Backend performance and code quality improvements

Performance (hot path):
- Fix double brightness: removed duplicate scaling from 9 device clients
  (wled, adalight, ambiled, openrgb, hue, spi, chroma, gamesense, usbhid,
  espnow) — processor loop is now the single source of brightness
- Bounded send_timestamps deque with maxlen, removed 3 cleanup loops
- Running FPS sum O(1) instead of sum()/len() O(n) per frame
- datetime.now(timezone.utc) → time.monotonic() with lazy conversion
- Device info refresh interval 30 → 300 iterations
- Composite: gate layer_snapshots copy on preview client flag
- Composite: versioned sub_streams snapshot (copy only on change)
- Composite: pre-resolved blend methods (dict lookup vs getattr)
- ApiInput: np.copyto in-place instead of astype allocation

Code quality:
- BaseJsonStore: RLock on get/delete/get_all/count (was created but unused)
- EntityNotFoundError → proper 404 responses across 15 route files
- Remove 21 defensive getattr(x,'tags',[]) — field guaranteed on all models
- Fix Dict[str,any] → Dict[str,Any] in template/audio_template stores
- Log 4 silenced exceptions (automation engine, metrics, system)
- ValueStream.get_value() now @abstractmethod
- Config.from_yaml: add encoding="utf-8"
- OutputTargetStore: remove 25-line _load override, use _legacy_json_keys
- BaseJsonStore: add _legacy_json_keys for migration support
- Remove unnecessary except Exception→500 from postprocessing list endpoint

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/src/wled_controller/core/devices/adalight_client.py

@@ -168,9 +168,7 @@ class AdalightClient(LEDClient):
         else:
             arr = np.array(pixels, dtype=np.uint16)
 
-        if brightness < 255:
-            arr = arr * brightness // 255
-
+        # Note: brightness already applied by processor loop (_cached_brightness)
         np.clip(arr, 0, 255, out=arr)
         rgb_bytes = arr.astype(np.uint8).tobytes()
         return self._header + rgb_bytes

server/src/wled_controller/core/devices/ambiled_client.py

@@ -40,9 +40,7 @@ class AmbiLEDClient(AdalightClient):
         else:
             arr = np.array(pixels, dtype=np.uint16)
 
-        if brightness < 255:
-            arr = arr * brightness // 255
-
+        # Note: brightness already applied by processor loop (_cached_brightness)
         # Clamp to 0–250: values >250 are command bytes in AmbiLED protocol
         np.clip(arr, 0, 250, out=arr)
         rgb_bytes = arr.astype(np.uint8).tobytes()

server/src/wled_controller/core/devices/chroma_client.py

@@ -145,7 +145,7 @@ class ChromaClient(LEDClient):
         else:
             pixel_arr = np.array(pixels, dtype=np.uint8)
 
-        bri_scale = brightness / 255.0
+        # Note: brightness already applied by processor loop (_cached_brightness)
         device_info = CHROMA_DEVICES.get(self._chroma_device_type)
         if not device_info:
             return False
@@ -156,10 +156,7 @@ class ChromaClient(LEDClient):
         # Chroma uses BGR packed as 0x00BBGGRR integers
         colors = []
         for i in range(n):
-            r, g, b = pixel_arr[i]
-            r = int(r * bri_scale)
-            g = int(g * bri_scale)
-            b = int(b * bri_scale)
+            r, g, b = int(pixel_arr[i][0]), int(pixel_arr[i][1]), int(pixel_arr[i][2])
             colors.append(r | (g << 8) | (b << 16))
 
         # Pad to max_leds if needed

server/src/wled_controller/core/devices/espnow_client.py

@@ -115,7 +115,8 @@ class ESPNowClient(LEDClient):
         else:
             pixel_bytes = bytes(c for rgb in pixels for c in rgb)
 
-        frame = _build_frame(self._peer_mac, pixel_bytes, brightness)
+        # Note: brightness already applied by processor loop; pass 255 to firmware
+        frame = _build_frame(self._peer_mac, pixel_bytes, 255)
         try:
             self._serial.write(frame)
         except Exception as e:

server/src/wled_controller/core/devices/gamesense_client.py

@@ -187,7 +187,7 @@ class GameSenseClient(LEDClient):
         else:
             pixel_arr = np.array(pixels, dtype=np.uint8)
 
-        bri_scale = brightness / 255.0
+        # Note: brightness already applied by processor loop (_cached_brightness)
 
         # Use average color for single-zone devices, or first N for multi-zone
         if len(pixel_arr) == 0:
@@ -195,9 +195,9 @@ class GameSenseClient(LEDClient):
 
         # Compute average color for the zone
         avg = pixel_arr.mean(axis=0)
-        r = int(avg[0] * bri_scale)
-        g = int(avg[1] * bri_scale)
-        b = int(avg[2] * bri_scale)
+        r = int(avg[0])
+        g = int(avg[1])
+        b = int(avg[2])
 
         event_data = {
             "game": GAME_NAME,

server/src/wled_controller/core/devices/hue_client.py

@@ -46,13 +46,13 @@ def _build_entertainment_frame(
     header[15] = 0x00  # reserved
 
