diff --git a/TODO-css-improvements.md b/TODO-css-improvements.md
index e3637d5..90de97f 100644
--- a/TODO-css-improvements.md
+++ b/TODO-css-improvements.md
@@ -81,9 +81,9 @@ Need to research HAOS communication options first (WebSocket API, REST API, MQTT
 
 ### `api_input`
 
-- [ ] Crossfade transition when new data arrives
-- [ ] Interpolation when incoming LED count differs from strip count
-- [ ] Last-write-wins from any client (no multi-source blending)
+- [x] ~~Crossfade transition~~ — won't do: external client owns temporal transitions; crossfading on our side would double-smooth
+- [x] Interpolation when incoming LED count differs from strip count (linear/nearest/none modes)
+- [x] Last-write-wins from any client — already the default behavior (push overwrites buffer)
 
 ## Architectural / Pipeline
 
diff --git a/server/src/wled_controller/api/schemas/color_strip_sources.py b/server/src/wled_controller/api/schemas/color_strip_sources.py
index f5db541..993922d 100644
--- a/server/src/wled_controller/api/schemas/color_strip_sources.py
+++ b/server/src/wled_controller/api/schemas/color_strip_sources.py
@@ -93,6 +93,7 @@ class ColorStripSourceCreate(BaseModel):
     # api_input-type fields
     fallback_color: Optional[List[int]] = Field(None, description="Fallback RGB color [R,G,B] when no data received (api_input type)")
     timeout: Optional[float] = Field(None, description="Seconds before reverting to fallback (api_input type)", ge=0.0, le=300.0)
+    interpolation: Optional[str] = Field(None, description="LED count interpolation mode: none|linear|nearest (api_input type)")
     # notification-type fields
     notification_effect: Optional[str] = Field(None, description="Notification effect: flash|pulse|sweep")
     duration_ms: Optional[int] = Field(None, ge=100, le=10000, description="Effect duration in milliseconds")
@@ -163,6 +164,7 @@ class ColorStripSourceUpdate(BaseModel):
     # api_input-type fields
     fallback_color: Optional[List[int]] = Field(None, description="Fallback RGB color [R,G,B] (api_input type)")
     timeout: Optional[float] = Field(None, description="Timeout before fallback (api_input type)", ge=0.0, le=300.0)
+    interpolation: Optional[str] = Field(None, description="LED count interpolation mode: none|linear|nearest (api_input type)")
     # notification-type fields
     notification_effect: Optional[str] = Field(None, description="Notification effect: flash|pulse|sweep")
     duration_ms: Optional[int] = Field(None, ge=100, le=10000, description="Effect duration in milliseconds")
@@ -234,6 +236,7 @@ class ColorStripSourceResponse(BaseModel):
     # api_input-type fields
     fallback_color: Optional[List[int]] = Field(None, description="Fallback RGB color [R,G,B] (api_input type)")
     timeout: Optional[float] = Field(None, description="Timeout before fallback (api_input type)")
+    interpolation: Optional[str] = Field(None, description="LED count interpolation mode: none|linear|nearest (api_input type)")
     # notification-type fields
     notification_effect: Optional[str] = Field(None, description="Notification effect: flash|pulse|sweep")
     duration_ms: Optional[int] = Field(None, description="Effect duration in milliseconds")
diff --git a/server/src/wled_controller/core/processing/api_input_stream.py b/server/src/wled_controller/core/processing/api_input_stream.py
index 9db157a..552b2a6 100644
--- a/server/src/wled_controller/core/processing/api_input_stream.py
+++ b/server/src/wled_controller/core/processing/api_input_stream.py
@@ -46,6 +46,7 @@ class ApiInputColorStripStream(ColorStripStream):
         fallback = source.fallback_color
         self._fallback_color = fallback if isinstance(fallback, list) and len(fallback) == 3 else [0, 0, 0]
         self._timeout = max(0.0, source.timeout if source.timeout else 5.0)
+        self._interpolation = source.interpolation if source.interpolation in ("none", "linear", "nearest") else "linear"
         self._led_count = _DEFAULT_LED_COUNT
 
         # Build initial fallback buffer
@@ -77,31 +78,59 @@ class ApiInputColorStripStream(ColorStripStream):
                 self._colors = self._fallback_array.copy()
             logger.debug(f"ApiInputColorStripStream buffer grown to {required} LEDs")
 
+    def _resize(self, colors: np.ndarray, target_count: int) -> np.ndarray:
+        """Resize colors array to target_count using the configured interpolation.
+
+        Args:
+            colors: np.ndarray shape (N, 3) uint8
+            target_count: desired LED count
+
+        Returns:
+            np.ndarray shape (target_count, 3) uint8
+        """
+        n = len(colors)
+        if n == target_count:
+            return colors
+
+        if self._interpolation == "none":
+            # Truncate or zero-pad (legacy behavior)
+            result = np.zeros((target_count, 3), dtype=np.uint8)
+            copy_len = min(n, target_count)
+            result[:copy_len] = colors[:copy_len]
+            return result
+
+        if self._interpolation == "nearest":
+            indices = np.round(np.linspace(0, n - 1, target_count)).astype(int)
+            return colors[indices].copy()
+
+        # linear (default)
+        src_positions = np.linspace(0, 1, n)
+        dst_positions = np.linspace(0, 1, target_count)
+        result = np.empty((target_count, 3), dtype=np.uint8)
+        for ch in range(3):
+            result[:, ch] = np.interp(dst_positions, src_positions, colors[:, ch].astype(np.float32)).astype(np.uint8)
+        return result
+
     def push_colors(self, colors: np.ndarray) -> None:
         """Push a new frame of LED colors.
 
