Added default backdrops to the chat.

app/shared/src/androidMain/kotlin/iris/platform/AndroidMedia.kt

@@ -40,16 +40,16 @@ import androidx.compose.ui.unit.sp
 import androidx.compose.ui.viewinterop.AndroidView
 import androidx.core.content.FileProvider
 import androidx.core.net.toUri
-import androidx.media3.common.MediaItem as M3MediaItem
 import androidx.media3.common.Player
 import androidx.media3.exoplayer.ExoPlayer
 import androidx.media3.ui.PlayerView
 import iris.data.MediaItem
 import iris.media.extForMime
 import iris.protocol.KIND_VIDEO
-import java.io.File
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.withContext
+import java.io.File
+import androidx.media3.common.MediaItem as M3MediaItem
 
 /** App context holder (set in MainActivity.onCreate). */
 object AndroidEnv {
@@ -59,24 +59,25 @@ object AndroidEnv {
 @Composable
 actual fun MediaFilePicker(onPicked: (PickedFile?) -> Unit) {
     val context = LocalContext.current
-    val launcher = rememberLauncherForActivityResult(ActivityResultContracts.GetContent()) { uri ->
-        if (uri == null) {
-            onPicked(null)
-            return@rememberLauncherForActivityResult
-        }
-        try {
-            val mime = context.contentResolver.getType(uri) ?: "application/octet-stream"
-            val name = queryDisplayName(context, uri) ?: "upload"
-            val dir = File(context.cacheDir, "uploads").apply { mkdirs() }
-            val target = File(dir, "${System.currentTimeMillis()}${extForMime(mime)}")
-            context.contentResolver.openInputStream(uri)!!.use { input ->
-                target.outputStream().use { output -> input.copyTo(output) }
+    val launcher =
+        rememberLauncherForActivityResult(ActivityResultContracts.GetContent()) { uri ->
+            if (uri == null) {
+                onPicked(null)
+                return@rememberLauncherForActivityResult
+            }
+            try {
+                val mime = context.contentResolver.getType(uri) ?: "application/octet-stream"
+                val name = queryDisplayName(context, uri) ?: "upload"
+                val dir = File(context.cacheDir, "uploads").apply { mkdirs() }
+                val target = File(dir, "${System.currentTimeMillis()}${extForMime(mime)}")
+                context.contentResolver.openInputStream(uri)!!.use { input ->
+                    target.outputStream().use { output -> input.copyTo(output) }
+                }
+                onPicked(PickedFile(target.absolutePath, name, mime, target.length()))
+            } catch (e: Exception) {
+                onPicked(null)
             }
-            onPicked(PickedFile(target.absolutePath, name, mime, target.length()))
-        } catch (e: Exception) {
-            onPicked(null)
         }
-    }
     Box(modifier = Modifier.fillMaxWidth(), contentAlignment = Alignment.Center) {
         Button(onClick = { launcher.launch("*/*") }) { Text("Pick a file") }
     }
@@ -85,29 +86,33 @@ actual fun MediaFilePicker(onPicked: (PickedFile?) -> Unit) {
 @Composable
 actual fun ImageFilePicker(onPicked: (PickedFile?) -> Unit) {
     val context = LocalContext.current
-    val launcher = rememberLauncherForActivityResult(ActivityResultContracts.GetContent()) { uri ->
-        if (uri == null) {
-            onPicked(null)
-            return@rememberLauncherForActivityResult
-        }
-        try {
-            val mime = context.contentResolver.getType(uri) ?: "image/jpeg"
-            val name = queryDisplayName(context, uri) ?: "background"
-            // Persistent (filesDir), unlike the upload staging dir in cacheDir.
-            val dir = File(context.filesDir, "theme").apply { mkdirs() }
-            val target = File(dir, "background${extForMime(mime)}")
-            context.contentResolver.openInputStream(uri)!!.use { input ->
-                target.outputStream().use { output -> input.copyTo(output) }
+    val launcher =
+        rememberLauncherForActivityResult(ActivityResultContracts.GetContent()) { uri ->
+            if (uri == null) {
+                onPicked(null)
+                return@rememberLauncherForActivityResult
+            }
+            try {
+                val mime = context.contentResolver.getType(uri) ?: "image/jpeg"
+                val name = queryDisplayName(context, uri) ?: "background"
+                // Persistent (filesDir), unlike the upload staging dir in cacheDir.
+                val dir = File(context.filesDir, "theme").apply { mkdirs() }
+                val target = File(dir, "background${extForMime(mime)}")
+                context.contentResolver.openInputStream(uri)!!.use { input ->
+                    target.outputStream().use { output -> input.copyTo(output) }
+                }
+                onPicked(PickedFile(target.absolutePath, name, mime, target.length()))
+            } catch (e: Exception) {
+                onPicked(null)
             }
-            onPicked(PickedFile(target.absolutePath, name, mime, target.length()))
-        } catch (e: Exception) {
-            onPicked(null)
         }
-    }
     Button(onClick = { launcher.launch("image/*") }) { Text("Choose image…") }
 }
 
-private fun queryDisplayName(context: Context, uri: Uri): String? {
+private fun queryDisplayName(
+    context: Context,
+    uri: Uri,
+): String? {
     context.contentResolver.query(uri, null, null, null, null)?.use { c ->
         val idx = c.getColumnIndex(OpenableColumns.DISPLAY_NAME)
         if (idx >= 0 && c.moveToFirst()) return c.getString(idx)
@@ -119,59 +124,99 @@ actual fun mediaCacheBaseDir(): String =
     AndroidEnv.context.externalCacheDir?.absolutePath
         ?: AndroidEnv.context.cacheDir.absolutePath
 
-actual suspend fun loadMediaImage(path: String): ImageBitmap? = withContext(Dispatchers.IO) {
-    try {
-        BitmapFactory.decodeFile(path)?.asImageBitmap()
-    } catch (e: Exception) {
-        null
+actual suspend fun loadMediaImage(path: String): ImageBitmap? =
+    withContext(Dispatchers.IO) {
+        try {
+            BitmapFactory.decodeFile(path)?.asImageBitmap()
+        } catch (e: Exception) {
+            null
+        }
     }
-}
 
-actual suspend fun loadScaledImage(path: String, maxSize: Int): ImageBitmap? = withContext(Dispatchers.IO) {
-    try {
-        // inJustDecodeBounds fills [bounds] and returns null by design — only
-        // the outWidth/outHeight are meaningful here.
-        val bounds = BitmapFactory.Options().apply { inJustDecodeBounds = true }
-        BitmapFactory.decodeFile(path, bounds)
-        if (bounds.outWidth <= 0 || bounds.outHeight <= 0) return@withContext null
-        var sample = 1
-        while (maxOf(bounds.outWidth, bounds.outHeight) / sample > maxSize) sample *= 2
-        val opts = BitmapFactory.Options().apply { inSampleSize = sample }
-        BitmapFactory.decodeFile(path, opts)?.asImageBitmap()
-    } catch (e: Exception) {
-        null
+actual suspend fun loadScaledImage(
+    path: String,
+    maxSize: Int,
+): ImageBitmap? =
+    withContext(Dispatchers.IO) {
+        try {
+            // inJustDecodeBounds fills [bounds] and returns null by design — only
+            // the outWidth/outHeight are meaningful here.
+            val bounds = BitmapFactory.Options().apply { inJustDecodeBounds = true }
+            BitmapFactory.decodeFile(path, bounds)
+            if (bounds.outWidth <= 0 || bounds.outHeight <= 0) return@withContext null
+            var sample = 1
+            while (maxOf(bounds.outWidth, bounds.outHeight) / sample > maxSize) sample *= 2
+            val opts = BitmapFactory.Options().apply { inSampleSize = sample }
+            BitmapFactory.decodeFile(path, opts)?.asImageBitmap()
+        } catch (e: Exception) {
+            null
+        }
     }
-}
 
-actual suspend fun encodeImageAsBase64(path: String, maxSize: Int): String? = withContext(Dispatchers.IO) {
-    try {
-        val bounds = BitmapFactory.Options().apply { inJustDecodeBounds = true }
-        BitmapFactory.decodeFile(path, bounds)
-        if (bounds.outWidth <= 0 || bounds.outHeight <= 0) return@withContext null
-        var sample = 1
-        while (maxOf(bounds.outWidth, bounds.outHeight) / sample > maxSize) sample *= 2
-        val opts = BitmapFactory.Options().apply { inSampleSize = sample }
-        val bitmap = BitmapFactory.decodeFile(path, opts) ?: return@withContext null
-        val stream = java.io.ByteArrayOutputStream()
-        bitmap.compress(android.graphics.Bitmap.CompressFormat.PNG, 100, stream)
-        bitmap.recycle()
-        android.util.Base64.encodeToString(stream.toByteArray(), android.util.Base64.NO_WRAP)
-    } catch (e: Exception) {
-        null
+actual suspend fun decodeImageBytes(
+    bytes: ByteArray,
+    maxSize: Int,
+): ImageBitmap? =
+    withContext(Dispatchers.IO) {
+        try {
+            val bounds = BitmapFactory.Options().apply { inJustDecodeBounds = true }
+            BitmapFactory.decodeByteArray(bytes, 0, bytes.size, bounds)
+            if (bounds.outWidth <= 0 || bounds.outHeight <= 0) return@withContext null
+            var sample = 1
+            while (maxOf(bounds.outWidth, bounds.outHeight) / sample > maxSize) sample *= 2
+            val opts = BitmapFactory.Options().apply { inSampleSize = sample }
+            BitmapFactory.decodeByteArray(bytes, 0, bytes.size, opts)?.asImageBitmap()
+        } catch (e: Exception) {
+            null
+        }
     }
-}
 
-actual suspend fun decodeBase64Image(base64: String): ImageBitmap? = withContext(Dispatchers.IO) {
+actual fun readBackdropBytes(id: String): ByteArray? =
     try {
-        val bytes = android.util.Base64.decode(base64, android.util.Base64.DEFAULT)
-        BitmapFactory.decodeByteArray(bytes, 0, bytes.size)?.asImageBitmap()
+        AndroidEnv.context.assets
+            .open("backdrops/$id.jpg")
+            .use { it.readBytes() }
     } catch (e: Exception) {
         null
     }
-}
+
+actual suspend fun encodeImageAsBase64(
+    path: String,
+    maxSize: Int,
+): String? =
+    withContext(Dispatchers.IO) {
+        try {
+            val bounds = BitmapFactory.Options().apply { inJustDecodeBounds = true }
+            BitmapFactory.decodeFile(path, bounds)
+            if (bounds.outWidth <= 0 || bounds.outHeight <= 0) return@withContext null
+            var sample = 1
+            while (maxOf(bounds.outWidth, bounds.outHeight) / sample > maxSize) sample *= 2
+            val opts = BitmapFactory.Options().apply { inSampleSize = sample }
+            val bitmap = BitmapFactory.decodeFile(path, opts) ?: return@withContext null
+            val stream = java.io.ByteArrayOutputStream()
+            bitmap.compress(android.graphics.Bitmap.CompressFormat.PNG, 100, stream)
+            bitmap.recycle()
+            android.util.Base64.encodeToString(stream.toByteArray(), android.util.Base64.NO_WRAP)
+        } catch (e: Exception) {
+            null
+        }
+    }
+
+actual suspend fun decodeBase64Image(base64: String): ImageBitmap? =
+    withContext(Dispatchers.IO) {
+        try {
+            val bytes = android.util.Base64.decode(base64, android.util.Base64.DEFAULT)
+            BitmapFactory.decodeByteArray(bytes, 0, bytes.size)?.asImageBitmap()
+        } catch (e: Exception) {
+            null
+        }
+    }
 
