diff --git a/app/desktop/build.gradle.kts b/app/desktop/build.gradle.kts
index 8119be5..e442ccb 100644
--- a/app/desktop/build.gradle.kts
+++ b/app/desktop/build.gradle.kts
@@ -392,6 +392,19 @@ tasks.named<Copy>("processResources") {
  * (`bundleProxyForCurrentProcess is nil`). :run is therefore launched from a
  * FromChat.app wrapper so Notification Center sees `ru.fromchat.desktop`.
  */
+private fun Project.fromChatGradleDevDataDir(): String {
+    val variant = if (
+        gradle.startParameter.taskNames.any { it.contains("Release", ignoreCase = true) }
+    ) {
+        "release"
+    } else {
+        "beta"
+    }
+    return rootProject.layout.buildDirectory.get().asFile
+        .resolve("dev-data/$variant")
+        .absolutePath
+}
+
 fun JavaExec.configureFromChatDesktopJvm() {
     val javafxJars = classpath.files.filter { file ->
         javafxModules.any { module -> file.name.startsWith("javafx-$module-") }
@@ -416,6 +429,7 @@ fun JavaExec.configureFromChatDesktopJvm() {
             }
             addAll(
                 listOf(
+                    "-Dfromchat.dev.data.dir=${project.fromChatGradleDevDataDir()}",
                     "-Dapple.awt.enableTemplateImages=true",
                     "--module-path",
                     javafxJars.joinToString(File.pathSeparator) { it.absolutePath },
diff --git a/app/desktop/src/main/kotlin/ru/fromchat/desktop/DatabaseLockGate.kt b/app/desktop/src/main/kotlin/ru/fromchat/desktop/DatabaseLockGate.kt
new file mode 100644
index 0000000..b2286eb
--- /dev/null
+++ b/app/desktop/src/main/kotlin/ru/fromchat/desktop/DatabaseLockGate.kt
@@ -0,0 +1,56 @@
+package ru.fromchat.desktop
+
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.isActive
+import kotlinx.coroutines.launch
+import ru.fromchat.Logger
+import ru.fromchat.api.local.db.store.MessageDatabasePaths
+import kotlin.time.Duration.Companion.milliseconds
+
+object DatabaseLockGate {
+    private val _blocked = MutableStateFlow(false)
+    val blocked: StateFlow<Boolean> = _blocked.asStateFlow()
+
+    private val _processes = MutableStateFlow<List<LockingProcessInfo>>(emptyList())
+    val processes: StateFlow<List<LockingProcessInfo>> = _processes.asStateFlow()
+
+    private var monitorJob: Job? = null
+
+    fun startMonitoring(scope: CoroutineScope, onUnlocked: () -> Unit) {
+        monitorJob?.cancel()
+        monitorJob = scope.launch {
+            var everBlocked = false
+            var bootstrapDelivered = false
+            while (isActive) {
+                val locked = MessageDatabasePaths.isDatabaseLocked()
+                if (locked) {
+                    everBlocked = true
+                    _blocked.value = true
+                    _processes.value = DatabaseLockingProcessResolver.findLockingProcesses(
+                        MessageDatabasePaths.lockTargetFiles(),
+                    )
+                } else {
+                    if (_blocked.value) {
+                        Logger.i("DatabaseLockGate", "database unlocked; resuming startup")
+                    }
+                    _blocked.value = false
+                    _processes.value = emptyList()
+                    if (!bootstrapDelivered) {
+                        bootstrapDelivered = true
+                        onUnlocked()
+                    }
+                    if (!everBlocked) return@launch
+                    if (!_blocked.value) return@launch
+                }
+                delay(750.milliseconds)
+            }
+        }
+    }
+
+    fun killProcess(pid: Long): Boolean = DatabaseLockingProcessResolver.killProcess(pid)
+}
diff --git a/app/desktop/src/main/kotlin/ru/fromchat/desktop/DatabaseLockModels.kt b/app/desktop/src/main/kotlin/ru/fromchat/desktop/DatabaseLockModels.kt
new file mode 100644
index 0000000..4f460de
--- /dev/null
+++ b/app/desktop/src/main/kotlin/ru/fromchat/desktop/DatabaseLockModels.kt
@@ -0,0 +1,11 @@
+package ru.fromchat.desktop
+
+import androidx.compose.ui.graphics.ImageBitmap
+
+data class LockingProcessInfo(
+    val pid: Long,
+    val name: String,
+    val description: String?,
+    val executablePath: String?,
+    val icon: ImageBitmap?,
+)
diff --git a/app/desktop/src/main/kotlin/ru/fromchat/desktop/DatabaseLockWindow.kt b/app/desktop/src/main/kotlin/ru/fromchat/desktop/DatabaseLockWindow.kt
new file mode 100644
index 0000000..7237421
--- /dev/null
+++ b/app/desktop/src/main/kotlin/ru/fromchat/desktop/DatabaseLockWindow.kt
@@ -0,0 +1,210 @@
+package ru.fromchat.desktop
+
+import androidx.compose.foundation.Image
+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.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.foundation.layout.widthIn
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Warning
+import androidx.compose.material3.Button
+import androidx.compose.material3.CircularProgressIndicator
+import androidx.compose.material3.Icon
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedButton
+import androidx.compose.material3.Surface
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.window.Window
+import androidx.compose.ui.window.rememberWindowState
+import org.jetbrains.compose.resources.stringResource
+import ru.fromchat.Res
+import ru.fromchat.desktop_database_locked_kill
+import ru.fromchat.desktop_database_locked_pid
+import ru.fromchat.desktop_database_locked_message
+import ru.fromchat.desktop_database_locked_title
+import ru.fromchat.desktop_database_locked_unknown_process
+import ru.fromchat.desktop_database_locked_waiting
+import ru.fromchat.desktop_quit
+import ru.fromchat.ui.FromChatTheme
+
+@Composable
+fun DatabaseLockWindow(
+    processes: List<LockingProcessInfo>,
+    onKillProcess: (Long) -> Unit,
+    onQuit: () -> Unit,
+) {
+    val title = stringResource(Res.string.desktop_database_locked_title)
+    val windowState = rememberWindowState(width = 520.dp, height = 420.dp)
+    Window(
+        onCloseRequest = onQuit,
+        title = title,
+        state = windowState,
+        resizable = false,
+        alwaysOnTop = true,
+    ) {
+        FromChatTheme(darkTheme = desktopAppDarkTheme()) {
+            Surface(color = MaterialTheme.colorScheme.background) {
+                DatabaseLockContent(
+                    processes = processes,
+                    onKillProcess = onKillProcess,
+                    onQuit = onQuit,
+                )
+            }
+        }
+    }
+}
+
+@Composable
+private fun DatabaseLockContent(
+    processes: List<LockingProcessInfo>,
+    onKillProcess: (Long) -> Unit,
+    onQuit: () -> Unit,
+) {
+    val unknownProcess = stringResource(Res.string.desktop_database_locked_unknown_process)
+    Column(
+        modifier = Modifier
+            .widthIn(min = 480.dp, max = 520.dp)
+            .padding(24.dp),
+        verticalArrangement = Arrangement.spacedBy(16.dp),
+    ) {
+        Row(
+            verticalAlignment = Alignment.CenterVertically,
+            horizontalArrangement = Arrangement.spacedBy(12.dp),
+        ) {
+            Icon(
+                imageVector = Icons.Default.Warning,
+                contentDescription = null,
+                tint = MaterialTheme.colorScheme.error,
+                modifier = Modifier.size(32.dp),
+            )
+            Text(
+                text = stringResource(Res.string.desktop_database_locked_title),
+                style = MaterialTheme.typography.headlineSmall,
+            )
+        }
+        Text(
+            text = stringResource(Res.string.desktop_database_locked_message),
+            style = MaterialTheme.typography.bodyMedium,
+            color = MaterialTheme.colorScheme.onSurfaceVariant,
+        )
+        if (processes.isEmpty()) {
+            LockingProcessRow(
+                process = LockingProcessInfo(
