Summary

Library — converted to Kotlin Multiplatform (Maven Central distribution):

• retrostash-core, retrostash-annotations, retrostash-ktor → android, jvm, ios{X64,Arm64,SimulatorArm64}, wasmJs.
• retrostash-okhttp → android, jvm (OkHttp is JVM-only); AndroidRetrostashStore + RetrostashOkHttpAndroid factory split into androidMain.
• iOS distribution: XCFramework built from retrostash-ktor (exports core + annotations) + Package.swift for SPM consumption.
• Publishing: com.vanniktech.maven.publish to Sonatype Central Portal; JitPack removed.
• AGP 9 KMP migration: KMP modules use com.android.kotlin.multiplatform.library; required new hierarchy template + node/yarn/binaryen Ivy repos in settings.gradle.kts.

Bug fixes (with regression tests):

• InMemoryRetrostashStore thread-safety — kotlinx.coroutines.sync.Mutex guards mutations + concurrent test.
• Ktor plugin: invalidate now gated on 2xx (was unconditional); response persistence wired for @CacheQuery on 2xx via response.call.save(); logger plumbing.
• Ktor runtime: invalidate(...) resolves placeholder templates against bindings (parity with OkHttp interceptor) — fixes mutation not invalidating cache.

Playground app — Compose Multiplatform:

• Split :app (legacy android.application) into :composeApp (KMP-library) + :androidApp (android.application). Avoids AGP 9 incompatibility with kotlin.multiplatform + android.application in same module.
• Targets: android, jvm desktop, ios*, wasmJs (browser).
• Three transport demos via segmented switcher: Ktor (all platforms), OkHttp (android + desktop), Retrofit (android-only). Disabled platforms show inline hint.
• iOS shell: iosApp/ Xcode project consumes composeApp framework via embedAndSignAppleFrameworkForXcode Gradle task.
• jvmAndAndroidMain shared dir for OkHttpDemoEngine (used by both desktop + android).

Other:

• :retrostash legacy module deleted (replaced by KMP modules).
• release.yml rewritten — macos-latest runner, runs full KMP test suite, builds + zips XCFramework, computes SHA-256, patches Package.swift, publishes via vanniktech, attaches XCFramework to GitHub Release.
• update_readme_version.py updates per-module Maven Central coords (was JitPack-style single coord).
• CONTRIBUTING.md + development.md rewritten for KMP/Maven Central/SPM workflow.
• README rewritten with module table, per-platform install (Gradle + SPM), 0.0.4 → 0.0.5 migration table.
• Heap bumped -Xmx2g → -Xmx6g (iOS framework link OOM'd).
• Compose Multiplatform 1.10.3, Kotlin 2.3.20, AGP 9.1.0.

Test plan

• ./gradlew :retrostash-core:jvmTest :retrostash-core:iosSimulatorArm64Test passes
• ./gradlew :retrostash-okhttp:jvmTest passes
• ./gradlew :retrostash-ktor:jvmTest :retrostash-ktor:iosSimulatorArm64Test passes (incl. invalidate-with-bindings + 5xx-no-invalidate + persistence)
• ./gradlew :retrostash-annotations:assemble passes
• ./gradlew :composeApp:assemble :androidApp:assembleDebug :composeApp:desktopMainClasses :composeApp:compileKotlinIosSimulatorArm64 :composeApp:compileKotlinWasmJs all succeed
• ./gradlew :retrostash-ktor:assembleRetrostashReleaseXCFramework produces retrostash-ktor/build/XCFrameworks/release/Retrostash.xcframework
• ./gradlew publishToMavenLocal emits per-target artifacts under ~/.m2/repository/dev/logickoder/retrostash-{core,annotations,ktor,okhttp}/
• :androidApp:installDebug runs on emulator; switch between Ktor / OkHttp / Retrofit tabs; query → mutate → re-query shows cache-hit then network refresh
• :composeApp:run launches desktop window; Ktor + OkHttp tabs work
• :composeApp:wasmJsBrowserDevelopmentRun opens browser; only Ktor tab available
• iOS: follow iosApp/README.md, ⌘R in Xcode; only Ktor tab available
• Maven Central secrets configured in repo (MAVEN_CENTRAL_USERNAME, MAVEN_CENTRAL_PASSWORD, SIGNING_KEY, SIGNING_KEY_ID, SIGNING_KEY_PASSWORD) before triggering release workflow

Migration note for consumers

Coords change from com.github.logickoder:retrostash:0.0.4 (JitPack) to dev.logickoder:retrostash-{core,annotations,ktor,okhttp}:<v> (Maven Central). Migration table in README.