feat: add chase and gradient flash notification effects with priority queue

New notification effects:
- Chase: light bounces across strip with Gaussian glow tail
- Gradient flash: bright center fades to edges with exponential decay

Queue priority: notifications with color_override get high priority and
interrupt the current effect.

Also fixes transient preview for notification sources — adds WebSocket
"fire" command so inline preview works without a saved source, plus
auto-fires on preview open so the effect is visible immediately.

server/src/wled_controller/api/routes/color_strip_sources.py

@@ -507,7 +507,7 @@ async def os_notification_history(_auth: AuthRequired):
 
 # ── Transient Preview WebSocket ────────────────────────────────────────
 
-_PREVIEW_ALLOWED_TYPES = {"static", "gradient", "color_cycle", "effect", "daylight", "candlelight"}
+_PREVIEW_ALLOWED_TYPES = {"static", "gradient", "color_cycle", "effect", "daylight", "candlelight", "notification"}
 
 
 @router.websocket("/api/v1/color-strip-sources/preview/ws")
@@ -648,6 +648,17 @@ async def preview_color_strip_ws(
             if msg is not None:
                 try:
                     new_config = _json.loads(msg)
+
+                    # Handle "fire" command for notification streams
+                    if new_config.get("action") == "fire":
+                        from wled_controller.core.processing.notification_stream import NotificationColorStripStream
+                        if isinstance(stream, NotificationColorStripStream):
+                            stream.fire(
+                                app_name=new_config.get("app", ""),
+                                color_override=new_config.get("color"),
+                            )
+                        continue
+
                     new_type = new_config.get("source_type")
                     if new_type not in _PREVIEW_ALLOWED_TYPES:
                         await websocket.send_text(_json.dumps({"type": "error", "detail": f"source_type must be one of {sorted(_PREVIEW_ALLOWED_TYPES)}"}))

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

@@ -106,7 +106,9 @@ class NotificationColorStripStream(ColorStripStream):
             color = _hex_to_rgb(self._default_color)
 
         # Push event to queue (thread-safe deque.append)
-        self._event_queue.append({"color": color, "start": time.monotonic()})
+        # Priority: 0 = normal, 1 = high (high interrupts current effect)
+        priority = 1 if color_override else 0
+        self._event_queue.append({"color": color, "start": time.monotonic(), "priority": priority})
         return True
 
     def configure(self, device_led_count: int) -> None:
@@ -190,10 +192,11 @@ class NotificationColorStripStream(ColorStripStream):
                 frame_time = self._frame_time
 
                 try:
-                    # Check for new events
+                    # Check for new events — high priority interrupts current
                     while self._event_queue:
                         try:
                             event = self._event_queue.popleft()
+                            if self._active_effect is None or event.get("priority", 0) >= self._active_effect.get("priority", 0):
                                 self._active_effect = event
                         except IndexError:
                             break
@@ -247,6 +250,10 @@ class NotificationColorStripStream(ColorStripStream):
             self._render_pulse(buf, n, color, progress)
         elif effect == "sweep":
             self._render_sweep(buf, n, color, progress)
+        elif effect == "chase":
+            self._render_chase(buf, n, color, progress)
+        elif effect == "gradient_flash":
+            self._render_gradient_flash(buf, n, color, progress)
         else:
             # Default: flash
             self._render_flash(buf, n, color, progress)
@@ -296,3 +303,62 @@ class NotificationColorStripStream(ColorStripStream):
             buf[:, 0] = r
             buf[:, 1] = g
             buf[:, 2] = b
+
+    def _render_chase(self, buf: np.ndarray, n: int, color: tuple, progress: float) -> None:
+        """Chase effect: light travels across strip and bounces back.
+
+        First half: light moves left-to-right with a glowing tail.
+        Second half: light moves right-to-left back to start.
+        Overall brightness fades as progress approaches 1.0.
+        """
+        buf[:] = 0
+        if n <= 0:
+            return
+
+        # Position: bounce (0→n→0)
+        if progress < 0.5:
+            pos = progress * 2.0 * (n - 1)
+        else:
+            pos = (1.0 - (progress - 0.5) * 2.0) * (n - 1)
+
+        # Overall fade
+        fade = max(0.0, 1.0 - progress * 0.6)
+
+        # Glow radius: ~5% of strip, minimum 2 LEDs
+        radius = max(2.0, n * 0.05)
+
+        for i in range(n):
+            dist = abs(i - pos)
+            if dist < radius * 3:
+                glow = math.exp(-0.5 * (dist / radius) ** 2) * fade
+                buf[i, 0] = min(255, int(color[0] * glow))
+                buf[i, 1] = min(255, int(color[1] * glow))
+                buf[i, 2] = min(255, int(color[2] * glow))
+
+    def _render_gradient_flash(self, buf: np.ndarray, n: int, color: tuple, progress: float) -> None:
+        """Gradient flash: bright center fades to edges, then all fades out.
+
+        Creates a gradient from the notification color at center to darker
+        edges, with overall brightness fading over the duration.
+        """
+        if n <= 0:
+            return
+
+        # Overall brightness envelope: quick attack, exponential decay
+        if progress < 0.1:
+            brightness = progress / 0.1
+        else:
+            brightness = math.exp(-3.0 * (progress - 0.1))
+
+        # Center-to-edge gradient
+        center = n / 2.0
+        max_dist = center if center > 0 else 1.0
+
+        for i in range(n):
+            dist = abs(i - center) / max_dist
+            # Smooth falloff from center
+            edge_factor = 1.0 - dist * 0.6
+            b_final = brightness * edge_factor
+            buf[i, 0] = min(255, int(color[0] * b_final))
+            buf[i, 1] = min(255, int(color[1] * b_final))
+            buf[i, 2] = min(255, int(color[2] * b_final))

