diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9a14c06..2cfebba 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,8 @@ ChangeLog
 
 --- develop ---
 * feature: Add a Fleet (Summary) Dashboard reached by a dashboard glyph on the Summary tab's Device Type rows: a draggable, add/remove card grid scoped to all devices or one OS type, with min/avg/max bullet charts (CPU/memory/swap/processes/uptime), a device-status stacked bar, OS type distribution, storage utilization, fleet stat tiles, and top processes by CPU and by memory; scope, card order, expanded state and refresh interval persist per user
+* issue: Make the per-device Dashboard device picker an AJAX callback (a Cacti drop_callback that searches Host MIB devices server-side via ?action=ajax_hosts) instead of rendering every host as an <option>, so installs with tens of thousands of devices no longer bloat the page
+* issue: Stop the per-device Dashboard card header from resizing when hovering the drag handle or header tool buttons (reserve a transparent 1px border with box-sizing and give the header a min-height)
 * issue: Fix 'Uncaught TypeError: runCollector(): Argument #2 ($lastrun) must be of type float, null given' in the poller when a collector's *_lastrun/*_freq setting has never been written (e.g. a task's first run); runCollector() now accepts null and normalizes it
 * issue: Fix the per-device Dashboard Storage, Per-Processor Load, Hardware and Installed Software cards rendering empty because they filtered on 'present = 1' while the underlying Storage/Hardware/Inventory tabs never did, and add a Process Use History card
 * feature: Add a per-device Dashboard that drills into a single host with a draggable, add/remove card grid (CPU/memory/swap gauges, per-processor load, storage, top processes, hardware, installed software, logins and system information); card order, expanded state, the selected device and the auto-refresh interval persist per user, and a dashboard glyph on the Devices tab opens a stateful Dashboard tab that remembers the last host opened
diff --git a/css/hmib.css b/css/hmib.css
index 2e61951..93e2f5a 100644
--- a/css/hmib.css
+++ b/css/hmib.css
@@ -190,7 +190,9 @@
 	display: flex;
 	align-items: center;
 	gap: 8px;
+	box-sizing: border-box;
 	padding: 7px 10px;
+	min-height: 34px;
 	border-bottom: 1px solid color-mix(in srgb, currentColor 18%, transparent);
 	background: color-mix(in srgb, currentColor 8%, transparent);
 }
@@ -203,8 +205,10 @@
 
 .hmibDashCardDrag {
 	flex: 0 0 auto;
+	box-sizing: border-box;
 	padding: 2px 5px;
-	border: 0;
+	/* reserve a transparent border so an inherited button:hover border cannot reflow the header */
+	border: 1px solid transparent;
 	border-radius: 4px;
 	background: transparent;
 	color: color-mix(in srgb, currentColor 50%, transparent);
@@ -216,6 +220,7 @@
 .hmibDashCardDrag:hover,
 .hmibDashCardDrag:focus-visible {
 	color: currentColor;
+	border-color: transparent;
 	background: color-mix(in srgb, currentColor 12%, transparent);
 	outline: none;
 }
@@ -244,8 +249,10 @@
 }
 
 .hmibDashCardTool {
+	box-sizing: border-box;
 	padding: 2px 5px;
-	border: 0;
+	/* reserve a transparent border so an inherited button:hover border cannot reflow the header */
+	border: 1px solid transparent;
 	border-radius: 4px;
 	background: transparent;
 	color: color-mix(in srgb, currentColor 50%, transparent);
@@ -257,6 +264,7 @@
 .hmibDashCardTool:hover,
 .hmibDashCardTool:focus-visible {
 	color: currentColor;
+	border-color: transparent;
 	background: color-mix(in srgb, currentColor 12%, transparent);
 	outline: none;
 }
diff --git a/hmib.php b/hmib.php
index 81cb03a..c662f06 100644
--- a/hmib.php
+++ b/hmib.php
@@ -28,7 +28,9 @@
 set_default_action('summary');
 
 if (get_request_var('action') == 'ajax_hosts') {
-	get_allowed_ajax_hosts(true, false, 'h.id IN (SELECT host_id FROM plugin_hmib_hrSystem)');
+	// Serves the dashboard's device drop_callback; no 'Any'/'None' entries since a
+	// dashboard always targets one real Host MIB device.
+	get_allowed_ajax_hosts(false, false, 'h.id IN (SELECT host_id FROM plugin_hmib_hrSystem)');
 	exit;
 }
 
@@ -4721,23 +4723,41 @@ function hmib_dashboard(): void {
 		$page_refresh_interval = [0 => __('No Refresh', 'hmib'), 30 => __('30 Seconds', 'hmib'), 60 => __('1 Minute', 'hmib'), 300 => __('5 Minutes', 'hmib')];
 	}
 
