From 44b1535387c326ed69fc239d38dbdb9776b629c2 Mon Sep 17 00:00:00 2001
From: rdlabo <sakakibara@rdlabo.jp>
Date: Wed, 23 Sep 2026 13:38:47 +0900
Subject: [PATCH] feat(transition): allow themes to omit fixed back-button
 animation

---
 src/transition/ios.transition.spec.ts | 29 +++++++++++++++++++++++++++
 src/transition/ios.transition.ts      |  4 +++-
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/src/transition/ios.transition.spec.ts b/src/transition/ios.transition.spec.ts
index b1de84a..0ab5341 100644
--- a/src/transition/ios.transition.spec.ts
+++ b/src/transition/ios.transition.spec.ts
@@ -52,6 +52,35 @@ describe('createIosTransitionAnimation radius', () => {
 });
 
 describe('createIosTransitionAnimation fixed back button', () => {
+  it('omits only its clone when the host opts out', () => {
+    const nav = document.createElement('ion-router-outlet');
+    const enteringEl = createPage(true);
+    const button = document.createElement('ion-back-button');
+    enteringEl.querySelector('ion-header')!.append(button);
+    nav.append(enteringEl);
+    document.body.append(nav);
+
+    Object.defineProperty(button, 'offsetWidth', { configurable: true, value: 40 });
+    const clone = document.createElement('ion-back-button');
+    clone.classList.add('ion-cloned-element');
+    document.body.append(clone);
+
+    const animation = createIosTransitionAnimation({
+      offLeftPercent: 30,
+      getIonPageElement: (element) => element,
+      shouldAnimateFixedBackButton: () => false,
+    })(nav, { enteringEl });
+    animation.progressStart(true);
+
+    expect(clone.parentElement).toBe(document.body);
+    expect(button.style.visibility).toBe('');
+    expect(animation.childAnimations.some((child) => child.elements.includes(enteringEl))).toBe(true);
+
+    animation.destroy();
+    nav.remove();
+    clone.remove();
+  });
+
   it('measures its coordinates when the transition starts', () => {
     const documentDirection = document.dir;
     document.dir = 'rtl';
diff --git a/src/transition/ios.transition.ts b/src/transition/ios.transition.ts
index cd0c2db..e19d903 100644
--- a/src/transition/ios.transition.ts
+++ b/src/transition/ios.transition.ts
@@ -22,6 +22,8 @@ export interface IosTransitionAnimationConfig {
   radius?: number;
   /** Resolves the ion-page (or fallback) element for a leaving view. */
   getIonPageElement: (element: HTMLElement) => Element;
+  /** Whether the fixed back button participates in the page transition. */
+  shouldAnimateFixedBackButton?: (navEl: HTMLElement) => boolean;
   /**
    * Optional hook invoked after the root animation is fully composed
    * (e.g. ios27 `connectNativeUIShellTransition`).
@@ -277,7 +279,7 @@ export const createIosTransitionAnimation = <TOpts extends IosTransitionAnimatio
         }
       }
 
-      if (topPage) {
+      if (topPage && config.shouldAnimateFixedBackButton?.(navEl) !== false) {
         animateFixedBackButton(
           rootAnimation,
           navEl,