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navi-1 / docs / android-client.md
@Eugene Sukhodolskiy Eugene Sukhodolskiy on 25 Apr 2 KB Add Android client documentation
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Android Client

Native Android app that wraps the Navi web client in a WebView.

Location

android-client/ — standalone Android project (Kotlin, Gradle).

Architecture

Single-activity app with two screens:

Activity Purpose
SetupActivity First-launch screen — prompts for server URL, saves to SharedPreferences
MainActivity Main screen — full-screen WebView loading the Navi web client

Server URL is stored in SharedPreferences under key server_url. If absent on launch, SetupActivity is shown. If the WebView fails to load the main frame, the saved URL is cleared so the next launch prompts again.

Build & Deploy

cd android-client

# Debug APK
./gradlew assembleDebug

# Install via adb (device connected via USB)
adb install -r app/build/outputs/apk/debug/app-debug.apk

# One-liner: build + install
./gradlew assembleDebug && adb install -r app/build/outputs/apk/debug/app-debug.apk

WebView configuration

Setting Value Reason
javaScriptEnabled true Required for the Vue app
domStorageEnabled true Session state, composables
cacheMode LOAD_NO_CACHE Always fetch fresh from server
mixedContentMode ALWAYS_ALLOW Local server may serve mixed content
userAgentString …original… NaviAndroid/1.0 Platform detection in web client

shouldOverrideUrlLoading intercepts all navigation:

  • URL host matches the Navi server → handled by WebView (returns false)
  • Any other host (external link) → opened via Intent.ACTION_VIEW in the system browser (returns true)

This means links Navi produces in chat (URLs to external sites, generated HTML pages served by nginx, etc.) open in the user's browser, not inside the app.

Platform detection in web client

The app appends NaviAndroid/1.0 to the WebView's User-Agent. The web client can detect this:

import { isAndroid } from '@/composables/usePlatform.js'

if (isAndroid) {
  // Android-specific behaviour
}

usePlatform.js is a single-line composable:

export const isAndroid = navigator.userAgent.includes('NaviAndroid')

Use this for any future UI differences between the web client and the Android app (hiding elements, adjusting layout, etc.).

Back navigation

Hardware back button navigates WebView history if available (webView.canGoBack()), otherwise falls through to the default Android behaviour (closes the activity).

File / image picker

WebChromeClient.onShowFileChooser is implemented to support image attachment in chat:

  • Requests CAMERA and READ_MEDIA_IMAGES / READ_EXTERNAL_STORAGE permissions at runtime
  • Presents a chooser combining gallery picker and camera capture
  • Camera photos are saved to getExternalFilesDir(DIRECTORY_PICTURES) via FileProvider