diff --git a/ui/admin/index.html b/ui/admin/index.html
index 52f27f5c..bcd31ca1 100644
--- a/ui/admin/index.html
+++ b/ui/admin/index.html
@@ -300,6 +300,6 @@ <h1 class="sec-title" id="ev-title">General</h1>
   </div></div>
 </div>
 
-<script type="module" src="/js/admin.js?v=2aaed21c"></script>
+<script type="module" src="/js/admin.js?v=10b7bd5e"></script>
 </body>
 </html>
diff --git a/ui/js/admin-app-form.js b/ui/js/admin-app-form.js
index 47ea9f68..d2c0f702 100644
--- a/ui/js/admin-app-form.js
+++ b/ui/js/admin-app-form.js
@@ -18,7 +18,7 @@ import {
   failureIsMissingApiPath,
   nextActiveIndex,
   sameIconName,
-} from '/js/admin-logic.js?v=fc7f0836';
+} from '/js/admin-logic.js?v=1cca36f5';
 import { t } from '/js/i18n.js?v=ed7c5565';
 import {
   toast,
@@ -31,10 +31,10 @@ import {
   reveal,
   setTogDisabled,
   swapContent,
-} from '/js/admin-shared.js?v=da7df247';
-import { createListbox } from '/js/listbox.js?v=4afb5969';
+} from '/js/admin-shared.js?v=5e6a023a';
+import { createListbox } from '/js/listbox.js?v=7d7867ae';
 import { MAX_LABELS } from '/js/badge-logic.js?v=5c72bd4c';
-import { renderColorControl, BADGE_DEFAULT } from '/js/admin-color-control.js?v=82916010';
+import { renderColorControl, BADGE_DEFAULT } from '/js/admin-color-control.js?v=64eef54d';
 import { badgeErrorAdvice, TONE } from '/js/admin-error.js?v=b0881957';
 import { fluidHoverClear, fluidHoverKb } from '/js/fluid-hover.js?v=cb886e86';
 import { iconSvg } from '/js/icon-set.js?v=628341d4';
diff --git a/ui/js/admin-auth.js b/ui/js/admin-auth.js
index 261fb8af..6fc95c7a 100644
--- a/ui/js/admin-auth.js
+++ b/ui/js/admin-auth.js
@@ -1,4 +1,4 @@
-import { apiGet, apiPost } from '/js/admin-shared.js?v=da7df247';
+import { apiGet, apiPost } from '/js/admin-shared.js?v=5e6a023a';
 import { initI18n, t } from '/js/i18n.js?v=ed7c5565';
 import { loginErrorKey } from '/js/admin-error.js?v=b0881957';
 import { pwStrength } from '/js/password-strength.js?v=389e0ed0';
diff --git a/ui/js/admin-color-control.js b/ui/js/admin-color-control.js
index 8be515eb..873e2c38 100644
--- a/ui/js/admin-color-control.js
+++ b/ui/js/admin-color-control.js
@@ -1,4 +1,4 @@
-import { PE_SVG, initInlineEdit, toast, reveal } from '/js/admin-shared.js?v=da7df247';
+import { PE_SVG, initInlineEdit, toast, reveal } from '/js/admin-shared.js?v=5e6a023a';
 import { t } from '/js/i18n.js?v=ed7c5565';
 import { html, raw, setHtml } from '/js/html.js?v=c71f8903';
 import { qa, q } from '/js/utils.js?v=dc4ac52e';
diff --git a/ui/js/admin-list.js b/ui/js/admin-list.js
index 8dc5a4ef..7b724752 100644
--- a/ui/js/admin-list.js
+++ b/ui/js/admin-list.js
@@ -13,13 +13,13 @@
 
 import { collapsedFolders, filter, state } from '/js/admin-state.js?v=af772a1b';
 import { snapshotItems } from '/js/admin-save-logic.js?v=5613a9fa';
-import { reorderItems } from '/js/admin-logic.js?v=fc7f0836';
+import { reorderItems } from '/js/admin-logic.js?v=1cca36f5';
 import { initDrag, wireRowDrag } from '/js/admin-drag.js?v=29e09aad';
-import { paintIcon } from '/js/admin-shared.js?v=da7df247';
+import { paintIcon } from '/js/admin-shared.js?v=5e6a023a';
 import { clr, el, focusFirst, initial, qa, setUserText } from '/js/utils.js?v=dc4ac52e';
 import { html, raw, setHtml } from '/js/html.js?v=c71f8903';
 import { t } from '/js/i18n.js?v=ed7c5565';
-import { sizeLabel } from '/js/admin-widget-form.js?v=047fef40';
+import { sizeLabel } from '/js/admin-widget-form.js?v=e0966417';
 import { widgetGlyph } from '/js/widget-glyphs.js?v=b383b7c8';
 import { iconSvg } from '/js/icon-set.js?v=628341d4';
 
