feat: check for updates page in settings

Add a full-screen update checker accessible from a button at the
bottom of the settings page. It queries the fork's GitHub latest
release and can download + install the APK in place.

- UpdateRepository (core/data): fetch releases/latest via GitHub API,
  parse tag/description/APK asset, stream APK download to cacheDir
- VersionComparator (core/domain): compare 4.4.6-ba7opf.N style tags
  (base version first, then build number; v-prefix tolerant) + tests
- IMainContainer/MainContainer: inject updateRepo
- UpdateCheckerScreen (feature/settings): shows current version,
  checks for updates, displays latest version + release notes, and a
  Download & install button; FileProvider hands the APK to the
  system installer
- SettingsScreen: bottom entry button, full-screen page toggle
- AndroidManifest: REQUEST_INSTALL_PACKAGES permission + FileProvider
- i18n strings (en/zh)

app/src/main/AndroidManifest.xml

@@ -13,6 +13,7 @@
     <uses-permission android:name="android.permission.BLUETOOTH_SCAN" />
     <uses-permission android:name="android.permission.INTERNET" />
     <uses-permission android:name="android.permission.RECORD_AUDIO" />
+    <uses-permission android:name="android.permission.REQUEST_INSTALL_PACKAGES" />
 
     <application
         android:name=".MainApplication"
@@ -45,5 +46,15 @@
             android:name="android.telephony.PROPERTY_SATELLITE_DATA_OPTIMIZED"
             android:value="com.rtbishop.look4sat" />
 
+        <provider
+            android:name="androidx.core.content.FileProvider"
+            android:authorities="${applicationId}.fileprovider"
+            android:exported="false"
+            android:grantUriPermissions="true">
+            <meta-data
+                android:name="android.support.FILE_PROVIDER_PATHS"
+                android:resource="@xml/file_paths" />
+        </provider>
+
     </application>
 </manifest>

app/src/main/res/xml/file_paths.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<paths xmlns:android="http://schemas.android.com/apk/res/android">
+    <cache-path name="updates" path="." />
+</paths>

core/data/src/main/java/com/rtbishop/look4sat/core/data/injection/MainContainer.kt

@@ -35,6 +35,7 @@ import com.rtbishop.look4sat.core.data.repository.SatelliteRepo
 import com.rtbishop.look4sat.core.data.repository.SelectionRepo
 import com.rtbishop.look4sat.core.data.repository.SensorsRepo
 import com.rtbishop.look4sat.core.data.repository.SettingsRepo
+import com.rtbishop.look4sat.core.data.repository.UpdateRepository
 import com.rtbishop.look4sat.core.data.source.LocalSource
 import com.rtbishop.look4sat.core.data.source.RemoteSource
 import com.rtbishop.look4sat.core.data.usecase.AddToCalendar
@@ -79,6 +80,7 @@ class MainContainer(private val context: Context) : IMainContainer {
     override val satelliteRepo = provideSatelliteRepo()
     override val databaseRepo = provideDatabaseRepo()
     override val amSatRepo by lazy { AmSatRepository(remoteSource, appScope) }
+    override val updateRepo by lazy { UpdateRepository(remoteSource) }
     override val radioTrackingService: IRadioTrackingService by lazy {
         val manager = context.getSystemService(Context.BLUETOOTH_SERVICE) as BluetoothManager
         RadioTrackingService(appScope, manager, satelliteRepo, settingsRepo)

core/data/src/main/java/com/rtbishop/look4sat/core/data/repository/UpdateRepository.kt

