[Android] Incorrect handling of coalescingKey

[t0maboro]

Description

In the CustomNativeComponentNativeLayoutEvent class, I’m providing a unique coalescingKey per event:

class CustomNativeComponentNativeLayoutEvent(
    surfaceId: Int,
    viewId: Int,
    val tabBarHeight: Int
) : Event<CustomNativeComponentNativeLayoutEvent>(surfaceId, viewId) {

    override fun getEventName() = EVENT_NAME

    // Our implementation (coalescing is enabled)
    override fun getCoalescingKey(): Short {
        return tabBarHeight.toShort()
    }
}

But in practice, only some events are being received on the JS side. The logs show events being emitted properly from native:

D  emitting from native 914
D  emitting from native 3
D  emitting from native 7
D  emitting from native 11
I  Received tabBarHeight on JS side 914
I  Received tabBarHeight on JS side 11
D  emitting from native 15
D  emitting from native 19
I  Received tabBarHeight on JS side 19
D  emitting from native 22
D  emitting from native 26
D  emitting from native 30
I  Received tabBarHeight on JS side 30
D  emitting from native 34
D  emitting from native 38
I  Received tabBarHeight on JS side 38

I would expect all events to be received since each has a unique coalescingKey.

After a quick investigation, I noticed this part of the code:

https://github.com/facebook/react-native/blob/v0.82.0-rc.5/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/events/FabricEventEmitter.kt#L36-L51

It seems like the coalescingKey is not passed forward. Is this expected behavior? Or should that value be forwarded so that events could be properly distinguished and delivered?

Steps to reproduce

1. Clone the repo (use the branch from the link) https://github.com/t0maboro/Screens3184/tree/%40t0maboro/issue-1
2. Run application on android
3. Observe logs with tag: ReactNativeJS - I used this tag to have native logs filtered together with console.log from JS

React Native Version

0.82.1

Affected Platforms

Runtime - Android

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

System:
  OS: macOS 15.6.1
  CPU: (10) arm64 Apple M2 Pro
  Memory: 101.11 MB / 16.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 24.3.0
    path: /opt/homebrew/bin/node
  Yarn:
    version: 1.22.22
    path: /opt/homebrew/bin/yarn
  npm:
    version: 11.4.2
    path: /opt/homebrew/bin/npm
  Watchman:
    version: 2025.09.15.00
    path: /opt/homebrew/bin/watchman
Managers:
  CocoaPods:
    version: 1.16.2
    path: /opt/homebrew/bin/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 25.0
      - iOS 26.0
      - macOS 26.0
      - tvOS 26.0
      - visionOS 26.0
      - watchOS 26.0
  Android SDK:
    API Levels:
      - "34"
      - "35"
      - "36"
    Build Tools:
      - 34.0.0
      - 35.0.0
      - 36.0.0
      - 36.1.0
      - 36.1.0
    System Images:
      - android-25 | Google APIs ARM 64 v8a
      - android-27 | Google APIs ARM 64 v8a
      - android-28 | Google APIs ARM 64 v8a
      - android-29 | Google APIs ARM 64 v8a
      - android-33 | Google APIs ARM 64 v8a
      - android-36 | Google Play ARM 64 v8a
    Android NDK: Not Found
IDEs:
  Android Studio: 2025.1 AI-251.26094.121.2512.13840223
  Xcode:
    version: 26.0.1/17A400
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 17.0.15
    path: /usr/bin/javac
  Ruby:
    version: 3.4.2
    path: /Users/tomaszboron/.rbenv/shims/ruby
npmPackages:
  "@react-native-community/cli":
    installed: 20.0.0
    wanted: 20.0.0
  react:
    installed: 19.1.1
    wanted: 19.1.1
  react-native:
    installed: 0.82.1
    wanted: 0.82.1
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: true
  newArchEnabled: true
iOS:
  hermesEnabled: Not found
  newArchEnabled: false

Stacktrace or Logs

D  emitting from native 914
D  emitting from native 3
D  emitting from native 7
D  emitting from native 11
I  Received tabBarHeight on JS side 914
I  Received tabBarHeight on JS side 11
D  emitting from native 15
D  emitting from native 19
I  Received tabBarHeight on JS side 19
D  emitting from native 22
D  emitting from native 26
D  emitting from native 30
I  Received tabBarHeight on JS side 30
D  emitting from native 34
D  emitting from native 38
I  Received tabBarHeight on JS side 38

MANDATORY Reproducer

https://github.com/t0maboro/Screens3184/tree/%40t0maboro/issue-1

Screenshots and Videos

No response

[Thotaharshavardhani]

I can confirm the reported behavior — seeing the same result when following the repro steps.