+                    pid = -1L,
+                    name = unknownProcess,
+                    description = null,
+                    executablePath = null,
+                    icon = null,
+                ),
+                killEnabled = false,
+                onKill = {},
+            )
+        } else {
+            processes.forEach { process ->
+                LockingProcessRow(
+                    process = process,
+                    killEnabled = process.pid > 0L,
+                    onKill = { onKillProcess(process.pid) },
+                )
+            }
+        }
+        Row(
+            modifier = Modifier.fillMaxWidth(),
+            verticalAlignment = Alignment.CenterVertically,
+            horizontalArrangement = Arrangement.spacedBy(8.dp),
+        ) {
+            CircularProgressIndicator(modifier = Modifier.size(18.dp), strokeWidth = 2.dp)
+            Text(
+                text = stringResource(Res.string.desktop_database_locked_waiting),
+                style = MaterialTheme.typography.bodySmall,
+                color = MaterialTheme.colorScheme.onSurfaceVariant,
+            )
+        }
+        Spacer(modifier = Modifier.height(4.dp))
+        Row(
+            modifier = Modifier.fillMaxWidth(),
+            horizontalArrangement = Arrangement.End,
+        ) {
+            OutlinedButton(onClick = onQuit) {
+                Text(stringResource(Res.string.desktop_quit))
+            }
+        }
+    }
+}
+
+@Composable
+private fun LockingProcessRow(
+    process: LockingProcessInfo,
+    killEnabled: Boolean,
+    onKill: () -> Unit,
+) {
+    Surface(
+        tonalElevation = 1.dp,
+        shape = MaterialTheme.shapes.medium,
+        modifier = Modifier.fillMaxWidth(),
+    ) {
+        Row(
+            modifier = Modifier
+                .fillMaxWidth()
+                .padding(12.dp),
+            verticalAlignment = Alignment.CenterVertically,
+        ) {
+            if (process.icon != null) {
+                Image(
+                    bitmap = process.icon,
+                    contentDescription = null,
+                    modifier = Modifier.size(40.dp),
+                )
+            } else {
+                Icon(
+                    imageVector = Icons.Default.Warning,
+                    contentDescription = null,
+                    modifier = Modifier.size(40.dp),
+                    tint = MaterialTheme.colorScheme.onSurfaceVariant,
+                )
+            }
+            Spacer(modifier = Modifier.width(12.dp))
+            Column(modifier = Modifier.weight(1f)) {
+                Text(
+                    text = process.name,
+                    style = MaterialTheme.typography.titleMedium,
+                    maxLines = 1,
+                    overflow = TextOverflow.Ellipsis,
+                )
+                process.description?.let { description ->
+                    Text(
+                        text = description,
+                        style = MaterialTheme.typography.bodySmall,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant,
+                        maxLines = 2,
+                        overflow = TextOverflow.Ellipsis,
+                    )
+                }
+                if (process.pid > 0L) {
+                    Text(
+                        text = stringResource(Res.string.desktop_database_locked_pid, process.pid.toInt()),
+                        style = MaterialTheme.typography.labelSmall,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant,
+                    )
+                }
+            }
+            if (killEnabled) {
+                Spacer(modifier = Modifier.width(8.dp))
+                Button(onClick = onKill) {
+                    Text(stringResource(Res.string.desktop_database_locked_kill))
+                }
+            }
+        }
+    }
+}
diff --git a/app/desktop/src/main/kotlin/ru/fromchat/desktop/DatabaseLockingProcessResolver.kt b/app/desktop/src/main/kotlin/ru/fromchat/desktop/DatabaseLockingProcessResolver.kt
new file mode 100644
index 0000000..360a10a
--- /dev/null
+++ b/app/desktop/src/main/kotlin/ru/fromchat/desktop/DatabaseLockingProcessResolver.kt
@@ -0,0 +1,79 @@
+package ru.fromchat.desktop
+
+import java.io.File
+import java.lang.ProcessHandle
+import java.util.concurrent.TimeUnit
+
+object DatabaseLockingProcessResolver {
+    fun findLockingProcesses(files: List<File>): List<LockingProcessInfo> {
+        val discovered = buildList {
+            if (isWindowsOs()) {
+                addAll(WindowsRestartManager.findLockingProcesses(files))
+            }
+            if (isMacOs()) {
+                addAll(findWithLsof(files))
+            }
+            if (isLinuxOs()) {
+                addAll(findWithFuser(files))
+            }
+            addAll(ProcessExecutableResolver.findFromChatProcesses())
+        }
+        return discovered
+            .distinctBy { it.pid }
+            .sortedBy { it.name.lowercase() }
+    }
+
+    fun killProcess(pid: Long): Boolean = ProcessExecutableResolver.killProcess(pid)
+
+    private fun findWithLsof(files: List<File>): List<LockingProcessInfo> {
+        val pids = linkedSetOf<Long>()
+        files.forEach { file ->
+            val process = runCatching {
+                ProcessBuilder("lsof", "-t", file.absolutePath)
+                    .redirectErrorStream(true)
+                    .start()
+            }.getOrNull() ?: return@forEach
+            process.waitFor(3, TimeUnit.SECONDS)
+            process.inputStream.bufferedReader().readLines()
+                .mapNotNull { it.trim().toLongOrNull() }
+                .forEach { pids += it }
+        }
+        return pids.mapNotNull { pidToLockingProcess(it) }
+    }
+
+    private fun findWithFuser(files: List<File>): List<LockingProcessInfo> {
+        val pids = linkedSetOf<Long>()
+        files.forEach { file ->
+            val process = runCatching {
+                ProcessBuilder("fuser", file.absolutePath)
+                    .redirectErrorStream(true)
+                    .start()
+            }.getOrNull() ?: return@forEach
+            process.waitFor(3, TimeUnit.SECONDS)
+            val output = process.inputStream.bufferedReader().readText()
+            output.split(Regex("\\s+"))
+                .mapNotNull { token -> token.trim().toLongOrNull() }
+                .forEach { pids += it }
+        }
+        return pids.mapNotNull { pidToLockingProcess(it) }
+    }
+
+    private fun pidToLockingProcess(pid: Long): LockingProcessInfo? {
+        if (pid == ProcessHandle.current().pid()) return null
+        val handle = ProcessHandle.of(pid)
+        if (handle.isEmpty) return null
+        val info = handle.get().info()
+        val command = info.command().orElse("")
+        val executable = ProcessExecutableResolver.executablePathForPid(pid)
+        val name = executable?.let { File(it).name }
+            ?: command.substringBefore(' ').takeIf { it.isNotBlank() }
+            ?: "PID $pid"
+        return LockingProcessInfo(
+            pid = pid,
+            name = name,
+            description = command.ifBlank { null },
+            executablePath = executable,
+            icon = ProcessExecutableResolver.iconForExecutable(executable),
+        )
+    }
+}
diff --git a/app/desktop/src/main/kotlin/ru/fromchat/desktop/DesktopWindowChrome.kt b/app/desktop/src/main/kotlin/ru/fromchat/desktop/DesktopWindowChrome.kt
index 64634d7..fb52b45 100644
--- a/app/desktop/src/main/kotlin/ru/fromchat/desktop/DesktopWindowChrome.kt
+++ b/app/desktop/src/main/kotlin/ru/fromchat/desktop/DesktopWindowChrome.kt
@@ -10,6 +10,9 @@ internal fun isMacOs(): Boolean =
 internal fun isWindowsOs(): Boolean =
     System.getProperty("os.name").orEmpty().lowercase().contains("win")
 
