Add brightness overlay and enlarge LED preview on target cards

Show effective brightness percentage on the LED preview when a
value source dims below 100%. Prepend a brightness byte to the
preview WebSocket wire format. Increase preview height to 32px.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/wled_controller/core/processing/wled_target_processor.py

@@ -433,12 +433,16 @@ class WledTargetProcessor(TargetProcessor):
         if ws in self._preview_clients:
             self._preview_clients.remove(ws)
 
-    async def _broadcast_led_preview(self, colors: np.ndarray) -> None:
+    async def _broadcast_led_preview(self, colors: np.ndarray, brightness: int = 255) -> None:
-        """Broadcast LED colors as binary RGB bytes to preview WebSocket clients."""
+        """Broadcast LED colors as binary RGB bytes to preview WebSocket clients.
+
+        Wire format: [brightness_byte] [R G B R G B ...]
+        First byte is the effective brightness (0-255), rest is RGB pixel data.
+        """
         if not self._preview_clients:
             return
 
-        data = colors.astype(np.uint8).tobytes()
+        data = bytes([brightness]) + colors.astype(np.uint8).tobytes()
 
         async def _send_safe(ws):
             try:
@@ -605,7 +609,7 @@ class WledTargetProcessor(TargetProcessor):
                                 send_timestamps.append(now)
                                 self._metrics.frames_keepalive += 1
                                 if self._preview_clients and (now - _last_preview_broadcast) >= 0.066:
-                                    await self._broadcast_led_preview(send_colors)
+                                    await self._broadcast_led_preview(send_colors, cur_brightness)
                                     _last_preview_broadcast = now
                             self._metrics.frames_skipped += 1
                             while send_timestamps and send_timestamps[0] < now - 1.0:
@@ -640,7 +644,7 @@ class WledTargetProcessor(TargetProcessor):
 
                         # Broadcast to LED preview WebSocket clients (throttled to ~15 fps)
                         if self._preview_clients and (now - _last_preview_broadcast) >= 0.066:
-                            await self._broadcast_led_preview(send_colors)
+                            await self._broadcast_led_preview(send_colors, cur_brightness)
                             _last_preview_broadcast = now
 
                         self._metrics.timing_send_ms = send_ms

server/src/wled_controller/static/css/cards.css

@@ -631,13 +631,27 @@ ul.section-tip li {
 
 .led-preview-panel {
     padding: 4px 0 0;
+    position: relative;
 }
 
 .led-preview-canvas {
     display: block;
     width: 100%;
-    height: 16px;
+    height: 32px;
     border-radius: 3px;
     image-rendering: pixelated;
     background: #111;
 }
+
+.led-preview-brightness {
+    position: absolute;
+    right: 4px;
+    top: 50%;
+    transform: translateY(-50%);
+    font-size: 0.8rem;
+    font-family: var(--font-mono, monospace);
+    color: #fff;
+    text-shadow: 0 0 3px rgba(0,0,0,0.8);
+    pointer-events: none;
+    opacity: 0.8;
+}

server/src/wled_controller/static/js/features/targets.js

@@ -846,6 +846,7 @@ export function createTargetCard(target, deviceMap, colorStripSourceMap, valueSo
             </div>
             <div id="led-preview-panel-${target.id}" class="led-preview-panel" style="display:${ledPreviewWebSockets[target.id] ? '' : 'none'}">
                 <canvas id="led-preview-canvas-${target.id}" class="led-preview-canvas"></canvas>
+                <span id="led-preview-brightness-${target.id}" class="led-preview-brightness" style="display:none"></span>
             </div>
             <div class="card-actions">
                 ${isProcessing ? `
@@ -1041,10 +1042,24 @@ function connectLedPreviewWS(targetId) {
 
         ws.onmessage = (event) => {
             if (event.data instanceof ArrayBuffer) {
-                const frame = new Uint8Array(event.data);
+                const raw = new Uint8Array(event.data);
+                // Wire format: [brightness_byte] [R G B R G B ...]
+                const brightness = raw[0];
+                const frame = raw.subarray(1);
                 _ledPreviewLastFrame[targetId] = frame;
                 const canvas = document.getElementById(`led-preview-canvas-${targetId}`);
                 if (canvas) _renderLedStrip(canvas, frame);
+                // Show brightness label when below 100%
+                const bLabel = document.getElementById(`led-preview-brightness-${targetId}`);
+                if (bLabel) {
+                    const pct = Math.round(brightness / 255 * 100);
+                    if (pct < 100) {
+                        bLabel.textContent = `☀ ${pct}%`;
+                        bLabel.style.display = '';
+                    } else {
+                        bLabel.style.display = 'none';
+                    }
+                }
             }
         };