Items in a list are unmounted if moved up but not if moved down

Description

https://github.com/user-attachments/assets/ada2ff0b-74d4-43c7-8afc-78830803998d

As visible from the video i have 2 text inputs rendered with a map with stable keys, i focus the one on top and then swap them and they swap keeping the focus on the active one which is what i need. If then i do the same but swapping the focused input from bottom to top it looses focus.

I dived a bit into the RN code and figured out that when going from bottom top top it gets unmounted and then remounted since Differentiator.cpp generated a remove and an insert commands. I understand nothing about how the diffing algo works so i have no idea if this is intendend behaviour or not but it's blocking me with this focus loss problem

I'm reporting the issue on iOS since is where i investigated it the most, on android it works bad as well but in a bit of a different way, with the same code i added in the reproduce section you can see the problem on android as well

Steps to reproduce

import { useState } from "react";
import { View, StyleSheet, TextInput, Button } from "react-native";

export default function TestPage() {
  const [keys, setKeys] = useState<string[]>(["1", "2"]);

  function swap() {
    const newKeys = [...keys];
    const temp = newKeys[0];
    newKeys[0] = newKeys[1];
    newKeys[1] = temp;
    setKeys(newKeys);
  }

  return (
    <View style={styles.container}>
      {keys.map((key, index) => (
        <TextInput
          key={key}
          style={styles.input}
          defaultValue={key == "1" ? "First input" : "Second input"}
        />
      ))}

      <Button title="Swap" onPress={swap} />
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: "center",
    alignItems: "center",
  },
  input: {
    height: 40,
    width: "80%",
    borderColor: "gray",
    borderWidth: 1,
    marginBottom: 10,
    paddingHorizontal: 10,
  },
});

React Native Version

0.79.2

Affected Platforms

Runtime - Android, Runtime - iOS

Output of npx @react-native-community/cli info

System:
  OS: macOS 15.3.2
  CPU: (10) arm64 Apple M1 Pro
  Memory: 864.30 MB / 32.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 20.15.1
    path: ~/.nvm/versions/node/v20.15.1/bin/node
  Yarn:
    version: 1.22.22
    path: ~/.nvm/versions/node/v20.15.1/bin/yarn
  npm:
    version: 10.7.0
    path: ~/.nvm/versions/node/v20.15.1/bin/npm
  Watchman:
    version: 2025.04.28.00
    path: /opt/homebrew/bin/watchman
Managers:
  CocoaPods:
    version: 1.16.2
    path: /Users/ipla/.rvm/gems/ruby-3.3.1/bin/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 24.4
      - iOS 18.4
      - macOS 15.4
      - tvOS 18.4
      - visionOS 2.4
      - watchOS 11.4
  Android SDK:
    Android NDK: 22.1.7171670
IDEs:
  Android Studio: 2024.2 AI-242.23726.103.2422.12816248
  Xcode:
    version: 16.3/16E140
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 21.0.6
    path: /usr/bin/javac
  Ruby:
    version: 3.3.1
    path: /Users/ipla/.rvm/rubies/ruby-3.3.1/bin/ruby
npmPackages:
  "@react-native-community/cli": Not Found
  react:
    installed: 19.0.0
    wanted: 19.0.0
  react-native:
    installed: 0.79.2
    wanted: 0.79.2
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: Not found
  newArchEnabled: Not found
iOS:
  hermesEnabled: Not found
  newArchEnabled: Not found

Stacktrace or Logs

Doesn't apply

MANDATORY Reproducer

https://snack.expo.dev/@ipla/rn-swap-reproducer

Screenshots and Videos

https://github.com/user-attachments/assets/3ea384d0-5762-4fb3-bec1-7d677c316b3f

Start with the mandatory Snack reproducer and inspect the React Native diffing path around Differentiator.cpp, comparing the generated commands when the focused input moves in each direction. Done means the two keyed TextInput elements retain focus after swapping in both directions on iOS and Android, as demonstrated by the reproducer.