[Shahroz16]

Refs MBL-2389

Docs only, no behaviour change. The README badges advertised iOS 13 and Android API 21, which are the native Customer.io SDKs' floors. A React Native app can't target below its React Native release's own minimum.

The wording follows the current support policy: keep minimums as low as actually works, and leave peerDependencies at * with no enforcement.

• Minimum that works: React Native 0.77. It's the first template on Kotlin 2.x, which the Android module's Compose compiler plugin needs.
• 0.81 is the first stock template whose app builds as generated. CI builds Android template apps with RN 0.81 and 0.88 (the Android build compatibility workflow in fix(android): build under AGP 9 built-in Kotlin and new DSL #669), and iOS with the example app (RN 0.83) and the scene E2E host (RN 0.88). The README states exactly that, rather than "tested end to end".
• On 0.77–0.80, apps raise compileSdk/buildTools to 36, and on 0.77–0.79 also AGP to 8.9.1 + Gradle 8.11.1. The README lists the exact edits.

Changes

• Badges: min iOS 15.1, min Android SDK 24, plus a new min React Native 0.77 badge. The Swift 5.3 badge is removed: the wrapper already uses Swift 5.7 syntax (shorthand if let, e.g. ios/wrappers/inapp/NativeMessagingInApp.swift:31), and no compiler minimum has been verified to replace it.
• New Requirements section: a minimum table (React Native, iOS, Android API, Android build) with where each number comes from, the 0.77–0.80 Android build edits, and an Expo note (SDK 54 = RN 0.81.5 and later meet the Android build requirement; SDK 53 = RN 0.79.6).
• The Android template-build sentence relies on fix(android): build under AGP 9 built-in Kotlin and new DSL #669's workflow, so merge this after fix(android): build under AGP 9 built-in Kotlin and new DSL #669, or drop that clause if fix(android): build under AGP 9 built-in Kotlin and new DSL #669 doesn't land. API 24 stays the Android floor because it comes from React Native itself. The module's own minSdkVersion=21 default is a separate change and isn't touched here.

Evidence for the numbers

Claim	Source
iOS 15.1	Helpers::Constants.min_ios_version_supported returns 15.1 in react-native@0.76.0 and 0.77.0 (scripts/cocoapods/helpers.rb). Our podspec uses min_ios_version_supported.
API 24	minSdk = 24 in react-native@0.76.0 and 0.77.0 gradle/libs.versions.toml, and in both templates.
React Native 0.81 (builds as generated)	First template with both compileSdk 36 (@react-native-community/template@0.81.6) and AGP ≥ 8.9.1 (8.11.0 in react-native@0.81.6's gradle/libs.versions.toml). The 0.80 template has compileSdk 35 / AGP 8.9.2; 0.79 has 35 / 8.8.2.
React Native 0.77 (minimum that works)	The Android module applies org.jetbrains.kotlin.plugin.compose from compose-compiler-gradle-plugin:$kotlinVersion. That plugin only exists for Kotlin 2.0+. The RN 0.76 template sets kotlinVersion = "1.9.24"; 0.77 sets "2.0.21". Codegen EventEmitter module events (used in src/specs/modules) need RN 0.76+. Local builds: see below.
New Architecture only since 6.0.0	CHANGELOG 6.0.0: "remove support for React Native old architecture (#553)".
compileSdk 36, AGP 8.9.1	androidx.core:core(-ktx):1.17.0 AAR metadata: minCompileSdk=36, minAndroidGradlePluginVersion=8.9.1. It's requested directly by io.customer.android:messaging-in-app:4.23.2. Native Android moved to 1.17.0 in 4.13.0, which this SDK picked up in 5.1.0.

Builds (stock templates, packed 6.13.1, :app:assembleDebug)

React Native template	Result
0.76.9	❌ Could not find org.jetbrains.kotlin:compose-compiler-gradle-plugin:1.9.25
0.77.3 as generated (compileSdk 35, AGP 8.7.2)	❌ checkDebugAarMetadata: AndroidX Core 1.17.0 needs compileSdk 36 and AGP ≥ 8.9.1
0.77.3 with the README's edits (compileSdk 36, buildTools 36.0.0, AGP 8.9.1, Gradle 8.11.1)	✅
0.81.6 as generated (compileSdk 36, AGP 8.11.0)	✅
0.88.0 as generated	✅

Templates 0.79 (compileSdk 35, AGP 8.8.2) and 0.80 (35, AGP 8.9.2) fall in between. Hence "0.77–0.80: compileSdk 36" and "0.77–0.79: also AGP". 0.79 and 0.80 weren't built individually.

peerDependencies stays *. The feat! draft #671 is kept only for reference and isn't planned. This PR only documents what is already true.

Codex review

Codex (gpt-6.1-sol, high) did an adversarial review in two passes:

• P2: the Requirements table omitted the Android toolchain. Fixed. Builds above confirmed it: the "Android build" row and per-version instructions were added.
• P3: the Swift 5.3 badge is wrong. Fixed by removing the badge.
• P3 (second pass): Expo apps regenerate android/. Fixed: added the expo-build-properties note.
• Found fine: iOS 15.1 and API 24 come from RN 0.76+ and the podspecs inherit RN's iOS minimum; the Gradle 8.11.1 requirement for AGP 8.9.1; targetSdk doesn't need to change.
• Third pass (on an earlier "0.81 supported" draft; the README is now 0.77 minimum / tested from 0.81):
  • Medium: the README claimed a module-only CI check that only exists in draft fix(android): build under AGP 9 built-in Kotlin and new DSL #669. Fixed: it now states only the validation done (a 0.77.3 app build).
  • Low: "0.76 and earlier cannot build" is too absolute. Fixed: "not supported".
  • Also: expo-build-properties can't raise AGP/Gradle. Fixed: point Expo users at SDK 54+.
• Fourth pass, on the 0.77-minimum / tested-from-0.81 wording:
  • Medium: "tested end to end" from 0.81 is only true once fix(android): build under AGP 9 built-in Kotlin and new DSL #669's full-app RN 0.81.6 job is on main. Kept as worded, because that's the policy statement requested. The merge order is the condition: merge fix(android): build under AGP 9 built-in Kotlin and new DSL #669 first, or soften that sentence here.
  • Codex found the rest consistent with the policy and the build evidence.
• Fifth pass (after an independent review found "tested end to end" overstated iOS coverage; the sentence now lists what CI builds):
  • Medium: the Android template builds come from draft fix(android): build under AGP 9 built-in Kotlin and new DSL #669. That's the merge-order condition above.
  • Low: "from React Native 0.81" implied coverage of every later release. Fixed to "with React Native 0.81 and 0.88".
  • Codex found the iOS wording fine.

🤖 Generated with Claude Code

[mrehan27]

CI on main doesn't build Android template apps yet; that's the android-build-compat job in #669, which is still open. Either merge this after #669, or drop the Android part here and add it back in #669.