修正 fa fab 的字体优先级，微信、QQ、微博等图标现在使用 Brands 字体。

assets/css/frontend/base.css

@@ -42,6 +42,13 @@ a[href] {
   transition: color 0.2s, background 0.3s, opacity 0.3s, box-shadow 0.3s, transform 0.3s;
 }
 
+/* Font Awesome 5: when legacy markup includes both `fa` and `fab`, the
+ * generic Solid rule must not override the Brands font face. */
+.fa.fab {
+  font-family: "Font Awesome 5 Brands";
+  font-weight: 400;
+}
+
 .skip-link {
   position: absolute;
   left: 16px;

src/Admin/SchemaProvider.php

@@ -215,6 +215,13 @@ class SchemaProvider {
                 }
 
 				if (in_array($type, ['select', 'radio', 'palette', 'image_select'], true) && !empty($field['options'])) {
+					// Optional enum fields use an empty string to mean "unset".
+					// This is required for clearable palettes such as the footer
+					// background preset, whose default is intentionally empty.
+					if ($value === '' && empty($field['required'])) {
+						continue;
+					}
+
                     $valid_values = array_column($field['options'], 'value');
                     // Multi-select: accept array values when schema.multiple is set
                     // (legacy / SPA may still use type=select multiple).

tests/widget-system/page-display-contract.test.cjs

@@ -14,6 +14,7 @@ const provider = read('src/Admin/SchemaProvider.php')
 const settingsFacade = read('src/Settings/Settings.php')
 const scriptsPart1c = read('src/Core/ScriptsPart1c.php')
 const footerCss = read('assets/css/frontend/footer/zibll-shell.css')
+const frontendBaseCss = read('assets/css/frontend/base.css')
 const headerMenuButtons = read('inc/helpers/aksrt-header-menu-buttons.php')
 
 function activeRepositorySource() {
@@ -178,6 +179,17 @@ test('front-end page-display consumers read only the canonical section contracts
   assert.doesNotMatch(scriptsPart1c, /\$runtime_routes\[['"]cart['"]\]/)
 })
 
+test('footer brand icons keep the Brands font when legacy fa prefix is present', () => {
+  const footer = read('footer.php')
+  const icons = read('inc/helpers/aksrt-icons.php')
+
+  assert.match(footer, /class="fa fab fa-weixin"/)
+  assert.match(footer, /class="fa fab fa-qq"/)
+  assert.match(footer, /class="fa fab fa-weibo"/)
+  assert.match(frontendBaseCss, /\.fa\.fab\s*\{[^}]*font-family:\s*"Font Awesome 5 Brands"[^}]*font-weight:\s*400/s)
+  assert.match(icons, /'wechat'\s*=>\s*'fa fab fa-weixin'/)
+})
+
 test('save contract rejects invalid input and round-trips canonical nested values', () => {
   const result = spawnSync(process.env.PHP_BINARY || 'php', [path.join(__dirname, 'page-display-save-harness.php')], {
     cwd: root,

tests/widget-system/page-display-save-harness.php

@@ -167,6 +167,8 @@ namespace {
 	$header_clean = $provider->sanitize_payload('page_display', $header_payload, 'header-components');
 
 	$footer_payload = [
+		// Empty means no preset background; it must remain a valid optional palette value.
+		'footer_theme_bg' => '',
 		'fcode_t1_code' => '<strong>Allowed</strong><script>bad()</script>',
 		'footer_contact_weibo' => 'javascript:alert(1)',
 		'footer_mini_img' => [[