 @Composable
-actual fun MediaPlayerView(media: MediaItem, modifier: Modifier) {
+actual fun MediaPlayerView(
+    media: MediaItem,
+    modifier: Modifier,
+) {
     val path = media.localPath
     if (path == null) {
         Box(modifier = modifier, contentAlignment = Alignment.Center) {
@@ -191,7 +236,10 @@ actual fun MediaPlayerView(media: MediaItem, modifier: Modifier) {
 }
 
 @Composable
-private fun VideoPlayerView(path: String, modifier: Modifier) {
+private fun VideoPlayerView(
+    path: String,
+    modifier: Modifier,
+) {
     AndroidView(
         factory = { ctx ->
             PlayerView(ctx).apply {
@@ -205,21 +253,27 @@ private fun VideoPlayerView(path: String, modifier: Modifier) {
         },
         update = {},
         onRelease = { view -> view.player?.release() },
-        modifier = modifier
-            .fillMaxWidth()
-            .height(220.dp),
+        modifier =
+            modifier
+                .fillMaxWidth()
+                .height(220.dp),
     )
 }
 
 @Composable
-private fun AudioPlayerView(path: String, filename: String, modifier: Modifier) {
+private fun AudioPlayerView(
+    path: String,
+    filename: String,
+    modifier: Modifier,
+) {
     val context = LocalContext.current
-    val player = remember {
-        ExoPlayer.Builder(context).build().apply {
-            setMediaItem(M3MediaItem.fromUri(path.toUri()))
-            prepare()
+    val player =
+        remember {
+            ExoPlayer.Builder(context).build().apply {
+                setMediaItem(M3MediaItem.fromUri(path.toUri()))
+                prepare()
+            }
         }
-    }
     DisposableEffect(player) { onDispose { player.release() } }
 
     var playing by remember { mutableStateOf(false) }
@@ -237,9 +291,10 @@ private fun AudioPlayerView(path: String, filename: String, modifier: Modifier)
     }
 
     Row(
-        modifier = modifier
-            .fillMaxWidth()
-            .padding(8.dp),
+        modifier =
+            modifier
+                .fillMaxWidth()
+                .padding(8.dp),
         verticalAlignment = Alignment.CenterVertically,
     ) {
         IconButton(onClick = {
@@ -270,17 +325,21 @@ private fun fmt(seconds: Float): String {
     return "%d:%02d".format(s / 60, s % 60)
 }
 
-actual fun openDocument(path: String, mime: String) {
+actual fun openDocument(
+    path: String,
+    mime: String,
+) {
     val context = AndroidEnv.context
     try {
         val file = File(path)
         val uri = FileProvider.getUriForFile(context, "${context.packageName}.fileprovider", file)
-        val intent = Intent(Intent.ACTION_VIEW).apply {
-            setDataAndType(uri, mime)
-            addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
-        }
+        val intent =
+            Intent(Intent.ACTION_VIEW).apply {
+                setDataAndType(uri, mime)
+                addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
+            }
         context.startActivity(intent)
     } catch (e: Exception) {
-        Toast.makeText(context, "No app to open ${mime}", Toast.LENGTH_SHORT).show()
+        Toast.makeText(context, "No app to open $mime", Toast.LENGTH_SHORT).show()
     }
-}
+}

app/shared/src/androidMain/kotlin/iris/platform/AndroidSecureStore.kt

@@ -6,6 +6,8 @@ import android.os.Build
 import androidx.security.crypto.EncryptedSharedPreferences
 import androidx.security.crypto.MasterKey
 import iris.data.SecureStore
+import iris.ui.theme.Backdrop
+import iris.ui.theme.BackgroundMode
 import iris.ui.theme.UserTheme
 import java.util.UUID
 
@@ -15,18 +17,22 @@ import java.util.UUID
  * values are migrated on first run (read old key, write encrypted, delete
  * old key) so an upgrade never loses the pairing.
  */
-class AndroidSecureStore(context: Context) : SecureStore {
+class AndroidSecureStore(
+    context: Context,
+) : SecureStore {
     private val appContext = context.applicationContext
     private val plainPrefs = appContext.getSharedPreferences(PLAIN_PREFS_NAME, Context.MODE_PRIVATE)
-    private val prefs: SharedPreferences = EncryptedSharedPreferences.create(
-        appContext,
-        SECURE_PREFS_NAME,
-        MasterKey.Builder(appContext)
-            .setKeyScheme(MasterKey.KeyScheme.AES256_GCM)
-            .build(),
-        EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
-        EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM,
-    )
+    private val prefs: SharedPreferences =
+        EncryptedSharedPreferences.create(
+            appContext,
+            SECURE_PREFS_NAME,
+            MasterKey
+                .Builder(appContext)
+                .setKeyScheme(MasterKey.KeyScheme.AES256_GCM)
+                .build(),
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM,
+        )
 
     init {
         migratePlainValues()
@@ -50,7 +56,8 @@ class AndroidSecureStore(context: Context) : SecureStore {
         }
         if (migrated) editor.apply()
         // The plain store must not keep a copy of any value.
-        plainPrefs.edit()
+        plainPrefs
+            .edit()
             .remove(KEY_URL)
             .remove(KEY_TOKEN)
             .remove(KEY_DEVICE_ID)
@@ -73,7 +80,12 @@ class AndroidSecureStore(context: Context) : SecureStore {
         get() {
             var id = prefs.getString(KEY_DEVICE_ID, null)
             if (id.isNullOrBlank()) {
-                id = "dev_" + UUID.randomUUID().toString().replace("-", "").take(16)
+                id = "dev_" +
+                    UUID
+                        .randomUUID()
+                        .toString()
+                        .replace("-", "")
+                        .take(16)
                 prefs.edit().putString(KEY_DEVICE_ID, id).apply()
             }
             return id
@@ -123,7 +135,11 @@ class AndroidSecureStore(context: Context) : SecureStore {
         set(value) = prefs.edit().putInt(KEY_AGENT_BUBBLE_COLOR, value).apply()
 
     override var backgroundMode: String
-        get() = prefs.getString(KEY_BACKGROUND_MODE, "color").orEmpty().ifBlank { "color" }
+        get() =
+            prefs
+                .getString(KEY_BACKGROUND_MODE, BackgroundMode.Image.name.lowercase())
+                .orEmpty()
+                .ifBlank { BackgroundMode.Image.name.lowercase() }
         set(value) = prefs.edit().putString(KEY_BACKGROUND_MODE, value).apply()
 
     override var backgroundColor: Int
@@ -131,20 +147,31 @@ class AndroidSecureStore(context: Context) : SecureStore {
         set(value) = prefs.edit().putInt(KEY_BACKGROUND_COLOR, value).apply()
 
     override var backgroundImagePath: String
-        get() = prefs.getString(KEY_BACKGROUND_IMAGE_PATH, "").orEmpty()
+        get() =
+            prefs
+                .getString(KEY_BACKGROUND_IMAGE_PATH, Backdrop.DEFAULT.path)
+                .orEmpty()
+                .ifBlank { Backdrop.DEFAULT.path }
         set(value) = prefs.edit().putString(KEY_BACKGROUND_IMAGE_PATH, value).apply()
 
     override var fontSizeScale: Float
         get() = prefs.getFloat(KEY_FONT_SIZE_SCALE, 1.0f)
         set(value) = prefs.edit().putFloat(KEY_FONT_SIZE_SCALE, value).apply()
 
-    override fun savePairing(url: String, token: String) {
+    override fun savePairing(
+        url: String,
+        token: String,
+    ) {
         serverUrl = url
         this.token = token
     }
 
     override fun clear() {
-        prefs.edit().remove(KEY_URL).remove(KEY_TOKEN).apply()
+        prefs
+            .edit()
+            .remove(KEY_URL)
+            .remove(KEY_TOKEN)
+            .apply()
     }
 
     private companion object {
@@ -168,4 +195,4 @@ class AndroidSecureStore(context: Context) : SecureStore {
         const val KEY_BACKGROUND_IMAGE_PATH = "background_image_path"
         const val KEY_FONT_SIZE_SCALE = "font_size_scale"
     }
-}
+}

app/shared/src/androidMain/kotlin/iris/platform/Platform.kt

@@ -1,3 +1,3 @@
 package iris.platform
 
-actual val isDesktop: Boolean = false
+actual val isDesktop: Boolean = false

app/shared/src/commonMain/kotlin/iris/platform/Platform.kt

@@ -1,4 +1,4 @@
 package iris.platform
 
 /** True on the desktop target (M6: big-screen layout, shortcuts, tray). */
-expect val isDesktop: Boolean
+expect val isDesktop: Boolean

app/shared/src/commonMain/kotlin/iris/platform/PlatformMedia.kt

@@ -35,21 +35,49 @@ expect fun mediaCacheBaseDir(): String
 expect suspend fun loadMediaImage(path: String): ImageBitmap?
 
 /** Load an image scaled to at most [maxSize] px on the longest edge. Null on failure. */
-expect suspend fun loadScaledImage(path: String, maxSize: Int): ImageBitmap?
+expect suspend fun loadScaledImage(
+    path: String,
+    maxSize: Int,
+): ImageBitmap?
+
+/**
+ * Decode an image from raw bytes (bundled backdrops), scaled to at most
+ * [maxSize] px on the longest edge. Null on failure.
+ */
+expect suspend fun decodeImageBytes(
+    bytes: ByteArray,
+    maxSize: Int,
+): ImageBitmap?
+
+/**
+ * Read a bundled backdrop image (shipped in the app) by its [id] (the file
+ * name without extension, e.g. `pexels-yunszyveli-12368637`). Android reads it
+ * from `assets/backdrops/`, desktop from the classpath. Null on failure.
+ */
+expect fun readBackdropBytes(id: String): ByteArray?
 
 /**
  * Encode a local image as a base64 PNG, downscaled to at most [maxSize] px on
  * the longest edge. Null on failure. Used for channel icons (stored on the
  * gateway, synced across devices).
  */
-expect suspend fun encodeImageAsBase64(path: String, maxSize: Int): String?
+expect suspend fun encodeImageAsBase64(
+    path: String,
+    maxSize: Int,
+): String?
 
 /** Decode a base64-encoded image (PNG/JPEG) into an [ImageBitmap]. Null on failure. */
 expect suspend fun decodeBase64Image(base64: String): ImageBitmap?
 
