feat(window): implement window state persistence and restoration

composeApp/src/commonMain/kotlin/org/spotube/spotube/core/db/Database.kt

@@ -77,6 +77,12 @@ class Database(val paths: Paths) {
         )
     }
 
+    val windowStateDataStore: DataStore<Preferences> by lazy {
+        PreferenceDataStoreFactory.createWithPath(
+            produceFile = { "${paths.getApplicationDataDirPath()}/spotube_window.preferences_pb".toPath() }
+        )
+    }
+
     private companion object {
         /** Preference files written by previous launches; their presence means an upgrade. */
         val EXISTING_INSTALL_PROBE_FILES = listOf(
@@ -95,4 +101,5 @@ object DatabaseKeys {
     val AUDIO_PLAYER_QUEUE_STATE_KEY = stringPreferencesKey("audio_player_queue_state")
     val LOCAL_MEDIA_CACHE_STATE_KEY = stringPreferencesKey("local_media_cache_state")
     val LOCAL_MEDIA_LAST_SCAN_AT_KEY = longPreferencesKey("local_media_last_scan_at")
+    val WINDOW_STATE_KEY = stringPreferencesKey("window_state")
 }

composeApp/src/jvmMain/kotlin/org/spotube/spotube/core/di/Modules.jvm.kt

@@ -30,9 +30,12 @@ import org.koin.core.module.dsl.createdAtStart
 import org.koin.core.module.dsl.singleOf
 import org.koin.core.module.dsl.withOptions
 import org.koin.dsl.module
+import org.spotube.spotube.core.db.Database
+import org.spotube.spotube.core.window.WindowStateRepository
 
 actual val platformModules = module {
     singleOf(::Paths)
+    single { WindowStateRepository(get<Database>()) }
     single<AudioPlayerInterface> { AudioPlayer(Unit) }
     single<LocalMediaDiscoveryService> { JvmLocalMediaDiscoveryService() }
     single<ShareService> { JvmShareService() }

composeApp/src/jvmMain/kotlin/org/spotube/spotube/core/window/WindowStateRepository.kt

@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2026 Kingkor Roy Tirtho and Spotube Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+package org.spotube.spotube.core.window
+
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.DpSize
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.window.WindowPlacement
+import androidx.datastore.core.DataStore
+import androidx.datastore.preferences.core.Preferences
+import androidx.datastore.preferences.core.edit
+import kotlinx.coroutines.flow.first
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.json.Json
+import org.spotube.spotube.core.db.Database
+import org.spotube.spotube.core.db.DatabaseKeys
+
+/**
+ * What survives a restart: the last *normal* (floating) size, and whether the window was
+ * maximized. The size is kept while maximized so un-maximizing after a restart restores it.
+ */
+@Serializable
+data class PersistedWindowState(
+    val widthDp: Float,
+    val heightDp: Float,
+    val maximized: Boolean
+) {
+    val size: DpSize get() = DpSize(widthDp.dp, heightDp.dp)
+    val placement: WindowPlacement
+        get() = if (maximized) WindowPlacement.Maximized else WindowPlacement.Floating
+
+    companion object {
+        fun of(size: DpSize, placement: WindowPlacement) = PersistedWindowState(
+            widthDp = size.width.value,
+            heightDp = size.height.value,
+            maximized = placement == WindowPlacement.Maximized)
+    }
+}
+
+class WindowStateRepository internal constructor(private val dataStore: DataStore<Preferences>) {
+    constructor(database: Database) : this(database.windowStateDataStore)
+
+    private val json = Json { ignoreUnknownKeys = true }
+
+    /** Returns null when nothing was saved yet or the stored value is unreadable. */
+    suspend fun load(): PersistedWindowState? = runCatching {
+        val raw = dataStore.data.first()[DatabaseKeys.WINDOW_STATE_KEY] ?: return null
+        json.decodeFromString<PersistedWindowState>(raw)
+    }.getOrNull()
+
+    suspend fun save(state: PersistedWindowState) {
+        runCatching {
+            dataStore.edit { prefs ->
+                prefs[DatabaseKeys.WINDOW_STATE_KEY] = json.encodeToString(PersistedWindowState.serializer(), state)
+            }
+        }
+    }
+}
+
+/**
+ * Keeps a restored [size] usable: never smaller than [min], and never bigger than the
+ * available screen ([maxWidth] x [maxHeight]) so a size saved on a larger monitor can't open
+ * off-screen. A null max means the screen size is unknown, so only [min] is enforced.
+ */
+fun DpSize.coerceForScreen(
+    min: DpSize,
+    maxWidth: Dp?,
+    maxHeight: Dp?
+): DpSize {
+    val width = width.coerceAtLeast(min.width).let { if (maxWidth != null) it.coerceAtMost(maxOf(maxWidth, min.width)) else it }
+    val height = height.coerceAtLeast(min.height).let { if (maxHeight != null) it.coerceAtMost(maxOf(maxHeight, min.height)) else it }
+    return DpSize(width, height)
+}