-        Thread-safe. Auto-grows the buffer if the incoming array is larger
-        than the current buffer; otherwise truncates or zero-pads.
+        Thread-safe. When the incoming LED count differs from the device
+        LED count, the data is resized according to the configured
+        interpolation mode (none/linear/nearest).
 
         Args:
             colors: np.ndarray shape (N, 3) uint8
         """
         with self._lock:
             n = len(colors)
-            # Auto-grow if incoming data is larger
-            if n > self._led_count:
-                self._ensure_capacity(n)
             if n == self._led_count:
                 if self._colors.shape == colors.shape:
                     np.copyto(self._colors, colors, casting='unsafe')
                 else:
                     self._colors = np.empty((n, 3), dtype=np.uint8)
                     np.copyto(self._colors, colors, casting='unsafe')
-            elif n < self._led_count:
-                # Zero-pad to led_count
-                padded = np.zeros((self._led_count, 3), dtype=np.uint8)
-                padded[:n] = colors[:n]
-                self._colors = padded
+            else:
+                self._colors = self._resize(colors, self._led_count)
             self._last_push_time = time.monotonic()
             self._push_generation += 1
             self._timed_out = False
@@ -228,12 +257,13 @@ class ApiInputColorStripStream(ColorStripStream):
         return self._push_generation
 
     def update_source(self, source) -> None:
-        """Hot-update fallback_color and timeout from updated source config."""
+        """Hot-update fallback_color, timeout, and interpolation from updated source config."""
         from wled_controller.storage.color_strip_source import ApiInputColorStripSource
         if isinstance(source, ApiInputColorStripSource):
             fallback = source.fallback_color
             self._fallback_color = fallback if isinstance(fallback, list) and len(fallback) == 3 else [0, 0, 0]
             self._timeout = max(0.0, source.timeout if source.timeout else 5.0)
+            self._interpolation = source.interpolation if source.interpolation in ("none", "linear", "nearest") else "linear"
             with self._lock:
                 self._fallback_array = self._build_fallback(self._led_count)
                 if self._timed_out:
diff --git a/server/src/wled_controller/static/css/dashboard.css b/server/src/wled_controller/static/css/dashboard.css
index aa5cdd5..eaa1a51 100644
--- a/server/src/wled_controller/static/css/dashboard.css
+++ b/server/src/wled_controller/static/css/dashboard.css
@@ -158,14 +158,15 @@
 }
 
 .dashboard-target-metrics {
-    display: flex;
-    gap: 12px;
+    display: grid;
+    grid-template-columns: auto 72px 36px;
+    gap: 8px;
     align-items: center;
 }
 
 .dashboard-metric {
     text-align: center;
-    min-width: 48px;
+    overflow: hidden;
 }
 
 .dashboard-metric-value {
@@ -174,6 +175,7 @@
     color: var(--primary-text-color);
     line-height: 1.2;
     font-family: var(--font-mono, monospace);
+    white-space: nowrap;
 }
 
 .dashboard-metric-label {
@@ -187,7 +189,7 @@
     display: flex;
     align-items: center;
     gap: 6px;
-    min-width: auto;
+    overflow: hidden;
 }
 
 .dashboard-fps-sparkline {
@@ -200,7 +202,8 @@
     display: flex;
     flex-direction: column;
     align-items: center;
-    min-width: 36px;
+    width: 44px;
+    flex-shrink: 0;
     line-height: 1.1;
 }
 
diff --git a/server/src/wled_controller/static/js/core/api.ts b/server/src/wled_controller/static/js/core/api.ts
index b875868..44e1e99 100644
--- a/server/src/wled_controller/static/js/core/api.ts
+++ b/server/src/wled_controller/static/js/core/api.ts
@@ -82,6 +82,27 @@ export async function fetchWithAuth(url: string, options: FetchAuthOpts = {}): P
     throw new Error('fetchWithAuth: unreachable code — retry loop exhausted');
 }
 
+// ── Cached metrics-history fetch ────────────────────────────
+let _metricsHistoryCache: { data: any; ts: number } | null = null;
+const _METRICS_CACHE_TTL = 5000; // 5 seconds
+
+/** Fetch metrics history with a short TTL cache to avoid duplicate requests across tabs. */
+export async function fetchMetricsHistory(): Promise<any | null> {
+    const now = Date.now();
+    if (_metricsHistoryCache && now - _metricsHistoryCache.ts < _METRICS_CACHE_TTL) {
+        return _metricsHistoryCache.data;
+    }
+    try {
+        const resp = await fetch(`${API_BASE}/system/metrics-history`, { headers: getHeaders() });
+        if (!resp.ok) return null;
+        const data = await resp.json();
+        _metricsHistoryCache = { data, ts: now };
+        return data;
+    } catch {
+        return null;
+    }
+}
+
 export function escapeHtml(text: string) {
     if (!text) return '';
     const div = document.createElement('div');
diff --git a/server/src/wled_controller/static/js/core/chart-utils.ts b/server/src/wled_controller/static/js/core/chart-utils.ts
index 5b2a3f3..f093ad1 100644
--- a/server/src/wled_controller/static/js/core/chart-utils.ts
+++ b/server/src/wled_controller/static/js/core/chart-utils.ts
@@ -8,6 +8,14 @@
  * Requires Chart.js to be registered globally (done by perf-charts.js).
  */
 