@@ -0,0 +1,67 @@
+package com.rtbishop.look4sat.core.data.repository
+
+import com.rtbishop.look4sat.core.domain.model.LatestRelease
+import com.rtbishop.look4sat.core.domain.repository.IUpdateRepository
+import com.rtbishop.look4sat.core.domain.source.IRemoteSource
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+import org.json.JSONObject
+import java.io.File
+
+class UpdateRepository(
+    private val remoteSource: IRemoteSource
+) : IUpdateRepository {
+
+    override suspend fun getLatestRelease(): LatestRelease? = withContext(Dispatchers.IO) {
+        val result = remoteSource.getNetworkStream(LATEST_RELEASE_URL)
+        val stream = result.stream ?: return@withContext null
+        try {
+            val json = stream.bufferedReader().use { it.readText() }
+            parseRelease(json)
+        } catch (e: Exception) {
+            println("UpdateRepository parse failure: $e")
+            null
+        }
+    }
+
+    override suspend fun downloadApk(url: String, dest: File): Boolean = withContext(Dispatchers.IO) {
+        if (url.isBlank()) return@withContext false
+        val result = remoteSource.getNetworkStream(url)
+        val stream = result.stream ?: return@withContext false
+        try {
+            dest.outputStream().use { out -> stream.use { it.copyTo(out) } }
+            true
+        } catch (e: Exception) {
+            println("UpdateRepository download failure: $e")
+            false
+        }
+    }
+
+    private fun parseRelease(json: String): LatestRelease? {
+        val obj = JSONObject(json)
+        val tag = obj.optString("tag_name")
+        if (tag.isBlank()) return null
+        val assets = obj.optJSONArray("assets")
+        var apkUrl: String? = null
+        if (assets != null) {
+            for (i in 0 until assets.length()) {
+                val asset = assets.optJSONObject(i) ?: continue
+                val name = asset.optString("name", "")
+                if (name.endsWith(".apk")) {
+                    apkUrl = asset.optString("browser_download_url", "").ifBlank { null }
+                    if (apkUrl != null) break
+                }
+            }
+        }
+        return LatestRelease(
+            versionTag = tag,
+            title = obj.optString("name", ""),
+            body = obj.optString("body", ""),
+            apkUrl = apkUrl
+        )
+    }
+
+    private companion object {
+        const val LATEST_RELEASE_URL = "https://api.github.com/repos/atsunatsu/Look4Sat/releases/latest"
+    }
+}

core/domain/src/main/java/com/rtbishop/look4sat/core/domain/model/LatestRelease.kt

@@ -0,0 +1,9 @@
+package com.rtbishop.look4sat.core.domain.model
+
+/** Latest release info fetched from the fork's GitHub releases API. */
+data class LatestRelease(
+    val versionTag: String, // e.g. "v4.4.6-ba7opf.6"
+    val title: String,      // release name, may be empty
+    val body: String,       // release notes / update description
+    val apkUrl: String?     // first .apk asset download URL, null if absent
+)

core/domain/src/main/java/com/rtbishop/look4sat/core/domain/repository/IMainContainer.kt

@@ -31,6 +31,7 @@ interface IMainContainer {
     val satelliteRepo: ISatelliteRepo
     val databaseRepo: IDatabaseRepo
     val amSatRepo: IAmSatRepository
+    val updateRepo: IUpdateRepository
     val radioTrackingService: IRadioTrackingService
     val mutualPassData: StateFlow<MutualPassData>
     fun setMutualPassData(data: MutualPassData)

core/domain/src/main/java/com/rtbishop/look4sat/core/domain/repository/IUpdateRepository.kt

@@ -0,0 +1,12 @@
+package com.rtbishop.look4sat.core.domain.repository
+
+import com.rtbishop.look4sat.core.domain.model.LatestRelease
+import java.io.File
+
+interface IUpdateRepository {
+    /** Fetch the latest release of the fork repo from GitHub; null on failure. */
+    suspend fun getLatestRelease(): LatestRelease?
+
+    /** Download the release APK from [url] into [dest]; true on success. */
+    suspend fun downloadApk(url: String, dest: File): Boolean
+}

core/domain/src/main/java/com/rtbishop/look4sat/core/domain/utility/VersionComparator.kt

