chore: upgrade Kotlin to 2.1.0

[lowrt]

這是什麼類型的 PR？

選擇所有符合的項目

• 重構
• 新功能
• 錯誤修復
• 最佳化
• 技術文件更新

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[claude]

Claude finished @lowrt's task —— View job

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Code Review: Kotlin 2.1.0 Upgrade

Review Summary

This PR successfully upgrades Kotlin from 2.0.20 to 2.1.0 and modernizes the Android Gradle configuration. The changes are well-structured and align with Flutter's latest best practices. Overall, this is a clean and well-executed upgrade with excellent code quality improvements.

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✅ Strengths

1. Modern Plugin System Migration - Correctly migrates from the deprecated kotlin-android plugin to the modern org.jetbrains.kotlin.android plugin (android/app/build.gradle:3)

2. Simplified MainActivity - Removes custom splash screen handling that's now redundant with Flutter's native splash screen support (android/app/src/main/kotlin/com/exptech/dpip/MainActivity.kt:1-5)

3. Gradle Configuration Cleanup - Eliminates the legacy buildscript block in favor of the modern Gradle plugins DSL (android/build.gradle:1-29)

4. Version Consistency - Updates both Kotlin (2.0.20 → 2.1.0) and Android Gradle Plugin (8.7.0 → 8.10.1) in lockstep (android/settings.gradle:22-23)

5. Gradle Wrapper Update - Upgrades to Gradle 8.11.1, which is compatible with the new plugin versions (android/gradle/wrapper/gradle-wrapper.properties:5)

6. Code Reduction - Net reduction of 39 lines while improving functionality demonstrates good refactoring

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🔍 Code Quality & Best Practices

Excellent:

• ✅ Follows Flutter 3.35.4+ conventions for Android configuration
• ✅ Kotlin 2.1.0 is compatible with the Flutter SDK version (>=3.35.4)
• ✅ Proper migration from deprecated plugin IDs to canonical ones
• ✅ Removal of unused/redundant code (launch_background.xml, custom splash logic)
• ✅ Gradle wrapper distribution changed from -all to -bin (smaller, faster downloads)

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🎯 Technical Analysis

1. Splash Screen Removal (MainActivity.kt)

The removal of the custom installSplashScreen() implementation is correct because:

• Flutter 3.35+ handles splash screens natively via core-splashscreen dependency (still present in android/app/build.gradle:93)
• The deleted launch_background.xml was a legacy approach
• Modern Flutter apps should use flutter_native_splash or rely on the framework's built-in splash support

2. Build Configuration Modernization (android/build.gradle)

The removal of the buildscript block is the recommended approach for:

• Gradle 7.0+ projects using the plugins DSL
• Better build performance and clarity
• Aligns with Flutter's declarative Gradle configuration pattern

3. Version Compatibility

• Kotlin 2.1.0 ✅ Compatible with Flutter 3.35.4
• Android Gradle Plugin 8.10.1 ✅ Compatible with Gradle 8.11.1
• All dependencies remain at appropriate versions

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⚠️ Observations & Recommendations

Minor Observations:

1. Missing Newline at EOF - MainActivity.kt is missing a newline at the end of the file (line 5). This is a minor style issue but some linters flag it.

2. Gradle Distribution Type - Changed from gradle-8.10.2-all.zip to gradle-8.11.1-bin.zip. The -bin variant is smaller and sufficient for most builds, but the -all variant includes sources and documentation which can be helpful for IDE navigation. This change is fine, but worth noting if developers experience slower IDE indexing.

Suggested Testing Checklist:

While I cannot run the build, please verify:

• Cold start splash screen appears correctly on Android 12+ devices
• App builds successfully with flutter build appbundle --release
• No Kotlin compilation warnings appear
• Firebase services (Crashlytics, Messaging) work correctly with new Kotlin version
• All Flutter plugins compile without issues

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🛡️ Security & Performance

• ✅ No security concerns introduced
• ✅ No new permissions or capabilities added
• ✅ Build performance should improve slightly with modern Gradle/Kotlin versions
• ✅ Smaller APK/AAB size expected due to simplified splash handling

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📝 Documentation

The PR description is minimal. Consider adding:

• Link to Kotlin 2.1.0 release notes
• Note about Flutter compatibility requirements
• Mention of splash screen handling changes
• Testing steps performed

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Final Verdict

Recommendation: ✅ APPROVE

This is a high-quality upgrade PR that:

• Modernizes the Android build configuration
• Removes legacy code appropriately
• Maintains compatibility with the Flutter ecosystem
• Follows current best practices

The changes are minimal, focused, and safe to merge after successful CI validation.

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