+const DEFAULT_MAX_SAMPLES = 120;
+
+/** Left-pad an array with nulls so it always has `maxSamples` entries. */
+function _padLeft(arr: number[], maxSamples: number): (number | null)[] {
+    const pad = maxSamples - arr.length;
+    return pad > 0 ? [...new Array(pad).fill(null), ...arr] : arr.slice(-maxSamples);
+}
+
 /**
  * Create an FPS sparkline Chart.js instance.
  *
@@ -23,23 +31,29 @@ export function createFpsSparkline(canvasId: string, actualHistory: number[], cu
     const canvas = document.getElementById(canvasId);
     if (!canvas) return null;
 
+    const maxSamples = opts.maxSamples || DEFAULT_MAX_SAMPLES;
+    const paddedActual = _padLeft(actualHistory, maxSamples);
+    const paddedCurrent = _padLeft(currentHistory, maxSamples);
+
     const datasets: any[] = [
         {
-            data: [...actualHistory],
+            data: paddedActual,
             borderColor: '#2196F3',
             backgroundColor: 'rgba(33,150,243,0.12)',
             borderWidth: 1.5,
             tension: 0.3,
             fill: true,
             pointRadius: 0,
+            spanGaps: false,
         },
         {
-            data: [...currentHistory],
+            data: paddedCurrent,
             borderColor: '#4CAF50',
             borderWidth: 1.5,
             tension: 0.3,
             fill: false,
             pointRadius: 0,
+            spanGaps: false,
         },
     ];
 
@@ -47,7 +61,7 @@ export function createFpsSparkline(canvasId: string, actualHistory: number[], cu
     const maxHwFps = opts.maxHwFps;
     if (maxHwFps && maxHwFps < fpsTarget * 1.15) {
         datasets.push({
-            data: actualHistory.map(() => maxHwFps),
+            data: paddedActual.map(() => maxHwFps),
             borderColor: 'rgba(255,152,0,0.5)',
             borderWidth: 1,
             borderDash: [4, 3],
@@ -56,10 +70,12 @@ export function createFpsSparkline(canvasId: string, actualHistory: number[], cu
         });
     }
 
+    const labels = new Array(maxSamples).fill('');
+
     return new Chart(canvas, {
         type: 'line',
         data: {
-            labels: actualHistory.map(() => ''),
+            labels,
             datasets,
         },
         options: {
diff --git a/server/src/wled_controller/static/js/features/color-strips.ts b/server/src/wled_controller/static/js/features/color-strips.ts
index e16bd1b..db66aec 100644
--- a/server/src/wled_controller/static/js/features/color-strips.ts
+++ b/server/src/wled_controller/static/js/features/color-strips.ts
@@ -90,6 +90,7 @@ class CSSEditorModal extends Modal {
             audio_mirror: (document.getElementById('css-editor-audio-mirror') as HTMLInputElement).checked,
             api_input_fallback_color: (document.getElementById('css-editor-api-input-fallback-color') as HTMLInputElement).value,
             api_input_timeout: (document.getElementById('css-editor-api-input-timeout') as HTMLInputElement).value,
+            api_input_interpolation: (document.getElementById('css-editor-api-input-interpolation') as HTMLInputElement).value,
             notification_os_listener: (document.getElementById('css-editor-notification-os-listener') as HTMLInputElement).checked,
             notification_effect: (document.getElementById('css-editor-notification-effect') as HTMLInputElement).value,
             notification_duration: (document.getElementById('css-editor-notification-duration') as HTMLInputElement).value,
@@ -392,6 +393,7 @@ let _audioVizIconSelect: any = null;
 let _gradientPresetIconSelect: any = null;
 let _gradientEasingIconSelect: any = null;
 let _candleTypeIconSelect: any = null;
+let _apiInputInterpolationIconSelect: any = null;
 const _icon = (d: any) => `<svg class="icon" viewBox="0 0 24 24">${d}</svg>`;
 
 function _ensureInterpolationIconSelect() {
@@ -406,6 +408,18 @@ function _ensureInterpolationIconSelect() {
     _interpolationIconSelect = new IconSelect({ target: sel, items, columns: 3 });
 }
 
