fix(android): skip explicit Kotlin plugin when AGP registers the kotlin extension by gabrieldonadel · Pull Request #85 · kuatsu/react-native-cloud-storage

gabrieldonadel · 2026-09-04T15:31:48Z

Problem

Android Gradle Plugin 9 ships built-in Kotlin support and enables it by default, so
AGP registers the kotlin extension itself. When a library also applies kotlin-android
explicitly, the two collide and configuration fails before anything compiles. AGP
words it two ways, both the same problem:

> Failed to apply plugin 'kotlin-android'.
   > Cannot add extension with name 'kotlin', as there is an extension already registered with that name.

> The 'kotlin-android' plugin is no longer required for Kotlin support since AGP 9.0.

The apply is unconditional in this module, so on an AGP 9 project this cannot be built
at all. There is no consumer-side workaround short of patching the file — setting
android.builtInKotlin=false project-wide just to build one dependency is not a
reasonable ask, and that escape hatch is removed in AGP 10.

Change

Apply the plugin only when nothing has registered the kotlin extension yet:

if (project.extensions.findByName('kotlin') == null) {
    apply plugin: 'kotlin-android'
}

Files changed:

packages/react-native-cloud-storage/android/build.gradle

This tests the condition that actually fails, so there is no AGP version table to
keep in sync, and it covers AGP 10 — where the android.builtInKotlin opt-out is
removed — without a special case.

AGP	`android.builtInKotlin`	`kotlin` extension	explicit apply
8.x	unset or `false`	absent	yes (unchanged)
9.x	unset or `true`	registered by AGP	no
9.x	`false`	absent	yes
10+	n/a (removed)	registered by AGP	no

The guard sits after apply plugin: 'com.android.library' in every file it touches,
so AGP has already registered its extensions by the time it runs. I checked that
ordering per file rather than assuming it.

What I verified, and what I did not

Verified end to end on a real Expo SDK 58 / React Native 0.87 project with AGP
9.2.1 and Gradle 9.4.1: :app:assembleDebug succeeds both with
-Pandroid.newDsl=true -Pandroid.builtInKotlin=true and with both flags off.
Confirmed both branches actually execute rather than one path always winning: with
the flags off, compileDebugKotlin runs from the explicitly applied plugin; with
them on the build completes without it.
Every changed file passes a Groovy Phases.CONVERSION syntax check.
Not run: this repo's own CI or example app.

Where this came from

A sweep of 500 popular React Native libraries against the AGP 9 defaults. 152 failed
with the new DSL enabled, and 144 of those failed on exactly this collision — by
far the most common blocker. Affects react-native-cloud-storage here.

The same guard shape was accepted in
RevenueCat/react-native-purchases#1934,
at that maintainer's suggestion.

Summary by CodeRabbit

Bug Fixes
- Fixed Android builds with AGP 9 by preventing a Kotlin configuration conflict during project setup.

…in extension AGP 9 ships built-in Kotlin support and registers the kotlin extension itself. Applying the Kotlin plugin again fails configuration with "Cannot add extension with name 'kotlin'". Check for the extension directly, which needs no AGP version table and covers AGP 10, where the android.builtInKotlin opt-out is removed.

vercel · 2026-09-04T15:31:57Z

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coderabbitai · 2026-09-04T15:32:06Z

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Walkthrough

The Android build script now checks for an existing kotlin extension before applying kotlin-android. This prevents duplicate extension registration when AGP 9 provides built-in Kotlin support.

Changes

Android build configuration

Layer / File(s)	Summary
Guard Kotlin plugin application `packages/react-native-cloud-storage/android/build.gradle`	The script applies `kotlin-android` only when the `kotlin` extension is not already registered.

Estimated code review effort: 2 (Simple) | ~5 minutes

Merge Risk: ⚪ Minimal · up to db974

Android builds now skip explicit Kotlin plugin application when AGP has already registered Kotlin support, preventing duplicate-extension failures while preserving existing behavior otherwise. No current merge-blocking risk is identified.

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✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: skipping the explicit Kotlin plugin when AGP registers the kotlin extension.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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mfkrause · 2026-09-04T15:58:35Z

Thanks!

vercel Bot temporarily deployed to Preview September 4, 2026 15:31 Inactive

style(android): shorten Kotlin plugin comment

a32caa1

vercel Bot temporarily deployed to Preview September 4, 2026 15:46 Inactive

mfkrause merged commit 13f40bb into kuatsu:main Sep 4, 2026
8 checks passed

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fix(android): skip explicit Kotlin plugin when AGP registers the kotlin extension - #85

fix(android): skip explicit Kotlin plugin when AGP registers the kotlin extension#85
mfkrause merged 2 commits into
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gabrieldonadel:fix/agp9-built-in-kotlin

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