Show max FPS hint in target editor, fix gradient sharing for multi-target

- Add dynamic "Hardware max ≈ N fps" recommendation below FPS slider,
  computed from LED count (WLED: protocol timing) or baud rate (serial).
  Reuses shared _computeMaxFps from devices.js with named constants.
- Fix gradient looking different across targets sharing the same stream:
  configure() now uses max LED count across all consumers; _fit_to_device
  uses np.interp linear interpolation instead of truncate/tile.

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

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

@@ -819,13 +819,16 @@ class GradientColorStripStream(ColorStripStream):
     def configure(self, device_led_count: int) -> None:
         """Size to device LED count when led_count was 0 (auto-size).
 
-        Only takes effect when the source was configured with led_count==0.
-        Silently ignored when an explicit led_count was set.
+        When multiple targets share this stream, uses the maximum LED count
+        so the gradient covers enough resolution for all consumers.  Targets
+        with fewer LEDs get a properly resampled gradient via _fit_to_device.
         """
-        if self._auto_size and device_led_count > 0 and device_led_count != self._led_count:
-            self._led_count = device_led_count
+        if self._auto_size and device_led_count > 0:
+            new_count = max(self._led_count, device_led_count)
+            if new_count != self._led_count:
+                self._led_count = new_count
                 self._rebuild_colors()
-            logger.debug(f"GradientColorStripStream auto-sized to {device_led_count} LEDs")
+                logger.debug(f"GradientColorStripStream auto-sized to {new_count} LEDs")
 
     @property
     def target_fps(self) -> int:

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

@@ -382,19 +382,23 @@ class WledTargetProcessor(TargetProcessor):
 
     @staticmethod
     def _fit_to_device(colors: np.ndarray, device_led_count: int) -> np.ndarray:
-        """Truncate or repeat colors to match the target device LED count.
+        """Resample colors to match the target device LED count.
 
-        Shared streams may be sized to a different consumer's LED count.
-        This ensures each target only sends what its device actually needs.
+        Uses linear interpolation so gradients look correct regardless of
+        source/target LED count mismatch (shared streams may be sized to a
+        different consumer's LED count).
         """
         n = len(colors)
         if n == device_led_count or device_led_count <= 0:
             return colors
-        if n > device_led_count:
-            return colors[:device_led_count]
-        # Tile to fill (rare — usually streams are >= device count)
-        reps = (device_led_count + n - 1) // n
-        return np.tile(colors, (reps, 1))[:device_led_count]
+        # Linear interpolation — preserves gradient appearance at any size
+        src_x = np.linspace(0, 1, n)
+        dst_x = np.linspace(0, 1, device_led_count)
+        result = np.column_stack([
+            np.interp(dst_x, src_x, colors[:, ch]).astype(np.uint8)
+            for ch in range(colors.shape[1])
+        ])
+        return result
 
     async def _processing_loop(self) -> None:
         """Main processing loop — poll ColorStripStream → apply brightness → send."""

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

@@ -309,11 +309,29 @@ export async function fetchDeviceBrightness(deviceId) {
     }
 }
 
-// FPS hint helpers (shared with device-discovery)
+// LED protocol timing constants
+const LED_US_PER_BIT = 1.25;              // SK6812/WS2812B bit time (μs)
+const LED_BITS_PER_PIXEL = 32;            // RGBW worst case (4 channels × 8 bits)
+const LED_US_PER_PIXEL = LED_BITS_PER_PIXEL * LED_US_PER_BIT;  // 40μs
+const LED_RESET_US = 80;                  // reset/latch pulse (μs)
+const US_PER_SECOND = 1_000_000;
+
+// Serial protocol constants
+const SERIAL_BITS_PER_BYTE = 10;          // 8N1: 1 start + 8 data + 1 stop
+const SERIAL_RGB_BYTES_PER_LED = 3;
+const ADALIGHT_HEADER_BYTES = 6;          // 'Ada' + count_hi + count_lo + checksum
+const AMBILED_HEADER_BYTES = 1;
+
+// FPS hint helpers (shared with device-discovery, targets)
 export function _computeMaxFps(baudRate, ledCount, deviceType) {
-    if (!baudRate || !ledCount || ledCount < 1) return null;
-    const overhead = deviceType === 'ambiled' ? 1 : 6;
-    const bitsPerFrame = (ledCount * 3 + overhead) * 10;
+    if (!ledCount || ledCount < 1) return null;
+    if (deviceType === 'wled') {
+        const frameUs = ledCount * LED_US_PER_PIXEL + LED_RESET_US;
+        return Math.floor(US_PER_SECOND / frameUs);
+    }
+    if (!baudRate) return null;
+    const overhead = deviceType === 'ambiled' ? AMBILED_HEADER_BYTES : ADALIGHT_HEADER_BYTES;
+    const bitsPerFrame = (ledCount * SERIAL_RGB_BYTES_PER_LED + overhead) * SERIAL_BITS_PER_BYTE;
     return Math.floor(baudRate / bitsPerFrame);
 }
 

