feat(playback): cache on-demand HLS videos in SimpleCache

Previously any URL containing ".m3u8" was routed through the non-caching
MediaSource factory under the assumption that HLS meant a live stream.
That was correct for kind-30311 live events but wrong for on-demand
NIP-71 videos with multi-rendition fMP4 segments: their .m4s files are
immutable and a perfect fit for SimpleCache's byte-range caching, yet
they were being re-downloaded on every scroll.

Plumb an explicit `isLiveStream` flag from the caller (LiveActivity sets
it to true; everything else keeps the default of false) down through
GetMediaItem / MediaItemData and stash it in MediaItem.mediaMetadata
extras. CustomMediaSourceFactory now reads that flag to decide whether
to use the caching or non-caching factory, falling back to the old URL
heuristic only if the flag is absent (e.g. a MediaItem built outside
the MediaItemCache path).

Also persist the flag through PiP's IntentExtras bundle and use the new
constants in MediaSessionPool for the callback URI key.

https://claude.ai/code/session_01W8yGieuEyMKeKY9vU9zjKH

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/composable/LoadThumbAndThenVideoView.kt

@@ -41,6 +41,7 @@ fun LoadThumbAndThenVideoView(
     roundedCorner: Boolean,
     contentScale: ContentScale,
     nostrUriCallback: String? = null,
+    isLiveStream: Boolean = false,
     accountViewModel: AccountViewModel,
     onDialog: (() -> Unit)? = null,
 ) {
@@ -75,6 +76,7 @@ fun LoadThumbAndThenVideoView(
                 artworkUri = thumbUri,
                 authorName = authorName,
                 nostrUriCallback = nostrUriCallback,
+                isLiveStream = isLiveStream,
                 accountViewModel = accountViewModel,
                 onDialog = onDialog,
             )
@@ -89,6 +91,7 @@ fun LoadThumbAndThenVideoView(
                 artworkUri = thumbUri,
                 authorName = authorName,
                 nostrUriCallback = nostrUriCallback,
+                isLiveStream = isLiveStream,
                 accountViewModel = accountViewModel,
                 onDialog = onDialog,
             )

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/composable/VideoView.kt

@@ -69,6 +69,7 @@ fun VideoView(
     accountViewModel: AccountViewModel,
     alwaysShowVideo: Boolean = false,
     thumbhash: String? = null,
+    isLiveStream: Boolean = false,
 ) {
     val borderModifier =
         if (roundedCorner) {
@@ -79,7 +80,7 @@ fun VideoView(
             Modifier
         }
 
-    VideoView(videoUri, mimeType, title, thumb, borderModifier, contentScale, waveform, artworkUri, authorName, dimensions, blurhash, nostrUriCallback, onDialog, alwaysShowVideo, accountViewModel = accountViewModel, thumbhash = thumbhash)
+    VideoView(videoUri, mimeType, title, thumb, borderModifier, contentScale, waveform, artworkUri, authorName, dimensions, blurhash, nostrUriCallback, onDialog, alwaysShowVideo, accountViewModel = accountViewModel, thumbhash = thumbhash, isLiveStream = isLiveStream)
 }
 
 @Composable
@@ -99,6 +100,7 @@ fun VideoView(
     onDialog: (() -> Unit)? = null,
     alwaysShowVideo: Boolean = false,
     showControls: Boolean = true,
+    isLiveStream: Boolean = false,
     accountViewModel: AccountViewModel,
     thumbhash: String? = null,
 ) {
@@ -138,6 +140,7 @@ fun VideoView(
                     authorName = authorName,
                     nostrUriCallback = nostrUriCallback,
                     automaticallyStartPlayback = autoplay,
+                    isLiveStream = isLiveStream,
                     onZoom = onDialog,
                     hasBlurhash = false,
                     accountViewModel = accountViewModel,
@@ -186,6 +189,7 @@ fun VideoView(
                     authorName = authorName,
                     nostrUriCallback = nostrUriCallback,
                     automaticallyStartPlayback = autoplay,
+                    isLiveStream = isLiveStream,
                     onZoom = onDialog,
                     hasBlurhash = true,
                     accountViewModel = accountViewModel,