@@ -0,0 +1,44 @@
+package com.rtbishop.look4sat.core.domain.utility
+
+/**
+ * Compares two version strings of the form "<major>.<minor>.<patch>[-<build>]" used by the
+ * BA7OPF fork releases (e.g. "4.4.6-ba7opf.6" or "v4.4.6-ba7opf.7").
+ *
+ * The comparison is done on the numeric version segments first; when the base versions are
+ * equal, the trailing build number (if any) decides. This lets a "4.4.6-ba7opf.7" release be
+ * detected as newer than "4.4.6-ba7opf.6" while "4.5.0" trumps any "4.4.x" build.
+ */
+object VersionComparator {
+
+    /** True when [candidate] is a newer version than [current]. */
+    fun isNewer(candidate: String, current: String): Boolean {
+        val cand = parse(candidate)
+        val curr = parse(current)
+        val maxLen = maxOf(cand.first.size, curr.first.size)
+        for (i in 0 until maxLen) {
+            val c = cand.first.getOrElse(i) { 0 }
+            val k = curr.first.getOrElse(i) { 0 }
+            if (c != k) return c > k
+        }
+        return cand.second > curr.second
+    }
+
+    /**
+     * Parses a version string into (numeric base segments, trailing build number).
+     * "v4.4.6-ba7opf.7" -> ([4,4,6], 7); "4.4.6" -> ([4,4,6], 0); "4.4.6-ba7opf" -> ([4,4,6], 0).
+     */
+    fun parse(version: String): Pair<List<Int>, Int> {
+        val cleaned = version.trim().removePrefix("v")
+        val dashIndex = cleaned.indexOf('-')
+        val basePart = if (dashIndex >= 0) cleaned.substring(0, dashIndex) else cleaned
+        val suffixPart = if (dashIndex >= 0) cleaned.substring(dashIndex + 1) else ""
+        val base = basePart.split('.').mapNotNull { it.toIntOrNull() }
+        // The build number is the trailing numeric segment of the suffix (e.g. "ba7opf.7" -> 7).
+        val build = suffixPart
+            .split('.')
+            .lastOrNull()
+            ?.toIntOrNull()
+            ?: 0
+        return base to build
+    }
+}

core/domain/src/test/java/com/rtbishop/look4sat/core/domain/VersionComparatorTest.kt

@@ -0,0 +1,48 @@
+package com.rtbishop.look4sat.core.domain
+
+import com.rtbishop.look4sat.core.domain.utility.VersionComparator
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+class VersionComparatorTest {
+
+    @Test
+    fun `newer build number wins when base version equal`() {
+        assertTrue(VersionComparator.isNewer("4.4.6-ba7opf.7", "4.4.6-ba7opf.6"))
+        assertTrue(VersionComparator.isNewer("v4.4.6-ba7opf.6", "4.4.6-ba7opf.5"))
+    }
+
+    @Test
+    fun `newer base version wins regardless of build number`() {
+        assertTrue(VersionComparator.isNewer("4.5.0", "4.4.6-ba7opf.99"))
+        assertTrue(VersionComparator.isNewer("4.4.7-ba7opf.1", "4.4.6-ba7opf.99"))
+    }
+
+    @Test
+    fun `older versions are not newer`() {
+        assertFalse(VersionComparator.isNewer("4.4.6-ba7opf.5", "4.4.6-ba7opf.6"))
+        assertFalse(VersionComparator.isNewer("4.4.5", "4.4.6-ba7opf.1"))
+        assertFalse(VersionComparator.isNewer("4.4.6-ba7opf.6", "4.4.6-ba7opf.6"))
+    }
+
+    @Test
+    fun `v prefix is ignored`() {
+        assertTrue(VersionComparator.isNewer("v4.4.7", "4.4.6"))
+        assertFalse(VersionComparator.isNewer("v4.4.6", "4.4.6-ba7opf.1"))
+    }
+
+    @Test
+    fun `non numeric suffix without number treated as zero build`() {
+        assertTrue(VersionComparator.isNewer("4.4.6-ba7opf.1", "4.4.6-ba7opf"))
+        assertFalse(VersionComparator.isNewer("4.4.6-ba7opf", "4.4.6-ba7opf.1"))
+    }
+
+    @Test
+    fun `parse extracts base and build number`() {
+        assertEquals(listOf(4, 4, 6) to 7, VersionComparator.parse("v4.4.6-ba7opf.7"))
+        assertEquals(listOf(4, 4, 6) to 0, VersionComparator.parse("4.4.6"))
+        assertEquals(listOf(4, 4, 6) to 0, VersionComparator.parse("4.4.6-ba7opf"))
+    }
+}