+internal fun isLinuxOs(): Boolean =
+    System.getProperty("os.name").orEmpty().lowercase().contains("linux")
+
 internal fun isWindowsArm64(): Boolean {
     if (!isWindowsOs()) return false
     val arch = System.getProperty("os.arch").orEmpty().lowercase()
diff --git a/app/desktop/src/main/kotlin/ru/fromchat/desktop/Main.kt b/app/desktop/src/main/kotlin/ru/fromchat/desktop/Main.kt
index 262a22a..5c28951 100644
--- a/app/desktop/src/main/kotlin/ru/fromchat/desktop/Main.kt
+++ b/app/desktop/src/main/kotlin/ru/fromchat/desktop/Main.kt
@@ -56,6 +56,7 @@ import ru.fromchat.action_copy
 import ru.fromchat.action_select
 import ru.fromchat.api.ApiClient
 import ru.fromchat.api.local.WebSocketManager
+import ru.fromchat.api.local.db.isSqliteBusy
 import ru.fromchat.api.local.db.store.ConnectionStateStore
 import ru.fromchat.api.local.db.store.ConnectionStatus
 import ru.fromchat.api.local.workers.AttachmentTransferBootstrap
@@ -260,6 +261,7 @@ private object DesktopProtocolRegistration {
 }
 
