diff --git a/templates/partials/slm_device_list.html b/templates/partials/slm_device_list.html
index 117decb..810bd0f 100644
--- a/templates/partials/slm_device_list.html
+++ b/templates/partials/slm_device_list.html
@@ -2,7 +2,14 @@
 {% if units %}
     {% for unit in units %}
     <div class="bg-gray-50 dark:bg-gray-800 rounded-lg p-4 border border-transparent hover:border-seismo-orange transition-colors relative">
-        <div class="absolute top-3 right-3 flex gap-2">
+        <div class="absolute top-3 right-3 flex gap-2 z-10">
+            <button onclick="event.preventDefault(); event.stopPropagation(); refreshSlmUnit('{{ unit.id }}', this);"
+                    class="text-gray-500 hover:text-seismo-orange dark:text-gray-400 dark:hover:text-seismo-orange"
+                    title="Refresh {{ unit.id }} from device">
+                <svg class="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                    <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M4 4v5h.582m15.356 2A8.001 8.001 0 004.582 9m0 0H9m11 11v-5h-.581m0 0a8.003 8.003 0 01-15.357-2m15.357 2H15"></path>
+                </svg>
+            </button>
             <button onclick="event.preventDefault(); event.stopPropagation(); showLiveChart('{{ unit.id }}');"
                     class="text-gray-500 hover:text-seismo-orange dark:text-gray-400 dark:hover:text-seismo-orange"
                     title="View live chart">
@@ -20,41 +27,42 @@
             </button>
         </div>
 
-        <a href="/slm/{{ unit.id }}" class="block">
-            <div class="flex items-start justify-between gap-4">
-                <div class="min-w-0 flex-1">
-                    <div class="flex items-center gap-2">
-                        <span class="font-semibold text-gray-900 dark:text-white">{{ unit.id }}</span>
-                        {% if unit.slm_model %}
-                            <span class="text-xs text-gray-500 dark:text-gray-400">• {{ unit.slm_model }}</span>
-                        {% endif %}
-                    </div>
-                    {% if unit.address %}
-                        <p class="text-sm text-gray-600 dark:text-gray-400 truncate mt-1">{{ unit.address }}</p>
-                    {% elif unit.location %}
-                        <p class="text-sm text-gray-600 dark:text-gray-400 truncate mt-1">{{ unit.location }}</p>
+        <a href="/slm/{{ unit.id }}" class="block pr-24">
+            <div class="min-w-0">
+                <div class="flex items-center gap-2">
+                    <span class="font-semibold text-gray-900 dark:text-white">{{ unit.id }}</span>
+                    {% if unit.slm_model %}
+                        <span class="text-xs text-gray-500 dark:text-gray-400">• {{ unit.slm_model }}</span>
                     {% endif %}
                 </div>
-
-                {% if unit.retired %}
-                    <span class="shrink-0 px-2 py-1 text-xs font-medium bg-gray-200 text-gray-700 dark:bg-gray-700 dark:text-gray-300 rounded-full">Retired</span>
-                {% elif not unit.deployed %}
-                    <span class="shrink-0 px-2 py-1 text-xs font-medium bg-amber-100 text-amber-800 dark:bg-amber-900/30 dark:text-amber-300 rounded-full">Benched</span>
-                {% elif unit.measurement_state == "Start" %}
-                    <span class="shrink-0 px-2 py-1 text-xs font-medium bg-green-100 text-green-800 dark:bg-green-900/30 dark:text-green-300 rounded-full">Measuring</span>
-                {% elif unit.is_recent %}
-                    <span class="shrink-0 px-2 py-1 text-xs font-medium bg-blue-100 text-blue-800 dark:bg-blue-900/30 dark:text-blue-300 rounded-full">Active</span>
-                {% else %}
-                    <span class="shrink-0 px-2 py-1 text-xs font-medium bg-yellow-100 text-yellow-800 dark:bg-yellow-900/30 dark:text-yellow-300 rounded-full">Idle</span>
+                {% if unit.address %}
+                    <p class="text-sm text-gray-600 dark:text-gray-400 truncate mt-1">{{ unit.address }}</p>
+                {% elif unit.location %}
+                    <p class="text-sm text-gray-600 dark:text-gray-400 truncate mt-1">{{ unit.location }}</p>
                 {% endif %}
             </div>
 