core/presentation/src/main/res/values-zh/strings.xml

@@ -251,5 +251,17 @@
     <string name="mutual_open_radar">查看雷达</string>
     <string name="mutual_station_a">站点A</string>
     <string name="mutual_station_b">站点B</string>
+    <string name="update_check_title">检查更新</string>
+    <string name="update_check_button">检查更新</string>
+    <string name="update_check_current">当前版本：%s</string>
+    <string name="update_check_latest">最新版本：%s</string>
+    <string name="update_check_up_to_date">已是最新版本</string>
+    <string name="update_check_available">发现新版本</string>
+    <string name="update_check_release_notes">更新内容</string>
+    <string name="update_check_download">下载并安装</string>
+    <string name="update_check_downloading">正在下载…</string>
+    <string name="update_check_error">检查更新失败，请检查网络连接。</string>
+    <string name="update_check_download_error">下载失败，请重试。</string>
+    <string name="update_check_no_apk">该版本未附带 APK 安装包。</string>
 
 </resources>

core/presentation/src/main/res/values/strings.xml

@@ -286,5 +286,17 @@
     <string name="mutual_open_radar">Open Radar</string>
     <string name="mutual_station_a">Station A</string>
     <string name="mutual_station_b">Station B</string>
+    <string name="update_check_title">Check for updates</string>
+    <string name="update_check_button">Check for updates</string>
+    <string name="update_check_current">Current version: %s</string>
+    <string name="update_check_latest">Latest version: %s</string>
+    <string name="update_check_up_to_date">You are up to date</string>
+    <string name="update_check_available">New version available</string>
+    <string name="update_check_release_notes">Release notes</string>
+    <string name="update_check_download">Download &amp; install</string>
+    <string name="update_check_downloading">Downloading…</string>
+    <string name="update_check_error">Failed to check for updates. Check your connection.</string>
+    <string name="update_check_download_error">Download failed. Try again.</string>
+    <string name="update_check_no_apk">No APK attached to this release.</string>
 
 </resources>

feature/settings/src/main/java/com/rtbishop/look4sat/feature/settings/SettingsScreen.kt

@@ -82,13 +82,25 @@ import java.util.Locale
 fun SettingsDestination() {
     val context = LocalContext.current
     val container = (context.applicationContext as IContainerProvider).getMainContainer()
-    val viewModel: SettingsViewModel = viewModel(factory = SettingsViewModel.factory(container))
+    val viewModel: SettingsViewModel = viewModel(factory = SettingsViewModel.factory(container, context))
     val uiState by viewModel.uiState.collectAsStateWithLifecycle()
     SettingsScreen(uiState, viewModel::onAction)
 }
 