 fun main(args: Array<String>) {
+    configureDesktopAppDataName()
     // Do NOT set compose.layers.type=WINDOW.
     // On macOS Metal that mode creates a JWindow + MetalRedrawer per Popup/Dialog; native
     // IOAccelerator surfaces are retained after dismiss and grew to multi-GB (Activity Monitor
@@ -291,9 +293,6 @@ fun main(args: Array<String>) {
         } else {
             System.setProperty("skiko.renderApi", "OPENGL")
         }
-        if (AppBuildInfo.isDebug && System.getProperty("fromchat.app.data.name").isNullOrBlank()) {
-            System.setProperty("fromchat.app.data.name", "FromChatBeta")
-        }
         setWindowsDesktopAppUserModelId(
             if (AppBuildInfo.isDebug) "FromChat Beta" else "FromChat",
         )
@@ -313,9 +312,36 @@ fun main(args: Array<String>) {
     application {
         UtilsLibrary.init()
         Thread.setDefaultUncaughtExceptionHandler { thread, throwable ->
-            Logger.e("Desktop", "uncaught on ${thread.name}", throwable)
+            if (isSqliteBusy(throwable)) {
+                Logger.w(
+                    "Desktop",
+                    "SQLite busy on ${thread.name}; database will retry on the next access",
+                    throwable,
+                )
+            } else {
+                Logger.e("Desktop", "uncaught on ${thread.name}", throwable)
+            }
+        }
+        var bootstrapStarted by remember { mutableStateOf(false) }
+        val databaseBlocked by DatabaseLockGate.blocked.collectAsState()
+        val lockingProcesses by DatabaseLockGate.processes.collectAsState()
+
+        LaunchedEffect(Unit) {
+            DatabaseLockGate.startMonitoring(this) {
+                if (!bootstrapStarted) {
+                    bootstrapStarted = true
+                    DesktopApplicationBootstrap.launchOnApplicationStart()
+                }
+            }
+        }
+
+        if (databaseBlocked) {
+            DatabaseLockWindow(
+                processes = lockingProcesses,
+                onKillProcess = { DatabaseLockGate.killProcess(it) },
+                onQuit = { exitApplication() },
+            )
         }
-        DesktopApplicationBootstrap.launchOnApplicationStart()
 
         val windowState = rememberWindowState(
             size = remember { DesktopWindowPrefs.loadSize() },
@@ -538,7 +564,7 @@ fun main(args: Array<String>) {
             onCloseRequest = { requestCloseToBackgroundOrQuit() },
             title = appName,
             state = windowState,
-            visible = contentReady && (windowVisible || !traySupported),
+            visible = contentReady && (windowVisible || !traySupported) && !databaseBlocked,
             icon = windowIcon,
             undecorated = windows,
             onPreviewKeyEvent = { event ->
@@ -688,7 +714,9 @@ fun main(args: Array<String>) {
                         .fillMaxSize()
                         .background(windowChrome),
                 ) {
-                    App(onContentReady = { contentReady = true })
+                    if (!databaseBlocked) {
+                        App(onContentReady = { contentReady = true })
+                    }
                     if (windows) {
                         MaterialTheme(colorScheme = getColorScheme(desktopAppDarkTheme(), dynamicColor = false)) {
                             WindowsDesktopTitleBar(
@@ -822,8 +850,13 @@ private fun performAwtEditAction(actionName: String) {
     action.actionPerformed(ActionEvent(focusOwner, ActionEvent.ACTION_PERFORMED, actionName))
 }
 