-            <div class="mt-2 text-xs text-gray-500 dark:text-gray-400">
-                {% if unit.slm_last_check %}
-                    Last check: {{ unit.slm_last_check|local_datetime }}
+            <!-- Status badge + last-check on one line (moved off the top-right so it
+                 no longer collides with the refresh/chart/gear action icons). -->
+            <div class="mt-2 flex items-center gap-2 flex-wrap">
+                {% if unit.retired %}
+                    <span class="px-2 py-0.5 text-xs font-medium bg-gray-200 text-gray-700 dark:bg-gray-700 dark:text-gray-300 rounded-full">Retired</span>
+                {% elif not unit.deployed %}
+                    <span class="px-2 py-0.5 text-xs font-medium bg-amber-100 text-amber-800 dark:bg-amber-900/30 dark:text-amber-300 rounded-full">Benched</span>
+                {% elif unit.measurement_state == "Start" %}
+                    <span class="px-2 py-0.5 text-xs font-medium bg-green-100 text-green-800 dark:bg-green-900/30 dark:text-green-300 rounded-full">Measuring</span>
+                {% elif unit.is_recent %}
+                    <span class="px-2 py-0.5 text-xs font-medium bg-blue-100 text-blue-800 dark:bg-blue-900/30 dark:text-blue-300 rounded-full">Active</span>
                 {% else %}
-                    No recent check-in
+                    <span class="px-2 py-0.5 text-xs font-medium bg-yellow-100 text-yellow-800 dark:bg-yellow-900/30 dark:text-yellow-300 rounded-full">Idle</span>
                 {% endif %}
+                <span class="text-xs text-gray-500 dark:text-gray-400">
+                    {% if unit.slm_last_check %}
+                        Last check: {{ unit.slm_last_check|local_datetime }}
+                    {% else %}
+                        No recent check-in
+                    {% endif %}
+                </span>
             </div>
         </a>
     </div>
diff --git a/templates/sound_level_meters.html b/templates/sound_level_meters.html
index 3055db9..360ddbd 100644
--- a/templates/sound_level_meters.html
+++ b/templates/sound_level_meters.html
@@ -51,13 +51,31 @@
 
 <!-- Live Measurement Chart - shows when a device is selected -->
 <div id="live-chart-panel" class="hidden bg-white dark:bg-slate-800 rounded-xl shadow-lg p-6 mb-8">
-    <div class="flex items-center justify-between mb-6">
-        <h2 class="text-xl font-semibold text-gray-900 dark:text-white">Live Measurements</h2>
-        <button onclick="closeLiveChart()" class="text-gray-500 hover:text-gray-700 dark:text-gray-400 dark:hover:text-gray-200">
-            <svg class="w-6 h-6" fill="none" stroke="currentColor" viewBox="0 0 24 24">
-                <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M6 18L18 6M6 6l12 12"></path>
-            </svg>
-        </button>
+    <div class="flex items-start justify-between mb-6">
+        <div>
+            <h2 class="text-xl font-semibold text-gray-900 dark:text-white">
+                Live Measurements
+                <span id="panel-unit-id" class="text-seismo-orange"></span>
+            </h2>
+            <!-- Measuring state + cache freshness (populated from cached /status, no device hit) -->
+            <div class="mt-1 flex items-center gap-2 text-sm">
+                <span id="panel-measuring-badge" class="hidden px-2 py-0.5 text-xs font-medium rounded-full"></span>
+                <span id="panel-freshness" class="text-gray-500 dark:text-gray-400"></span>
+            </div>
+        </div>
+        <div class="flex items-center gap-3">
+            <button onclick="refreshDashboardPanel()" title="Refresh from device"
+                    class="text-gray-500 hover:text-seismo-orange dark:text-gray-400 dark:hover:text-seismo-orange">
+                <svg id="panel-refresh-icon" class="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                    <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M4 4v5h.582m15.356 2A8.001 8.001 0 004.582 9m0 0H9m11 11v-5h-.581m0 0a8.003 8.003 0 01-15.357-2m15.357 2H15"></path>
+                </svg>
+            </button>
+            <button onclick="closeLiveChart()" class="text-gray-500 hover:text-gray-700 dark:text-gray-400 dark:hover:text-gray-200">
+                <svg class="w-6 h-6" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                    <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M6 18L18 6M6 6l12 12"></path>
+                </svg>
+            </button>
+        </div>
     </div>
 
