Enable Java 8+ API desugaring for API 24/25 support (Sentry COLUMBA-8M)

[torlando-tech]

Summary

Fixes Sentry COLUMBA-8M — NoClassDefFoundError: java.time.LocalDateTime on Android 7.x devices (API 24/25).

Captured stack:
```
java.lang.NoClassDefFoundError: Failed resolution of: Ljava/time/LocalDateTime;
at network.reticulum.transport.Transport.log(Transport.kt:5697)
at network.reticulum.transport.Transport.registerDestination(Transport.kt:874)
at network.reticulum.destination.Destination$Companion.create(Destination.kt:845)
at NativeReticulumProtocol.buildIdentityResult(NativeReticulumProtocol.kt:1018)
at NativeReticulumProtocol$importIdentityFile$2.invokeSuspend(NativeReticulumProtocol.kt:983)
Caused by: ClassNotFoundException: java.time.LocalDateTime
```
For the captured user this fired during identity import via the deep link `/identity_manager?base32Key={...}`, but any code path that registers a destination would crash identically.

Root cause

Upstream `reticulum-kt`'s public API references `java.time.LocalDateTime` (verified by grepping the cached jars: 8 refs in `rns-core-v0.0.12.jar`, 20 in `rns-interfaces-v0.0.12.jar`). `java.time.*` was only added to the Android runtime in API 26.

Columba's `minSdk` is 24 in every Android module, but `coreLibraryDesugaring` was not configured anywhere — zero hits across all `build.gradle.kts` files. So on API 24/25 the class loader trips the moment `Transport` touches a `LocalDateTime`-bearing method.

Fix

Enable Java 8+ API desugaring in the three Android modules (`app`, `reticulum`, `data`) and add `desugar_jdk_libs` 2.1.5 as a `coreLibraryDesugaring` dependency in each. The `domain` and `micron` modules are pure JVM (`java-library` / `kotlin("jvm")`) and don't need it.

```kotlin
compileOptions {
sourceCompatibility = JavaVersion.VERSION_17
targetCompatibility = JavaVersion.VERSION_17
isCoreLibraryDesugaringEnabled = true
}
```
```kotlin
dependencies {
coreLibraryDesugaring(libs.android.desugar.jdk.libs)
}
```

Affected scope

• Devices: Android 7.x (API 24/25) — roughly the bottom ~2% of active Android.
• Code paths: not just identity import — anything that touches `Transport` in reticulum-kt eventually hits a `LocalDateTime`-bearing method.

Test plan

• `./gradlew :app:assembleNoSentryDebug` builds clean (BUILD SUCCESSFUL in 2m 17s)
• No new dependencies pulled into `domain` / `micron` (verified — they're pure JVM)
• Manual smoke on an API 24 emulator: install, import identity via deep link, confirm no NCDFE
• Sentry COLUMBA-8M event count drops to zero on subsequent releases

Notes

• An upstream fix in `reticulum-kt` to avoid `java.time.*` in public API would also resolve this without consumer-side desugaring, but that's a larger change. Desugaring is the safe, mechanical fix and is the standard solution for this exact scenario.
• `desugar_jdk_libs` 2.1.5 is the current stable release; works with AGP 8.x and Kotlin 2.x.

🤖 Generated with Claude Code

[greptile-apps]

Greptile Summary

This PR fixes a NoClassDefFoundError: java.time.LocalDateTime crash on Android 7.x (API 24/25) caused by reticulum-kt's public API referencing java.time.* classes that are only natively available on API 26+.

• Enables isCoreLibraryDesugaringEnabled = true in compileOptions for the three Android modules (app, reticulum, data) and adds coreLibraryDesugaring(libs.android.desugar.jdk.libs) to each, using the full desugar_jdk_libs 2.1.5 artifact which covers all java.time.* APIs.
• Adds the version entry and library alias to libs.versions.toml; the pure-JVM domain and micron modules are correctly left untouched.
• The reticulum module is the most critical recipient since it api-exposes the rns-core/rns-interfaces artifacts that carry the LocalDateTime references, making the fix transitive to :app; enabling it on :app directly as well is required for the final merged APK.

Confidence Score: 5/5

Safe to merge — this is a well-scoped, mechanical build-config change that fixes a confirmed production crash with no logic changes.

All three Android modules correctly get isCoreLibraryDesugaringEnabled = true paired with the coreLibraryDesugaring dependency. The correct full artifact (com.android.tools:desugar_jdk_libs, not the minimal variant) is chosen, which is required since java.time.LocalDateTime is in the full desugaring library. Version 2.1.5 is compatible with AGP 8.x. The pure-JVM modules are correctly excluded. The build has been verified clean by the author.

No files require special attention. The screenshot-tests module (noted in a prior review comment) does not yet depend on :reticulum, so it is unaffected for now.

Important Files Changed

Filename	Overview
gradle/libs.versions.toml	Adds desugarJdkLibs = "2.1.5" version and android-desugar-jdk-libs library alias pointing to com.android.tools:desugar_jdk_libs — correct artifact group/name and a stable version compatible with AGP 8.x.
reticulum/build.gradle.kts	Enables isCoreLibraryDesugaringEnabled = true and adds coreLibraryDesugaring(libs.android.desugar.jdk.libs) — most critical module since it directly api-exposes rns-core/rns-interfaces which contain the java.time.LocalDateTime references.
app/build.gradle.kts	Enables desugaring and adds coreLibraryDesugaring dependency; the app module consumes :reticulum so this is required for the final merged APK to work on API 24/25.
data/build.gradle.kts	Desugaring enabled; data only depends on :domain (pure JVM), not :reticulum, so this is forward-proofing in case Room TypeConverters or future code uses java.time.* directly — harmless and consistent with the other modules.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    subgraph JVM["Pure JVM - no desugaring needed"]
        domain[":domain java-library"]
        micron[":micron kotlin jvm"]
    end

    subgraph Android["Android modules - isCoreLibraryDesugaringEnabled = true"]
        reticulum[":reticulum android-library"]
        data[":data android-library"]
        app[":app com.android.application"]
    end

    subgraph Upstream["reticulum-kt JitPack JARs"]
        rnscore["rns-core-v0.0.16 - 8 LocalDateTime refs"]
        rnsinterfaces["rns-interfaces-v0.0.16 - 20 LocalDateTime refs"]
    end

    rnscore -->|api| reticulum
    rnsinterfaces -->|api| reticulum
    reticulum -->|implementation| app
    data -->|implementation| app
    domain -->|implementation| data
    domain -->|implementation| app
    micron -->|implementation| app

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_{Reviews (2): Last reviewed commit: "Enable Java 8+ API desugaring for API 24..." | Re-trigger Greptile}

[sentry]

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