composeApp/src/jvmMain/kotlin/org/spotube/spotube/main.kt

@@ -18,18 +18,37 @@
 package org.spotube.spotube
 
 import androidx.compose.runtime.CompositionLocalProvider
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.snapshotFlow
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.ExperimentalComposeUiApi
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.DpSize
+import androidx.compose.ui.unit.isSpecified
+import androidx.compose.ui.window.WindowPlacement
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.window.rememberWindowState
-import com.sun.jna.Library
-import com.sun.jna.Native
+import dev.nucleusframework.application.DecoratedWindow
+import dev.nucleusframework.application.NucleusBackend
+import dev.nucleusframework.application.nucleusApplication
+import dev.nucleusframework.window.tao.TaoScreenGeometry
+import io.github.vinceglb.filekit.FileKit
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.SupervisorJob
+import kotlinx.coroutines.FlowPreview
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.flow.debounce
+import kotlinx.coroutines.flow.onEach
+import kotlinx.coroutines.runBlocking
+import org.koin.core.component.KoinComponent
+import org.koin.core.component.get
 import org.spotube.spotube.core.di.initKoin
-import org.spotube.spotube.core.deeplink.ExternalUriHandler
+import org.spotube.spotube.core.i18n.AppLocaleProvider
 import org.spotube.spotube.core.newpipe.NewPipeDownloader
 import org.spotube.spotube.core.paths.Paths
 import org.spotube.spotube.core.systemtray.SystemTray
@@ -37,19 +56,11 @@ import org.spotube.spotube.core.systemtray.SystemTrayService
 import org.spotube.spotube.core.ui.component.LocalApplicationScope
 import org.spotube.spotube.core.ui.component.LocalWindowScope
 import org.spotube.spotube.core.ui.component.LocalWindowState
-import org.spotube.spotube.core.i18n.AppLocaleProvider
+import org.spotube.spotube.core.window.PersistedWindowState
+import org.spotube.spotube.core.window.WindowStateRepository
+import org.spotube.spotube.core.window.coerceForScreen
 import org.spotube.spotube.modules.settings.SettingsProvider
 import org.spotube.spotube.modules.settings.SupportedLanguages
-import dev.nucleusframework.application.DecoratedWindow
-import dev.nucleusframework.application.NucleusBackend
-import dev.nucleusframework.application.nucleusApplication
-import io.github.vinceglb.filekit.FileKit
-import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.SupervisorJob
-import kotlinx.coroutines.cancel
-import org.koin.core.component.KoinComponent
-import org.koin.core.component.get
 
 object KoinPathsProvider : KoinComponent {
     val paths: Paths get() = get()
@@ -58,9 +69,65 @@ object KoinPathsProvider : KoinComponent {
 private object KoinServicesProvider : KoinComponent {
     val systemTrayService: SystemTrayService get() = get()
     val settingsProvider: SettingsProvider get() = get()
+    val windowStateRepository: WindowStateRepository get() = get()
 }
 
