Kill Kotlin daemon before R8 to reduce peak memory on release builds

[kaeawc]

Summary

• Implements the Kotlin daemon kill technique from Inaki's blog post directly in the build script
• Scoped to release builds only, preventing the circular task dependency bug in the R8Booster plugin that breaks debug unit tests
• Frees ~14-15% peak memory by releasing the Kotlin compile daemon process before R8 starts

Details

The R8Booster plugin (io.github.cdsap.r8booster) has a bug: it applies finalizedBy(killKotlinCompileDaemon) to all KotlinCompile tasks project-wide (including test tasks), and dependsOn(killKotlinCompileDaemon) to all JavaCompile tasks. This creates a circular dependency when running debug unit tests:

bundleDebugClassesToCompileJar → compileDebugJavaWithJavac → killKotlinCompileDaemon
    ↑ (finalizer of) compileDebugUnitTestKotlin → bundleDebugClassesToCompileJar ↑

The manual implementation scopes the wiring to release tasks only:

• tasks.withType<KotlinCompile>().configureEach with a name guard for release (no test) tasks
• tasks.matching { startsWith("minify") && endsWith("WithR8") } instead of tasks.named() since AGP 9.x registers these tasks lazily

Test Plan

• assembleRelease — killKotlinCompileDaemon runs after compileReleaseKotlin, before minifyReleaseWithR8
• testDebugUnitTest — no circular dependency error
• spotlessCheck — formatting passes
• tasks — configuration resolves cleanly

🤖 Generated with Claude Code

[github-actions]

Diffuse output:

OLD: app-base-debug.apk (signature: V2)
NEW: app-debug.apk (signature: V2)

          │          compressed          │         uncompressed         
          ├───────────┬───────────┬──────┼───────────┬───────────┬──────
 APK      │ old       │ new       │ diff │ old       │ new       │ diff 
──────────┼───────────┼───────────┼──────┼───────────┼───────────┼──────
      dex │  17.8 MiB │  17.8 MiB │  0 B │  60.1 MiB │  60.1 MiB │  0 B 
     arsc │ 468.7 KiB │ 468.7 KiB │  0 B │ 468.6 KiB │ 468.6 KiB │  0 B 
 manifest │   1.9 KiB │   1.9 KiB │  0 B │   6.1 KiB │   6.1 KiB │  0 B 
      res │  56.5 KiB │  56.5 KiB │  0 B │  64.4 KiB │  64.4 KiB │  0 B 
   native │  37.1 KiB │  37.1 KiB │  0 B │  36.5 KiB │  36.5 KiB │  0 B 
    asset │       0 B │       0 B │  0 B │       0 B │       0 B │  0 B 
    other │    46 KiB │    46 KiB │  0 B │ 104.2 KiB │ 104.2 KiB │  0 B 
──────────┼───────────┼───────────┼──────┼───────────┼───────────┼──────
    total │  18.4 MiB │  18.4 MiB │  0 B │  60.8 MiB │  60.8 MiB │  0 B 

         │          raw           │           unique            
         ├────────┬────────┬──────┼────────┬────────┬───────────
 DEX     │ old    │ new    │ diff │ old    │ new    │ diff      
─────────┼────────┼────────┼──────┼────────┼────────┼───────────
   files │     14 │     14 │    0 │        │        │           
 strings │ 241498 │ 241498 │    0 │ 222331 │ 222331 │ 0 (+0 -0) 
   types │  32802 │  32802 │    0 │  30118 │  30118 │ 0 (+0 -0) 
 classes │  28549 │  28549 │    0 │  28549 │  28549 │ 0 (+0 -0) 
 methods │ 146696 │ 146696 │    0 │ 141575 │ 141575 │ 0 (+0 -0) 
  fields │  61016 │  61016 │    0 │  60139 │  60139 │ 0 (+0 -0) 

 ARSC    │ old │ new │ diff 
─────────┼─────┼─────┼──────
 configs │ 106 │ 106 │  0   
 entries │ 372 │ 372 │  0