-private fun isLinuxOs(): Boolean =
-    System.getProperty("os.name").orEmpty().lowercase().contains("linux")
+/** Beta and release builds must not share the same on-disk data directory. */
+private fun configureDesktopAppDataName() {
+    if (!System.getProperty("fromchat.app.data.name").isNullOrBlank()) return
+    if (AppBuildInfo.isDebug) {
+        System.setProperty("fromchat.app.data.name", "FromChatBeta")
+    }
+}
 
 /**
  * JFrame uses UIManager "control" as its default background before Compose draws.
diff --git a/app/desktop/src/main/kotlin/ru/fromchat/desktop/ProcessExecutableResolver.kt b/app/desktop/src/main/kotlin/ru/fromchat/desktop/ProcessExecutableResolver.kt
new file mode 100644
index 0000000..c4663e4
--- /dev/null
+++ b/app/desktop/src/main/kotlin/ru/fromchat/desktop/ProcessExecutableResolver.kt
@@ -0,0 +1,100 @@
+package ru.fromchat.desktop
+
+import androidx.compose.ui.graphics.ImageBitmap
+import androidx.compose.ui.graphics.toComposeImageBitmap
+import java.awt.image.BufferedImage
+import java.io.ByteArrayOutputStream
+import java.io.File
+import java.lang.ProcessHandle
+import javax.imageio.ImageIO
+import javax.swing.ImageIcon
+import javax.swing.filechooser.FileSystemView
+import org.jetbrains.skia.Image as SkiaImage
+
+internal object ProcessExecutableResolver {
+    fun executablePathForPid(pid: Long): String? {
+        if (pid <= 0L) return null
+        return runCatching {
+            ProcessHandle.of(pid).flatMap { handle ->
+                handle.info().command().map { command ->
+                    extractExecutablePath(command)
+                }
+            }.orElse(null)
+        }.getOrNull()
+    }
+
+    fun commandLineForPid(pid: Long): String? {
+        if (pid <= 0L) return null
+        return runCatching {
+            ProcessHandle.of(pid).flatMap { it.info().command() }.orElse(null)
+        }.getOrNull()
+    }
+
+    fun iconForExecutable(path: String?): ImageBitmap? {
+        if (path.isNullOrBlank()) return null
+        val file = File(path)
+        if (!file.exists()) return null
+        val awtIcon = runCatching {
+            val icon = FileSystemView.getFileSystemView().getSystemIcon(file)
+            when (icon) {
+                is ImageIcon -> icon.image as? BufferedImage
+                else -> null
+            }
+        }.getOrNull() ?: return null
+        return bufferedImageToImageBitmap(awtIcon)
+    }
+
+    private fun bufferedImageToImageBitmap(image: BufferedImage): ImageBitmap {
+        val bytes = ByteArrayOutputStream().use { out ->
+            ImageIO.write(image, "png", out)
+            out.toByteArray()
+        }
+        return SkiaImage.makeFromEncoded(bytes).toComposeImageBitmap()
+    }
+
+    fun findFromChatProcesses(): List<LockingProcessInfo> {
+        val currentPid = ProcessHandle.current().pid()
+        return ProcessHandle.allProcesses().toList().mapNotNull { handle ->
+            val pid = handle.pid()
+            if (pid == currentPid) return@mapNotNull null
+            val command = handle.info().command().orElse("")
+            if (!looksLikeFromChatProcess(command)) return@mapNotNull null
+            val executable = extractExecutablePath(command)
+            LockingProcessInfo(
+                pid = pid,
+                name = handle.info().command().map { File(it).name }.orElse("FromChat"),
+                description = command,
+                executablePath = executable,
+                icon = iconForExecutable(executable),
+            )
+        }
+    }
+
+    private fun looksLikeFromChatProcess(command: String): Boolean {
+        if (command.isBlank()) return false
+        val lower = command.lowercase()
+        return lower.contains("ru.fromchat.desktop.mainkt") ||
+            lower.contains("fromchat.desktop.main") ||
+            (lower.contains("fromchat") && (lower.contains("java") || lower.contains("javaw")))
+    }
+
+    private fun extractExecutablePath(command: String): String? {
+        val trimmed = command.trim()
+        if (trimmed.isEmpty()) return null
+        if (trimmed.first() == '"') {
+            val end = trimmed.indexOf('"', startIndex = 1)
+            if (end > 1) return trimmed.substring(1, end)
+        }
+        return trimmed.substringBefore(' ').takeIf { it.isNotBlank() }
+    }
+
+    fun killProcess(pid: Long): Boolean {
+        if (pid <= 0L) return false
+        val handle = ProcessHandle.of(pid)
+        if (handle.isEmpty) return false
+        return runCatching {
+            handle.get().destroyForcibly()
+            true
+        }.getOrDefault(false)
+    }
+}
diff --git a/app/desktop/src/main/kotlin/ru/fromchat/desktop/WindowsRestartManager.kt b/app/desktop/src/main/kotlin/ru/fromchat/desktop/WindowsRestartManager.kt
new file mode 100644
index 0000000..cb1f47a
--- /dev/null
+++ b/app/desktop/src/main/kotlin/ru/fromchat/desktop/WindowsRestartManager.kt
@@ -0,0 +1,133 @@
+package ru.fromchat.desktop
+
+import com.sun.jna.Native
+import com.sun.jna.Structure
+import com.sun.jna.WString
+import com.sun.jna.platform.win32.WinBase
+import com.sun.jna.platform.win32.WinDef.DWORD
+import com.sun.jna.platform.win32.WinNT
+import com.sun.jna.ptr.IntByReference
+import com.sun.jna.win32.StdCallLibrary
+import com.sun.jna.win32.W32APIOptions
+import java.io.File
+
+internal object WindowsRestartManager {
+    private const val ERROR_MORE_DATA = 234
+    private const val CCH_RM_MAX_APP_NAME = 255
+    private const val CCH_RM_MAX_SVC_NAME = 63
+
+    fun findLockingProcesses(files: List<File>): List<LockingProcessInfo> {
+        if (!isWindowsOs()) return emptyList()
+        val paths = files.map { it.absolutePath }.filter { it.isNotBlank() }
+        if (paths.isEmpty()) return emptyList()
+
+        val session = IntByReference()
+        val sessionKey = CharArray(33)
+        val start = RestartManager.INSTANCE.RmStartSession(session, 0, sessionKey)
+        if (start != WinNT.ERROR_SUCCESS) return emptyList()
+        val sessionHandle = session.value
+
+        try {
+            val register = RestartManager.INSTANCE.RmRegisterResources(