diff --git a/ui/js/admin-logic.js b/ui/js/admin-logic.js
index 1a1e529b..50569c2c 100644
--- a/ui/js/admin-logic.js
+++ b/ui/js/admin-logic.js
@@ -336,3 +336,13 @@ export function createDirtyTracker(read) {
     },
   };
 }
+
+/** What a single-choice picker shows as chosen. An empty string is a choice
+    only when an option carries it.
+    @param {unknown} value @param {{ value?: unknown, group?: unknown }[]} options
+    @returns {string[]} */
+export function singleChoice(value, options) {
+  if (value == null) return [];
+  const v = String(value);
+  return v !== '' || options.some(o => o.group == null && String(o.value) === '') ? [v] : [];
+}
diff --git a/ui/js/admin-settings.js b/ui/js/admin-settings.js
index 967e42f0..d3bae93c 100644
--- a/ui/js/admin-settings.js
+++ b/ui/js/admin-settings.js
@@ -1,4 +1,4 @@
-import { toast, apiGet, apiPost, errorText, reveal, swapContent, wireInlineEdit } from '/js/admin-shared.js?v=da7df247';
+import { toast, apiGet, apiPost, errorText, reveal, swapContent, wireInlineEdit } from '/js/admin-shared.js?v=5e6a023a';
 import { socketProbeAdvice } from '/js/admin-error.js?v=b0881957';
 import { pwStrength } from '/js/password-strength.js?v=389e0ed0';
 import { t } from '/js/i18n.js?v=ed7c5565';
@@ -9,12 +9,12 @@ import {
   needsCurrentPassword,
   createDirtyTracker,
   BLOCK,
-} from '/js/admin-logic.js?v=fc7f0836';
+} from '/js/admin-logic.js?v=1cca36f5';
 import { confirmText, promptModal } from '/js/modal.js?v=6b0320bd';
 import { el, inp, setUserText } from '/js/utils.js?v=dc4ac52e';
 import { formatNumber } from '/js/format-number.js?v=abcd4ae4';
 import { serialWrites } from '/js/admin-save-logic.js?v=5613a9fa';
-import { renderColorControl } from '/js/admin-color-control.js?v=82916010';
+import { renderColorControl } from '/js/admin-color-control.js?v=64eef54d';
 import { BACKDROP } from '/js/background.js?v=d6f2e701';
 import {
   ALLOWED_HOSTS_MAX,
diff --git a/ui/js/admin-shared.js b/ui/js/admin-shared.js
index 7734dfd8..177ddf86 100644
--- a/ui/js/admin-shared.js
+++ b/ui/js/admin-shared.js
@@ -1,5 +1,5 @@
 /* Stateless helpers shared by the admin modules. Mutable state stays out. */
-import { recoversSession, toastHoldMs } from '/js/admin-logic.js?v=fc7f0836';
+import { recoversSession, toastHoldMs } from '/js/admin-logic.js?v=1cca36f5';
 import { el, isolate, q } from '/js/utils.js?v=dc4ac52e';
 import { t } from '/js/i18n.js?v=ed7c5565';
 import { errorAdvice } from '/js/admin-error.js?v=b0881957';
diff --git a/ui/js/admin-widget-form.js b/ui/js/admin-widget-form.js
index d04e086a..c1c63da1 100644
--- a/ui/js/admin-widget-form.js
+++ b/ui/js/admin-widget-form.js
@@ -1,9 +1,9 @@
 import { state } from '/js/admin-state.js?v=af772a1b';
-import { PE_SVG, initInlineEdit, swapContent } from '/js/admin-shared.js?v=da7df247';
-import { createListbox } from '/js/listbox.js?v=4afb5969';
-import { renderWidgetConfigForm } from '/js/widget-config-form.js?v=c4755d57';
+import { PE_SVG, initInlineEdit, swapContent } from '/js/admin-shared.js?v=5e6a023a';
