fix(share): reject inherited style keys during restore

src/sharelink.celestial.test.mjs

@@ -778,3 +778,20 @@ test('visual input listeners are revoked before asynchronous UI teardown', () =>
   assert.match(VisualSettings.prototype.stop.toString(), /this\._styleParameters\?\.destroy\(\)/);
   assert.match(VisualSettings.prototype.stop.toString(), /this\._visualEffects\.stop\(\)/);
 });
+
+
+test('share restore rejects inherited styles while continuing later fields', () => {
+  for (const style of ['constructor', '__proto__', 'toString', 'hasOwnProperty', 'unknown']) {
+    const restored = makeManager(`#lat=10&lon=20&style=${style}&cr=1`).parseInitialHash();
+    assert.equal(restored.style, 'normal');
+    assert.equal(restored.celestialRing, true);
+  }
+});
+
+test('programmatic invalid styles are ignored before changing visual state', () => {
+  const target = { activeStyle: 'normal' };
+  for (const value of ['constructor', '__proto__', 'toString', 'hasOwnProperty', 'unknown', {}, null, () => {}]) {
+    assert.doesNotThrow(() => VisualSettings.prototype.setStyle.call(target, value));
+    assert.equal(target.activeStyle, 'normal');
+  }
+});