 /** Inline audio/video player (ExoPlayer on Android; placeholder on desktop). */
 @Composable
-expect fun MediaPlayerView(media: MediaItem, modifier: Modifier)
+expect fun MediaPlayerView(
+    media: MediaItem,
+    modifier: Modifier,
+)
 
 /** Open a document with the system handler (best effort). */
-expect fun openDocument(path: String, mime: String)
+expect fun openDocument(
+    path: String,
+    mime: String,
+)

app/shared/src/commonMain/kotlin/iris/state/IrisController.kt

@@ -1,7 +1,7 @@
 package iris.state
 
-import iris.data.ChatStore
 import iris.data.ChannelStore
+import iris.data.ChatStore
 import iris.data.MediaItem
 import iris.data.MessageItem
 import iris.data.MsgStatus
@@ -24,22 +24,21 @@ import iris.protocol.MessageDeletedPayload
 import iris.protocol.MessagePayload
 import iris.protocol.MessageStopPayload
 import iris.protocol.NotificationPayload
-import iris.protocol.ReadReceiptPayload
 import iris.protocol.ROLE_ASSISTANT
+import iris.protocol.ReadReceiptPayload
 import iris.protocol.SearchHit
 import iris.protocol.SearchResultsPayload
 import iris.protocol.SlashCommand
 import iris.protocol.StatusPayload
 import iris.protocol.SyncDonePayload
-import iris.protocol.TYPE_ERROR
-import iris.protocol.TYPE_HISTORY
-import iris.protocol.TYPE_NOTIFICATION
 import iris.protocol.TYPE_CHANNEL_CREATED
 import iris.protocol.TYPE_CHANNEL_DELETED
 import iris.protocol.TYPE_CHANNEL_LIST
 import iris.protocol.TYPE_CHANNEL_RENAMED
 import iris.protocol.TYPE_COMMANDS_CATALOG
 import iris.protocol.TYPE_COMMENTARY
+import iris.protocol.TYPE_ERROR
+import iris.protocol.TYPE_HISTORY
 import iris.protocol.TYPE_MEDIA_OFFER
 import iris.protocol.TYPE_MESSAGE
 import iris.protocol.TYPE_MESSAGE_DELETE
@@ -47,6 +46,7 @@ import iris.protocol.TYPE_MESSAGE_DELETED
 import iris.protocol.TYPE_MESSAGE_START
 import iris.protocol.TYPE_MESSAGE_STOP
 import iris.protocol.TYPE_MESSAGE_UPDATE
+import iris.protocol.TYPE_NOTIFICATION
 import iris.protocol.TYPE_READ_RECEIPT
 import iris.protocol.TYPE_SEARCH_RESULTS
 import iris.protocol.TYPE_STATUS
@@ -69,6 +69,7 @@ import iris.protocol.historyFrame
 import iris.protocol.messageDeleteFrame
 import iris.protocol.searchFrame
 import iris.protocol.syncFrame
+import iris.ui.theme.Backdrop
 import iris.ui.theme.BackgroundMode
 import iris.ui.theme.UserTheme
 import kotlinx.coroutines.CoroutineScope
@@ -105,11 +106,12 @@ class IrisController(
     val toolDetail: StateFlow<ToolDetail> = _toolDetail.asStateFlow()
 
     fun cycleToolDetail() {
-        _toolDetail.value = when (_toolDetail.value) {
-            ToolDetail.EVERYTHING -> ToolDetail.TRUNCATED
-            ToolDetail.TRUNCATED -> ToolDetail.NOTHING
-            ToolDetail.NOTHING -> ToolDetail.EVERYTHING
-        }
+        _toolDetail.value =
+            when (_toolDetail.value) {
+                ToolDetail.EVERYTHING -> ToolDetail.TRUNCATED
+                ToolDetail.TRUNCATED -> ToolDetail.NOTHING
+                ToolDetail.NOTHING -> ToolDetail.EVERYTHING
+            }
         store.toolDetail = _toolDetail.value.name.lowercase()
     }
 
@@ -170,17 +172,19 @@ class IrisController(
     // ── Appearance (Settings → Appearance) ────────────────────────────────
     // User-customizable bubble colors + background (color or image).
     // Persisted as ARGB ints + an image path (see UserTheme).
-    private val _theme = MutableStateFlow(
-        UserTheme(
-            userBubbleColor = store.userBubbleColor,
-            agentBubbleColor = store.agentBubbleColor,
-            backgroundMode = BackgroundMode.entries.firstOrNull {
-                it.name.equals(store.backgroundMode, ignoreCase = true)
-            } ?: BackgroundMode.Color,
-            backgroundColor = store.backgroundColor,
-            backgroundImagePath = store.backgroundImagePath.ifBlank { null },
+    private val _theme =
+        MutableStateFlow(
+            UserTheme(
+                userBubbleColor = store.userBubbleColor,
+                agentBubbleColor = store.agentBubbleColor,
+                backgroundMode =
+                    BackgroundMode.entries.firstOrNull {
+                        it.name.equals(store.backgroundMode, ignoreCase = true)
+                    } ?: BackgroundMode.Color,
+                backgroundColor = store.backgroundColor,
+                backgroundImagePath = store.backgroundImagePath.ifBlank { null },
+            ),
         )
-    )
     val theme: StateFlow<UserTheme> = _theme.asStateFlow()
 
     fun setUserBubbleColor(argb: Int) = updateTheme { it.copy(userBubbleColor = argb) }
@@ -189,13 +193,25 @@ class IrisController(
 
     fun setBackgroundColor(argb: Int) = updateTheme { it.copy(backgroundColor = argb) }
 
-    fun setBackgroundMode(mode: BackgroundMode) = updateTheme { it.copy(backgroundMode = mode) }
+    fun setBackgroundMode(mode: BackgroundMode) =
+        updateTheme {
+            // Switching to image mode without an image falls back to the default
+            // bundled backdrop instead of silently showing the solid color.
+            it.copy(
+                backgroundMode = mode,
+                backgroundImagePath =
+                    if (mode == BackgroundMode.Image && it.backgroundImagePath.isNullOrBlank()) {
+                        Backdrop.DEFAULT.path
+                    } else {
+                        it.backgroundImagePath
+                    },
+            )
+        }
 
     fun setBackgroundImagePath(path: String?) = updateTheme { it.copy(backgroundImagePath = path) }
 
     /** Clears the background image and falls back to the solid color. */
-    fun removeBackgroundImage() =
-        updateTheme { it.copy(backgroundImagePath = null, backgroundMode = BackgroundMode.Color) }
+    fun removeBackgroundImage() = updateTheme { it.copy(backgroundImagePath = null, backgroundMode = BackgroundMode.Color) }
 
     fun resetTheme() = updateTheme { UserTheme() }
 
@@ -261,6 +277,7 @@ class IrisController(
     val attachments: StateFlow<List<PendingAttachment>> = _attachments.asStateFlow()
 
     // ── M5: notification banners (docs/08 §8.3) ───────────────────────────
+
     /** An in-app notification banner shown above the composer. */
     data class Banner(
         val id: Long,
@@ -280,7 +297,13 @@ class IrisController(
         _banners.value = _banners.value.filterNot { it.id == id }
     }
 
-    private fun pushBanner(kind: String, title: String, body: String, chatId: String?, threadId: String?) {
+    private fun pushBanner(
+        kind: String,
+        title: String,
+        body: String,
+        chatId: String?,
+        threadId: String?,
+    ) {
         val persistent = kind in HIGH_PRIORITY_NOTIF_KINDS
         val banner = Banner(bannerSeq++, kind, title, body, chatId, threadId, persistent)
         _banners.value = (_banners.value + banner).takeLast(5)
@@ -299,7 +322,11 @@ class IrisController(
      * the chat (deep link). The same per-chat notification id is reused, so a
      * multi-segment turn updates one notification instead of stacking.
      */
-    private fun notifyMessageIfBackgrounded(chatId: String?, threadId: String?, text: String) {
+    private fun notifyMessageIfBackgrounded(
+        chatId: String?,
+        threadId: String?,
+        text: String,
+    ) {
         if (isAppForeground()) return
         if (text.isBlank()) return
         val id = chatId ?: "android:default"
@@ -308,7 +335,10 @@ class IrisController(
     }
 
     /** Single-line preview for a notification body (lock-screen privacy). */
-    private fun preview(text: String, limit: Int = 120): String {
+    private fun preview(
+        text: String,
+        limit: Int = 120,
+    ): String {
         val flat = text.replace('\n', ' ').replace('\t', ' ').trim()
         return if (flat.length <= limit) flat else flat.take(limit).trimEnd() + "…"
     }
@@ -318,7 +348,10 @@ class IrisController(
 