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/composable/VideoViewInner.kt

@@ -49,6 +49,7 @@ fun VideoViewInner(
     authorName: String? = null,
     nostrUriCallback: String? = null,
     automaticallyStartPlayback: Boolean,
+    isLiveStream: Boolean = false,
     controllerVisible: MutableState<Boolean> = mutableStateOf(false),
     onZoom: (() -> Unit)? = null,
     hasBlurhash: Boolean = false,
@@ -69,6 +70,7 @@ fun VideoViewInner(
         proxyPort = accountViewModel.httpClientBuilder.proxyPortForVideo(videoUri),
         keepPlaying = true,
         waveformData = waveform,
+        isLiveStream = isLiveStream,
     ) { mediaItem ->
         GetVideoController(
             mediaItem = mediaItem,

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/composable/mediaitem/GetMediaItem.kt

@@ -40,6 +40,7 @@ fun GetMediaItem(
     proxyPort: Int? = null,
     keepPlaying: Boolean = false,
     waveformData: WaveformData? = null,
+    isLiveStream: Boolean = false,
     inner: @Composable (LoadedMediaItem) -> Unit,
 ) {
     val data =
@@ -55,6 +56,7 @@ fun GetMediaItem(
                 proxyPort = proxyPort,
                 keepPlaying = keepPlaying,
                 waveformData = waveformData,
+                isLiveStream = isLiveStream,
             )
         }
 

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/composable/mediaitem/MediaItemCache.kt

@@ -30,6 +30,11 @@ import kotlinx.coroutines.withContext
 import kotlin.coroutines.cancellation.CancellationException
 
 class MediaItemCache : GenericBaseCache<MediaItemData, LoadedMediaItem>(20) {
+    companion object {
+        const val EXTRA_CALLBACK_URI = "callbackUri"
+        const val EXTRA_IS_LIVE_STREAM = "isLiveStream"
+    }
+
     override suspend fun compute(key: MediaItemData): LoadedMediaItem =
         withContext(Dispatchers.IO) {
             LoadedMediaItem(
@@ -45,7 +50,8 @@ class MediaItemCache : GenericBaseCache<MediaItemData, LoadedMediaItem>(20) {
                             .setTitle(key.title?.ifBlank { null } ?: key.videoUri)
                             .setExtras(
                                 Bundle().apply {
-                                    putString("callbackUri", key.callbackUri)
+                                    putString(EXTRA_CALLBACK_URI, key.callbackUri)
+                                    putBoolean(EXTRA_IS_LIVE_STREAM, key.isLiveStream)
                                 },
                             ).setArtworkUri(
                                 try {

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/composable/mediaitem/MediaItemData.kt

@@ -36,6 +36,10 @@ data class MediaItemData(
     val proxyPort: Int? = null,
     val keepPlaying: Boolean = true,
     val waveformData: WaveformData? = null,
+    // True only for true live streams (e.g. kind 30311). On-demand HLS
+    // (e.g. multi-rendition NIP-71 videos) must leave this false so that
+    // ExoPlayer's SimpleCache can cache their immutable segments.
+    val isLiveStream: Boolean = false,
 )
 
 @Immutable

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/pip/IntentExtras.kt

@@ -61,6 +61,7 @@ class IntentExtras {
                 proxyPort = if (port > 0) port else null,
                 keepPlaying = intent.getBoolean("keepPlaying", true),
                 waveformData = intent.getFloatArray("wavefrontData")?.toList()?.let { WaveformData(it) },
+                isLiveStream = intent.getBoolean("isLiveStream", false),
             )
         }
 
@@ -79,6 +80,7 @@ class IntentExtras {
                 data.proxyPort?.let { putInt("proxyPort", it) }
                 putBoolean("keepPlaying", data.keepPlaying)
                 data.waveformData?.let { putFloatArray("wavefrontData", it.wave.toFloatArray()) }
+                putBoolean("isLiveStream", data.isLiveStream)
 
                 bounds?.let { putInt("boundLeft", it.left) }
                 bounds?.let { putInt("boundRight", it.right) }

