fix(mobile): pop to home when leaving a host so the back chevron animates backward (#9723)

mobile/src/host-route-exit.test.ts

@@ -4,16 +4,18 @@ import { leaveHostRoute } from './host-route-exit'
 
 function makeRouter() {
   return {
-    replace: vi.fn()
+    dismissTo: vi.fn()
   }
 }
 
 describe('leaveHostRoute', () => {
-  it('returns to home instead of depending on route history', () => {
+  // Why: dismissTo (not replace) is what makes the chevron animate back like swipe-back, so the
+  // call shape is the behavior under test, not an implementation detail.
+  it('dismisses to home instead of depending on route history', () => {
     const router = makeRouter()
 
     leaveHostRoute(router)
 
-    expect(router.replace).toHaveBeenCalledWith('/')
+    expect(router.dismissTo).toHaveBeenCalledWith('/')
   })
 })

mobile/src/host-route-exit.ts

@@ -1,9 +1,10 @@
 type HostRouteExitRouter = {
-  replace: (href: '/') => void
+  dismissTo: (href: '/') => void
 }
 
 export function leaveHostRoute(router: HostRouteExitRouter): void {
-  // Why: direct pairing can open /h/:hostId as the root route, and split-view
-  // detail history is not the host/home screen the header is meant to exit to.
-  router.replace('/')
+  // Why: direct pairing can open /h/:hostId as the root route, and split-view detail history is
+  // not the host/home screen the header is meant to exit to. dismissTo pops to home when it is on
+  // the stack, so the chevron animates back like swipe-back, and replaces when it is not.
+  router.dismissTo('/')
 }