     <!-- Current Metrics -->
@@ -244,12 +262,25 @@ function showLiveChart(unitId) {
         initializeDashboardChart();
     }
 
-    // Reset data
-    window.dashboardChartData = {
-        timestamps: [],
-        lp: [],
-        leq: []
-    };
+    // Reset data for the newly-selected unit (clears any prior unit's line)
+    window.dashboardChartData = { timestamps: [], lp: [], leq: [] };
+    if (window.dashboardChart) {
+        window.dashboardChart.data.labels = [];
+        window.dashboardChart.data.datasets[0].data = [];
+        window.dashboardChart.data.datasets[1].data = [];
+        window.dashboardChart.update('none');
+    }
+
+    // Name the unit; clear stale status until the cache read returns
+    const unitLabel = document.getElementById('panel-unit-id');
+    if (unitLabel) unitLabel.textContent = '· ' + unitId;
+    setPanelStatus(null, null);
+
+    // Populate immediately from CACHE (no device hit): KPI cards + chart trail.
+    prefillDashboardPanel(unitId);
+    backfillDashboardChart(unitId);
+    // Keep the cards updating from cache (~15s) without opening a device stream.
+    startPanelCachePolling(unitId);
 
     // Scroll to chart
     panel.scrollIntoView({ behavior: 'smooth', block: 'start' });
@@ -257,6 +288,7 @@ function showLiveChart(unitId) {
 
 function closeLiveChart() {
     stopDashboardStream();
+    stopPanelCachePolling();
     document.getElementById('live-chart-panel').classList.add('hidden');
     window.selectedUnitId = null;
 }
@@ -270,14 +302,9 @@ function startDashboardStream() {
         window.dashboardWebSocket.close();
     }
 
-    // Reset chart data
-    window.dashboardChartData = { timestamps: [], lp: [], leq: [] };
-    if (window.dashboardChart) {
-        window.dashboardChart.data.labels = [];
-        window.dashboardChart.data.datasets[0].data = [];
-        window.dashboardChart.data.datasets[1].data = [];
-        window.dashboardChart.update();
-    }
+    // The live WS takes over from the cache poller; keep the backfilled trail on
+    // the chart so the live frames continue the line instead of blanking it.
+    stopPanelCachePolling();
 
     const wsProtocol = window.location.protocol === 'https:' ? 'wss:' : 'ws:';
     const wsUrl = `${wsProtocol}//${window.location.host}/api/slmm/${window.selectedUnitId}/monitor`;
@@ -320,6 +347,10 @@ function stopDashboardStream() {
         window.dashboardWebSocket.close();
         window.dashboardWebSocket = null;
     }
+    // Fall back to cache polling so the cards keep refreshing while the panel is open.
+    if (window.selectedUnitId && !document.getElementById('live-chart-panel').classList.contains('hidden')) {
+        startPanelCachePolling(window.selectedUnitId);
+    }
 }
 
 function updateDashboardMetrics(data) {
@@ -340,8 +371,8 @@ function updateDashboardChart(data) {
     window.dashboardChartData.lp.push(parseFloat(data.lp || 0));
     window.dashboardChartData.leq.push(parseFloat(data.leq || 0));
 
-    // Keep only last 60 data points
-    if (window.dashboardChartData.timestamps.length > 60) {
+    // Keep a generous window (backfill seeds up to ~120 points from the 2h trail).
+    if (window.dashboardChartData.timestamps.length > 600) {
         window.dashboardChartData.timestamps.shift();
         window.dashboardChartData.lp.shift();
         window.dashboardChartData.leq.shift();
@@ -355,6 +386,168 @@ function updateDashboardChart(data) {
     }
 }
 