     /** Open the chat referenced by a push notification tap. Applied now if
      *  connected, otherwise on the next hello.ack (lane may not exist yet). */
-    fun openDeepLink(chatId: String?, threadId: String?) {
+    fun openDeepLink(
+        chatId: String?,
+        threadId: String?,
+    ) {
         if (chatId.isNullOrBlank()) return
         pendingDeepLink = chatId to threadId
         if (client.state.value is GatewayClient.State.Connected) applyDeepLink()
@@ -343,7 +376,8 @@ class IrisController(
                     TYPE_TOOL_PROGRESS,
                     TYPE_TOOL_END,
                     TYPE_COMMENTARY,
-                    TYPE_MEDIA_OFFER -> {
+                    TYPE_MEDIA_OFFER,
+                    -> {
                         chat.onFrame(frame)
                         // M4: pull offered media into the local cache.
                         if (frame.type == TYPE_MEDIA_OFFER) {
@@ -356,23 +390,31 @@ class IrisController(
                         // message.stop; non-streaming replies are a single
                         // assistant `message`.
                         when (frame.type) {
-                            TYPE_MESSAGE_STOP ->
+                            TYPE_MESSAGE_STOP -> {
                                 frame.payloadAs<MessageStopPayload>()?.let {
                                     notifyMessageIfBackgrounded(frame.chatId, frame.threadId, it.finalText)
                                 }
-                            TYPE_MESSAGE ->
+                            }
+
+                            TYPE_MESSAGE -> {
                                 frame.payloadAs<MessagePayload>()?.let {
                                     if (it.role == ROLE_ASSISTANT) {
                                         notifyMessageIfBackgrounded(frame.chatId, frame.threadId, it.text)
                                     }
                                 }
-                            else -> Unit
+                            }
+
+                            else -> {
+                                Unit
+                            }
                         }
                     }
+
                     TYPE_CHANNEL_CREATED,
                     TYPE_CHANNEL_RENAMED,
                     TYPE_CHANNEL_DELETED,
-                    TYPE_CHANNEL_LIST -> {
+                    TYPE_CHANNEL_LIST,
+                    -> {
                         channels.onFrame(frame)
                         // Auto-created thread (Settings → "Threads"): the
                         // gateway minted it for a message in the flat lane we
@@ -396,26 +438,37 @@ class IrisController(
                             frame.payloadAs<ChannelDeletedPayload>()?.let { p ->
                                 val (curChat, curThread) = chat.parseLane(chat.currentLane.value)
                                 when {
-                                    curThread == p.chatId -> openChannel(curChat)
-                                    curChat == p.chatId ->
+                                    curThread == p.chatId -> {
+                                        openChannel(curChat)
+                                    }
+
+                                    curChat == p.chatId -> {
                                         channels.defaultChannel()?.let { openChannel(it.chatId) }
-                                    else -> Unit
+                                    }
+
+                                    else -> {
+                                        Unit
+                                    }
                                 }
                             }
                         }
                     }
+
                     TYPE_SEARCH_RESULTS -> {
                         frame.payloadAs<SearchResultsPayload>()?.let { _searchResults.value = it.hits }
                         _searching.value = false
                     }
+
                     TYPE_COMMANDS_CATALOG -> {
                         frame.payloadAs<CommandsCatalogPayload>()?.let { _slashCommands.value = it.commands }
                     }
+
                     TYPE_SYNC_DONE -> {
                         // Replayed frames already flowed through [events]; the
                         // cursor is authoritative server-side (outbox).
                         frame.payloadAs<SyncDonePayload>()?.let { store.syncCursor = it.cursor }
                     }
+
                     TYPE_HISTORY -> {
                         // Full message history for a chat/thread (initial open /
                         // restart restore). `sync` only replays the outbox delta
@@ -432,6 +485,7 @@ class IrisController(
                             )
                         }
                     }
+
                     TYPE_NOTIFICATION -> {
                         frame.payloadAs<NotificationPayload>()?.let { p ->
                             pushBanner(p.kind, p.title, p.body, p.chatId, p.threadId)
@@ -444,12 +498,15 @@ class IrisController(
                             }
                         }
                     }
+
                     TYPE_TYPING -> {
                         frame.payloadAs<TypingPayload>()?.let { _typing.value = it.on }
                     }
+
                     TYPE_READ_RECEIPT -> {
                         frame.payloadAs<ReadReceiptPayload>()?.let { chat.markRead(it.messageId) }
                     }
+
                     TYPE_MESSAGE_DELETED -> {
                         // A message was deleted (by this or another device).
                         // Idempotent: dropping an unknown id is a no-op.
@@ -457,16 +514,21 @@ class IrisController(
                             chat.removeMessages(it.messageIds.toSet())
                         }
                     }
+
                     TYPE_STATUS -> {
                         frame.payloadAs<StatusPayload>()?.let { _gatewayStatus.value = it.state }
                     }
+
                     TYPE_ERROR -> {
                         // M7: error frames are global, not per-message — fail
                         // any optimistic sends still in flight so they don't
                         // sit at "sending…" forever.
                         chat.failPending()
                     }
-                    else -> Unit
+
+                    else -> {
+                        Unit
+                    }
                 }
             }
         }
@@ -537,7 +599,10 @@ class IrisController(
 
     /** Switch to a specific thread lane under [chatId]. Loads the full history
      *  on first open this session. */
-    fun openThread(chatId: String, threadId: String) {
+    fun openThread(
+        chatId: String,
+        threadId: String,
+    ) {
         chat.setLane(chat.laneKey(chatId, threadId))
         loadHistory(chatId, threadId)
     }
@@ -550,13 +615,19 @@ class IrisController(
         client.sendFrame(channelCreateFrame(0, trimmed))
     }
 
-    fun createThread(name: String, parentChatId: String) {
+    fun createThread(
+        name: String,
+        parentChatId: String,
+    ) {
         val trimmed = name.trim()
         if (trimmed.isEmpty()) return
         client.sendFrame(channelCreateFrame(0, trimmed, kind = "thread", parentChatId = parentChatId))
     }
 
-    fun renameChannel(chatId: String, name: String) {
+    fun renameChannel(
+        chatId: String,
+        name: String,
+    ) {
         val trimmed = name.trim()
         if (trimmed.isEmpty()) return
         client.sendFrame(channelRenameFrame(0, chatId, trimmed))
@@ -567,19 +638,29 @@ class IrisController(
     }
 
     /** Toggle the cosmetic favorite flag (sorts the channel to the top). */
-    fun setChannelFavorite(chatId: String, on: Boolean) {
+    fun setChannelFavorite(
+        chatId: String,
+        on: Boolean,
+    ) {
         client.sendFrame(channelFavoriteFrame(0, chatId, on))
     }
 
     /** Mark the channel as automation (read-only; cron/webhook output only).
      *  The default channel cannot be marked (the server enforces this too). */
-    fun setChannelAutomation(chatId: String, on: Boolean) {
+    fun setChannelAutomation(
+        chatId: String,
+        on: Boolean,
+    ) {
         client.sendFrame(channelSetAutomationFrame(0, chatId, on))
     }
 
     /** Set the channel's cosmetic icon (base64 image) and/or avatar color.
      *  Pass null to clear a field. */
-    fun setChannelIcon(chatId: String, icon: String?, color: String?) {
+    fun setChannelIcon(
+        chatId: String,
+        icon: String?,
+        color: String?,
+    ) {
         client.sendFrame(channelIconFrame(0, chatId, icon, color))
     }
 
@@ -593,7 +674,12 @@ class IrisController(
 
     // ── M3: search ────────────────────────────────────────────────────────
 
-    fun search(query: String, scope: String = "all", chatId: String? = null, threadId: String? = null) {
+    fun search(
+        query: String,
+        scope: String = "all",
+        chatId: String? = null,
+        threadId: String? = null,
+    ) {
         val q = query.trim()
         if (q.isEmpty()) return
         _lastQuery.value = q
@@ -626,7 +712,10 @@ class IrisController(
      *  Populates the lane via the `history` response; used on first open of a
      *  chat and after a process death (restart) to restore the view, since the
      *  `sync` delta does not cover messages older than the saved cursor. */
-    fun loadHistory(chatId: String, threadId: String? = null) {
+    fun loadHistory(
+        chatId: String,
+        threadId: String? = null,
+    ) {
         val lane = chat.laneKey(chatId, threadId)
         if (lane in historyLoaded) return
         historyLoaded.add(lane)
@@ -636,20 +725,27 @@ class IrisController(
     }
 
     /** Optimistic send: show immediately in the current lane, then hand to the gateway.
- *  M4: [attachments] (uploaded) are attached via media_refs. */
-    fun send(text: String, attachments: List<PendingAttachment> = emptyList()) {
+     *  M4: [attachments] (uploaded) are attached via media_refs. */
+    fun send(
+        text: String,
+        attachments: List<PendingAttachment> = emptyList(),
+    ) {
         val trimmed = text.trim()
         val refs = attachments.mapNotNull { it.mediaRef }
         if (trimmed.isEmpty() && refs.isEmpty()) return
         val lane = chat.currentLane.value
         val (chatId, threadId) = chat.parseLane(lane)
-        val media = attachments.map {
-            MediaItem(
-                mediaId = it.mediaRef ?: it.filename,
-                kind = it.kind, mime = it.mime, size = it.size, filename = it.filename,
-                localPath = it.path,
-            )
-        }
+        val media =
+            attachments.map {
+                MediaItem(
+                    mediaId = it.mediaRef ?: it.filename,
+                    kind = it.kind,
+                    mime = it.mime,
+                    size = it.size,
+                    filename = it.filename,
+                    localPath = it.path,
+                )
+            }
         chat.addPending(trimmed, lane, media)
         client.sendMessage(chatId, trimmed, threadId, refs, autoThread = wantsAutoThread(trimmed, threadId, chatId))
         _attachments.value = emptyList()
@@ -660,7 +756,11 @@ class IrisController(
      *  gateway (Telegram topic-mode workflow). Threading is only active on
      *  the default channel; other channels stay flat. Slash commands and
      *  media-only sends stay in the flat lane. */
-    private fun wantsAutoThread(text: String, threadId: String?, chatId: String): Boolean =
+    private fun wantsAutoThread(
+        text: String,
+        threadId: String?,
+        chatId: String,
+    ): Boolean =
         _threadsEnabled.value &&
             threadId == null &&
             text.isNotEmpty() &&
@@ -700,28 +800,36 @@ class IrisController(
     /** Stage a picked file: upload it, then keep it as a pending attachment. */
     fun attachFile(picked: PickedFile) {
         val kind = kindFromMime(picked.mime)
-        val placeholder = PendingAttachment(
-            filename = picked.name, mime = picked.mime, size = picked.size, kind = kind,
-            path = picked.path,
-        )
+        val placeholder =
+            PendingAttachment(
+                filename = picked.name,
+                mime = picked.mime,
+                size = picked.size,
+                kind = kind,
+                path = picked.path,
+            )
         _attachments.value = _attachments.value + placeholder
         scope.launch {
             val mediaRef = "up_${Random.nextLong(1_000_000_000L, 9_999_999_999L)}"
-            val result = client.uploadMedia(
-                path = picked.path,
-                mime = picked.mime,
-                kind = kind,
-                filename = picked.name,
-                mediaRef = mediaRef,
-            )
-            _attachments.value = _attachments.value.map {
-                if (it.filename == picked.name && it.uploading) {
-                    result.fold(
-                        { ref -> it.copy(uploading = false, mediaRef = ref) },
-                        { e -> it.copy(uploading = false, error = e.message) },
-                    )
-                } else it
-            }
+            val result =
+                client.uploadMedia(
+                    path = picked.path,
+                    mime = picked.mime,
+                    kind = kind,
+                    filename = picked.name,
+                    mediaRef = mediaRef,
+                )
+            _attachments.value =
+                _attachments.value.map {
+                    if (it.filename == picked.name && it.uploading) {
+                        result.fold(
+                            { ref -> it.copy(uploading = false, mediaRef = ref) },
+                            { e -> it.copy(uploading = false, error = e.message) },
+                        )
+                    } else {
+                        it
+                    }
+                }
         }
     }
 
@@ -748,7 +856,10 @@ class IrisController(
     }
 
     /** Connect-screen action: real hello test, then save + (re)connect. */
-    suspend fun connect(url: String, token: String): Result<Unit> {
+    suspend fun connect(
+        url: String,
+        token: String,
+    ): Result<Unit> {
         val test = client.testHello(url, token)
         if (test.isFailure) return test
         store.savePairing(url, token)
@@ -779,9 +890,10 @@ private fun HistoryMessage.toMessageItem(): MessageItem =
         reasoning = reasoning,
         model = model,
         tokens = tokens,
-        media = media.map {
-            MediaItem(mediaId = it.mediaId, kind = it.kind, mime = it.mime, size = it.size, filename = it.filename)
-        },
+        media =
+            media.map {
+                MediaItem(mediaId = it.mediaId, kind = it.kind, mime = it.mime, size = it.size, filename = it.filename)
+            },
     )
 
 // Gateway restart routine (hermes, same icon + wording on all platforms). The
@@ -797,14 +909,13 @@ private const val GATEWAY_ONLINE_MSG =
 