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/playerPool/CustomMediaSourceFactory.kt

@@ -27,11 +27,19 @@ import androidx.media3.exoplayer.drm.DrmSessionManagerProvider
 import androidx.media3.exoplayer.source.DefaultMediaSourceFactory
 import androidx.media3.exoplayer.source.MediaSource
 import androidx.media3.exoplayer.upstream.LoadErrorHandlingPolicy
+import com.vitorpamplona.amethyst.service.playback.composable.mediaitem.MediaItemCache
 import com.vitorpamplona.amethyst.service.playback.diskCache.VideoCache
 import com.vitorpamplona.amethyst.service.playback.diskCache.isLiveStreaming
 
 /**
- * HLS LiveStreams cannot use cache.
+ * True live streams (kind 30311) must not be cached. On-demand HLS
+ * (e.g. multi-rendition NIP-71 videos) is cached like any other video,
+ * because its segments are immutable.
+ *
+ * The `isLiveStream` flag is carried on [MediaItem.mediaMetadata] extras
+ * and set by [MediaItemCache] from [com.vitorpamplona.amethyst.service.playback.composable.mediaitem.MediaItemData].
+ * If the flag is absent (e.g. a [MediaItem] built outside the cache path),
+ * we fall back to the URL-based heuristic.
  */
 @UnstableApi
 class CustomMediaSourceFactory(
@@ -58,9 +66,19 @@ class CustomMediaSourceFactory(
     override fun getSupportedTypes(): IntArray = nonCachingFactory.supportedTypes
 
     override fun createMediaSource(mediaItem: MediaItem): MediaSource {
-        if (isLiveStreaming(mediaItem.mediaId)) {
+        if (isLiveStream(mediaItem)) {
             return nonCachingFactory.createMediaSource(mediaItem)
         }
         return cachingFactory.createMediaSource(mediaItem)
     }
+
+    private fun isLiveStream(mediaItem: MediaItem): Boolean {
+        val extras = mediaItem.mediaMetadata.extras
+        return if (extras != null && extras.containsKey(MediaItemCache.EXTRA_IS_LIVE_STREAM)) {
+            extras.getBoolean(MediaItemCache.EXTRA_IS_LIVE_STREAM, false)
+        } else {
+            // Fallback for MediaItems that weren't built via MediaItemCache.
+            isLiveStreaming(mediaItem.mediaId)
+        }
+    }
 }

amethyst/src/main/java/com/vitorpamplona/amethyst/service/playback/playerPool/MediaSessionPool.kt

@@ -35,6 +35,7 @@ import androidx.media3.exoplayer.ExoPlayer
 import androidx.media3.session.MediaSession
 import com.google.common.util.concurrent.Futures
 import com.google.common.util.concurrent.ListenableFuture
+import com.vitorpamplona.amethyst.service.playback.composable.mediaitem.MediaItemCache
 import com.vitorpamplona.amethyst.ui.MainActivity
 import com.vitorpamplona.quartz.utils.TimeUtils
 import kotlinx.coroutines.CoroutineExceptionHandler
@@ -198,7 +199,7 @@ class MediaSessionPool(
             mediaItems: List<MediaItem>,
         ): ListenableFuture<List<MediaItem>> {
             // set up return call when clicking on the Notification bar
-            mediaItems.firstOrNull()?.mediaMetadata?.extras?.getString("callbackUri")?.let {
+            mediaItems.firstOrNull()?.mediaMetadata?.extras?.getString(MediaItemCache.EXTRA_CALLBACK_URI)?.let {
                 mediaSession.setSessionActivity(
                     PendingIntent.getActivity(
                         appContext,

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/note/types/LiveActivity.kt

@@ -199,6 +199,7 @@ fun RenderLiveActivityEventInner(
                             contentScale = ContentScale.FillWidth,
                             accountViewModel = accountViewModel,
                             nostrUriCallback = "nostr:${baseNote.toNEvent()}",
+                            isLiveStream = true,
                         )
                     }
                 } else {