A single Activity holding one WebView, in Java rather than Kotlin — for
~120 lines of setup Kotlin would only add its Gradle plugin, its stdlib
in the APK and a third version to keep aligned with Gradle and AGP. One
dependency: androidx.webkit 1.16.0.
The assets are served from https://appassets.androidplatform.net through
WebViewAssetLoader rather than file://. That is the part that matters: an
https origin is a secure context, and localStorage — which holds every
setting and the match in progress — is blocked on file://, so a saved
game would silently vanish. Confirmed on device: force-quit mid-match and
everything comes back.
public_html stays the only copy of the web app. A task syncs it into the
assets at build time, so the browser version and the app version cannot
drift; the APK's index.html hashes identical to the working tree. sw.js
is left out on purpose — it is cache-first, and a service-worker cache
outlives an app upgrade, so it would serve a stale index.html with no way
to clear it. The APK is the cache now.
Three web APIs don't exist in a WebView, so the Activity supplies them:
FLAG_KEEP_SCREEN_ON for navigator.wakeLock, native immersive mode for
requestFullscreen(), and LAYOUT_IN_DISPLAY_CUTOUT_MODE_SHORT_EDGES so the
panels' env(safe-area-inset-*) has something to report. textZoom is
pinned to 100: the layout is built on clamp() and vw, and a large system
font would scale the text inside it.
The manifest declares no permissions whatsoever.
Wiring note: AGP 9 refuses a Provider in sourceSets.assets.srcDir, since
it can't tell generated from static directories. The sync is a task with
a DirectoryProperty output, attached via androidComponents.onVariants,
which is the supported path and carries the task dependency.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