 /** How much tool detail to show (Settings → "Tool detail"). */
 enum class ToolDetail {
-    EVERYTHING,   // name + full args (collapsible) + output preview
-    TRUNCATED,    // one-liner "emoji name: preview", collapsible (default)
-    NOTHING,      // suppress tool cards entirely
+    EVERYTHING, // name + full args (collapsible) + output preview
+    TRUNCATED, // one-liner "emoji name: preview", collapsible (default)
+    NOTHING, // suppress tool cards entirely
     ;
 
     companion object {
         /** Parse a persisted value; unknown/blank falls back to the default. */
-        fun fromName(name: String): ToolDetail =
-            entries.firstOrNull { it.name.equals(name, ignoreCase = true) } ?: TRUNCATED
+        fun fromName(name: String): ToolDetail = entries.firstOrNull { it.name.equals(name, ignoreCase = true) } ?: TRUNCATED
     }
-}
+}

app/shared/src/commonMain/kotlin/iris/ui/screens/SettingsScreen.kt

@@ -8,6 +8,7 @@ import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.FlowRow
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxSize
@@ -44,9 +45,12 @@ import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
 import iris.platform.ImageFilePicker
+import iris.platform.decodeImageBytes
 import iris.platform.loadScaledImage
+import iris.platform.readBackdropBytes
 import iris.state.IrisController
 import iris.state.ToolDetail
+import iris.ui.theme.Backdrop
 import iris.ui.theme.BackgroundMode
 import iris.ui.theme.IrisColors
 import iris.ui.theme.LocalUserTheme
@@ -56,11 +60,15 @@ import kotlin.math.roundToInt
  * Settings screen (post-M7): app-level preferences, opened from the channel
  * drawer / rail. More settings land here over time.
  */
+
 /** Which color the picker dialog is editing. */
 private enum class PickerTarget { UserBubble, AgentBubble, Background }
 
 @Composable
-fun SettingsScreen(controller: IrisController, onBack: () -> Unit) {
+fun SettingsScreen(
+    controller: IrisController,
+    onBack: () -> Unit,
+) {
     val threadsEnabled by controller.threadsEnabled.collectAsState()
     val streamingEnabled by controller.streamingEnabled.collectAsState()
     val reasoningAutoCollapse by controller.reasoningAutoCollapse.collectAsState()
@@ -71,10 +79,11 @@ fun SettingsScreen(controller: IrisController, onBack: () -> Unit) {
 
     Box(modifier = Modifier.fillMaxSize().background(theme.background)) {
         Column(
-            modifier = Modifier
-                .fillMaxSize()
-                .verticalScroll(rememberScrollState())
-                .padding(12.dp),
+            modifier =
+                Modifier
+                    .fillMaxSize()
+                    .verticalScroll(rememberScrollState())
+                    .padding(12.dp),
             verticalArrangement = Arrangement.spacedBy(8.dp),
         ) {
             Row(
@@ -220,14 +229,36 @@ fun SettingsScreen(controller: IrisController, onBack: () -> Unit) {
                         ColorSwatch(theme.background) { pickerTarget = PickerTarget.Background }
                     }
                 } else {
+                    Spacer(modifier = Modifier.height(8.dp))
+                    Text("Backdrops", fontSize = 12.sp, color = IrisColors.textDim)
+                    Spacer(modifier = Modifier.height(6.dp))
+                    FlowRow(
+                        horizontalArrangement = Arrangement.spacedBy(8.dp),
+                        verticalArrangement = Arrangement.spacedBy(8.dp),
+                    ) {
+                        Backdrop.ALL.forEach { backdrop ->
+                            BackdropThumb(
+                                backdrop = backdrop,
+                                selected = theme.backgroundImagePath == backdrop.path,
+                                onClick = {
+                                    controller.setBackgroundMode(BackgroundMode.Image)
+                                    controller.setBackgroundImagePath(backdrop.path)
+                                },
+                            )
+                        }
+                    }
                     Spacer(modifier = Modifier.height(8.dp))
                     Row(verticalAlignment = Alignment.CenterVertically) {
                         BackgroundPreview(theme.backgroundImagePath)
                         Spacer(modifier = Modifier.width(8.dp))
                         Column(modifier = Modifier.weight(1f)) {
                             Text(
-                                if (theme.backgroundImagePath.isNullOrBlank()) "No image selected"
-                                else fileNameOf(theme.backgroundImagePath!!),
+                                if (theme.backgroundImagePath.isNullOrBlank()) {
+                                    "No image selected"
+                                } else {
+                                    Backdrop.fromPath(theme.backgroundImagePath)?.name
+                                        ?: fileNameOf(theme.backgroundImagePath!!)
+                                },
                                 fontSize = 12.sp,
                                 color = IrisColors.textDim,
                             )
@@ -328,58 +359,73 @@ fun SettingsScreen(controller: IrisController, onBack: () -> Unit) {
         }
 
         when (pickerTarget) {
-            PickerTarget.UserBubble -> ColorPickerDialog(
-                title = "Your bubble",
-                initialArgb = theme.userBubbleColor,
-                onApply = { controller.setUserBubbleColor(it) },
-                onConfirm = {
-                    controller.setUserBubbleColor(it)
-                    pickerTarget = null
-                },
-                onDismiss = { pickerTarget = null },
-            )
-            PickerTarget.AgentBubble -> ColorPickerDialog(
-                title = "Agent bubble",
-                initialArgb = theme.agentBubbleColor,
-                onApply = { controller.setAgentBubbleColor(it) },
-                onConfirm = {
-                    controller.setAgentBubbleColor(it)
-                    pickerTarget = null
-                },
-                onDismiss = { pickerTarget = null },
-            )
-            PickerTarget.Background -> ColorPickerDialog(
-                title = "Background",
-                initialArgb = theme.backgroundColor,
-                onApply = { controller.setBackgroundColor(it) },
-                onConfirm = {
-                    controller.setBackgroundColor(it)
-                    pickerTarget = null
-                },
-                onDismiss = { pickerTarget = null },
-            )
-            null -> Unit
+            PickerTarget.UserBubble -> {
+                ColorPickerDialog(
+                    title = "Your bubble",
+                    initialArgb = theme.userBubbleColor,
+                    onApply = { controller.setUserBubbleColor(it) },
+                    onConfirm = {
+                        controller.setUserBubbleColor(it)
+                        pickerTarget = null
+                    },
+                    onDismiss = { pickerTarget = null },
+                )
+            }
+
+            PickerTarget.AgentBubble -> {
+                ColorPickerDialog(
+                    title = "Agent bubble",
+                    initialArgb = theme.agentBubbleColor,
+                    onApply = { controller.setAgentBubbleColor(it) },
+                    onConfirm = {
+                        controller.setAgentBubbleColor(it)
+                        pickerTarget = null
+                    },
+                    onDismiss = { pickerTarget = null },
+                )
+            }
+
+            PickerTarget.Background -> {
+                ColorPickerDialog(
+                    title = "Background",
+                    initialArgb = theme.backgroundColor,
+                    onApply = { controller.setBackgroundColor(it) },
+                    onConfirm = {
+                        controller.setBackgroundColor(it)
+                        pickerTarget = null
+                    },
+                    onDismiss = { pickerTarget = null },
+                )
+            }
+
+            null -> {
+                Unit
+            }
         }
     }
 }
 
 /** Material-style back arrow (vector, matches the app's icon weight). */
 @Composable
-private fun BackArrow(size: Dp = 22.dp, color: Color = IrisColors.onSurface) {
+private fun BackArrow(
+    size: Dp = 22.dp,
+    color: Color = IrisColors.onSurface,
+) {
     Canvas(modifier = Modifier.size(size)) {
         val s = this.size.width / 24f
-        val path = Path().apply {
-            moveTo(20f * s, 11f * s)
-            lineTo(7.83f * s, 11f * s)
-            lineTo(13.42f * s, 5.41f * s)
-            lineTo(12f * s, 4f * s)
-            lineTo(4f * s, 12f * s)
-            lineTo(12f * s, 20f * s)
-            lineTo(13.41f * s, 18.59f * s)
-            lineTo(7.83f * s, 13f * s)
-            lineTo(20f * s, 13f * s)
-            close()
-        }
+        val path =
+            Path().apply {
+                moveTo(20f * s, 11f * s)
+                lineTo(7.83f * s, 11f * s)
+                lineTo(13.42f * s, 5.41f * s)
+                lineTo(12f * s, 4f * s)
+                lineTo(4f * s, 12f * s)
+                lineTo(12f * s, 20f * s)
+                lineTo(13.41f * s, 18.59f * s)
+                lineTo(7.83f * s, 13f * s)
+                lineTo(20f * s, 13f * s)
+                close()
+            }
         drawPath(path, color)
     }
 }
@@ -388,11 +434,12 @@ private fun BackArrow(size: Dp = 22.dp, color: Color = IrisColors.onSurface) {
 @Composable
 private fun SettingsCard(content: @Composable () -> Unit) {
     Column(
-        modifier = Modifier
-            .fillMaxWidth()
-            .clip(RoundedCornerShape(12.dp))
-            .background(IrisColors.panel)
-            .padding(12.dp),
+        modifier =
+            Modifier
+                .fillMaxWidth()
+                .clip(RoundedCornerShape(12.dp))
+                .background(IrisColors.panel)
+                .padding(12.dp),
     ) {
         content()
     }
@@ -400,14 +447,18 @@ private fun SettingsCard(content: @Composable () -> Unit) {
 
 /** Clickable rounded chip showing a color; opens the picker on tap. */
 @Composable
-private fun ColorSwatch(color: Color, onClick: () -> Unit) {
+private fun ColorSwatch(
+    color: Color,
+    onClick: () -> Unit,
+) {
     Box(
-        modifier = Modifier
-            .size(32.dp)
-            .clip(RoundedCornerShape(8.dp))
-            .background(color)
-            .border(1.dp, IrisColors.divider, RoundedCornerShape(8.dp))
-            .clickable(onClick = onClick),
+        modifier =
+            Modifier
+                .size(32.dp)
+                .clip(RoundedCornerShape(8.dp))
+                .background(color)
+                .border(1.dp, IrisColors.divider, RoundedCornerShape(8.dp))
+                .clickable(onClick = onClick),
     )
 }
 
@@ -416,14 +467,25 @@ private fun ColorSwatch(color: Color, onClick: () -> Unit) {
 private fun BackgroundPreview(path: String?) {
     var bmp by remember(path) { mutableStateOf<ImageBitmap?>(null) }
     LaunchedEffect(path) {
-        bmp = if (path.isNullOrBlank()) null else loadScaledImage(path, 128)
+        bmp =
+            if (path.isNullOrBlank()) {
+                null
+            } else {
+                val bytes = Backdrop.fromPath(path)?.let { readBackdropBytes(it.id) }
+                if (bytes != null) {
+                    decodeImageBytes(bytes, 128)
+                } else {
+                    loadScaledImage(path, 128)
+                }
+            }
     }
     Box(
-        modifier = Modifier
-            .size(44.dp)
-            .clip(RoundedCornerShape(8.dp))
-            .background(IrisColors.panel)
-            .border(1.dp, IrisColors.divider, RoundedCornerShape(8.dp)),
+        modifier =
+            Modifier
+                .size(44.dp)
+                .clip(RoundedCornerShape(8.dp))
+                .background(IrisColors.panel)
+                .border(1.dp, IrisColors.divider, RoundedCornerShape(8.dp)),
         contentAlignment = Alignment.Center,
     ) {
         val b = bmp
@@ -438,6 +500,43 @@ private fun BackgroundPreview(path: String?) {
     }
 }
 