+import { createListbox } from '/js/listbox.js?v=7d7867ae';
+import { renderWidgetConfigForm } from '/js/widget-config-form.js?v=294805cc';
 import { html, raw, setHtml } from '/js/html.js?v=c71f8903';
-import { sizesForView, widgetConfigMode, rejectionLines, carriesTypedValues } from '/js/admin-logic.js?v=fc7f0836';
+import { sizesForView, widgetConfigMode, rejectionLines, carriesTypedValues } from '/js/admin-logic.js?v=1cca36f5';
 import { t } from '/js/i18n.js?v=ed7c5565';
 import { focusFirst, q, qi, qa } from '/js/utils.js?v=dc4ac52e';
 import { iconSvg } from '/js/icon-set.js?v=628341d4';
diff --git a/ui/js/admin.js b/ui/js/admin.js
index c0648aba..0d47b958 100644
--- a/ui/js/admin.js
+++ b/ui/js/admin.js
@@ -1,8 +1,8 @@
-import { buildAppForm, buildFolderForm, captureActLabels, serializeKvRows } from '/js/admin-app-form.js?v=92c6949c';
-import { checkAuth, requireLogin, wirePasswordStrength } from '/js/admin-auth.js?v=73ed7df1';
+import { buildAppForm, buildFolderForm, captureActLabels, serializeKvRows } from '/js/admin-app-form.js?v=deccbdee';
+import { checkAuth, requireLogin, wirePasswordStrength } from '/js/admin-auth.js?v=104be7f0';
 import { recoveryShown } from '/js/config-recovery.js?v=85138697';
-import { focusRow, initList, render, syncFilterUI } from '/js/admin-list.js?v=02db1758';
-import { resolveAdminSection } from '/js/admin-logic.js?v=fc7f0836';
+import { focusRow, initList, render, syncFilterUI } from '/js/admin-list.js?v=14782161';
+import { resolveAdminSection } from '/js/admin-logic.js?v=1cca36f5';
 import {
   afterImport,
   buildAppItem,
@@ -23,7 +23,7 @@ import {
   showBgFields,
   showWallpaperFile,
   wireUnsplashKey,
-} from '/js/admin-settings.js?v=9ffe0860';
+} from '/js/admin-settings.js?v=584aae78';
 import {
   apiGet,
   apiPost,
@@ -37,13 +37,13 @@ import {
   setReauthHandler,
   toast,
   withheldText,
-} from '/js/admin-shared.js?v=da7df247';
+} from '/js/admin-shared.js?v=5e6a023a';
 import { collapsedFolders, filter, state } from '/js/admin-state.js?v=af772a1b';
-import { buildWidgetForm } from '/js/admin-widget-form.js?v=047fef40';
+import { buildWidgetForm } from '/js/admin-widget-form.js?v=e0966417';
 import { initFluidHover } from '/js/fluid-hover.js?v=cb886e86';
 import { formatNumber } from '/js/format-number.js?v=abcd4ae4';
 import { initGlideSelect, syncGlideSelect } from '/js/glide-select.js?v=8b39e9d0';
-import { createListbox } from '/js/listbox.js?v=4afb5969';
+import { createListbox } from '/js/listbox.js?v=7d7867ae';
 import { html, raw, setHtml } from '/js/html.js?v=c71f8903';
 import { initI18n, LANGUAGES, t } from '/js/i18n.js?v=ed7c5565';
 import { loadLocalIcons } from '/js/icons.js?v=5ac01d72';
diff --git a/ui/js/listbox.js b/ui/js/listbox.js
index d574e6c4..ef9a591e 100644
--- a/ui/js/listbox.js
+++ b/ui/js/listbox.js
@@ -6,7 +6,7 @@
    Do not use popover. The top layer makes iOS collapse its browser toolbar,
    which exposes a strip of page canvas and misplaces the menu. */
 
