build: compress DEX and native libs in APK (legacy packaging)

[TimeToBuildBob]

Summary

Proposes dex.useLegacyPackaging = true and jniLibs.useLegacyPackaging = true in mobile/build.gradle, compressing DEX and native-library ZIP entries. The current diff applies to both universal and per-ABI APKs; it is not a universal-only change.

Related: #61. This is a packaging experiment, not an issue-closing fix or an IzzyOnDroid relisting path.

Distribution decision still needed

IzzySoft's follow-up confirms that ActivityWatch is not eligible for IzzyOnDroid under its no-LLM policy. A smaller APK does not change that decision.

The remaining motivation is reducing download/transfer cost, especially for the universal APK. Compressing native libraries requires extraction on install, trading smaller APKs against extraction overhead and an additional native-library copy on device. Universal and single-ABI builds have different trade-offs; do not infer installed-size savings from download savings alone.

Before adopting this globally, maintainers should decide whether compression should be universal-only or also apply to per-ABI builds, and clarify F-Droid's preference as IzzySoft suggested. This PR does not establish that preference.

Verification

Current-head tests passed, including the release-variant R8 smoke test and Android API 29 E2E check. The APK build matrix was skipped, so these checks do not provide before/after release APK size measurements or installed-footprint evidence.

Still required before choosing a default: comparable universal/per-ABI build sizes, installed-footprint and startup checks for the compressed native-library path, and a maintainer decision on distribution scope. The size reductions discussed in the issue remain estimates, not measurements of this PR.

[TimeToBuildBob]

🤖 AI code review

Adds a packaging block to mobile/build.gradle that sets useLegacyPackaging = true for both dex and jniLibs, forcing DEX and native libraries to be stored compressed in APKs. This is intended to reduce APK download size for distribution channels with size limits, at the cost of requiring extraction of native libraries at install time.

Safe to merge — no P0/P1 findings

Confidence 5/5

✅ No findings. The diff looks correct to me on this pass.

Files changed (1) — the diff as I read it

• mobile/build.gradle — Adds a packaging block with dex.useLegacyPackaging = true and jniLibs.useLegacyPackaging = true.

Previous review passes

commit	score	findings	engine	when
59b89c1963fa	5/5	0	llm	2026-10-11 18:22 UTC

_{Reviewed 59b89c1963fa · openrouter/deepseek/deepseek-v4-flash-0731 · llm engine · 15s · about this reviewer}

_{Maintainer commands}

_{@TimeToBuildBob review (own line) — fresh review · @TimeToBuildBob fix — a worker acts on the findings. Once per comment; 👀 = received.}

[TimeToBuildBob]

Updated after IzzySoft's clarification on ActivityWatch/aw-android#61: this PR is now draft, not waiting only on a merge click.

IzzyOnDroid relisting is ruled out under its no-LLM policy. The diff currently enables compression globally, while universal and per-ABI builds have different download/installed-storage trade-offs. The APK build matrix was skipped, so passing tests do not supply the promised size comparison.

Removed the issue-closing claim from the description. Maintainer distribution-scope/F-Droid preference and measured APK/installed-footprint evidence remain prerequisites to selecting a default; no code change or merge made.