+                sessionHandle,
+                paths.size,
+                paths.toTypedArray(),
+                0,
+                null,
+                0,
+                null,
+            )
+            if (register != WinNT.ERROR_SUCCESS) return emptyList()
+
+            val needed = IntByReference()
+            val count = IntByReference()
+            var result = RestartManager.INSTANCE.RmGetList(
+                sessionHandle,
+                needed,
+                count,
+                null,
+                null,
+            )
+            if (result != ERROR_MORE_DATA && result != WinNT.ERROR_SUCCESS) return emptyList()
+
+            val processCount = needed.value.coerceAtLeast(count.value).coerceAtLeast(1)
+            val processes = Array(processCount) { RmProcessInfo() }
+            count.value = processCount
+            result = RestartManager.INSTANCE.RmGetList(
+                sessionHandle,
+                needed,
+                count,
+                processes,
+                null,
+            )
+            if (result != WinNT.ERROR_SUCCESS) return emptyList()
+
+            return processes
+                .take(count.value.coerceAtMost(processes.size))
+                .mapNotNull { info ->
+                    val pid = info.dwProcessId.toLong()
+                    if (pid <= 0L) return@mapNotNull null
+                    val appName = info.appName().trim()
+                    val executable = ProcessExecutableResolver.executablePathForPid(pid)
+                    LockingProcessInfo(
+                        pid = pid,
+                        name = appName.ifBlank { executable?.let { File(it).name } ?: "PID $pid" },
+                        description = executable ?: ProcessExecutableResolver.commandLineForPid(pid),
+                        executablePath = executable,
+                        icon = ProcessExecutableResolver.iconForExecutable(executable),
+                    )
+                }
+                .distinctBy { it.pid }
+        } finally {
+            RestartManager.INSTANCE.RmEndSession(sessionHandle)
+        }
+    }
+
+    @Structure.FieldOrder(
+        "dwProcessId",
+        "processStartTime",
+        "strAppName",
+        "strServiceShortName",
+        "applicationType",
+        "appStatus",
+        "tsSessionId",
+        "restartable",
+    )
+    private class RmProcessInfo : Structure(), Structure.ByReference {
+        @JvmField var dwProcessId = 0
+        @JvmField var processStartTime = WinBase.FILETIME()
+        @JvmField var strAppName = CharArray(CCH_RM_MAX_APP_NAME + 1)
+        @JvmField var strServiceShortName = CharArray(CCH_RM_MAX_SVC_NAME + 1)
+        @JvmField var applicationType = DWORD(0)
+        @JvmField var appStatus = DWORD(0)
+        @JvmField var tsSessionId = DWORD(0)
+        @JvmField var restartable = 0
+
+        fun appName(): String = Native.toString(strAppName)
+    }
+
+    private interface RestartManager : StdCallLibrary {
+        fun RmStartSession(sessionHandle: IntByReference, sessionFlags: Int, sessionKey: CharArray): Int
+        fun RmEndSession(sessionHandle: Int): Int
+        fun RmRegisterResources(
+            sessionHandle: Int,
+            fileCount: Int,
+            fileNames: Array<String>?,
+            serviceCount: Int,
+            serviceNames: Array<WString>?,
+            processCount: Int,
+            processIds: IntArray?,
+        ): Int
+        fun RmGetList(
+            sessionHandle: Int,
+            procInfoNeeded: IntByReference,
+            procInfoCount: IntByReference,
+            affectedApps: Array<RmProcessInfo>?,
+            rebootReasons: IntByReference?,
+        ): Int
+
+        companion object {
+            val INSTANCE: RestartManager = Native.load("Rstrtmgr", RestartManager::class.java, W32APIOptions.DEFAULT_OPTIONS)
+        }
+    }
+}
diff --git a/app/shared/src/commonMain/composeResources/values-ru/strings.xml b/app/shared/src/commonMain/composeResources/values-ru/strings.xml
index 9b86a9a..83cb88b 100644
--- a/app/shared/src/commonMain/composeResources/values-ru/strings.xml
+++ b/app/shared/src/commonMain/composeResources/values-ru/strings.xml
@@ -33,6 +33,12 @@
     <string name="desktop_select_all">Выделить всё</string>
     <string name="desktop_minimize">Свернуть</string>
     <string name="desktop_zoom">Масштабировать</string>
+    <string name="desktop_database_locked_title">База данных заблокирована</string>
+    <string name="desktop_database_locked_message">FromChat не может получить доступ к базе данных — её использует другой процесс.</string>
+    <string name="desktop_database_locked_kill">Завершить процесс</string>
+    <string name="desktop_database_locked_waiting">Ожидание освобождения базы данных…</string>
+    <string name="desktop_database_locked_unknown_process">Неизвестный процесс</string>
+    <string name="desktop_database_locked_pid">PID %1$d</string>
     <string name="welcome">Добро пожаловать!</string>
     <string name="login">Войти</string>
     <string name="login_d">Войдите в свой аккаунт</string>
diff --git a/app/shared/src/commonMain/composeResources/values/strings.xml b/app/shared/src/commonMain/composeResources/values/strings.xml
index 9f726f7..82cb09c 100644
--- a/app/shared/src/commonMain/composeResources/values/strings.xml
+++ b/app/shared/src/commonMain/composeResources/values/strings.xml
@@ -38,6 +38,12 @@
     <string name="desktop_select_all">Select All</string>
     <string name="desktop_minimize">Minimize</string>
     <string name="desktop_zoom">Zoom</string>
+    <string name="desktop_database_locked_title">Database locked</string>
+    <string name="desktop_database_locked_message">FromChat cannot access its database because another process is using it.</string>
+    <string name="desktop_database_locked_kill">End process</string>
+    <string name="desktop_database_locked_waiting">Waiting for the database to become available…</string>
+    <string name="desktop_database_locked_unknown_process">Unknown process</string>
+    <string name="desktop_database_locked_pid">PID %1$d</string>
 