-	print '<div class="hmibDashToolbar">';
-	print '<label class="hmibDashToolbarLabel" for="hmib_dashboard_host">' . __esc('Device', 'hmib') . '</label>';
-	print '<select id="hmib_dashboard_host" class="hmibDashHost">';
+	// Device picker: a Cacti drop_callback (select2 AJAX) that searches Host MIB
+	// devices server-side via ?action=ajax_hosts, so installs with tens of
+	// thousands of hosts never materialize the full option list in the DOM.
+	// select2 ignores the 'sql' and invokes 'on_change' (data-callback) by name
+	// on selection; the 'sql' only feeds the plain-<select> fallback used when
+	// the admin has set autocomplete > 0, so it must list every Host MIB device
+	// there (that mode already renders full option lists site-wide, so this does
+	// not regress the AJAX scaling path).
+	form_start('hmib.php', 'hmib_dashboard_device_form');
+
+	html_start_box('', '100%', '', '3', 'center', '');
+
+	draw_edit_form([
+		'config' => ['no_form_tag' => true],
+		'fields' => [
+			'hmib_dashboard_host' => [
+				'method'        => 'drop_callback',
+				'action'        => 'ajax_hosts',
+				'id'            => $host_id,
+				'sql'           => 'SELECT h.id, h.description AS name FROM host AS h WHERE h.id IN (SELECT host_id FROM plugin_hmib_hrSystem) ORDER BY h.description',
+				'on_change'     => 'hmibDashboardNavigate()',
+				'friendly_name' => __('Device', 'hmib'),
+				'description'   => __('Search Host MIB devices as you type to open that device\'s dashboard.', 'hmib'),
+				'value'         => $host_id,
+				'size'          => 40,
+				'max_length'    => 64
+			]
+		]
+	]);
 
-	$hosts = db_fetch_assoc("SELECT host.id, host.description
-		FROM plugin_hmib_hrSystem AS hrs
-		INNER JOIN host ON host.id = hrs.host_id
-		WHERE host.description != ''
-		ORDER BY host.description");
+	html_end_box(false);
 
-	if (cacti_sizeof($hosts)) {
-		foreach ($hosts as $host) {
-			print '<option value="' . (int) $host['id'] . '"' . ((int) $host['id'] === $host_id ? ' selected' : '') . '>' . html_escape($host['description']) . '</option>';
-		}
-	}
+	form_end();
 
-	print '</select>';
+	print '<div class="hmibDashToolbar">';
 
 	print '<label class="hmibDashToolbarLabel" for="hmib_dashboard_add">' . __esc('Add card', 'hmib') . '</label>';
 	print '<select id="hmib_dashboard_add" class="hmibDashAdd"><option value="">' . __esc('Add a card…', 'hmib') . '</option>';
diff --git a/js/hmib_dashboard.js b/js/hmib_dashboard.js
index 44a0b02..cc931bd 100644
--- a/js/hmib_dashboard.js
+++ b/js/hmib_dashboard.js
@@ -23,6 +23,18 @@
 
 var hmibDashDragging = null;
 
+/* Named navigation callback for the device picker. The select2 drop_callback
+ * invokes this by name (via the field's on_change/data-callback) on selection
+ * instead of emitting a change event, so it reads the picker value itself and
+ * opens that device's dashboard. Must stay global for executeFunctionByName(). */
+function hmibDashboardNavigate() {
+	var host = document.getElementById('hmib_dashboard_host');
+
+	if (host && host.value) {
+		window.location = 'hmib.php?action=dashboard&device=' + encodeURIComponent(host.value);
+	}
+}
+
 function initHmibDashboard() {
 	$(function() {
 		var grid = document.getElementById('hmib_dashboard');
@@ -87,10 +99,12 @@ function initHmibDashboard() {
 
 		var host = document.getElementById('hmib_dashboard_host');
 		if (host) {
+			// Native change covers the plain-<select> autocomplete fallback; the
+			// select2 AJAX control instead invokes the named hmibDashboardNavigate()
+			// callback (wired via the field's on_change/data-callback), which does
+			// not emit a change event on older Cacti, so both paths are handled.
 			$(host).off('change.hmibdash').on('change.hmibdash', function() {
-				if (this.value) {
-					window.location = 'hmib.php?action=dashboard&device=' + encodeURIComponent(this.value);
-				}
+				hmibDashboardNavigate();
 			});
 		}
 
diff --git a/locales/po/cacti.pot b/locales/po/cacti.pot
index 1928286..1e46e23 100644
--- a/locales/po/cacti.pot
+++ b/locales/po/cacti.pot
@@ -785,6 +785,10 @@ msgstr ""
 msgid "No Refresh"
 msgstr ""
 
+#: hmib.php
+msgid "Search Host MIB devices as you type to open that device's dashboard."
+msgstr ""
+
 #: hmib.php
 msgid "Add card"
 msgstr ""