server/src/wled_controller/static/js/features/color-strips-notification.ts

@@ -34,9 +34,11 @@ export function ensureNotificationEffectIconSelect() {
         { value: 'flash',          icon: _icon(P.zap),         label: t('color_strip.notification.effect.flash'),          desc: t('color_strip.notification.effect.flash.desc') },
         { value: 'pulse',          icon: _icon(P.activity),     label: t('color_strip.notification.effect.pulse'),          desc: t('color_strip.notification.effect.pulse.desc') },
         { value: 'sweep',          icon: _icon(P.fastForward),  label: t('color_strip.notification.effect.sweep'),          desc: t('color_strip.notification.effect.sweep.desc') },
+        { value: 'chase',          icon: _icon(P.rocket),       label: t('color_strip.notification.effect.chase'),          desc: t('color_strip.notification.effect.chase.desc') },
+        { value: 'gradient_flash', icon: _icon(P.rainbow),      label: t('color_strip.notification.effect.gradient_flash'), desc: t('color_strip.notification.effect.gradient_flash.desc') },
     ];
     if (_notificationEffectIconSelect) { _notificationEffectIconSelect.updateItems(items); return; }
-    _notificationEffectIconSelect = new IconSelect({ target: sel, items, columns: 3 });
+    _notificationEffectIconSelect = new IconSelect({ target: sel, items, columns: 2 });
 }
 
 export function ensureNotificationFilterModeIconSelect() {

server/src/wled_controller/static/js/features/color-strips-test.ts

@@ -15,11 +15,12 @@ import {
 import { EntitySelect } from '../core/entity-palette.ts';
 import { hexToRgbArray, getGradientStops } from './css-gradient-editor.ts';
 import { testNotification, _getAnimationPayload, _colorCycleGetColors } from './color-strips.ts';
+import { notificationGetAppColorsDict } from './color-strips-notification.ts';
 
 /* ── Preview config builder ───────────────────────────────────── */
 
 const _PREVIEW_TYPES = new Set([
-    'static', 'gradient', 'color_cycle', 'effect', 'daylight', 'candlelight',
+    'static', 'gradient', 'color_cycle', 'effect', 'daylight', 'candlelight', 'notification',
 ]);
 