-@OptIn(ExperimentalComposeUiApi::class)
+private const val WINDOW_SCREEN_FRACTION = 0.85f
+private const val WINDOW_ASPECT_RATIO = 16f / 10f
+private val MAX_WINDOW_WIDTH = 1440.dp
+private val MAX_WINDOW_HEIGHT = 960.dp
+private val MIN_WINDOW_SIZE = DpSize(800.dp, 500.dp)
+private const val WINDOW_STATE_SAVE_DEBOUNCE_MS = 500L
+
+/** Largest [WINDOW_ASPECT_RATIO] size that fits inside [maxWidth] x [maxHeight]. */
+private fun fitAspectRatio(maxWidth: Dp, maxHeight: Dp): DpSize {
+    val width = minOf(maxWidth, maxHeight * WINDOW_ASPECT_RATIO)
+    return DpSize(width, width / WINDOW_ASPECT_RATIO)
+}
+
+/**
+ * A 16:10 window that fits in 85% of the primary monitor's work area (screen minus
+ * taskbar/dock), capped at 1440x960.
+ *
+ * Uses Nucleus' Tao screen geometry rather than AWT, which doesn't exist on the Tao runtime.
+ * The work area is in physical pixels, so it's divided by the monitor scale factor to get dp.
+ * Falls back to the cap box when the platform bridge can't report a monitor.
+ */
+private fun initialWindowSize(): DpSize {
+    val workArea = availableScreenSize()
+        ?: return fitAspectRatio(MAX_WINDOW_WIDTH, MAX_WINDOW_HEIGHT)
+
+    return fitAspectRatio(
+        maxWidth = (workArea.width * WINDOW_SCREEN_FRACTION).coerceAtMost(MAX_WINDOW_WIDTH),
+        maxHeight = (workArea.height * WINDOW_SCREEN_FRACTION).coerceAtMost(MAX_WINDOW_HEIGHT))
+}
+
+/** The primary monitor's work area in dp, or null when the platform bridge can't report it. */
+private fun availableScreenSize(): DpSize? {
+    val workArea = runCatching { TaoScreenGeometry.primaryMonitorWorkAreaPx() }.getOrNull()
+    if (workArea == null || workArea.size < 4 || workArea[2] <= 0 || workArea[3] <= 0) return null
+
+    val scale = runCatching { TaoScreenGeometry.primaryMonitorScaleFactor() }
+        .getOrDefault(1f)
+        .takeIf { it > 0f } ?: 1f
+
+    return DpSize((workArea[2] / scale).dp, (workArea[3] / scale).dp)
+}
+
+/** Saved size if there is one (clamped to this screen), otherwise the default for a first launch. */
+private fun restoreWindowState(saved: PersistedWindowState?): PersistedWindowState {
+    if (saved == null || saved.widthDp <= 0f || saved.heightDp <= 0f) {
+        return PersistedWindowState.of(initialWindowSize(), WindowPlacement.Floating)
+    }
+    val screen = availableScreenSize()
+    val size = saved.size.coerceForScreen(
+        min = MIN_WINDOW_SIZE,
+        maxWidth = screen?.width,
+        maxHeight = screen?.height)
+    return PersistedWindowState.of(size, saved.placement)
+}
+
+@OptIn(ExperimentalComposeUiApi::class, FlowPreview::class)
 fun main() {
     FileKit.init(appId = "org.spotube.spotube")
     initKoin()
@@ -68,10 +135,28 @@ fun main() {
     val appScope = CoroutineScope(SupervisorJob() + Dispatchers.Default)
 
     nucleusApplication(backend = NucleusBackend.Tao) {
-        val windowState = rememberWindowState(
-            width = 1080.dp,
-            height = 720.dp
-        )
+        val windowStateRepository = remember { KoinServicesProvider.windowStateRepository }
+        // Needed before the window is created, so the one-time read at startup is blocking
+        val restored = remember { restoreWindowState(runBlocking { windowStateRepository.load() }) }
+        val windowState = rememberWindowState(placement = restored.placement, size = restored.size)
+
+        // The size to restore into when un-maximizing; only floating windows update it
+        var normalSize by remember { mutableStateOf(restored.size) }
+        val currentWindowState = { PersistedWindowState.of(normalSize, windowState.placement) }
+        // Exit paths can't wait on a coroutine that is about to be cancelled
+        val persistWindowStateBlocking = { runBlocking { windowStateRepository.save(currentWindowState()) } }
+
+        LaunchedEffect(windowState) {
+            snapshotFlow { windowState.placement to windowState.size }
+                .onEach { (placement, size) ->
+                    if (placement == WindowPlacement.Floating && size.isSpecified &&
+                        size.width > 0.dp && size.height > 0.dp) {
+                        normalSize = size
+                    }
+                }
+                .debounce(WINDOW_STATE_SAVE_DEBOUNCE_MS)
+                .collect { windowStateRepository.save(currentWindowState()) }
+        }
 