 @Composable
 private fun SettingsScreen(uiState: SettingsState, onAction: (SettingsAction) -> Unit) {
+    var showUpdateChecker by rememberSaveable { mutableStateOf(false) }
+    if (showUpdateChecker) {
+        UpdateCheckerScreen(
+            currentVersion = uiState.appVersionName,
+            state = uiState.updateChecker,
+            onBack = { showUpdateChecker = false },
+            onCheck = { onAction(SettingsAction.CheckForUpdate) },
+            onDownload = { onAction(SettingsAction.DownloadUpdate) },
+            onConsumeApk = { onAction(SettingsAction.ConsumeDownloadedApk) }
+        )
+        return
+    }
     val dialogs = rememberDialogVisibility()
     val pendingCustomSourcesGrant = remember { mutableStateOf<(() -> Unit)?>(null) }
     val pendingCustomSourcesDeny = remember { mutableStateOf<(() -> Unit)?>(null) }
@@ -128,11 +140,19 @@ private fun SettingsScreen(uiState: SettingsState, onAction: (SettingsAction) ->
         DataSourcesDialog(
             satelliteUrls = uiState.dataSourcesSettings.satelliteUrls,
             transceiversUrls = uiState.dataSourcesSettings.transceiversUrls,
+            satelliteEnabled = uiState.dataSourcesSettings.satelliteEnabled,
+            transceiversEnabled = uiState.dataSourcesSettings.transceiversEnabled,
+            statusCodes = uiState.dataSourcesStatus,
             onImportTle = { permissions.launchTleImport(); dialogs.dataSources = false },
             onImportTransceivers = { permissions.launchTransceiverImport(); dialogs.dataSources = false },
             onDismiss = { dialogs.dataSources = false },
-            onSave = { satUrls, txUrls ->
+            onSave = { satUrls, txUrls, satEnabled, txEnabled ->
-                val newSettings = DataSourcesSettings(satelliteUrls = satUrls, transceiversUrls = txUrls)
+                val newSettings = DataSourcesSettings(
+                    satelliteUrls = satUrls,
+                    transceiversUrls = txUrls,
+                    satelliteEnabled = satEnabled,
+                    transceiversEnabled = txEnabled
+                )
                 if (newSettings != uiState.dataSourcesSettings) onAction(SettingsAction.UpdateDataSources(newSettings))
                 onAction(SettingsAction.UpdateFromWeb)
             }
@@ -287,6 +307,13 @@ private fun SettingsScreen(uiState: SettingsState, onAction: (SettingsAction) ->
             }
             item { OtherCard(uiState.otherSettings, onAction) }
             item { CardCredits() }
+            item(span = { GridItemSpan(maxLineSpan) }) {
+                CardButton(
+                    onClick = { showUpdateChecker = true },
+                    text = stringResource(R.string.update_check_button),
+                    modifier = Modifier.fillMaxWidth()
+                )
+            }
         }
     }
 }

feature/settings/src/main/java/com/rtbishop/look4sat/feature/settings/SettingsState.kt

@@ -18,10 +18,12 @@
 package com.rtbishop.look4sat.feature.settings
 
 import com.rtbishop.look4sat.core.domain.model.DataSourcesSettings
+import com.rtbishop.look4sat.core.domain.model.LatestRelease
 import com.rtbishop.look4sat.core.domain.model.OtherSettings
 import com.rtbishop.look4sat.core.domain.model.RCSettings
 import com.rtbishop.look4sat.core.domain.model.RadioControlSettings
 import com.rtbishop.look4sat.core.domain.predict.GeoPos
+import java.io.File
 
 data class PositionSettings(
     val isUpdating: Boolean, val stationPos: GeoPos, val messageResId: Int
@@ -34,6 +36,15 @@ data class DataSettings(
     val timestamp: Long
 )
 
+data class UpdateCheckerState(
+    val isChecking: Boolean = false,
+    val release: LatestRelease? = null,
+    val hasUpdate: Boolean = false,
+    val isDownloading: Boolean = false,
+    val apkFile: File? = null,
+    val errorResId: Int? = null
+)
+
 data class SettingsState(
     val appVersionName: String,
     val positionSettings: PositionSettings,
@@ -41,7 +52,9 @@ data class SettingsState(
     val otherSettings: OtherSettings,
     val rcSettings: RCSettings,
     val radioControlSettings: RadioControlSettings,
-    val dataSourcesSettings: DataSourcesSettings
+    val dataSourcesSettings: DataSourcesSettings,
+    val dataSourcesStatus: Map<String, Int> = emptyMap(),
+    val updateChecker: UpdateCheckerState = UpdateCheckerState()
 )
 
 sealed interface SettingsAction {
@@ -72,6 +85,11 @@ sealed interface SettingsAction {
     // Data sources
     data class UpdateDataSources(val settings: DataSourcesSettings) : SettingsAction
 