+function _ensureApiInputInterpolationIconSelect() {
+    const sel = document.getElementById('css-editor-api-input-interpolation') as HTMLSelectElement | null;
+    if (!sel) return;
+    const items = [
+        { value: 'linear',  icon: _icon(P.activity),  label: t('color_strip.api_input.interpolation.linear'),  desc: t('color_strip.api_input.interpolation.linear.desc') },
+        { value: 'nearest', icon: _icon(P.hash),       label: t('color_strip.api_input.interpolation.nearest'), desc: t('color_strip.api_input.interpolation.nearest.desc') },
+        { value: 'none',    icon: _icon(P.circleOff),  label: t('color_strip.api_input.interpolation.none'),    desc: t('color_strip.api_input.interpolation.none.desc') },
+    ];
+    if (_apiInputInterpolationIconSelect) { _apiInputInterpolationIconSelect.updateItems(items); return; }
+    _apiInputInterpolationIconSelect = new IconSelect({ target: sel, items, columns: 3 });
+}
+
 function _ensureEffectTypeIconSelect() {
     const sel = document.getElementById('css-editor-effect-type') as HTMLSelectElement | null;
     if (!sel) return;
@@ -1042,11 +1056,13 @@ const CSS_CARD_RENDERERS: Record<string, CardPropsRenderer> = {
     api_input: (source) => {
         const fbColor = rgbArrayToHex(source.fallback_color || [0, 0, 0]);
         const timeoutVal = (source.timeout ?? 5.0).toFixed(1);
+        const interpLabel = t('color_strip.api_input.interpolation.' + (source.interpolation || 'linear')) || source.interpolation || 'linear';
         return `
             <span class="stream-card-prop" title="${t('color_strip.api_input.fallback_color')}">
                 <span style="display:inline-block;width:14px;height:14px;background:${fbColor};border:1px solid #888;border-radius:2px;vertical-align:middle;margin-right:4px"></span>${fbColor.toUpperCase()}
             </span>
             <span class="stream-card-prop" title="${t('color_strip.api_input.timeout')}">${ICON_TIMER} ${timeoutVal}s</span>
+            <span class="stream-card-prop" title="${t('color_strip.api_input.interpolation')}">${escapeHtml(interpLabel)}</span>
         `;
     },
     notification: (source) => {
@@ -1416,12 +1432,16 @@ const _typeHandlers: Record<string, { load: (...args: any[]) => any; reset: (...
             (document.getElementById('css-editor-api-input-timeout') as HTMLInputElement).value = css.timeout ?? 5.0;
             (document.getElementById('css-editor-api-input-timeout-val') as HTMLElement).textContent =
                 parseFloat(css.timeout ?? 5.0).toFixed(1);
+            (document.getElementById('css-editor-api-input-interpolation') as HTMLSelectElement).value = css.interpolation || 'linear';
+            _ensureApiInputInterpolationIconSelect();
             _showApiInputEndpoints(css.id);
         },
         reset() {
             (document.getElementById('css-editor-api-input-fallback-color') as HTMLInputElement).value = '#000000';
             (document.getElementById('css-editor-api-input-timeout') as HTMLInputElement).value = 5.0 as any;
             (document.getElementById('css-editor-api-input-timeout-val') as HTMLElement).textContent = '5.0';
+            (document.getElementById('css-editor-api-input-interpolation') as HTMLSelectElement).value = 'linear';
+            _ensureApiInputInterpolationIconSelect();
             _showApiInputEndpoints(null);
         },
         getPayload(name) {
@@ -1430,6 +1450,7 @@ const _typeHandlers: Record<string, { load: (...args: any[]) => any; reset: (...
                 name,
                 fallback_color: hexToRgbArray(fbHex),
                 timeout: parseFloat((document.getElementById('css-editor-api-input-timeout') as HTMLInputElement).value),
+                interpolation: (document.getElementById('css-editor-api-input-interpolation') as HTMLSelectElement).value,
             };
         },
     },
diff --git a/server/src/wled_controller/static/js/features/dashboard.ts b/server/src/wled_controller/static/js/features/dashboard.ts
index e93de72..d53da59 100644
--- a/server/src/wled_controller/static/js/features/dashboard.ts
+++ b/server/src/wled_controller/static/js/features/dashboard.ts
@@ -3,7 +3,7 @@
  */
 
 import { apiKey, _dashboardLoading, set_dashboardLoading, dashboardPollInterval, setDashboardPollInterval, colorStripSourcesCache, devicesCache, outputTargetsCache } from '../core/state.ts';
-import { API_BASE, getHeaders, fetchWithAuth, escapeHtml } from '../core/api.ts';
+import { API_BASE, getHeaders, fetchWithAuth, escapeHtml, fetchMetricsHistory } from '../core/api.ts';
 import { t } from '../core/i18n.ts';
 import { showToast, showConfirm, formatUptime, formatCompact, setTabRefreshing } from '../core/ui.ts';
 import { renderPerfSection, initPerfCharts, startPerfPolling, stopPerfPolling } from './perf-charts.ts';
@@ -99,21 +99,16 @@ function _createFpsChart(canvasId: string, actualHistory: number[], currentHisto
 async function _initFpsCharts(runningTargetIds: string[]): Promise<void> {
     _destroyFpsCharts();
 
-    // Seed FPS history from server ring buffer on first load
-    if (Object.keys(_fpsHistory).length === 0 && runningTargetIds.length > 0) {
-        try {
-            const resp = await fetch(`${API_BASE}/system/metrics-history`, { headers: getHeaders() });
-            if (resp.ok) {
-                const data = await resp.json();
-                const serverTargets = data.targets || {};
-                for (const id of runningTargetIds) {
-                    const samples = serverTargets[id] || [];
-                    _fpsHistory[id] = samples.map(s => s.fps).filter(v => v != null);
-                    _fpsCurrentHistory[id] = samples.map(s => s.fps_current).filter(v => v != null);
-                }
+    // Seed FPS history from server ring buffer (on first load and tab switches)
+    if (runningTargetIds.length > 0) {
+        const data = await fetchMetricsHistory();
+        if (data) {
+            const serverTargets = data.targets || {};
+            for (const id of runningTargetIds) {
+                const samples = serverTargets[id] || [];
+                _fpsHistory[id] = samples.map(s => s.fps).filter(v => v != null);
+                _fpsCurrentHistory[id] = samples.map(s => s.fps_current).filter(v => v != null);
             }
-        } catch {
-            // Silently ignore — charts will fill from polling
         }
     }
 