+/** Thumbnail of a bundled backdrop; highlighted when selected. */
+@Composable
+private fun BackdropThumb(
+    backdrop: Backdrop,
+    selected: Boolean,
+    onClick: () -> Unit,
+) {
+    var bmp by remember(backdrop.id) { mutableStateOf<ImageBitmap?>(null) }
+    LaunchedEffect(backdrop.id) {
+        val bytes = readBackdropBytes(backdrop.id)
+        bmp = if (bytes != null) decodeImageBytes(bytes, 128) else null
+    }
+    Box(
+        modifier =
+            Modifier
+                .size(64.dp)
+                .clip(RoundedCornerShape(8.dp))
+                .background(IrisColors.panel)
+                .border(
+                    if (selected) 2.dp else 1.dp,
+                    if (selected) IrisColors.primary else IrisColors.divider,
+                    RoundedCornerShape(8.dp),
+                ).clickable(onClick = onClick),
+        contentAlignment = Alignment.Center,
+    ) {
+        val b = bmp
+        if (b != null) {
+            Image(
+                bitmap = b,
+                contentDescription = backdrop.name,
+                contentScale = ContentScale.Crop,
+                modifier = Modifier.fillMaxSize(),
+            )
+        }
+    }
+}
+
 /**
  * HSV color picker dialog (hue / saturation / brightness sliders).
  * [onApply] applies the color and keeps the dialog open for further tweaks;
@@ -462,11 +561,12 @@ private fun ColorPickerDialog(
         text = {
             Column(modifier = Modifier.fillMaxWidth()) {
                 Box(
-                    modifier = Modifier
-                        .fillMaxWidth()
-                        .height(48.dp)
-                        .clip(RoundedCornerShape(8.dp))
-                        .background(color),
+                    modifier =
+                        Modifier
+                            .fillMaxWidth()
+                            .height(48.dp)
+                            .clip(RoundedCornerShape(8.dp))
+                            .background(color),
                 )
                 Spacer(modifier = Modifier.height(12.dp))
                 Slider(value = hue, onValueChange = { hue = it }, valueRange = 0f..360f)
@@ -505,11 +605,12 @@ private fun argbToHsv(argb: Int): FloatArray {
     val delta = max - min
     var hue = 0f
     if (delta != 0f) {
-        hue = when (max) {
-            r -> ((g - b) / delta) % 6f
-            g -> (b - r) / delta + 2f
-            else -> (r - g) / delta + 4f
-        }
+        hue =
+            when (max) {
+                r -> ((g - b) / delta) % 6f
+                g -> (b - r) / delta + 2f
+                else -> (r - g) / delta + 4f
+            }
         hue *= 60f
         if (hue < 0f) hue += 360f
     }
@@ -518,5 +619,4 @@ private fun argbToHsv(argb: Int): FloatArray {
 }
 
 /** File name from a path (no java.io.File in common code). */
-private fun fileNameOf(path: String): String =
-    path.substringAfterLast('/').ifEmpty { path.substringAfterLast('\\') }
+private fun fileNameOf(path: String): String = path.substringAfterLast('/').ifEmpty { path.substringAfterLast('\\') }

app/shared/src/commonMain/kotlin/iris/ui/theme/Backdrop.kt

@@ -0,0 +1,40 @@
+package iris.ui.theme
+
+/**
+ * A bundled backdrop image shipped in the app (Android `assets/backdrops/`,
+ * desktop classpath `backdrops/`), loaded via [iris.platform.readBackdropBytes].
+ *
+ * Bundled backdrops are referenced in [UserTheme.backgroundImagePath] by the
+ * sentinel path `backdrop://<id>` (see [path]); user-picked images use a real
+ * file path. [DEFAULT] is the background for fresh installs.
+ */
+data class Backdrop(
+    val id: String,
+    val name: String,
+) {
+    /** Sentinel path stored in the theme for this bundled backdrop. */
+    val path: String get() = "backdrop://$id"
+
+    companion object {
+        const val PATH_PREFIX = "backdrop://"
+
+        val ALL: List<Backdrop> =
+            listOf(
+                Backdrop("pexels-yunszyveli-12368637", "Yun Syzveli"),
+                Backdrop("pexels-bogdankrupin-12049700", "Bogdan Krupin"),
+                Backdrop("pexels-bosichong-27940302", "Bosi Chong"),
+                Backdrop("pexels-farhan-najeer-644774196-32490483", "Farhan Najeer"),
+                Backdrop("pexels-soubhagya23-8060218", "Soubhagya"),
+                Backdrop("pexels-steve-29390703", "Steve"),
+            )
+
+        /** Default background for new chats / fresh installs. */
+        val DEFAULT: Backdrop = ALL.first { it.id == "pexels-yunszyveli-12368637" }
+
+        /** True when [path] references a bundled backdrop. */
+        fun isBackdropPath(path: String?): Boolean = !path.isNullOrBlank() && path.startsWith(PATH_PREFIX)
+
+        /** The bundled backdrop for a sentinel path, or null. */
+        fun fromPath(path: String?): Backdrop? = if (isBackdropPath(path)) ALL.firstOrNull { it.path == path } else null
+    }
+}

app/shared/src/commonMain/kotlin/iris/ui/theme/Theme.kt

@@ -11,7 +11,9 @@ import androidx.compose.runtime.setValue
 import androidx.compose.runtime.staticCompositionLocalOf
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.ImageBitmap
+import iris.platform.decodeImageBytes
 import iris.platform.loadScaledImage
+import iris.platform.readBackdropBytes
 
 /**
  * Centralized palette (M7). Dark is the only theme; every screen reads colors
@@ -54,16 +56,17 @@ object IrisColors {
     val errorText = Color(0xFFFF8A80)
 }
 
-private val IrisDark = darkColorScheme(
-    background = IrisColors.background,
-    surface = IrisColors.surface,
-    onBackground = IrisColors.onBackground,
-    onSurface = IrisColors.onSurface,
-    onSurfaceVariant = IrisColors.textDim,
-    primary = IrisColors.primary,
-    onPrimary = Color.White,
-    error = IrisColors.statusRed,
-)
+private val IrisDark =
+    darkColorScheme(
+        background = IrisColors.background,
+        surface = IrisColors.surface,
+        onBackground = IrisColors.onBackground,
+        onSurface = IrisColors.onSurface,
+        onSurfaceVariant = IrisColors.textDim,
+        primary = IrisColors.primary,
+        onPrimary = Color.White,
+        error = IrisColors.statusRed,
+    )
 
 @Composable
 fun IrisTheme(content: @Composable () -> Unit) {
@@ -85,9 +88,11 @@ fun avatarColor(name: String): Color {
 data class UserTheme(
     val userBubbleColor: Int = DEFAULT_USER_BUBBLE,
     val agentBubbleColor: Int = DEFAULT_AGENT_BUBBLE,
-    val backgroundMode: BackgroundMode = BackgroundMode.Color,
+    // Fresh installs start with the default bundled backdrop (Settings →
+    // Appearance to change it).
+    val backgroundMode: BackgroundMode = BackgroundMode.Image,
     val backgroundColor: Int = DEFAULT_BACKGROUND,
-    val backgroundImagePath: String? = null,
+    val backgroundImagePath: String? = Backdrop.DEFAULT.path,
 ) {
     val userBubble: Color get() = Color(userBubbleColor)
     val agentBubble: Color get() = Color(agentBubbleColor)
@@ -114,8 +119,10 @@ fun Color.contrastText(): Color {
 
 /**
  * Decodes the theme's background image (image mode only), scaled to at most
- * 2048 px on the longest edge. Null in color mode or on decode failure — the
- * caller then falls back to the solid background color.
+ * 2048 px on the longest edge. Bundled backdrops (`backdrop://<id>`) are read
+ * from the app resources; anything else is a user-picked file path. Null in
+ * color mode or on decode failure — the caller then falls back to the solid
+ * background color.
  */
 @Composable
 fun rememberBackgroundImage(theme: UserTheme): ImageBitmap? {
@@ -123,7 +130,18 @@ fun rememberBackgroundImage(theme: UserTheme): ImageBitmap? {
     val wantImage = theme.backgroundMode == BackgroundMode.Image && !path.isNullOrBlank()
     var image by remember { mutableStateOf<ImageBitmap?>(null) }
     LaunchedEffect(wantImage, path) {
-        image = if (wantImage) loadScaledImage(path!!, 2048) else null
+        image =
+            if (!wantImage) {
+                null
+            } else {
+                val backdrop = Backdrop.fromPath(path)
+                val bytes = backdrop?.let { readBackdropBytes(it.id) }
+                if (bytes != null) {
+                    decodeImageBytes(bytes, 2048)
+                } else {
+                    loadScaledImage(path!!, 2048)
+                }
+            }
     }
     return image
-}
+}

app/shared/src/desktopMain/kotlin/iris/platform/DesktopMedia.kt

@@ -1,5 +1,7 @@
 package iris.platform
 
+import androidx.compose.foundation.background
+import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Row
@@ -8,8 +10,6 @@ import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.shape.RoundedCornerShape
-import androidx.compose.foundation.background
-import androidx.compose.foundation.clickable
 import androidx.compose.material3.Button
 import androidx.compose.material3.IconButton
 import androidx.compose.material3.Slider
@@ -31,17 +31,6 @@ import androidx.compose.ui.graphics.toComposeImageBitmap
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
 import iris.data.MediaItem
-import java.awt.image.BufferedImage
-import java.io.ByteArrayOutputStream
-import java.io.File
-import java.net.StandardProtocolFamily
-import java.net.UnixDomainSocketAddress
-import java.nio.ByteBuffer
-import java.nio.channels.SocketChannel
-import java.util.concurrent.TimeUnit
-import javax.imageio.ImageIO
-import javax.swing.JFileChooser
-import javax.swing.filechooser.FileNameExtensionFilter
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.withContext
@@ -53,6 +42,18 @@ import kotlinx.serialization.json.buildJsonArray
 import kotlinx.serialization.json.buildJsonObject
 import kotlinx.serialization.json.jsonObject
 import kotlinx.serialization.json.jsonPrimitive
+import java.awt.image.BufferedImage
+import java.io.ByteArrayInputStream
+import java.io.ByteArrayOutputStream
+import java.io.File
+import java.net.StandardProtocolFamily
+import java.net.UnixDomainSocketAddress
+import java.nio.ByteBuffer
+import java.nio.channels.SocketChannel
+import java.util.concurrent.TimeUnit
+import javax.imageio.ImageIO
+import javax.swing.JFileChooser
+import javax.swing.filechooser.FileNameExtensionFilter
 import kotlin.random.Random
 