+    // Update checker
+    data object CheckForUpdate : SettingsAction
+    data object DownloadUpdate : SettingsAction
+    data object ConsumeDownloadedApk : SettingsAction
+
     // System
     data class ShowToast(val message: String) : SettingsAction
 }

feature/settings/src/main/java/com/rtbishop/look4sat/feature/settings/SettingsViewModel.kt

@@ -17,6 +17,7 @@
  */
 package com.rtbishop.look4sat.feature.settings
 
+import android.content.Context
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import androidx.lifecycle.viewmodel.initializer
@@ -24,16 +25,21 @@ import androidx.lifecycle.viewmodel.viewModelFactory
 import com.rtbishop.look4sat.core.domain.repository.IDatabaseRepo
 import com.rtbishop.look4sat.core.domain.repository.IMainContainer
 import com.rtbishop.look4sat.core.domain.repository.ISettingsRepo
+import com.rtbishop.look4sat.core.domain.repository.IUpdateRepository
 import com.rtbishop.look4sat.core.domain.usecase.IShowToast
+import com.rtbishop.look4sat.core.domain.utility.VersionComparator
 import com.rtbishop.look4sat.core.presentation.R
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.launch
+import java.io.File
 
 class SettingsViewModel(
     private val databaseRepo: IDatabaseRepo,
     private val settingsRepo: ISettingsRepo,
+    private val updateRepo: IUpdateRepository,
+    private val apkFile: File,
     private val showToast: IShowToast
 ) : ViewModel() {
 
@@ -47,7 +53,8 @@ class SettingsViewModel(
             otherSettings = settingsRepo.otherSettings.value,
             rcSettings = settingsRepo.rcSettings.value,
             radioControlSettings = settingsRepo.radioControlSettings.value,
-            dataSourcesSettings = settingsRepo.dataSourcesSettings.value
+            dataSourcesSettings = settingsRepo.dataSourcesSettings.value,
+            dataSourcesStatus = settingsRepo.dataSourcesStatus.value
         )
     )
 
@@ -90,6 +97,11 @@ class SettingsViewModel(
                 _uiState.update { it.copy(dataSourcesSettings = settings) }
             }
         }
+        viewModelScope.launch {
+            settingsRepo.dataSourcesStatus.collect { status ->
+                _uiState.update { it.copy(dataSourcesStatus = status) }
+            }
+        }
         viewModelScope.launch {
             settingsRepo.radioControlSettings.collect { settings ->
                 _uiState.update { it.copy(radioControlSettings = settings) }
@@ -125,11 +137,59 @@ class SettingsViewModel(
             is SettingsAction.UpdateRC -> settingsRepo.updateRCSettings(action.settings)
             is SettingsAction.UpdateRadioControl -> settingsRepo.updateRadioControlSettings(action.settings)
             is SettingsAction.UpdateDataSources -> settingsRepo.updateDataSourcesSettings(action.settings)
+            // Update checker
+            SettingsAction.CheckForUpdate -> checkForUpdate()
+            SettingsAction.DownloadUpdate -> downloadUpdate()
+            SettingsAction.ConsumeDownloadedApk -> consumeDownloadedApk()
             // System
             is SettingsAction.ShowToast -> showToast(action.message)
         }
     }
 
+    // region Update checker
+
+    private fun checkForUpdate() {
+        _uiState.update { it.copy(updateChecker = it.updateChecker.copy(isChecking = true, errorResId = null)) }
+        viewModelScope.launch {
+            val release = updateRepo.getLatestRelease()
+            val hasUpdate = release != null &&
+                VersionComparator.isNewer(release.versionTag, settingsRepo.appVersionName)
+            _uiState.update {
+                it.copy(
+                    updateChecker = it.updateChecker.copy(
+                        isChecking = false,
+                        release = release,
+                        hasUpdate = hasUpdate,
+                        errorResId = if (release == null) R.string.update_check_error else null
+                    )
+                )
+            }
+        }
+    }
+
+    private fun downloadUpdate() {
+        val url = _uiState.value.updateChecker.release?.apkUrl ?: return
+        _uiState.update { it.copy(updateChecker = it.updateChecker.copy(isDownloading = true, errorResId = null)) }
+        viewModelScope.launch {
+            val success = updateRepo.downloadApk(url, apkFile)
+            _uiState.update {
+                it.copy(
+                    updateChecker = it.updateChecker.copy(
+                        isDownloading = false,
+                        apkFile = if (success) apkFile else null,
+                        errorResId = if (success) null else R.string.update_check_download_error
+                    )
+                )
+            }
+        }
+    }
+
+    private fun consumeDownloadedApk() {
+        _uiState.update { it.copy(updateChecker = it.updateChecker.copy(apkFile = null)) }
+    }
+
+    // endregion
+
     // region Position helpers — consolidated from 3 near-identical functions
 