@@ -162,15 +157,18 @@ function _updateRunningMetrics(enrichedRunning: any[]): void {
         if (chart) {
             const actualH = _fpsHistory[target.id] || [];
             const currentH = _fpsCurrentHistory[target.id] || [];
-            // Mutate in-place to avoid array copies
+            // Left-pad with nulls so all charts span full width
+            const pad0 = MAX_FPS_SAMPLES - actualH.length;
+            const pad1 = MAX_FPS_SAMPLES - currentH.length;
             const ds0 = chart.data.datasets[0].data;
             ds0.length = 0;
+            if (pad0 > 0) for (let i = 0; i < pad0; i++) ds0.push(null);
             ds0.push(...actualH);
             const ds1 = chart.data.datasets[1].data;
             ds1.length = 0;
+            if (pad1 > 0) for (let i = 0; i < pad1; i++) ds1.push(null);
             ds1.push(...currentH);
-            while (chart.data.labels.length < ds0.length) chart.data.labels.push('');
-            chart.data.labels.length = ds0.length;
+            chart.data.labels.length = MAX_FPS_SAMPLES;
             chart.update('none');
         }
 
diff --git a/server/src/wled_controller/static/js/features/graph-editor.ts b/server/src/wled_controller/static/js/features/graph-editor.ts
index 3f4d8b1..c9d39ab 100644
--- a/server/src/wled_controller/static/js/features/graph-editor.ts
+++ b/server/src/wled_controller/static/js/features/graph-editor.ts
@@ -13,7 +13,7 @@ import {
     outputTargetsCache, patternTemplatesCache, scenePresetsCache,
     automationsCacheObj, csptCache,
 } from '../core/state.ts';
-import { fetchWithAuth } from '../core/api.ts';
+import { fetchWithAuth, fetchMetricsHistory } from '../core/api.ts';
 import { showToast, showConfirm, formatUptime, formatCompact } from '../core/ui.ts';
 import { createFpsSparkline } from '../core/chart-utils.ts';
 import { t } from '../core/i18n.ts';
@@ -2436,10 +2436,9 @@ async function _showNodeTooltip(nodeId: string, nodeEl: Element, container: HTML
 
     // Seed from server-side metrics history (non-blocking)
     try {
-        const histResp = await fetchWithAuth('/system/metrics-history');
+        const hist = await fetchMetricsHistory();
         if (_hoverNodeId !== nodeId) return; // user moved away during fetch
-        if (histResp.ok) {
-            const hist = await histResp.json();
+        if (hist) {
             const samples = hist.targets?.[nodeId] || [];
             for (const s of samples) {
                 if (s.fps != null) _hoverFpsHistory.push(s.fps);
diff --git a/server/src/wled_controller/static/js/features/perf-charts.ts b/server/src/wled_controller/static/js/features/perf-charts.ts
index 368cec4..2088ec1 100644
--- a/server/src/wled_controller/static/js/features/perf-charts.ts
+++ b/server/src/wled_controller/static/js/features/perf-charts.ts
@@ -7,7 +7,7 @@ import { Chart, registerables } from 'chart.js';
 Chart.register(...registerables);
 window.Chart = Chart;  // expose globally for targets.js, dashboard.js
 
-import { API_BASE, getHeaders } from '../core/api.ts';
+import { API_BASE, getHeaders, fetchMetricsHistory } from '../core/api.ts';
 import { t } from '../core/i18n.ts';
 import { dashboardPollInterval } from '../core/state.ts';
 import { createColorPicker, registerColorPicker } from '../core/color-picker.ts';
@@ -112,9 +112,8 @@ function _createChart(canvasId: string, key: string): any {
 /** Seed charts from server-side metrics history. */
 async function _seedFromServer(): Promise<void> {
     try {
-        const resp = await fetch(`${API_BASE}/system/metrics-history`, { headers: getHeaders() });
-        if (!resp.ok) return;
-        const data = await resp.json();
+        const data = await fetchMetricsHistory();
+        if (!data) return;
         const samples = data.system || [];
         _history.cpu = samples.map(s => s.cpu).filter(v => v != null);
         _history.ram = samples.map(s => s.ram_pct).filter(v => v != null);
diff --git a/server/src/wled_controller/static/js/features/targets.ts b/server/src/wled_controller/static/js/features/targets.ts
index e42a356..384669a 100644
--- a/server/src/wled_controller/static/js/features/targets.ts
+++ b/server/src/wled_controller/static/js/features/targets.ts
@@ -12,7 +12,7 @@ import {
     streamsCache, audioSourcesCache, syncClocksCache,
     colorStripSourcesCache, devicesCache, outputTargetsCache, patternTemplatesCache,
 } from '../core/state.ts';
-import { API_BASE, getHeaders, fetchWithAuth, escapeHtml, isOpenrgbDevice } from '../core/api.ts';
+import { API_BASE, getHeaders, fetchWithAuth, escapeHtml, isOpenrgbDevice, fetchMetricsHistory } from '../core/api.ts';
 import { t } from '../core/i18n.ts';
 import { showToast, showConfirm, formatUptime, formatCompact, setTabRefreshing, desktopFocus } from '../core/ui.ts';
 import { Modal } from '../core/modal.ts';
@@ -132,7 +132,7 @@ function _pushTargetFps(targetId: any, actual: any, current: any) {
 }
 