         val settingsProvider = KoinServicesProvider.settingsProvider
         val settings by settingsProvider.settingsState.collectAsState(initial = null)
@@ -83,6 +168,7 @@ fun main() {
 
         val onToggleWindowVisibility = { isWindowVisible = !isWindowVisible }
         val onExit = {
+            persistWindowStateBlocking()
             trayService.close()
             appScope.cancel()
             exitApplication()
@@ -96,7 +182,8 @@ fun main() {
                 SystemTray(
                     isWindowVisible = isWindowVisible,
                     onToggleWindowVisibility = onToggleWindowVisibility,
-                    onExit = onExit)
+                    onExit = onExit
+                )
             }
         }
 
@@ -106,13 +193,15 @@ fun main() {
                 if (minimizeToTray) {
                     isWindowVisible = false
                 } else {
+                    persistWindowStateBlocking()
                     trayService.close()
                     appScope.cancel()
                     exitApplication()
                 }
             },
             title = "Spotube",
-            visible = isWindowVisible) {
+            visible = isWindowVisible
+        ) {
             CompositionLocalProvider(
                 LocalApplicationScope provides this@nucleusApplication,
                 LocalWindowScope provides this@DecoratedWindow,

composeApp/src/jvmTest/kotlin/org/spotube/spotube/core/window/WindowStateRepositoryTest.kt

@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2026 Kingkor Roy Tirtho and Spotube Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package org.spotube.spotube.core.window
+
+import androidx.compose.ui.unit.DpSize
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.window.WindowPlacement
+import androidx.datastore.preferences.core.PreferenceDataStoreFactory
+import kotlinx.coroutines.runBlocking
+import okio.Path.Companion.toPath
+import java.io.File
+import java.nio.file.Files
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertNull
+
+class WindowStateRepositoryTest {
+    private fun repository(): WindowStateRepository {
+        val dir = Files.createTempDirectory("window-state-test").toFile()
+        val file = File(dir, "window.preferences_pb")
+        return WindowStateRepository(
+            PreferenceDataStoreFactory.createWithPath(produceFile = { file.absolutePath.toPath() }))
+    }
+
+    @Test
+    fun missingValueLoadsNull() = runBlocking {
+        assertNull(repository().load())
+    }
+
+    @Test
+    fun roundTripsNormalState() = runBlocking {
+        val store = repository()
+        store.save(PersistedWindowState.of(DpSize(1200.dp, 750.dp), WindowPlacement.Floating))
+
+        val loaded = store.load()!!
+        assertEquals(DpSize(1200.dp, 750.dp), loaded.size)
+        assertEquals(WindowPlacement.Floating, loaded.placement)
+    }
+
+    @Test
+    fun roundTripsMaximizedStateKeepingNormalSize() = runBlocking {
+        val store = repository()
+        store.save(PersistedWindowState.of(DpSize(1100.dp, 700.dp), WindowPlacement.Maximized))
+
+        val loaded = store.load()!!
+        assertEquals(WindowPlacement.Maximized, loaded.placement)
+        assertEquals(DpSize(1100.dp, 700.dp), loaded.size)
+    }
+
+    @Test
+    fun oversizedSavedSizeIsClampedToScreen() {
+        val clamped = DpSize(3000.dp, 2000.dp)
+            .coerceForScreen(DpSize(800.dp, 500.dp), maxWidth = 1800.dp, maxHeight = 1000.dp)
+        assertEquals(DpSize(1800.dp, 1000.dp), clamped)
+    }
+
+    @Test
+    fun tinySavedSizeIsRaisedToMinimum() {
+        val clamped = DpSize(100.dp, 100.dp)
+            .coerceForScreen(DpSize(800.dp, 500.dp), maxWidth = 1800.dp, maxHeight = 1000.dp)
+        assertEquals(DpSize(800.dp, 500.dp), clamped)
+    }
+
+    @Test
+    fun unknownScreenOnlyEnforcesMinimum() {
+        val clamped = DpSize(3000.dp, 2000.dp)
+            .coerceForScreen(DpSize(800.dp, 500.dp), maxWidth = null, maxHeight = null)
+        assertEquals(DpSize(3000.dp, 2000.dp), clamped)
+    }
+}