border stroke of `StyleSheet.hairlineWidth`not always rendered

Comienza ejecutando el HairlineBorderRepro obligatorio contra React Native 0.87.0 en iOS, comparando el trazo del borde con el relleno de fondo en distintos desplazamientos absolutos de Y. Sigue la ruta de Fabric/New Renderer para los bordes de StyleSheet.hairlineWidth y verifica que el borde se renderice en cada desplazamiento mostrado por el reproductor.

Description

a border stroke of StyleSheet.hairlineWidth is not drawn when the view lands at certain absolute Y offsets, while a plain background fill with the identical height (height: StyleSheet.hairlineWidth) renders at every offset.

Steps to reproduce

1. Launch the repro
2. Compare the two columns - the left one would have missing lines

React Native Version

0.87.0

Affected Platforms

Runtime - iOS

Areas

Fabric - The New Renderer

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

System:
  OS: macOS 26.6.1
  CPU: (11) arm64 Apple M3 Pro
  Memory: 134.08 MB / 18.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 24.18.0
    path: /Users/oleksiibulenok/.nvm/versions/node/v24.18.0/bin/node
  Yarn:
    version: 1.22.22
    path: /Users/oleksiibulenok/.nvm/versions/node/v24.18.0/bin/yarn
  npm:
    version: 11.16.0
    path: /Users/oleksiibulenok/.nvm/versions/node/v24.18.0/bin/npm
  Watchman: Not Found
Managers:
  CocoaPods:
    version: 1.16.2
    path: /opt/homebrew/bin/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 25.5
      - iOS 26.5
      - macOS 26.5
      - tvOS 26.5
      - visionOS 26.5
      - watchOS 26.5
  Android SDK:
    API Levels:
      - "34"
      - "35"
      - "36"
    Build Tools:
      - 34.0.0
      - 35.0.0
      - 36.0.0
    System Images:
      - android-35 | Google Play ARM 64 v8a
      - android-36 | Google Play ARM 64 v8a
    Android NDK: Not Found
IDEs:
  Android Studio: 2025.1 AI-251.26094.121.2512.13991807
  Xcode:
    version: 26.6/17F113
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 17.0.14
    path: /Users/oleksiibulenok/Library/Java/JavaVirtualMachines/jbr-17.0.14/Contents/Home/bin/javac
  Ruby:
    version: 2.7.6
    path: /Users/oleksiibulenok/.rbenv/shims/ruby
npmPackages:
  "@react-native-community/cli":
    installed: 20.2.0
    wanted: 20.2.0
  react:
    installed: 19.2.3
    wanted: 19.2.3
  react-native:
    installed: 0.87.0
    wanted: 0.87.0
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: true
  newArchEnabled: true
iOS:
  hermesEnabled: true
  newArchEnabled: true

Stacktrace or Logs

N/A

MANDATORY Reproducer

https://github.com/abulenok/HairlineBorderRepro

Screenshots and Videos