Harden persistent download reliability

[aShanki]

Summary

Hardens Launchly's first-stage download reliability without mixing in the larger authentication, APK trust, installer, or release-pipeline redesigns.

• use a dedicated persistent-download OkHttp client with no whole-call deadline while retaining connect/read-idle timeouts
• require HTTPS artifact URLs, validate range responses strictly, and bound artifact count plus streamed bytes
• preflight free storage while accounting for reusable finals and resumable partials
• reset rejected, oversized, stale, and size-mismatched partial files so retries can restart cleanly
• atomically promote exact-size completed partials after a crash instead of issuing an invalid end-of-file range request
• invalidate cached APKs after every validator exception, including malformed-APK parser failures, and retry once when cached finals or partials were involved
• await encrypted auth restoration before GPlay requests and before sign-in/sign-out/profile mutations
• replace Room REPLACE with @Upsert so managed-version edits do not cascade-delete download records
• allow Android 13+ downloads to start when notification permission is denied, with an explanatory snackbar
• bump the release metadata to version 0.3.0 (versionCode 4)

Verification

Executed locally against Android SDK 35:

./gradlew --no-daemon clean testDebugUnitTest lintDebug assembleDebug assembleDebugAndroidTest :app:verifyReleaseArtifact

Results:

• 21 JVM tests passed; 0 failures/errors/skips
• debug APK assembled
• debug Android-test APK assembled
• unsigned release artifact verification passed
• generated debug and release APK manifests report version 0.3.0 / code 4
• lint: 0 errors, 15 existing dependency/version warnings
• generated Room DAO uses an UPDATE ... WHERE id = ? adapter for existing managed-version rows rather than delete-and-insert replacement

The connected instrumented tests were compiled but not executed locally because no Android emulator/device is attached. The added Room regression test is included in the Android-test APK.

Review follow-ups handled

Two independent pre-commit reviews identified and this branch fixed:

• malformed same-size APKs could throw parser exceptions outside ApkValidationException and evade cache invalidation
• asynchronous auth restoration could overwrite a newer sign-in/sign-out operation
• a crash after fully writing a partial APK but before its final move could trigger repeated HTTP 416 responses

Out of scope

SHA-256 verification, clean generation-specific staging, official Minecraft signer pinning/lineage, durable downgrade transactions, Ackpine upgrade, and CI/release hardening remain separate follow-up PRs.