     <!-- Authentication -->
     <string name="welcome">Welcome!</string>
diff --git a/app/shared/src/commonMain/kotlin/ru/fromchat/api/local/db/SqliteConcurrency.kt b/app/shared/src/commonMain/kotlin/ru/fromchat/api/local/db/SqliteConcurrency.kt
new file mode 100644
index 0000000..989e5cd
--- /dev/null
+++ b/app/shared/src/commonMain/kotlin/ru/fromchat/api/local/db/SqliteConcurrency.kt
@@ -0,0 +1,38 @@
+package ru.fromchat.api.local.db
+
+import ru.fromchat.Logger
+
+fun isSqliteBusy(throwable: Throwable): Boolean {
+    var current: Throwable? = throwable
+    while (current != null) {
+        val message = current.message.orEmpty()
+        if (message.contains("SQLITE_BUSY", ignoreCase = true)) return true
+        if (message.contains("database is locked", ignoreCase = true)) return true
+        if (message.contains("database file is locked", ignoreCase = true)) return true
+        current = current.cause
+    }
+    return false
+}
+
+internal fun <T> withSqliteBusyRetry(
+    maxAttempts: Int = 8,
+    initialDelayMs: Long = 25L,
+    block: () -> T,
+): T {
+    var attempt = 0
+    var delayMs = initialDelayMs
+    while (true) {
+        try {
+            return block()
+        } catch (e: Throwable) {
+            attempt++
+            if (!isSqliteBusy(e) || attempt >= maxAttempts) throw e
+            Logger.w(
+                "MessageDatabase",
+                "SQLite busy (attempt $attempt/$maxAttempts), retrying in ${delayMs}ms",
+            )
+            Thread.sleep(delayMs)
+            delayMs = minOf(delayMs * 2, 500L)
+        }
+    }
+}
diff --git a/app/shared/src/commonMain/kotlin/ru/fromchat/api/local/db/store/MessageDatabaseProvider.kt b/app/shared/src/commonMain/kotlin/ru/fromchat/api/local/db/store/MessageDatabaseProvider.kt
index 8150d97..cfabc4d 100644
--- a/app/shared/src/commonMain/kotlin/ru/fromchat/api/local/db/store/MessageDatabaseProvider.kt
+++ b/app/shared/src/commonMain/kotlin/ru/fromchat/api/local/db/store/MessageDatabaseProvider.kt
@@ -4,6 +4,7 @@ import app.cash.sqldelight.db.SqlDriver
 import ru.fromchat.api.local.db.ensureMessageDatabaseSchema
 import ru.fromchat.api.local.db.rebindUnboundMigrationInstance
 import ru.fromchat.api.local.db.withMessageDatabaseLock
+import ru.fromchat.api.local.db.withSqliteBusyRetry
 import ru.fromchat.db.MessageDatabase
 
 /**
@@ -33,15 +34,16 @@ object MessageDatabaseProvider {
     }
 
     /** Runs [block] once; on a stale connection after cache wipe, resets and retries. */
-    internal fun <T> withDatabaseRecover(block: () -> T): T {
-        return try {
-            block()
-        } catch (e: Exception) {
-            if (!isStaleSqliteConnection(e)) throw e
-            closeAndReset()
-            block()
+    internal fun <T> withDatabaseRecover(block: () -> T): T =
+        withSqliteBusyRetry {
+            try {
+                block()
+            } catch (e: Exception) {
+                if (!isStaleSqliteConnection(e)) throw e
+                closeAndReset()
+                block()
+            }
         }
-    }
 
     internal fun isStaleSqliteConnection(throwable: Throwable): Boolean {
         var current: Throwable? = throwable
diff --git a/app/shared/src/commonMain/kotlin/ru/fromchat/ui/chat/MessageItem.kt b/app/shared/src/commonMain/kotlin/ru/fromchat/ui/chat/MessageItem.kt
index 2068e8f..a671798 100644
--- a/app/shared/src/commonMain/kotlin/ru/fromchat/ui/chat/MessageItem.kt
+++ b/app/shared/src/commonMain/kotlin/ru/fromchat/ui/chat/MessageItem.kt
@@ -815,7 +815,15 @@ fun MessageItem(
                                 }
 
                                 Box(modifier = Modifier.fillMaxWidth()) {
-                                    Column {
+                                    Column(
+                                        verticalArrangement = if (
+                                            replyRef != null && primaryIsImageContent
+                                        ) {
+                                            Arrangement.spacedBy(6.dp)
+                                        } else {
+                                            Arrangement.Top
+                                        },
+                                    ) {
                                         replyRef?.let { replyToMsg ->
                                             MessageReplyQuote(
                                                 replyTo = replyToMsg,
@@ -827,6 +835,8 @@ fun MessageItem(
                                                 isContextMenuOpen = isContextMenuOpen,
                                                 onReplyClick = onReplyClick,
                                                 onReplyPressedChange = { replyPressed = it },
+                                                inImageBubble = primaryIsImageContent,
+                                                hasAttachmentBelow = primaryIsImageContent,
                                             )
                                         }
 
@@ -1256,6 +1266,8 @@ private fun MessageReplyQuote(
     isContextMenuOpen: Boolean,
     onReplyClick: ((Int) -> Unit)?,
     onReplyPressedChange: (Boolean) -> Unit,
+    inImageBubble: Boolean = false,
+    hasAttachmentBelow: Boolean = false,
 ) {
     val replyName = messageDisplayUsername(replyTo, currentUserId)
     val replyTapEnabled = onReplyClick != null && replyTo.id > 0
@@ -1300,7 +1312,12 @@ private fun MessageReplyQuote(
 
     Box(
         Modifier
-            .padding(bottom = 4.dp, start = 6.dp, end = 6.dp)
+            .padding(
+                top = if (inImageBubble) 6.dp else 0.dp,
+                bottom = if (hasAttachmentBelow) 0.dp else 4.dp,
+                start = 6.dp,
+                end = 6.dp,
+            )
             .graphicsLayer(
                 scaleX = replyScale,
                 scaleY = replyScale,
diff --git a/app/shared/src/commonMain/kotlin/ru/fromchat/ui/main/DesktopDetailNavHosts.kt b/app/shared/src/commonMain/kotlin/ru/fromchat/ui/main/DesktopDetailNavHosts.kt
index 8bcc7fc..a305f5f 100644
--- a/app/shared/src/commonMain/kotlin/ru/fromchat/ui/main/DesktopDetailNavHosts.kt
+++ b/app/shared/src/commonMain/kotlin/ru/fromchat/ui/main/DesktopDetailNavHosts.kt
@@ -91,7 +91,18 @@ fun DesktopSettingsDetailNavHost(
     onOpenChatFromProfile: (Int) -> Unit,
     modifier: Modifier = Modifier,
 ) {
+    val detailRoute =
+        navController.currentBackStackEntryAsState().value?.destination?.route
+    val showPanel =
+        detailRoute != null && detailRoute != DesktopDetailNav.SETTINGS_ROOT
     Box(modifier.fillMaxSize()) {
+        if (showPanel) {
+            Box(
+                Modifier
+                    .fillMaxSize()
+                    .background(MaterialTheme.colorScheme.background),
+            )
+        }
         CompositionLocalProvider(LocalNavController provides navController) {
             NavHost(
                 navController = navController,
@@ -116,17 +127,6 @@ fun DesktopSettingsDetailNavHost(
                 )
             }
         }
-        val detailRoute =
-            navController.currentBackStackEntryAsState().value?.destination?.route
-        val showPanel =
-            detailRoute != null && detailRoute != DesktopDetailNav.SETTINGS_ROOT
-        if (showPanel) {
-            Box(
-                Modifier
-                    .fillMaxSize()
-                    .background(MaterialTheme.colorScheme.background),
-            )
-        }
     }
 }
 