 function _createTargetFpsChart(canvasId: any, actualHistory: any, currentHistory: any, fpsTarget: any, maxHwFps: any) {
-    return createFpsSparkline(canvasId, actualHistory, currentHistory, fpsTarget, { maxHwFps });
+    return createFpsSparkline(canvasId, actualHistory, currentHistory, fpsTarget, { maxHwFps, maxSamples: _TARGET_MAX_FPS_SAMPLES });
 }
 
 function _updateTargetFpsChart(targetId: any, fpsTarget: any) {
@@ -140,7 +140,6 @@ function _updateTargetFpsChart(targetId: any, fpsTarget: any) {
     if (!chart) return;
     const actualH = _targetFpsHistory[targetId] || [];
     const currentH = _targetFpsCurrentHistory[targetId] || [];
-    // Mutate in-place to avoid array copies
     const ds0 = chart.data.datasets[0].data;
     ds0.length = 0;
     ds0.push(...actualH);
@@ -832,6 +831,25 @@ export async function loadTargetsTab() {
         // Push FPS samples and create/update charts for running targets
         const allTargets = [...ledTargets, ...kcTargets];
         const runningIds = new Set();
+        const runningTargetIds = allTargets.filter(t => t.state?.processing).map(t => t.id);
+
+        // Seed FPS history from server if empty (first load / page reload)
+        if (runningTargetIds.length > 0 && runningTargetIds.some(id => !_targetFpsHistory[id]?.length)) {
+            const data = await fetchMetricsHistory();
+            if (data) {
+                const serverTargets = data.targets || {};
+                for (const id of runningTargetIds) {
+                    if (!_targetFpsHistory[id]?.length) {
+                        const samples = serverTargets[id] || [];
+                        const actual = samples.map((s: any) => s.fps).filter((v: any) => v != null);
+                        const current = samples.map((s: any) => s.fps_current).filter((v: any) => v != null);
+                        _targetFpsHistory[id] = actual.slice(-_TARGET_MAX_FPS_SAMPLES);
+                        _targetFpsCurrentHistory[id] = current.slice(-_TARGET_MAX_FPS_SAMPLES);
+                    }
+                }
+            }
+        }
+
         allTargets.forEach(target => {
             if (target.state && target.state.processing) {
                 runningIds.add(target.id);
@@ -1322,6 +1340,8 @@ function _renderLedStripZones(panel: any, rgbBytes: any) {
         return;
     }
 
+    // Separate mode: each zone gets the full source frame resampled to its LED count
+    // (matches backend OpenRGB separate-mode behavior)
     for (const canvas of zoneCanvases) {
         const zoneName = canvas.dataset.zoneName;
         const zoneSize = cache[zoneName.toLowerCase()];
@@ -1381,28 +1401,45 @@ function connectLedPreviewWS(targetId: any) {
 
                 const panel = document.getElementById(`led-preview-panel-${targetId}`);
 
-                // Composite wire format: [brightness] [0xFE] [layer_count] [led_count_hi] [led_count_lo] [layers...] [composite...]
-                if (raw.length > 4 && raw[1] === 0xFE && panel && panel.dataset.composite === '1') {
+                // Detect composite wire format: [brightness] [0xFE] [layer_count] [led_count_hi] [led_count_lo] [layers...] [composite...]
+                const isCompositeWire = raw.length > 4 && raw[1] === 0xFE;
+
+                if (isCompositeWire) {
                     const layerCount = raw[2];
                     const ledCount = (raw[3] << 8) | raw[4];
                     const rgbSize = ledCount * 3;
                     let offset = 5;
 
-                    // Render per-layer canvases (individual layers)
-                    const layerCanvases = panel.querySelectorAll('.led-preview-layer-canvas[data-layer-idx]');
-                    for (let i = 0; i < layerCount; i++) {
-                        const layerRgb = raw.subarray(offset, offset + rgbSize);
-                        offset += rgbSize;
-                        // layer canvases: idx 0 = "composite", idx 1..N = individual layers
-                        const canvas = layerCanvases[i + 1]; // +1 because composite canvas is first
-                        if (canvas) _renderLedStrip(canvas, layerRgb);
+                    // Render per-layer canvases if panel supports it
+                    if (panel && panel.dataset.composite === '1') {
+                        const layerCanvases = panel.querySelectorAll('.led-preview-layer-canvas[data-layer-idx]');
+                        for (let i = 0; i < layerCount; i++) {
+                            const layerRgb = raw.subarray(offset, offset + rgbSize);
+                            offset += rgbSize;
+                            // layer canvases: idx 0 = "composite", idx 1..N = individual layers
+                            const canvas = layerCanvases[i + 1]; // +1 because composite canvas is first
+                            if (canvas) _renderLedStrip(canvas, layerRgb);
+                        }
+                    } else {
+                        // Skip layer data (panel doesn't have layer canvases)
+                        offset += layerCount * rgbSize;
                     }
 