+// ---- Cached-data panel population (no device hit) -----------------------
+
+// Fill the KPI cards + measuring/freshness from the cached NL43Status snapshot.
+async function prefillDashboardPanel(unitId) {
+    try {
+        const r = await fetch(`/api/slmm/${encodeURIComponent(unitId)}/status`);
+        if (!r.ok) {                       // 404 = device has never reported yet
+            setPanelStatus(null, null);
+            return;
+        }
+        const d = (await r.json()).data || {};
+        updateDashboardMetrics(d);         // lp/leq/lmax/ln1/ln2 (ln guards keep cached percentiles)
+        const measuring = d.measurement_state === 'Start' || d.measurement_state === 'Measure';
+        setPanelStatus(measuring, d.last_seen);
+    } catch (e) {
+        console.warn('Panel cache prefill failed:', e);
+    }
+}
+
+// Seed the chart from the downsampled DOD trail so it shows recent trend on open.
+async function backfillDashboardChart(unitId) {
+    try {
+        const r = await fetch(`/api/slmm/${encodeURIComponent(unitId)}/history?hours=2`);
+        if (!r.ok) return;
+        const readings = (await r.json()).readings || [];
+        const cd = window.dashboardChartData;
+        if (!cd) return;
+        for (const row of readings) {
+            // Trail timestamps are naive UTC; append 'Z' to render in local time
+            // consistently with the live frames (which use local Date.now()).
+            cd.timestamps.push(row.timestamp ? new Date(row.timestamp + 'Z').toLocaleTimeString() : '');
+            cd.lp.push(parseFloat(row.lp || 0));
+            cd.leq.push(parseFloat(row.leq || 0));
+        }
+        if (window.dashboardChart) {
+            window.dashboardChart.data.labels = cd.timestamps;
+            window.dashboardChart.data.datasets[0].data = cd.lp;
+            window.dashboardChart.data.datasets[1].data = cd.leq;
+            window.dashboardChart.update('none');
+        }
+    } catch (e) {
+        console.warn('Panel chart backfill failed:', e);
+    }
+}
+
+// Measuring badge + "as of <time> (Xm ago)" freshness, so a cached value is never
+// mistaken for a live one. measuring: true | false | null(unknown).
+function setPanelStatus(measuring, lastSeenIso) {
+    const badge = document.getElementById('panel-measuring-badge');
+    const fresh = document.getElementById('panel-freshness');
+    if (badge) {
+        if (measuring === null) {
+            badge.className = 'hidden px-2 py-0.5 text-xs font-medium rounded-full';
+            badge.textContent = '';
+        } else if (measuring) {
+            badge.className = 'px-2 py-0.5 text-xs font-medium rounded-full bg-green-100 text-green-800 dark:bg-green-900/30 dark:text-green-300';
+            badge.textContent = '● Measuring';
+        } else {
+            badge.className = 'px-2 py-0.5 text-xs font-medium rounded-full bg-gray-200 text-gray-700 dark:bg-gray-700 dark:text-gray-300';
+            badge.textContent = '■ Stopped';
+        }
+    }
+    if (fresh) fresh.innerHTML = fmtFreshness(lastSeenIso);
+}
+
+// Human "x ago" with a staleness hint. Cached timestamps are naive UTC.
+function fmtFreshness(lastSeenIso) {
+    if (!lastSeenIso) return '<span class="text-gray-400">no cached reading yet</span>';
+    const t = new Date(lastSeenIso.endsWith('Z') ? lastSeenIso : lastSeenIso + 'Z');
+    const secs = Math.max(0, Math.round((Date.now() - t.getTime()) / 1000));
+    let ago, stale = false;
+    if (secs < 10) ago = 'just now';
+    else if (secs < 60) ago = secs + 's ago';
+    else if (secs < 3600) { ago = Math.round(secs / 60) + 'm ago'; stale = secs >= 300; }
+    else { ago = Math.round(secs / 3600) + 'h ago'; stale = true; }
