The bundled WebView build is only compatible from Android 10 (API 29); on Android 9 it lands on
the in-app unsupported-engine screen. Declaring minSdk 29 lets RuStore/Google Play block older
devices at install rather than shipping a known-incompatible build.
Add @capacitor/{core,android,app,cli,assets} to ui/, a capacitor.config.ts (appId ru.eruditgame.app, appName Эрудит, webDir dist — bundle model, no server.url), and the generated ui/android/ Gradle project (tracked; build outputs and the machine-specific local.properties gitignored, keystore patterns un-commented so signing material can never be committed). Wire the Android hardware Back button in ui/src/lib/native.ts behind a dynamic @capacitor/app import (web/mock bundles never load it), called from App.svelte onMount and reusing routeDepth for the navigation-root check. Whitelist sharp in pnpm-workspace.yaml for @capacitor/assets icon generation.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>