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

@@ -12,7 +12,7 @@ import { API_BASE, getHeaders, fetchWithAuth, escapeHtml } from '../core/api.js'
 import { t } from '../core/i18n.js';
 import { showToast, showConfirm } from '../core/ui.js';
 import { Modal } from '../core/modal.js';
-import { createDeviceCard, attachDeviceListeners, fetchDeviceBrightness } from './devices.js';
+import { createDeviceCard, attachDeviceListeners, fetchDeviceBrightness, _computeMaxFps } from './devices.js';
 import { createKCTargetCard, connectKCWebSocket, disconnectKCWebSocket } from './kc-targets.js';
 import { createColorStripCard } from './color-strips.js';
 
@@ -93,6 +93,23 @@ function _autoGenerateTargetName() {
     document.getElementById('target-editor-name').value = `${deviceName} \u00b7 ${cssName}`;
 }
 
+function _updateFpsRecommendation() {
+    const el = document.getElementById('target-editor-fps-rec');
+    const deviceSelect = document.getElementById('target-editor-device');
+    const device = _targetEditorDevices.find(d => d.id === deviceSelect.value);
+    if (!device || !device.led_count) {
+        el.style.display = 'none';
+        return;
+    }
+    const fps = _computeMaxFps(device.baud_rate, device.led_count, device.device_type);
+    if (fps !== null) {
+        el.textContent = t('targets.fps.rec', { fps, leds: device.led_count });
+        el.style.display = '';
+    } else {
+        el.style.display = 'none';
+    }
+}
+
 function _updateStandbyVisibility() {
     const deviceSelect = document.getElementById('target-editor-device');
     const standbyGroup = document.getElementById('target-editor-standby-group');
@@ -167,12 +184,13 @@ export async function showTargetEditor(targetId = null) {
         // Auto-name generation
         _targetNameManuallyEdited = !!targetId;
         document.getElementById('target-editor-name').oninput = () => { _targetNameManuallyEdited = true; };
-        deviceSelect.onchange = () => { _updateStandbyVisibility(); _autoGenerateTargetName(); };
+        deviceSelect.onchange = () => { _updateStandbyVisibility(); _updateFpsRecommendation(); _autoGenerateTargetName(); };
         cssSelect.onchange = () => _autoGenerateTargetName();
         if (!targetId) _autoGenerateTargetName();
 
         // Show/hide standby interval based on selected device capabilities
         _updateStandbyVisibility();
+        _updateFpsRecommendation();
 
         targetEditorModal.snapshot();
         targetEditorModal.open();

server/src/wled_controller/static/locales/en.json

@@ -362,6 +362,7 @@
   "targets.source.none": "-- No source assigned --",
   "targets.fps": "Target FPS:",
   "targets.fps.hint": "Target frames per second for capture and LED updates (1-90)",
+  "targets.fps.rec": "Hardware max ≈ {fps} fps ({leds} LEDs)",
   "targets.border_width": "Border Width (px):",
   "targets.border_width.hint": "How many pixels from the screen edge to sample for LED colors (1-100)",
   "targets.interpolation": "Interpolation Mode:",

server/src/wled_controller/static/locales/ru.json

@@ -362,6 +362,7 @@
   "targets.source.none": "-- Источник не назначен --",
   "targets.fps": "Целевой FPS:",
   "targets.fps.hint": "Целевая частота кадров для захвата и обновления LED (1-90)",
+  "targets.fps.rec": "Макс. аппаратный ≈ {fps} fps ({leds} LED)",
   "targets.border_width": "Ширина границы (px):",
   "targets.border_width.hint": "Сколько пикселей от края экрана выбирать для цвета LED (1-100)",
   "targets.interpolation": "Режим интерполяции:",

server/src/wled_controller/templates/modals/target-editor.html

@@ -45,6 +45,7 @@
                         <input type="range" id="target-editor-fps" min="1" max="90" value="30" oninput="document.getElementById('target-editor-fps-value').textContent = this.value">
                         <span class="slider-value">fps</span>
                     </div>
+                    <small id="target-editor-fps-rec" class="input-hint" style="display:none"></small>
                 </div>
 
                 <div class="form-group" id="target-editor-standby-group">