+    const cls = stale ? 'text-amber-600 dark:text-amber-400' : 'text-gray-500 dark:text-gray-400';
+    const tag = stale ? ' · cached' : '';
+    return `as of ${t.toLocaleTimeString()} <span class="${cls}">(${ago}${tag})</span>`;
+}
+
+// Cache polling: refresh the cards from cache every 15s while the panel is open
+// and not live-streaming. Pure cache reads — no device contention.
+function startPanelCachePolling(unitId) {
+    stopPanelCachePolling();
+    window.panelCacheTimer = setInterval(() => {
+        if (window.selectedUnitId) prefillDashboardPanel(window.selectedUnitId);
+    }, 15000);
+}
+function stopPanelCachePolling() {
+    if (window.panelCacheTimer) { clearInterval(window.panelCacheTimer); window.panelCacheTimer = null; }
+}
+
+// ---- On-demand device refresh (the per-unit + panel refresh buttons) -----
+
+// One bounded, user-initiated device read: hits the device, updates the cache,
+// returns the fresh data. Throws on unreachable/disabled.
+async function forceDeviceRead(unitId) {
+    const r = await fetch(`/api/slmm/${encodeURIComponent(unitId)}/live`);
+    if (!r.ok) {
+        let detail = 'device unreachable';
+        try { detail = (await r.json()).detail || detail; } catch (e) {}
+        throw new Error(detail);
+    }
+    return (await r.json()).data || {};
+}
+
+function spinIcon(el, on) {
+    if (el) el.classList.toggle('animate-spin', on);
+}
+
+function applyFreshReadToPanel(unitId, d) {
+    if (window.selectedUnitId !== unitId) return;
+    updateDashboardMetrics(d);
+    const measuring = d.measurement_state === 'Start' || d.measurement_state === 'Measure';
+    // The read just happened, so "now" is the accurate freshness even if the
+    // /live payload doesn't echo last_seen.
+    setPanelStatus(measuring, d.last_seen || new Date().toISOString());
+}
+
+// Device-list row refresh button.
+async function refreshSlmUnit(unitId, btn) {
+    const icon = btn ? btn.querySelector('svg') : null;
+    if (btn) btn.disabled = true;
+    spinIcon(icon, true);
+    try {
+        const d = await forceDeviceRead(unitId);
+        applyFreshReadToPanel(unitId, d);
+        // Reload the list so the row's badge + last-check reflect the new cache.
+        if (typeof htmx !== 'undefined' && document.getElementById('slm-devices-list')) {
+            htmx.trigger('#slm-devices-list', 'load');
+        }
+        if (window.showToast) window.showToast(`${unitId} refreshed`, 'success');
+    } catch (e) {
+        if (window.showToast) window.showToast(`${unitId}: ${e.message}`, 'error');
+        else console.warn('refresh failed', e);
+    } finally {
+        if (btn) btn.disabled = false;
+        spinIcon(icon, false);
+    }
+}
+
+// Panel header refresh button (refreshes the unit the panel is showing).
+async function refreshDashboardPanel() {
+    const unitId = window.selectedUnitId;
+    if (!unitId) return;
+    const icon = document.getElementById('panel-refresh-icon');
+    spinIcon(icon, true);
+    try {
+        const d = await forceDeviceRead(unitId);
+        applyFreshReadToPanel(unitId, d);
+        updateDashboardChart(d);   // append the fresh point to the chart
+        if (typeof htmx !== 'undefined' && document.getElementById('slm-devices-list')) {
+            htmx.trigger('#slm-devices-list', 'load');
+        }
+        if (window.showToast) window.showToast(`${unitId} refreshed`, 'success');
+    } catch (e) {
+        if (window.showToast) window.showToast(`${unitId}: ${e.message}`, 'error');
+    } finally {
+        spinIcon(icon, false);
+    }
+}
+
 // Configuration modal - use unified SLM settings modal
 function openDeviceConfigModal(unitId) {
     // Call the unified modal function from slm_settings_modal.html