function defined")
+        print("  ✓ Uses fetch with POST method")
+        print("  ✓ Correct endpoint: /devices/{deviceId}/set")
+        print("  ✓ Correct payload: {type:'light', payload:{power:...}}")
+        print()
+        return True
+        
+    except Exception as e:
+        print(f"  ✗ FAILED: {e}")
+        print()
+        return False
+
+
+def test_device_controls():
+    """Test 4: Devices have correct controls."""
+    print("Test 4: Device Controls")
+    print("-" * 60)
+    
+    try:
+        response = httpx.get("http://localhost:8002/dashboard", timeout=5.0)
+        response.raise_for_status()
+        
+        html = response.text
+        soup = BeautifulSoup(html, 'html.parser')
+        
+        # Find device tiles
+        tiles = soup.find_all('div', class_='device-tile')
+        
+        for tile in tiles:
+            device_id = tile.get('data-device-id')
+            
+            # Check for device header
+            header = tile.find('div', class_='device-header')
+            if not header:
+                print(f"  ✗ FAILED: Device {device_id} missing header")
+                return False
+            
+            # Check for icon and title
+            icon = tile.find('div', class_='device-icon')
+            title = tile.find('h3', class_='device-title')
+            device_id_elem = tile.find('p', class_='device-id')
+            
+            if not icon or not title or not device_id_elem:
+                print(f"  ✗ FAILED: Device {device_id} missing icon/title/id")
+                return False
+            
+            # Check for state indicator
+            state_span = tile.find('span', id=f'state-{device_id}')
+            if not state_span:
+                print(f"  ✗ FAILED: Device {device_id} missing state indicator")
+                return False
+        
+        print(f"  ✓ All {len(tiles)} devices have:")
+        print("    • Icon, title, and device_id")
+        print("    • State indicator (span#state-{{device_id}})")
+        print("    • ON/OFF buttons (for lights with power feature)")
+        print()
+        return True
+        
+    except Exception as e:
+        print(f"  ✗ FAILED: {e}")
+        print()
+        return False
+
+
+def test_rank_sorting():
+    """Test 5: Devices sorted by rank."""
+    print("Test 5: Device Rank Sorting")
+    print("-" * 60)
+    
+    try:
+        response = httpx.get("http://localhost:8002/dashboard", timeout=5.0)
+        response.raise_for_status()
+        
+        html = response.text
+        
+        # In Wohnzimmer: Deckenlampe (rank=5) should come before Stehlampe (rank=10)
+        deckenlampe_pos = html.find('device-title">Deckenlampe<')
+        stehlampe_pos = html.find('device-title">Stehlampe<')
+        
+        if deckenlampe_pos == -1 or stehlampe_pos == -1:
+            print("  ℹ INFO: Test devices not found (expected for test)")
+            print()
+            return True
+        
+        if deckenlampe_pos > stehlampe_pos:
+            print("  ✗ FAILED: Devices not sorted by rank")
+            return False
+        
+        print("  ✓ Devices sorted by rank (Deckenlampe before Stehlampe)")
+        print()
+        return True
+        
+    except Exception as e:
+        print(f"  ✗ FAILED: {e}")
+        print()
+        return False
+
+
+def main():
+    """Run all acceptance tests."""
+    print("=" * 60)
+    print("Testing Responsive Dashboard")
+    print("=" * 60)
+    print()
+    
+    # Check if UI is running
+    print("Prerequisites: Checking if UI is running on port 8002...")
+    try:
+        response = httpx.get("http://localhost:8002/dashboard", timeout=3.0)
+        print("✓ UI is running")
+        print()
+    except Exception as e:
+        print(f"✗ Cannot reach UI: {e}")
+        print("  Start UI with: poetry run uvicorn apps.ui.main:app --port 8002")
+        print()
+        sys.exit(1)
+    
+    results = []
+    
+    # Run tests
+    results.append(("HTML Structure", test_dashboard_html_structure()))
+    results.append(("Responsive CSS", test_responsive_css()))
+    results.append(("JavaScript POST", test_javascript_functions()))
+    results.append(("Device Controls", test_device_controls()))
+    results.append(("Rank Sorting", test_rank_sorting()))
+    
+    # Summary
+    print("=" * 60)
+    passed = sum(1 for _, result in results if result)
+    total = len(results)
+    print(f"Results: {passed}/{total} tests passed")
+    print("=" * 60)
+    
+    for name, result in results:
+        status = "✓" if result else "✗"
+        print(f"  {status} {name}")
+    
+    print()
+    print("Manual Tests Required:")
+    print("  1. Open http://localhost:8002/dashboard in browser")
+    print("  2. Resize browser window to test responsive breakpoints:")
+    print("     - Desktop (>1024px): Should show 4 columns")
+    print("     - Tablet (640-1024px): Should show 2 columns")
+    print("     - Mobile (<640px): Should show 1 column")
+    print("  3. Click ON/OFF buttons and check Network tab in DevTools")
+    print("     - Should see POST to http://localhost:8001/devices/.../set")
+    print("     - No JavaScript errors in Console")
+    print("  4. Verify no horizontal scrolling at any viewport size")
+    
+    if passed == total:
+        print()
+        print("All automated tests passed!")
+        sys.exit(0)
+    else:
+        print()
+        print("Some tests failed.")
+        sys.exit(1)
+
+
+if __name__ == "__main__":
+    main()