fix: support radio groups across inset lists

demo/src/app/index/pages/radio/radio.page.html

@@ -52,4 +52,20 @@ <h2>radio</h2>
       <ion-item><ion-radio value="error-b">Error option B</ion-radio></ion-item>
     </ion-radio-group>
   </ion-list>
+
+  <ion-radio-group value="voice-1">
+    <ion-list [inset]="true">
+      <ion-item-group>
+        <ion-item><ion-radio value="system-default">System default</ion-radio></ion-item>
+      </ion-item-group>
+    </ion-list>
+
+    <ion-list [inset]="true">
+      <ion-list-header><ion-label>Radio Group Across Lists</ion-label></ion-list-header>
+      <ion-item-group>
+        <ion-item><ion-radio value="voice-1">Voice 1</ion-radio></ion-item>
+        <ion-item><ion-radio value="voice-2">Voice 2</ion-radio></ion-item>
+      </ion-item-group>
+    </ion-list>
+  </ion-radio-group>
 </ion-content>

demo/src/app/index/pages/radio/radio.page.spec.ts

@@ -18,4 +18,12 @@ describe('RadioPage', () => {
   it('should create', () => {
     expect(component).toBeTruthy();
   });
+
+  it('should demonstrate one radio group across multiple inset lists', () => {
+    const radioGroup = fixture.nativeElement.querySelector('ion-radio-group:has(> ion-list)');
+
+    expect(radioGroup).not.toBeNull();
+    expect(radioGroup.querySelectorAll(':scope > ion-list')).toHaveLength(2);
+    expect(radioGroup.querySelectorAll(':scope > ion-list > ion-item-group')).toHaveLength(2);
+  });
 });

demo/src/app/index/pages/radio/radio.page.ts

@@ -11,6 +11,7 @@ import {
   IonItemGroup,
   IonLabel,
   IonList,
+  IonListHeader,
   IonRadio,
   IonRadioGroup,
   IonText,
@@ -35,6 +36,7 @@ import {
     IonItemGroup,
     IonLabel,
     IonList,
+    IonListHeader,
     IonText,
     IonRadioGroup,
     IonRadio,

src/styles/components/ion-list.scss

@@ -21,7 +21,7 @@ ion-list.list-inset.ios:not(.ios26-disabled) {
     padding-inline-end: calc(var(--ion-safe-area-right, 0) + 20px);
   }
 
-  :is(#{structured-list.$groups}):not(:is(#{structured-list.$groups}) :is(#{structured-list.$groups})) {
+  > :is(#{structured-list.$groups}) {
     ion-item {
       // To draw lines inside
       --inner-padding-end: 0;

src/styles/utils/structured-list.scss

@@ -75,7 +75,7 @@ $groups: ion-item-group, ion-reorder-group, ion-accordion-group, ion-radio-group
     }
   }
 
-  :is(#{$groups}):not(:is(#{$groups}) :is(#{$groups})) {
+  > :is(#{$groups}) {
     display: block;
     border-radius: $group-border-radius;
     overflow: hidden;