 /**
@@ -63,9 +64,10 @@ import kotlin.random.Random
 actual fun MediaFilePicker(onPicked: (PickedFile?) -> Unit) {
     var busy by remember { mutableStateOf(false) }
     Column(
-        modifier = Modifier
-            .fillMaxWidth()
-            .padding(16.dp),
+        modifier =
+            Modifier
+                .fillMaxWidth()
+                .padding(16.dp),
     ) {
         Text("Attach a file:", fontSize = 13.sp)
         Spacer(modifier = Modifier.height(8.dp))
@@ -98,9 +100,10 @@ private fun pickFile(): PickedFile? {
 @Composable
 actual fun ImageFilePicker(onPicked: (PickedFile?) -> Unit) {
     Button(onClick = {
-        val chooser = JFileChooser().apply {
-            fileFilter = FileNameExtensionFilter("Images", "jpg", "jpeg", "png", "webp", "bmp", "gif")
-        }
+        val chooser =
+            JFileChooser().apply {
+                fileFilter = FileNameExtensionFilter("Images", "jpg", "jpeg", "png", "webp", "bmp", "gif")
+            }
         if (chooser.showOpenDialog(null) != JFileChooser.APPROVE_OPTION) {
             onPicked(null)
             return@Button
@@ -151,62 +154,110 @@ actual fun mediaCacheBaseDir(): String {
     return dir.absolutePath
 }
 
-actual suspend fun loadMediaImage(path: String): ImageBitmap? = withContext(Dispatchers.IO) {
+actual suspend fun loadMediaImage(path: String): ImageBitmap? =
+    withContext(Dispatchers.IO) {
+        try {
+            val img = ImageIO.read(File(path)) ?: return@withContext null
+            img.toComposeImageBitmap()
+        } catch (_: Exception) {
+            null
+        }
+    }
+
+actual suspend fun loadScaledImage(
+    path: String,
+    maxSize: Int,
+): ImageBitmap? =
+    withContext(Dispatchers.IO) {
+        try {
+            val img = ImageIO.read(File(path)) ?: return@withContext null
+            val scale = (maxSize.toFloat() / maxOf(img.width, img.height)).coerceAtMost(1f)
+            if (scale >= 1f) {
+                img.toComposeImageBitmap()
+            } else {
+                val sw = (img.width * scale).toInt().coerceAtLeast(1)
+                val sh = (img.height * scale).toInt().coerceAtLeast(1)
+                val scaled = BufferedImage(sw, sh, BufferedImage.TYPE_INT_ARGB)
+                val g = scaled.createGraphics()
+                g.drawImage(img, 0, 0, sw, sh, null)
+                g.dispose()
+                scaled.toComposeImageBitmap()
+            }
+        } catch (_: Exception) {
+            null
+        }
+    }
+
+actual suspend fun decodeImageBytes(
+    bytes: ByteArray,
+    maxSize: Int,
+): ImageBitmap? =
+    withContext(Dispatchers.IO) {
+        try {
+            val img = ImageIO.read(ByteArrayInputStream(bytes)) ?: return@withContext null
+            val scale = (maxSize.toFloat() / maxOf(img.width, img.height)).coerceAtMost(1f)
+            if (scale >= 1f) {
+                img.toComposeImageBitmap()
+            } else {
+                val sw = (img.width * scale).toInt().coerceAtLeast(1)
+                val sh = (img.height * scale).toInt().coerceAtLeast(1)
+                val scaled = BufferedImage(sw, sh, BufferedImage.TYPE_INT_ARGB)
+                val g = scaled.createGraphics()
+                g.drawImage(img, 0, 0, sw, sh, null)
+                g.dispose()
+                scaled.toComposeImageBitmap()
+            }
+        } catch (_: Exception) {
+            null
+        }
+    }
+
+actual fun readBackdropBytes(id: String): ByteArray? =
     try {
-        val img = ImageIO.read(File(path)) ?: return@withContext null
-        img.toComposeImageBitmap()
-    } catch (_: Exception) {
+        // Top-level function: no `javaClass`, so anchor the classpath lookup to a
+        // class in this module (PickedFile, same package).
+        PickedFile::class.java.getResourceAsStream("/backdrops/$id.jpg")?.use { it.readBytes() }
+    } catch (e: Exception) {
         null
     }
-}
 
-actual suspend fun loadScaledImage(path: String, maxSize: Int): ImageBitmap? = withContext(Dispatchers.IO) {
-    try {
-        val img = ImageIO.read(File(path)) ?: return@withContext null
-        val scale = (maxSize.toFloat() / maxOf(img.width, img.height)).coerceAtMost(1f)
-        if (scale >= 1f) {
-            img.toComposeImageBitmap()
-        } else {
+actual suspend fun encodeImageAsBase64(
+    path: String,
+    maxSize: Int,
+): String? =
+    withContext(Dispatchers.IO) {
+        try {
+            val img = ImageIO.read(File(path)) ?: return@withContext null
+            val scale = (maxSize.toFloat() / maxOf(img.width, img.height)).coerceAtMost(1f)
             val sw = (img.width * scale).toInt().coerceAtLeast(1)
             val sh = (img.height * scale).toInt().coerceAtLeast(1)
             val scaled = BufferedImage(sw, sh, BufferedImage.TYPE_INT_ARGB)
             val g = scaled.createGraphics()
             g.drawImage(img, 0, 0, sw, sh, null)
             g.dispose()
-            scaled.toComposeImageBitmap()
+            val baos = ByteArrayOutputStream()
+            ImageIO.write(scaled, "png", baos)
+            java.util.Base64
+                .getEncoder()
+                .encodeToString(baos.toByteArray())
+        } catch (_: Exception) {
+            null
         }
-    } catch (_: Exception) {
-        null
     }
-}
 
-actual suspend fun encodeImageAsBase64(path: String, maxSize: Int): String? = withContext(Dispatchers.IO) {
-    try {
-        val img = ImageIO.read(File(path)) ?: return@withContext null
-        val scale = (maxSize.toFloat() / maxOf(img.width, img.height)).coerceAtMost(1f)
-        val sw = (img.width * scale).toInt().coerceAtLeast(1)
-        val sh = (img.height * scale).toInt().coerceAtLeast(1)
-        val scaled = BufferedImage(sw, sh, BufferedImage.TYPE_INT_ARGB)
-        val g = scaled.createGraphics()
-        g.drawImage(img, 0, 0, sw, sh, null)
-        g.dispose()
-        val baos = ByteArrayOutputStream()
-        ImageIO.write(scaled, "png", baos)
-        java.util.Base64.getEncoder().encodeToString(baos.toByteArray())
-    } catch (_: Exception) {
-        null
+actual suspend fun decodeBase64Image(base64: String): ImageBitmap? =
+    withContext(Dispatchers.IO) {
+        try {
+            val bytes =
+                java.util.Base64
+                    .getDecoder()
+                    .decode(base64)
+            val img = ImageIO.read(java.io.ByteArrayInputStream(bytes)) ?: return@withContext null
+            img.toComposeImageBitmap()
+        } catch (_: Exception) {
+            null
+        }
     }
-}
-
-actual suspend fun decodeBase64Image(base64: String): ImageBitmap? = withContext(Dispatchers.IO) {
-    try {
-        val bytes = java.util.Base64.getDecoder().decode(base64)
-        val img = ImageIO.read(java.io.ByteArrayInputStream(bytes)) ?: return@withContext null
-        img.toComposeImageBitmap()
-    } catch (_: Exception) {
-        null
-    }
-}
 
 /**
  * M6: inline media playback backed by mpv (docs/11 §11.2).
@@ -219,7 +270,10 @@ actual suspend fun decodeBase64Image(base64: String): ImageBitmap? = withContext
  * - no mpv on PATH: an info chip (the WebView fallback is a stretch goal).
  */
 @Composable
-actual fun MediaPlayerView(media: MediaItem, modifier: Modifier) {
+actual fun MediaPlayerView(
+    media: MediaItem,
+    modifier: Modifier,
+) {
     val path = media.localPath
     if (path == null || !File(path).exists()) {
         Box(modifier = modifier.fillMaxWidth(), contentAlignment = Alignment.Center) {
@@ -246,7 +300,12 @@ private object Mpv {
     val available: Boolean by lazy {
         try {
             val p = ProcessBuilder("which", "mpv").redirectErrorStream(true).start()
-            val found = p.inputStream.bufferedReader().readText().trim().isNotBlank()
+            val found =
+                p.inputStream
+                    .bufferedReader()
+                    .readText()
+                    .trim()
+                    .isNotBlank()
             p.waitFor(2, TimeUnit.SECONDS)
             found
         } catch (_: Exception) {
@@ -256,7 +315,10 @@ private object Mpv {
 }
 
 @Composable
-private fun AudioPlayer(media: MediaItem, path: String) {
+private fun AudioPlayer(
+    media: MediaItem,
+    path: String,
+) {
     val session = remember(path) { MpvAudioSession(path) }
     var paused by remember { mutableStateOf(true) }
     var position by remember { mutableStateOf(0.0) }
@@ -278,11 +340,12 @@ private fun AudioPlayer(media: MediaItem, path: String) {
     }
 
     Column(
-        modifier = Modifier
-            .fillMaxWidth()
-            .clip(RoundedCornerShape(10.dp))
-            .background(Color(0xFF20242E))
-            .padding(10.dp),
+        modifier =
+            Modifier
+                .fillMaxWidth()
+                .clip(RoundedCornerShape(10.dp))
+                .background(Color(0xFF20242E))
+                .padding(10.dp),
     ) {
         Text(media.filename, fontSize = 12.sp, maxLines = 1)
         Spacer(modifier = Modifier.height(6.dp))
@@ -309,14 +372,18 @@ private fun AudioPlayer(media: MediaItem, path: String) {
 }
 
