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navi-1 / docs / android-client.md
@Eugene Sukhodolskiy Eugene Sukhodolskiy on 30 Apr 3 KB Open artifact links externally on Android

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 navigation:

  • Normal Navi app URLs on the configured server host → handled by WebView.
  • API, iframe, and artifact preview loads without a user gesture → handled by WebView.
  • External hosts → opened via Intent.ACTION_VIEW in the system browser.
  • User-clicked same-host artifact/file URLs → opened via Intent.ACTION_VIEW in the system browser:
    • /content-viewers/...
    • /sessions/{session_id}/files/{filename}
    • URLs with download=1

This means inline preview cards still render inside the app, but when the user explicitly opens a preview, raw file, download link, or external URL, it leaves the app and opens in the user's browser.

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