 function _collectPreviewConfig() {
@@ -44,6 +45,17 @@ function _collectPreviewConfig() {
         config = { source_type: 'daylight', speed: parseFloat((document.getElementById('css-editor-daylight-speed') as HTMLInputElement).value), use_real_time: (document.getElementById('css-editor-daylight-real-time') as HTMLInputElement).checked, latitude: parseFloat((document.getElementById('css-editor-daylight-latitude') as HTMLInputElement).value), longitude: parseFloat((document.getElementById('css-editor-daylight-longitude') as HTMLInputElement).value) };
     } else if (sourceType === 'candlelight') {
         config = { source_type: 'candlelight', color: hexToRgbArray((document.getElementById('css-editor-candlelight-color') as HTMLInputElement).value), intensity: parseFloat((document.getElementById('css-editor-candlelight-intensity') as HTMLInputElement).value), num_candles: parseInt((document.getElementById('css-editor-candlelight-num-candles') as HTMLInputElement).value) || 3, speed: parseFloat((document.getElementById('css-editor-candlelight-speed') as HTMLInputElement).value), wind_strength: parseFloat((document.getElementById('css-editor-candlelight-wind') as HTMLInputElement).value), candle_type: (document.getElementById('css-editor-candlelight-type') as HTMLSelectElement).value };
+    } else if (sourceType === 'notification') {
+        const filterList = (document.getElementById('css-editor-notification-filter-list') as HTMLInputElement).value.split('\n').map(s => s.trim()).filter(Boolean);
+        config = {
+            source_type: 'notification',
+            notification_effect: (document.getElementById('css-editor-notification-effect') as HTMLInputElement).value,
+            duration_ms: parseInt((document.getElementById('css-editor-notification-duration') as HTMLInputElement).value) || 1500,
+            default_color: (document.getElementById('css-editor-notification-default-color') as HTMLInputElement).value,
+            app_filter_mode: (document.getElementById('css-editor-notification-filter-mode') as HTMLInputElement).value,
+            app_filter_list: filterList,
+            app_colors: notificationGetAppColorsDict(),
+        };
     }
     const clockEl = document.getElementById('css-editor-clock') as HTMLSelectElement | null;
     if (clockEl && clockEl.value) config.clock_id = clockEl.value;
@@ -245,6 +257,14 @@ function _cssTestConnect(sourceId: string, ledCount: number, fps?: number) {
         _cssTestWs.onopen = () => {
             if (gen !== _cssTestGeneration) return;
             _cssTestWs!.send(JSON.stringify(_cssTestTransientConfig));
+            // Auto-fire notification after stream starts so user sees the effect immediately
+            if (_cssTestTransientConfig.source_type === 'notification') {
+                setTimeout(() => {
+                    if (gen === _cssTestGeneration && _cssTestWs && _cssTestWs.readyState === WebSocket.OPEN) {
+                        _cssTestWs.send(JSON.stringify({ action: 'fire', color: _cssTestTransientConfig.default_color }));
+                    }
+                }, 300);
+            }
         };
     }
 
@@ -826,6 +846,12 @@ function _cssTestRenderStripAxis(canvasId: string, ledCount: number) {
 }
 
 export function fireCssTestNotification() {
+    // Transient preview: fire via WebSocket command
+    if (_cssTestTransientConfig && _cssTestWs && _cssTestWs.readyState === WebSocket.OPEN) {
+        _cssTestWs.send(JSON.stringify({ action: 'fire', color: _cssTestTransientConfig.default_color }));
+        return;
+    }
+    // Saved source: fire via REST endpoint
     for (const id of _cssTestNotificationIds) {
         testNotification(id);
     }

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

@@ -1067,6 +1067,10 @@
     "color_strip.notification.effect.pulse.desc": "Smooth bell-curve glow",
     "color_strip.notification.effect.sweep": "Sweep",
     "color_strip.notification.effect.sweep.desc": "Fills left-to-right then fades",
+    "color_strip.notification.effect.chase": "Chase",
+    "color_strip.notification.effect.chase.desc": "Light travels across strip and bounces back",
+    "color_strip.notification.effect.gradient_flash": "Gradient Flash",
+    "color_strip.notification.effect.gradient_flash.desc": "Bright center fades to edges, then all fades out",
     "color_strip.notification.duration": "Duration (ms):",
     "color_strip.notification.duration.hint": "How long the notification effect plays, in milliseconds.",
     "color_strip.notification.default_color": "Default Color:",

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

@@ -443,6 +443,8 @@
                             <option value="flash" data-i18n="color_strip.notification.effect.flash">Flash</option>
                             <option value="pulse" data-i18n="color_strip.notification.effect.pulse">Pulse</option>
                             <option value="sweep" data-i18n="color_strip.notification.effect.sweep">Sweep</option>
+                            <option value="chase" data-i18n="color_strip.notification.effect.chase">Chase</option>
+                            <option value="gradient_flash" data-i18n="color_strip.notification.effect.gradient_flash">Gradient Flash</option>
                         </select>
                     </div>