diff --git a/app/shared/src/jvmMain/kotlin/ru/fromchat/api/local/db/MessageDatabaseLock.jvm.kt b/app/shared/src/jvmMain/kotlin/ru/fromchat/api/local/db/MessageDatabaseLock.jvm.kt
index 31bf25f..2ae5984 100644
--- a/app/shared/src/jvmMain/kotlin/ru/fromchat/api/local/db/MessageDatabaseLock.jvm.kt
+++ b/app/shared/src/jvmMain/kotlin/ru/fromchat/api/local/db/MessageDatabaseLock.jvm.kt
@@ -1,6 +1,8 @@
 package ru.fromchat.api.local.db
 
 internal actual fun <T> withMessageDatabaseLock(block: () -> T): T =
-    synchronized(MessageDatabaseLock) { block() }
+    withSqliteBusyRetry {
+        synchronized(MessageDatabaseLock) { block() }
+    }
 
 private object MessageDatabaseLock
diff --git a/app/shared/src/jvmMain/kotlin/ru/fromchat/api/local/db/store/MessageDatabaseDriver.jvm.kt b/app/shared/src/jvmMain/kotlin/ru/fromchat/api/local/db/store/MessageDatabaseDriver.jvm.kt
index 31f0c33..2f58800 100644
--- a/app/shared/src/jvmMain/kotlin/ru/fromchat/api/local/db/store/MessageDatabaseDriver.jvm.kt
+++ b/app/shared/src/jvmMain/kotlin/ru/fromchat/api/local/db/store/MessageDatabaseDriver.jvm.kt
@@ -11,9 +11,18 @@ actual fun provideMessageDatabaseDriver(): SqlDriver {
     dir.mkdirs()
     val dbFile = File(dir, "message_database.db")
     val needsCreate = !dbFile.exists()
-    val driver = JdbcSqliteDriver("jdbc:sqlite:${dbFile.absolutePath}")
+    val jdbc = JdbcSqliteDriver(
+        "jdbc:sqlite:${dbFile.absolutePath}?busy_timeout=30000&journal_mode=WAL",
+    )
     if (needsCreate) {
-        MessageDatabase.Schema.create(driver)
+        MessageDatabase.Schema.create(jdbc)
     }
-    return driver
+    configureJvmSqliteDriver(jdbc)
+    return SynchronizedRetryingSqlDriver(jdbc)
+}
+
+private fun configureJvmSqliteDriver(driver: SqlDriver) {
+    driver.execute(null, "PRAGMA busy_timeout = 30000;", 0)
+    driver.execute(null, "PRAGMA journal_mode = WAL;", 0)
+    driver.execute(null, "PRAGMA synchronous = NORMAL;", 0)
 }
diff --git a/app/shared/src/jvmMain/kotlin/ru/fromchat/api/local/db/store/MessageDatabasePaths.kt b/app/shared/src/jvmMain/kotlin/ru/fromchat/api/local/db/store/MessageDatabasePaths.kt
new file mode 100644
index 0000000..b25b84b
--- /dev/null
+++ b/app/shared/src/jvmMain/kotlin/ru/fromchat/api/local/db/store/MessageDatabasePaths.kt
@@ -0,0 +1,58 @@
+package ru.fromchat.api.local.db.store
+
+import app.cash.sqldelight.driver.jdbc.sqlite.JdbcSqliteDriver
+import com.pr0gramm3r101.utils.files.PlatformFileSystem
+import ru.fromchat.api.local.db.isSqliteBusy
+import java.io.File
+import java.io.RandomAccessFile
+import java.nio.channels.OverlappingFileLockException
+
+object MessageDatabasePaths {
+    fun databaseFile(): File {
+        val dir = File(PlatformFileSystem.getAppCacheDirectory(), "fromchat")
+        return File(dir, "message_database.db")
+    }
+
+    fun lockTargetFiles(): List<File> {
+        val db = databaseFile()
+        return listOf(
+            db,
+            File("${db.path}-wal"),
+            File("${db.path}-shm"),
+            File("${db.path}-journal"),
+        ).filter { it.exists() }
+    }
+
+    fun isDatabaseLocked(): Boolean {
+        val targets = lockTargetFiles()
+        if (targets.isEmpty()) return false
+        if (targets.any { isFileLockedExclusively(it) }) return true
+        return isSqliteWriteLocked(databaseFile())
+    }
+
+    private fun isFileLockedExclusively(file: File): Boolean =
+        runCatching {
+            RandomAccessFile(file, "rw").use { raf ->
+                val channel = raf.channel
+                val lock = try {
+                    channel.tryLock()
+                } catch (_: OverlappingFileLockException) {
+                    return true
+                }
+                lock?.release()
+                lock == null
+            }
+        }.getOrDefault(true)
+
+    private fun isSqliteWriteLocked(dbFile: File): Boolean =
+        runCatching {
+            val probe = JdbcSqliteDriver("jdbc:sqlite:${dbFile.absolutePath}?busy_timeout=1")
+            try {
+                probe.execute(null, "BEGIN IMMEDIATE;", 0)
+                probe.execute(null, "ROLLBACK;", 0)
+                false
+            } finally {
+                probe.close()
+            }
+        }.getOrElse { isSqliteBusy(it) }
+}
diff --git a/app/shared/src/jvmMain/kotlin/ru/fromchat/api/local/db/store/SynchronizedRetryingSqlDriver.kt b/app/shared/src/jvmMain/kotlin/ru/fromchat/api/local/db/store/SynchronizedRetryingSqlDriver.kt
new file mode 100644
index 0000000..d472c41
--- /dev/null
+++ b/app/shared/src/jvmMain/kotlin/ru/fromchat/api/local/db/store/SynchronizedRetryingSqlDriver.kt
@@ -0,0 +1,60 @@
+package ru.fromchat.api.local.db.store
+
+import app.cash.sqldelight.Query
+import app.cash.sqldelight.Transacter
+import app.cash.sqldelight.db.QueryResult
+import app.cash.sqldelight.db.SqlCursor
+import app.cash.sqldelight.db.SqlDriver
+import app.cash.sqldelight.db.SqlPreparedStatement
+import ru.fromchat.api.local.db.withSqliteBusyRetry
+
+/**
+ * Serializes JDBC SQLite access and retries transient [SQLITE_BUSY] errors.
+ * Desktop can hit the DB from multiple threads while the provider lock is not held per query.
+ */
+internal class SynchronizedRetryingSqlDriver(
+    private val delegate: SqlDriver,
+) : SqlDriver {
+    private val accessLock = Any()
+
+    override fun close() = synchronized(accessLock) { delegate.close() }
+
+    override fun execute(
+        identifier: Int?,
+        sql: String,
+        parameters: Int,
+        binders: (SqlPreparedStatement.() -> Unit)?,
+    ): QueryResult<Long> = synchronized(accessLock) {
+        withSqliteBusyRetry { delegate.execute(identifier, sql, parameters, binders) }
+    }
+
+    override fun <R> executeQuery(
+        identifier: Int?,
+        sql: String,
+        mapper: (SqlCursor) -> QueryResult<R>,
+        parameters: Int,
+        binders: (SqlPreparedStatement.() -> Unit)?,
+    ): QueryResult<R> = synchronized(accessLock) {
+        withSqliteBusyRetry { delegate.executeQuery(identifier, sql, mapper, parameters, binders) }
+    }
+
+    override fun newTransaction(): QueryResult<Transacter.Transaction> = synchronized(accessLock) {
+        withSqliteBusyRetry { delegate.newTransaction() }
+    }
+
+    override fun currentTransaction(): Transacter.Transaction? = synchronized(accessLock) {
+        delegate.currentTransaction()
+    }
+
+    override fun addListener(vararg queryKeys: String, listener: Query.Listener) {
+        delegate.addListener(*queryKeys, listener = listener)
+    }
+
+    override fun removeListener(vararg queryKeys: String, listener: Query.Listener) {
+        delegate.removeListener(*queryKeys, listener = listener)
+    }
+
+    override fun notifyListeners(vararg queryKeys: String) {
+        delegate.notifyListeners(*queryKeys)
+    }
+}
diff --git a/utils/shared/src/jvmMain/kotlin/com/pr0gramm3r101/utils/files/AppDataRoot.jvm.kt b/utils/shared/src/jvmMain/kotlin/com/pr0gramm3r101/utils/files/AppDataRoot.jvm.kt
index f786e78..1b10174 100644
--- a/utils/shared/src/jvmMain/kotlin/com/pr0gramm3r101/utils/files/AppDataRoot.jvm.kt
+++ b/utils/shared/src/jvmMain/kotlin/com/pr0gramm3r101/utils/files/AppDataRoot.jvm.kt
@@ -5,17 +5,22 @@ import java.io.File
 /**
  * Resolves the FromChat desktop data/cache root on the JVM.
  *
- * - Portable (`-Dfromchat.portable=true`): `<exeDir>/fromchat-data`
- * - Windows installed: `%LOCALAPPDATA%\FromChat` (or `FromChat Beta` when `-Dfromchat.app.data.name` is set)
- * - macOS: `~/Library/Application Support/FromChat`
- * - Linux: `${XDG_DATA_HOME:-~/.local/share}/FromChat`
+ * - Custom data root (`-Dfromchat.dev.data.dir=…`): use only when set explicitly (e.g. IDE run config)
+ * - Portable (`-Dfromchat.portable=true`): `<exeDir>/fromchat-data` or `fromchat-data-beta`
+ * - Windows: `%LOCALAPPDATA%\FromChat` or `%LOCALAPPDATA%\FromChat Beta`
+ * - macOS: `~/Library/Application Support/FromChat` or `…/FromChat Beta`
+ * - Linux: `~/.local/share/FromChat` or `…/FromChat Beta`
+ *
+ * Variant is selected via `-Dfromchat.app.data.name` (`FromChatBeta` → `FromChat Beta`; default `FromChat`).
  *
  * Migrates once from the legacy `~/.fromchat/cache` directory when present.
  */
 internal object AppDataRoot {
     private const val LEGACY_RELATIVE = ".fromchat/cache"
     private const val PORTABLE_DIR_NAME = "fromchat-data"
+    private const val PORTABLE_BETA_DIR_NAME = "fromchat-data-beta"
     private const val APP_DIR_NAME = "FromChat"
+    private const val APP_BETA_DIR_NAME = "FromChat Beta"
 
     @Volatile
     private var cached: File? = null
@@ -32,8 +37,9 @@ internal object AppDataRoot {
     }
 
     private fun resolveUncached(): File {
+        devDataRoot()?.let { return it }
         if (isPortable()) {
-            return File(executableDirectory(), PORTABLE_DIR_NAME)
+            return File(executableDirectory(), portableDirName())
         }
         val os = System.getProperty("os.name").orEmpty().lowercase()
         return when {
@@ -43,6 +49,11 @@ internal object AppDataRoot {
         }
     }
 
+    private fun devDataRoot(): File? {
+        val explicit = System.getProperty("fromchat.dev.data.dir")?.trim()?.takeIf { it.isNotEmpty() }
+        return explicit?.let { File(it).absoluteFile }
+    }
+
     private fun isPortable(): Boolean =
         System.getProperty("fromchat.portable")
             ?.equals("true", ignoreCase = true) == true
@@ -66,11 +77,14 @@ internal object AppDataRoot {
     private fun installedAppDirName(): String {
         val raw = System.getProperty("fromchat.app.data.name")?.trim()?.takeIf { it.isNotEmpty() }
         return when (raw) {
-            "FromChatBeta" -> "FromChat Beta"
+            "FromChatBeta", APP_BETA_DIR_NAME -> APP_BETA_DIR_NAME
             else -> raw ?: APP_DIR_NAME
         }
     }
 
+    private fun portableDirName(): String =
+        if (installedAppDirName() == APP_BETA_DIR_NAME) PORTABLE_BETA_DIR_NAME else PORTABLE_DIR_NAME
+
     private fun windowsInstalledRoot(): File {
         val dirName = installedAppDirName()
         val localAppData = System.getenv("LOCALAPPDATA")?.takeIf { it.isNotBlank() }