     private fun setGpsPosition() {
@@ -201,11 +261,13 @@ class SettingsViewModel(
 
     companion object {
 
-        fun factory(container: IMainContainer) = viewModelFactory {
+        fun factory(container: IMainContainer, context: Context) = viewModelFactory {
             initializer {
                 SettingsViewModel(
                     databaseRepo = container.databaseRepo,
                     settingsRepo = container.settingsRepo,
+                    updateRepo = container.updateRepo,
+                    apkFile = File(context.cacheDir, "look4sat-update.apk"),
                     showToast = container.provideShowToast()
                 )
             }

feature/settings/src/main/java/com/rtbishop/look4sat/feature/settings/UpdateCheckerScreen.kt

@@ -0,0 +1,216 @@
+/*
+ * Look4Sat. Amateur radio satellite tracker and pass predictor.
+ * Copyright (C) 2019-2026 Arty Bishop and contributors.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.rtbishop.look4sat.feature.settings
+
+import android.content.Intent
+import android.net.Uri
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
+import androidx.compose.material3.CircularProgressIndicator
+import androidx.compose.material3.ElevatedCard
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.rotate
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.res.painterResource
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextAlign
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.unit.sp
+import androidx.core.content.FileProvider
+import com.rtbishop.look4sat.core.presentation.CardButton
+import com.rtbishop.look4sat.core.presentation.IconCard
+import com.rtbishop.look4sat.core.presentation.R
+import com.rtbishop.look4sat.core.presentation.ScreenColumn
+import com.rtbishop.look4sat.core.presentation.TopBar
+
+@Composable
+fun UpdateCheckerScreen(
+    currentVersion: String,
+    state: UpdateCheckerState,
+    onBack: () -> Unit,
+    onCheck: () -> Unit,
+    onDownload: () -> Unit,
+    onConsumeApk: () -> Unit
+) {
+    val context = LocalContext.current
+
+    // When the APK finishes downloading, hand it to the system installer.
+    LaunchedEffect(state.apkFile) {
+        val file = state.apkFile ?: return@LaunchedEffect
+        val uri: Uri = FileProvider.getUriForFile(context, "${context.packageName}.fileprovider", file)
+        val intent = Intent(Intent.ACTION_VIEW).apply {
+            setDataAndType(uri, "application/vnd.android.package-archive")
+            addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
+            addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
+        }
+        context.startActivity(intent)
+        onConsumeApk()
+    }
+
+    ScreenColumn(
+        topBar = { isVerticalLayout ->
+            TopBar {
+                IconCard(
+                    action = onBack,
+                    resId = R.drawable.ic_arrow,
+                    modifier = Modifier.rotate(180f)
+                )
+                Text(
+                    text = stringResource(R.string.update_check_title),
+                    style = MaterialTheme.typography.titleMedium,
+                    modifier = Modifier.weight(1f)
+                )
+            }
+        }
+    ) {
+        Column(
+            verticalArrangement = Arrangement.spacedBy(10.dp),
+            modifier = Modifier
+                .fillMaxSize()
+                .padding(10.dp)
+        ) {
+            ElevatedCard(modifier = Modifier.fillMaxWidth()) {
+                Column(
+                    horizontalAlignment = Alignment.CenterHorizontally,
+                    modifier = Modifier
+                        .fillMaxWidth()
+                        .padding(horizontal = 12.dp, vertical = 10.dp)
+                ) {
+                    Text(
+                        text = stringResource(R.string.update_check_current, currentVersion),
+                        color = MaterialTheme.colorScheme.primary,
+                        fontWeight = FontWeight.Medium
+                    )
+                    Spacer(modifier = Modifier.height(8.dp))