 @Composable
-private fun VideoPlayer(media: MediaItem, path: String) {
+private fun VideoPlayer(
+    media: MediaItem,
+    path: String,
+) {
     var process by remember { mutableStateOf<Process?>(null) }
     Column(
-        modifier = Modifier
-            .fillMaxWidth()
-            .clip(RoundedCornerShape(10.dp))
-            .background(Color(0xFF20242E))
-            .padding(10.dp),
+        modifier =
+            Modifier
+                .fillMaxWidth()
+                .clip(RoundedCornerShape(10.dp))
+                .background(Color(0xFF20242E))
+                .padding(10.dp),
     ) {
         Text(media.filename, fontSize = 12.sp, maxLines = 1)
         Spacer(modifier = Modifier.height(6.dp))
@@ -352,7 +419,9 @@ private fun fmtTime(sec: Double): String {
  * An mpv process + its JSON IPC socket (unix domain). Commands carry a
  * [requestId] so responses can be matched and async events skipped.
  */
-private class MpvAudioSession(private val path: String) {
+private class MpvAudioSession(
+    private val path: String,
+) {
     private var process: Process? = null
     private var channel: SocketChannel? = null
     private val socketPath =
@@ -362,10 +431,15 @@ private class MpvAudioSession(private val path: String) {
 
     fun start() {
         try {
-            process = ProcessBuilder(
-                "mpv", "--no-video", "--really-quiet", "--no-terminal",
-                "--input-ipc-server=$socketPath", path,
-            ).redirectErrorStream(true).start()
+            process =
+                ProcessBuilder(
+                    "mpv",
+                    "--no-video",
+                    "--really-quiet",
+                    "--no-terminal",
+                    "--input-ipc-server=$socketPath",
+                    path,
+                ).redirectErrorStream(true).start()
             connectIpc()
         } catch (_: Exception) {
         }
@@ -406,9 +480,24 @@ private class MpvAudioSession(private val path: String) {
                 } catch (_: Exception) {
                 }
             }
-            answers["p1"]?.get("data")?.jsonPrimitive?.content?.toDoubleOrNull()?.let { pos = it }
-            answers["p2"]?.get("data")?.jsonPrimitive?.content?.toDoubleOrNull()?.let { dur = it }
-            answers["p3"]?.get("data")?.jsonPrimitive?.content?.toBooleanStrictOrNull()?.let { pause = it }
+            answers["p1"]
+                ?.get("data")
+                ?.jsonPrimitive
+                ?.content
+                ?.toDoubleOrNull()
+                ?.let { pos = it }
+            answers["p2"]
+                ?.get("data")
+                ?.jsonPrimitive
+                ?.content
+                ?.toDoubleOrNull()
+                ?.let { dur = it }
+            answers["p3"]
+                ?.get("data")
+                ?.jsonPrimitive
+                ?.content
+                ?.toBooleanStrictOrNull()
+                ?.let { pause = it }
         } catch (_: Exception) {
         }
         return Triple(pos, dur, pause)
@@ -440,12 +529,16 @@ private class MpvAudioSession(private val path: String) {
         }
     }
 
-    private fun send(cmd: List<String>, requestId: String?) {
+    private fun send(
+        cmd: List<String>,
+        requestId: String?,
+    ) {
         val ch = channel ?: return
-        val obj = buildJsonObject {
-            put("command", buildJsonArray { cmd.forEach { add(JsonPrimitive(it)) } })
-            requestId?.let { put("request_id", JsonPrimitive(it)) }
-        }
+        val obj =
+            buildJsonObject {
+                put("command", buildJsonArray { cmd.forEach { add(JsonPrimitive(it)) } })
+                requestId?.let { put("request_id", JsonPrimitive(it)) }
+            }
         val bytes = (obj.toString() + "\n").toByteArray(Charsets.UTF_8)
         ch.write(ByteBuffer.wrap(bytes))
     }
@@ -471,15 +564,25 @@ private class MpvAudioSession(private val path: String) {
     }
 }
 
-actual fun openDocument(path: String, mime: String) {
+actual fun openDocument(
+    path: String,
+    mime: String,
+) {
     try {
         val os = System.getProperty("os.name").lowercase()
         when {
-            os.contains("mac") -> ProcessBuilder("open", path).start()
-            os.contains("win") ->
+            os.contains("mac") -> {
+                ProcessBuilder("open", path).start()
+            }
+
+            os.contains("win") -> {
                 ProcessBuilder("rundll32", "url.dll,FileProtocolHandler", path).start()
-            else -> ProcessBuilder("xdg-open", path).start()
+            }
+
+            else -> {
+                ProcessBuilder("xdg-open", path).start()
+            }
         }
     } catch (_: Exception) {
     }
-}
+}

app/shared/src/desktopMain/kotlin/iris/platform/DesktopSecureStore.kt

@@ -2,14 +2,16 @@ package iris.platform
 
 import iris.data.SecureStore
 import iris.protocol.IrisJson
+import iris.ui.theme.Backdrop
+import iris.ui.theme.BackgroundMode
 import iris.ui.theme.UserTheme
+import kotlinx.serialization.Serializable
 import java.io.File
 import java.security.SecureRandom
 import java.util.UUID
 import javax.crypto.Cipher
 import javax.crypto.spec.GCMParameterSpec
 import javax.crypto.spec.SecretKeySpec
-import kotlinx.serialization.Serializable
 
 /**
  * M6: desktop pairing storage (docs/11 §11.2).
@@ -41,9 +43,9 @@ class DesktopSecureStore : SecureStore {
         val reasoningAutoCollapse: Boolean = true,
         val userBubbleColor: Int = UserTheme.DEFAULT_USER_BUBBLE,
         val agentBubbleColor: Int = UserTheme.DEFAULT_AGENT_BUBBLE,
-        val backgroundMode: String = "color",
+        val backgroundMode: String = BackgroundMode.Image.name.lowercase(),
         val backgroundColor: Int = UserTheme.DEFAULT_BACKGROUND,
-        val backgroundImagePath: String = "",
+        val backgroundImagePath: String = Backdrop.DEFAULT.path,
         val fontSizeScale: Float = 1.0f,
     )
 
@@ -53,11 +55,12 @@ class DesktopSecureStore : SecureStore {
 
     private fun migrateLegacy() {
         if (!legacyFile.exists()) return
-        val legacy = try {
-            IrisJson.instance.decodeFromString(PairingData.serializer(), legacyFile.readText())
-        } catch (_: Exception) {
-            null
-        }
+        val legacy =
+            try {
+                IrisJson.instance.decodeFromString(PairingData.serializer(), legacyFile.readText())
+            } catch (_: Exception) {
+                null
+            }
         if (legacy != null) {
             val s = load()
             save(
@@ -108,7 +111,13 @@ class DesktopSecureStore : SecureStore {
         get() {
             val d = load()
             if (d.deviceId.isNotBlank()) return d.deviceId
-            val id = "dev_" + UUID.randomUUID().toString().replace("-", "").take(16)
+            val id =
+                "dev_" +
+                    UUID
+                        .randomUUID()
+                        .toString()
+                        .replace("-", "")
+                        .take(16)
             save(d.copy(deviceId = id))
             return id
         }
@@ -214,7 +223,10 @@ class DesktopSecureStore : SecureStore {
             save(d.copy(fontSizeScale = value))
         }
 
-    override fun savePairing(url: String, token: String) {
+    override fun savePairing(
+        url: String,
+        token: String,
+    ) {
         val d = load()
         save(d.copy(serverUrl = url.trim()))
         if (token.isBlank()) secret.clear() else secret.write(token.trim())
@@ -243,7 +255,9 @@ private data class PairingData(
  * Token storage: OS keyring when available, else an AES-GCM encrypted file.
  * All backend failures degrade to the encrypted file (never plaintext).
  */
-private class SecretBackend(private val baseDir: File) {
+private class SecretBackend(
+    private val baseDir: File,
+) {
     private val encFile = File(baseDir, "pairing.enc")
     private val keyFile = File(baseDir, ".key")
     private val keyring: KeyringBackend? = KeyringBackend().takeIf { it.available }
@@ -318,32 +332,49 @@ private class KeyringBackend {
 
     /** macOS Keychain (`security`) or Linux Secret Service (`secret-tool`). */
     val available: Boolean by lazy {
-        if (isMac) true
-        else if (isLinux) which("secret-tool") != null
-        else false
+        if (isMac) {
+            true
+        } else if (isLinux) {
+            which("secret-tool") != null
+        } else {
+            false
+        }
     }
 
-    fun read(): String? = try {
-        if (isMac) {
-            out(listOf("security", "find-generic-password", "-a", "iris", "-s", "iris-gateway-token", "-w"))
-        } else {
-            out(listOf("secret-tool", "lookup", "app", "iris"))
+    fun read(): String? =
+        try {
+            if (isMac) {
+                out(listOf("security", "find-generic-password", "-a", "iris", "-s", "iris-gateway-token", "-w"))
+            } else {
+                out(listOf("secret-tool", "lookup", "app", "iris"))
+            }
+        } catch (_: Exception) {
+            null
         }
-    } catch (_: Exception) {
-        null
-    }
 
     fun write(value: String) {
         try {
             if (isMac) {
                 ProcessBuilder(
-                    "security", "add-generic-password", "-U",
-                    "-a", "iris", "-s", "iris-gateway-token", "-w", value,
+                    "security",
+                    "add-generic-password",
+                    "-U",
+                    "-a",
+                    "iris",
+                    "-s",
+                    "iris-gateway-token",
+                    "-w",
+                    value,
                 ).inheritIO().start().waitFor()
             } else {
                 ProcessBuilder(
-                    "secret-tool", "store", "--label=Iris gateway token",
-                    "app", "iris", "token", value,
+                    "secret-tool",
+                    "store",
+                    "--label=Iris gateway token",
+                    "app",
+                    "iris",
+                    "token",
+                    value,
                 ).inheritIO().start().waitFor()
             }
         } catch (_: Exception) {
@@ -354,12 +385,19 @@ private class KeyringBackend {
         try {
             if (isMac) {
                 ProcessBuilder(
-                    "security", "delete-generic-password",
-                    "-a", "iris", "-s", "iris-gateway-token",
+                    "security",
+                    "delete-generic-password",
+                    "-a",
+                    "iris",
+                    "-s",
+                    "iris-gateway-token",
                 ).inheritIO().start().waitFor()
             } else {
                 ProcessBuilder(
-                    "secret-tool", "clear", "app", "iris",
+                    "secret-tool",
+                    "clear",
+                    "app",
+                    "iris",
                 ).inheritIO().start().waitFor()
             }
         } catch (_: Exception) {
@@ -368,17 +406,26 @@ private class KeyringBackend {
 
     private fun out(cmd: List<String>): String? {
         val p = ProcessBuilder(cmd).redirectErrorStream(true).start()
-        val text = p.inputStream.bufferedReader().readText().trim()
+        val text =
+            p.inputStream
+                .bufferedReader()
+                .readText()
+                .trim()
         p.waitFor()
         return text.ifBlank { null }
     }
 
-    private fun which(bin: String): String? = try {
-        val p = ProcessBuilder("which", bin).redirectErrorStream(true).start()
-        val text = p.inputStream.bufferedReader().readText().trim()
-        p.waitFor()
-        text.ifBlank { null }
-    } catch (_: Exception) {
-        null
-    }
-}
+    private fun which(bin: String): String? =
+        try {
+            val p = ProcessBuilder("which", bin).redirectErrorStream(true).start()
+            val text =
+                p.inputStream
+                    .bufferedReader()
+                    .readText()
+                    .trim()
+            p.waitFor()
+            text.ifBlank { null }
+        } catch (_: Exception) {
+            null
+        }
+}

app/shared/src/desktopMain/kotlin/iris/platform/Platform.kt

@@ -1,3 +1,3 @@
 package iris.platform
 
-actual val isDesktop: Boolean = true
+actual val isDesktop: Boolean = true