     # Light data
-    bri_scale = brightness / 255.0
+    # Note: brightness already applied by processor loop (_cached_brightness)
     data = bytearray()
     for idx, (r, g, b) in enumerate(lights):
         light_id = idx  # 0-based light index in entertainment group
-        r16 = int(r * bri_scale * 257)  # scale 0-255 to 0-65535
-        g16 = int(g * bri_scale * 257)
-        b16 = int(b * bri_scale * 257)
+        r16 = int(r * 257)  # scale 0-255 to 0-65535
+        g16 = int(g * 257)
+        b16 = int(b * 257)
         data += struct.pack(">BHHH", light_id, r16, g16, b16)
 
     return bytes(header) + bytes(data)

server/src/wled_controller/core/devices/openrgb_client.py

@@ -302,9 +302,7 @@ class OpenRGBLEDClient(LEDClient):
                 return
         self._last_sent_pixels = pixel_array.copy()
 
-        # Apply brightness scaling after dedup
-        if brightness < 255:
-            pixel_array = (pixel_array.astype(np.uint16) * brightness >> 8).astype(np.uint8)
+        # Note: brightness already applied by processor loop (_cached_brightness)
 
         # Separate mode: resample full pixel array independently per zone
         if self._zone_mode == "separate" and len(self._target_zones) > 1:

server/src/wled_controller/core/devices/spi_client.py

@@ -162,7 +162,7 @@ class SPIClient(LEDClient):
         if not self._connected:
             return
 
-        bri_scale = brightness / 255.0
+        # Note: brightness already applied by processor loop (_cached_brightness)
 
         if isinstance(pixels, np.ndarray):
             pixel_arr = pixels
@@ -176,7 +176,7 @@ class SPIClient(LEDClient):
             except ImportError:
                 return
 
-            self._strip.setBrightness(brightness)
+            self._strip.setBrightness(255)
             for i in range(min(len(pixel_arr), self._led_count)):
                 r, g, b = pixel_arr[i]
                 self._strip.setPixelColor(i, Color(int(r), int(g), int(b)))
@@ -185,7 +185,7 @@ class SPIClient(LEDClient):
         elif self._spi:
             # SPI bitbang path: convert RGB to WS2812 wire format
             # Each bit is encoded as 3 SPI bits: 1=110, 0=100
-            scaled = (pixel_arr[:self._led_count].astype(np.float32) * bri_scale).astype(np.uint8)
+            scaled = pixel_arr[:self._led_count]
             # GRB order for WS2812
             grb = scaled[:, [1, 0, 2]]
             raw_bytes = grb.tobytes()

server/src/wled_controller/core/devices/usbhid_client.py

@@ -100,7 +100,7 @@ class USBHIDClient(LEDClient):
         else:
             pixel_list = list(pixels)
 
-        bri_scale = brightness / 255.0
+        # Note: brightness already applied by processor loop (_cached_brightness)
 
         # Build HID reports — split across multiple reports if needed
         # Each report: [REPORT_ID][CMD][OFFSET_LO][OFFSET_HI][COUNT][R G B R G B ...]
@@ -119,9 +119,9 @@ class USBHIDClient(LEDClient):
 
             for i, (r, g, b) in enumerate(chunk):
                 base = 5 + i * 3
-                report[base] = int(r * bri_scale)
-                report[base + 1] = int(g * bri_scale)
-                report[base + 2] = int(b * bri_scale)
+                report[base] = int(r)
+                report[base + 1] = int(g)
+                report[base + 2] = int(b)
 
             reports.append(bytes(report))
             offset += len(chunk)

server/src/wled_controller/core/devices/wled_client.py

@@ -378,9 +378,7 @@ class WLEDClient(LEDClient):
             True if successful
         """
         try:
-            if brightness < 255:
-                pixels = (pixels.astype(np.uint16) * brightness >> 8).astype(np.uint8)
-
+            # Note: brightness already applied by processor loop (_cached_brightness)
             logger.debug(f"Sending {len(pixels)} LEDs via DDP")
             self._ddp_client.send_pixels_numpy(pixels)
             logger.debug(f"Successfully sent pixel colors via DDP")
@@ -419,7 +417,7 @@ class WLEDClient(LEDClient):
             # Build WLED JSON state
             payload = {
                 "on": True,
-                "bri": int(brightness),
+                "bri": 255,  # brightness already applied by processor loop
                 "seg": [
                     {
                         "id": segment_id,
@@ -461,9 +459,7 @@ class WLEDClient(LEDClient):
         else:
             pixel_array = np.array(pixels, dtype=np.uint8)
 
-        if brightness < 255:
-            pixel_array = (pixel_array.astype(np.uint16) * brightness >> 8).astype(np.uint8)
-
+        # Note: brightness already applied by processor loop (_cached_brightness)
         self._ddp_client.send_pixels_numpy(pixel_array)
 
     # ===== LEDClient abstraction methods =====