                     // Final composite result
                     const compositeRgb = raw.subarray(offset, offset + rgbSize);
                     _ledPreviewLastFrame[targetId] = compositeRgb;
-                    const compositeCanvas = panel.querySelector('[data-layer-idx="composite"]');
-                    if (compositeCanvas) _renderLedStrip(compositeCanvas, compositeRgb);
+
+                    if (panel) {
+                        if (panel.dataset.composite === '1') {
+                            const compositeCanvas = panel.querySelector('[data-layer-idx="composite"]');
+                            if (compositeCanvas) _renderLedStrip(compositeCanvas, compositeRgb);
+                        } else if (panel.dataset.zoneMode === 'separate') {
+                            _renderLedStripZones(panel, compositeRgb);
+                        } else {
+                            const canvas = panel.querySelector('.led-preview-canvas');
+                            if (canvas) _renderLedStrip(canvas, compositeRgb);
+                        }
+                    }
                 } else {
                     // Standard wire format: [brightness_byte] [R G B R G B ...]
                     const frame = raw.subarray(1);
@@ -1461,9 +1498,13 @@ function _restoreLedPreviewState(targetId: any) {
     _setPreviewButtonState(targetId, true);
     // Re-render cached frame onto the new canvas
     const frame = _ledPreviewLastFrame[targetId];
-    if (frame) {
-        const canvas = panel?.querySelector('.led-preview-canvas');
-        if (canvas) _renderLedStrip(canvas, frame);
+    if (frame && panel) {
+        if (panel.dataset.zoneMode === 'separate') {
+            _renderLedStripZones(panel, frame);
+        } else {
+            const canvas = panel.querySelector('.led-preview-canvas');
+            if (canvas) _renderLedStrip(canvas, frame);
+        }
     }
 }
 
diff --git a/server/src/wled_controller/static/js/types.ts b/server/src/wled_controller/static/js/types.ts
index 4d86563..eeed46d 100644
--- a/server/src/wled_controller/static/js/types.ts
+++ b/server/src/wled_controller/static/js/types.ts
@@ -203,6 +203,7 @@ export interface ColorStripSource {
     // API Input
     fallback_color?: number[];
     timeout?: number;
+    interpolation?: string;
 
     // Notification
     notification_effect?: string;
diff --git a/server/src/wled_controller/static/locales/en.json b/server/src/wled_controller/static/locales/en.json
index dd2dbdf..23b8e4a 100644
--- a/server/src/wled_controller/static/locales/en.json
+++ b/server/src/wled_controller/static/locales/en.json
@@ -1061,6 +1061,14 @@
     "color_strip.api_input.endpoints": "Push Endpoints:",
     "color_strip.api_input.endpoints.hint": "Use these URLs to push LED color data from your external application. REST accepts JSON, WebSocket accepts both JSON and raw binary frames.",
     "color_strip.api_input.save_first": "Save the source first to see the push endpoint URLs.",
+    "color_strip.api_input.interpolation": "LED Interpolation:",
+    "color_strip.api_input.interpolation.hint": "How to resize incoming LED data when its count differs from the device's LED count. Linear gives smooth blending, Nearest preserves sharp edges, None truncates or zero-pads.",
+    "color_strip.api_input.interpolation.linear": "Linear",
+    "color_strip.api_input.interpolation.linear.desc": "Smooth blending between LEDs",
+    "color_strip.api_input.interpolation.nearest": "Nearest",
+    "color_strip.api_input.interpolation.nearest.desc": "Sharp edges, no blending",
+    "color_strip.api_input.interpolation.none": "None",
+    "color_strip.api_input.interpolation.none.desc": "Truncate or zero-pad",
     "color_strip.type.notification": "Notification",
     "color_strip.type.notification.desc": "One-shot effect on webhook trigger",
     "color_strip.type.notification.hint": "Fires a one-shot visual effect (flash, pulse, sweep) when triggered via a webhook. Designed for use as a composite layer over a persistent base source.",
diff --git a/server/src/wled_controller/static/locales/ru.json b/server/src/wled_controller/static/locales/ru.json
index 1085caf..1b13ee3 100644
--- a/server/src/wled_controller/static/locales/ru.json
+++ b/server/src/wled_controller/static/locales/ru.json
@@ -1044,6 +1044,14 @@
     "color_strip.api_input.endpoints": "Эндпоинты для отправки:",
     "color_strip.api_input.endpoints.hint": "Используйте эти URL для отправки данных о цветах LED из вашего внешнего приложения. REST принимает JSON, WebSocket принимает как JSON, так и бинарные кадры.",
     "color_strip.api_input.save_first": "Сначала сохраните источник, чтобы увидеть URL эндпоинтов.",
+    "color_strip.api_input.interpolation": "Интерполяция LED:",
+    "color_strip.api_input.interpolation.hint": "Как масштабировать входящие данные LED, когда их количество отличается от количества LED на устройстве. Линейная — плавное смешивание, Ближайший — чёткие границы, Нет — обрезка или дополнение нулями.",
+    "color_strip.api_input.interpolation.linear": "Линейная",
+    "color_strip.api_input.interpolation.linear.desc": "Плавное смешивание между LED",
+    "color_strip.api_input.interpolation.nearest": "Ближайший",
+    "color_strip.api_input.interpolation.nearest.desc": "Чёткие границы, без смешивания",
+    "color_strip.api_input.interpolation.none": "Нет",
+    "color_strip.api_input.interpolation.none.desc": "Обрезка или дополнение нулями",
     "color_strip.type.notification": "Уведомления",
     "color_strip.type.notification.desc": "Разовый эффект по вебхуку",
     "color_strip.type.notification.hint": "Вспышка, пульс или волна при срабатывании через вебхук. Предназначен для использования как слой в композитном источнике.",
diff --git a/server/src/wled_controller/static/locales/zh.json b/server/src/wled_controller/static/locales/zh.json
index 5c662e8..17848be 100644
--- a/server/src/wled_controller/static/locales/zh.json
+++ b/server/src/wled_controller/static/locales/zh.json
@@ -1044,6 +1044,14 @@
     "color_strip.api_input.endpoints": "推送端点：",
     "color_strip.api_input.endpoints.hint": "使用这些 URL 从外部应用程序推送 LED 颜色数据。REST 接受 JSON，WebSocket 接受 JSON 和原始二进制帧。",
     "color_strip.api_input.save_first": "请先保存源以查看推送端点 URL。",
+    "color_strip.api_input.interpolation": "LED 插值：",
+    "color_strip.api_input.interpolation.hint": "当传入的 LED 数量与设备 LED 数量不同时如何调整大小。线性提供平滑混合，最近邻保持锐利边缘，无则截断或补零。",
+    "color_strip.api_input.interpolation.linear": "线性",
+    "color_strip.api_input.interpolation.linear.desc": "LED 之间平滑混合",
+    "color_strip.api_input.interpolation.nearest": "最近邻",
+    "color_strip.api_input.interpolation.nearest.desc": "锐利边缘，无混合",
+    "color_strip.api_input.interpolation.none": "无",
+    "color_strip.api_input.interpolation.none.desc": "截断或补零",
     "color_strip.type.notification": "通知",
     "color_strip.type.notification.desc": "通过Webhook触发的一次性效果",
     "color_strip.type.notification.hint": "通过 Webhook 触发时显示一次性视觉效果（闪烁、脉冲、扫描）。设计为组合源中的叠加层。",
diff --git a/server/src/wled_controller/storage/color_strip_source.py b/server/src/wled_controller/storage/color_strip_source.py
index 04c662a..8ae3586 100644
--- a/server/src/wled_controller/storage/color_strip_source.py
+++ b/server/src/wled_controller/storage/color_strip_source.py
@@ -768,21 +768,27 @@ class ApiInputColorStripSource(ColorStripSource):
 