+                    CardButton(
+                        onClick = onCheck,
+                        text = stringResource(R.string.update_check_button),
+                        modifier = Modifier.fillMaxWidth()
+                    )
+                }
+            }
+
+            when {
+                state.isChecking -> StatusRow(showSpinner = true)
+                state.errorResId != null -> StatusRow(showSpinner = false, message = stringResource(state.errorResId))
+                state.release == null -> Unit // not checked yet
+                !state.hasUpdate -> StatusRow(showSpinner = false, message = stringResource(R.string.update_check_up_to_date))
+                else -> ReleaseCard(
+                    state = state,
+                    onDownload = onDownload
+                )
+            }
+        }
+    }
+}
+
+@Composable
+private fun StatusRow(showSpinner: Boolean, message: String? = null) {
+    Row(
+        horizontalArrangement = Arrangement.Center,
+        verticalAlignment = Alignment.CenterVertically,
+        modifier = Modifier.fillMaxWidth()
+    ) {
+        if (showSpinner) {
+            CircularProgressIndicator(modifier = Modifier.size(20.dp))
+            Spacer(modifier = Modifier.width(8.dp))
+        }
+        if (message != null) {
+            Text(
+                text = message,
+                textAlign = TextAlign.Center,
+                color = MaterialTheme.colorScheme.onSurfaceVariant
+            )
+        }
+    }
+}
+
+@Composable
+private fun ReleaseCard(state: UpdateCheckerState, onDownload: () -> Unit) {
+    val release = state.release ?: return
+    ElevatedCard(modifier = Modifier.fillMaxWidth()) {
+        Column(
+            modifier = Modifier
+                .fillMaxWidth()
+                .padding(horizontal = 12.dp, vertical = 10.dp)
+        ) {
+            Text(
+                text = stringResource(R.string.update_check_available),
+                color = MaterialTheme.colorScheme.primary,
+                fontWeight = FontWeight.Medium
+            )
+            Spacer(modifier = Modifier.height(4.dp))
+            Text(
+                text = stringResource(R.string.update_check_latest, release.versionTag.removePrefix("v")),
+                fontSize = 14.sp
+            )
+            if (release.title.isNotBlank() && release.title != release.versionTag) {
+                Text(text = release.title, fontSize = 12.sp, color = MaterialTheme.colorScheme.onSurfaceVariant)
+            }
+            if (release.body.isNotBlank()) {
+                Spacer(modifier = Modifier.height(8.dp))
+                Text(
+                    text = stringResource(R.string.update_check_release_notes),
+                    fontWeight = FontWeight.Medium,
+                    fontSize = 13.sp
+                )
+                Text(
+                    text = release.body,
+                    fontSize = 12.sp,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant
+                )
+            }
+            Spacer(modifier = Modifier.height(10.dp))
+            when {
+                release.apkUrl == null -> Text(
+                    text = stringResource(R.string.update_check_no_apk),
+                    color = MaterialTheme.colorScheme.error,
+                    fontSize = 12.sp
+                )
+                state.isDownloading -> Row(
+                    horizontalArrangement = Arrangement.Center,
+                    verticalAlignment = Alignment.CenterVertically,
+                    modifier = Modifier.fillMaxWidth()
+                ) {
+                    CircularProgressIndicator(modifier = Modifier.size(18.dp))
+                    Spacer(modifier = Modifier.width(8.dp))
+                    Text(text = stringResource(R.string.update_check_downloading))
+                }
+                else -> CardButton(
+                    onClick = onDownload,
+                    text = stringResource(R.string.update_check_download),
+                    modifier = Modifier.fillMaxWidth()
+                )
+            }
+        }
+    }
+}