-import { nextActiveIndex } from '/js/admin-logic.js?v=fc7f0836';
+import { nextActiveIndex, singleChoice } from '/js/admin-logic.js?v=1cca36f5';
 import { fluidHoverClear, fluidHoverKb } from '/js/fluid-hover.js?v=cb886e86';
 import { formatList } from '/js/format-number.js?v=abcd4ae4';
 import { html, raw, setHtml } from '/js/html.js?v=c71f8903';
@@ -81,9 +81,7 @@ export function createListbox(
   } = /** @type {any} */ ({}),
 ) {
   let opts = options.slice();
-  let chosen = multiple
-    ? new Set((Array.isArray(value) ? value : []).map(String))
-    : new Set(value == null || value === '' ? [] : [String(value)]);
+  let chosen = multiple ? new Set((Array.isArray(value) ? value : []).map(String)) : new Set(singleChoice(value, opts));
 
   /* The list is not a descendant of its button, so the two are tied by id. */
   const listId = id ? `${id}-list` : `lb-${++seq}`;
@@ -331,17 +329,13 @@ export function createListbox(
     list,
     getValue,
     setValue(v) {
-      chosen = multiple
-        ? new Set((Array.isArray(v) ? v : []).map(String))
-        : new Set(v == null || v === '' ? [] : [String(v)]);
+      chosen = multiple ? new Set((Array.isArray(v) ? v : []).map(String)) : new Set(singleChoice(v, opts));
       paint();
     },
     setOptions(next, v) {
       opts = (next || []).slice();
       if (v !== undefined) {
-        chosen = multiple
-          ? new Set((Array.isArray(v) ? v : []).map(String))
-          : new Set(v == null || v === '' ? [] : [String(v)]);
+        chosen = multiple ? new Set((Array.isArray(v) ? v : []).map(String)) : new Set(singleChoice(v, opts));
       } else if (!multiple) {
         /* A refreshed list may no longer carry what was chosen. */
         const still = [...chosen].filter(c => opts.some(o => String(o.value) === c));
diff --git a/ui/js/widget-config-form.js b/ui/js/widget-config-form.js
index c1ec50a9..d6f1e097 100644
--- a/ui/js/widget-config-form.js
+++ b/ui/js/widget-config-form.js
@@ -3,9 +3,9 @@
 
 import { t } from '/js/i18n.js?v=ed7c5565';
 import { html, raw, setHtml } from '/js/html.js?v=c71f8903';
-import { reveal, wireInlineEdit } from '/js/admin-shared.js?v=da7df247';
-import { createListbox } from '/js/listbox.js?v=4afb5969';
-import { renderColorControl } from '/js/admin-color-control.js?v=82916010';
+import { reveal, wireInlineEdit } from '/js/admin-shared.js?v=5e6a023a';
+import { createListbox } from '/js/listbox.js?v=7d7867ae';
+import { renderColorControl } from '/js/admin-color-control.js?v=64eef54d';
 import {
   seedCarried,
   applyOptionSet,
@@ -13,7 +13,7 @@ import {
   requiredFieldMissing,
   groupBounds,
   visibleFieldFlags,
-} from '/js/admin-logic.js?v=fc7f0836';
+} from '/js/admin-logic.js?v=1cca36f5';
 import { optionsErrorAdvice, TONE } from '/js/admin-error.js?v=b0881957';
 import { qi } from '/js/utils.js?v=dc4ac52e';
 import { formatNumber } from '/js/format-number.js?v=abcd4ae4';
diff --git a/ui/test/admin-logic.test.mjs b/ui/test/admin-logic.test.mjs
index 69194cfb..922819fe 100644
--- a/ui/test/admin-logic.test.mjs
+++ b/ui/test/admin-logic.test.mjs
@@ -27,6 +27,7 @@ import {
   failureIsMissingApiPath,
   createDirtyTracker,
   BLOCK,
+  singleChoice,
 } from '../js/admin-logic.js';
 
 test('createDirtyTracker is clean until the value moves, and clean again after reset', () => {
@@ -651,3 +652,20 @@ test('sameIconName treats nothing as nothing', () => {
   assert.equal(sameIconName(null, undefined), false);
   assert.equal(sameIconName('---', '***'), false);
 });
+
+test('an empty string is a choice when an option carries it', () => {
+  const opts = [
+    { value: '', label: 'Default' },
+    { value: 'no-referrer', label: 'no-referrer' },
+  ];
+  assert.deepEqual(singleChoice('', opts), ['']);
+  assert.deepEqual(singleChoice('no-referrer', opts), ['no-referrer']);
+});
+
+test('an empty string or nothing is no choice otherwise', () => {
+  const opts = [{ value: 'a' }, { group: 'Heading', value: '' }];
+  assert.deepEqual(singleChoice('', opts), []);
+  assert.deepEqual(singleChoice(null, opts), []);
+  assert.deepEqual(singleChoice(undefined, opts), []);
+  assert.deepEqual(singleChoice(3, [{ value: 3 }]), ['3']);
+});
diff --git a/ui/test/listbox.test.mjs b/ui/test/listbox.test.mjs
index a321d334..d667cae1 100644
--- a/ui/test/listbox.test.mjs
+++ b/ui/test/listbox.test.mjs
@@ -222,3 +222,8 @@ test('the language picker marks each language name with its language', () => {
     'the button does not carry it',
   );
 });
+
+test('every single-choice value goes through singleChoice', () => {
+  assert.equal((src.match(/new Set\(singleChoice\(/g) || []).length, 3);
+  assert.doesNotMatch(src, /=== '' \? \[\] :/);
+});