     fallback_color: list = field(default_factory=lambda: [0, 0, 0])  # [R, G, B]
     timeout: float = 5.0               # seconds before reverting to fallback
+    interpolation: str = "linear"      # none | linear | nearest
 
     def to_dict(self) -> dict:
         d = super().to_dict()
         d["fallback_color"] = list(self.fallback_color)
         d["timeout"] = self.timeout
+        d["interpolation"] = self.interpolation
         return d
 
     @classmethod
     def from_dict(cls, data: dict) -> "ApiInputColorStripSource":
         common = _parse_css_common(data)
         fallback_color = _validate_rgb(data.get("fallback_color"), [0, 0, 0])
+        interpolation = data.get("interpolation", "linear")
+        if interpolation not in ("none", "linear", "nearest"):
+            interpolation = "linear"
         return cls(
             **common, source_type="api_input",
             fallback_color=fallback_color,
             timeout=float(data.get("timeout") or 5.0),
+            interpolation=interpolation,
         )
 
     @classmethod
@@ -790,14 +796,17 @@ class ApiInputColorStripSource(ColorStripSource):
                            created_at: datetime, updated_at: datetime,
                            description=None, clock_id=None, tags=None,
                            fallback_color=None, timeout=None,
+                           interpolation=None,
                            **_kwargs):
         fb = _validate_rgb(fallback_color, [0, 0, 0])
+        interp = interpolation if interpolation in ("none", "linear", "nearest") else "linear"
         return cls(
             id=id, name=name, source_type="api_input",
             created_at=created_at, updated_at=updated_at,
             description=description, clock_id=clock_id, tags=tags or [],
             fallback_color=fb,
             timeout=float(timeout) if timeout is not None else 5.0,
+            interpolation=interp,
         )
 
     def apply_update(self, **kwargs) -> None:
@@ -806,6 +815,9 @@ class ApiInputColorStripSource(ColorStripSource):
             self.fallback_color = fallback_color
         if kwargs.get("timeout") is not None:
             self.timeout = float(kwargs["timeout"])
+        interpolation = kwargs.get("interpolation")
+        if interpolation in ("none", "linear", "nearest"):
+            self.interpolation = interpolation
 
 
 @dataclass
diff --git a/server/src/wled_controller/templates/modals/css-editor.html b/server/src/wled_controller/templates/modals/css-editor.html
index 44edebe..9c85682 100644
--- a/server/src/wled_controller/templates/modals/css-editor.html
+++ b/server/src/wled_controller/templates/modals/css-editor.html
@@ -363,6 +363,19 @@
                                oninput="document.getElementById('css-editor-api-input-timeout-val').textContent = parseFloat(this.value).toFixed(1)">
                     </div>
 
+                    <div class="form-group">
+                        <div class="label-row">
+                            <label for="css-editor-api-input-interpolation" data-i18n="color_strip.api_input.interpolation">LED Interpolation:</label>
+                            <button type="button" class="hint-toggle" onclick="toggleHint(this)" title="?" data-i18n-aria-label="aria.hint">?</button>
+                        </div>
+                        <small class="input-hint" style="display:none" data-i18n="color_strip.api_input.interpolation.hint">How to resize incoming LED data when its count differs from the device's LED count.</small>
+                        <select id="css-editor-api-input-interpolation">
+                            <option value="linear">Linear</option>
+                            <option value="nearest">Nearest</option>
+                            <option value="none">None</option>
+                        </select>
+                    </div>
+
                     <div class="form-group" id="css-editor-api-input-endpoints-group">
                         <div class="label-row">
                             <label data-i18n="color_strip.api_input.endpoints">Push Endpoints:</label>