channels: Show a banner and harden D-pad activation

Channel pages now load the channel record itself and use the newest
video's thumbnail as a banner fallback, so channels never render
without a header image. Focus cards in re-sorting rows only hand out
initial focus once per screen visit so streaming stats can't steal
focus mid-navigation.

D-pad activation now also accepts ENTER/NUMPAD_ENTER/SPACE, matching
how the Compose platform fires clickable cards; consuming in the
preview phase keeps OK from double-activating.

app/src/main/java/net/jeena/jtubetv/data/PeerTubeRepository.kt

@@ -125,14 +125,20 @@ class PeerTubeRepository(
             var videos = 0L
             var plays = 0L
             var total: Long? = null
+            var latestThumb: String? = null
             repeat(maxPages) {
                 val page = network.api.channelVideos(handle, start, 25)
-                if (total == null) total = page.total
+                if (total == null) {
+                    total = page.total
+                    latestThumb = page.data.firstOrNull()?.thumbnailPath?.let { path ->
+                        if (path.startsWith("http")) path else baseUrl + "/" + path.trimStart('/')
+                    }
+                }
                 plays += page.data.sumOf { it.views }
                 start += page.data.size
                 videos = total ?: videos
             }
-            net.jeena.jtubetv.data.api.ChannelStats(videos, plays)
+            net.jeena.jtubetv.data.api.ChannelStats(videos, plays, latestThumb)
         }
 
     private fun unauthenticatedApiFor(base: String): PeerTubeApi =
@@ -178,6 +184,9 @@ class PeerTubeRepository(
             response.data to response.total
         }
 
+    suspend fun videoChannel(handle: String): Result<VideoChannelDto> =
+        runCatching { network.api.videoChannel(handle) }
+
     suspend fun accountChannels(username: String): Result<List<VideoChannelDto>> =
         runCatching {
             val response: VideoChannelListResponse = network.api.accountChannels(username)

app/src/main/java/net/jeena/jtubetv/data/api/Dtos.kt

@@ -158,6 +158,8 @@ data class InstanceInfoDto(
 data class ChannelStats(
     val videos: Long,
     val plays: Long,
+    /** Thumbnail of the newest video — banner fallback for channels without one. */
+    val latestThumbUrl: String? = null,
 )
 
 @Serializable

app/src/main/java/net/jeena/jtubetv/data/api/PeerTubeApi.kt

@@ -83,6 +83,11 @@ interface PeerTubeApi {
         @Path("account") account: String,
     ): VideoChannelListResponse
 
+    @GET("video-channels/{handle}")
+    suspend fun videoChannel(
+        @Path("handle") handle: String,
+    ): VideoChannelDto
+
     @GET("video-channels/{handle}/videos")
     suspend fun channelVideos(
         @Path("handle") handle: String,

app/src/main/java/net/jeena/jtubetv/ui/list/VideoListViewModel.kt

@@ -1,8 +1,13 @@
 package net.jeena.jtubetv.ui.list
 
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.ViewModelProvider
+import androidx.lifecycle.viewModelScope
 import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.launch
 import net.jeena.jtubetv.AppGraph
 import net.jeena.jtubetv.data.PeerTubeRepository
 
@@ -30,6 +35,12 @@ class VideoListViewModel(
     val query = MutableStateFlow("")
     private var activeSearch: String? = null
 
+    /** For channel pages: the channel itself (banner + display name) as page header. */
+    var channelHeader by androidx.compose.runtime.mutableStateOf<net.jeena.jtubetv.data.api.VideoChannelDto?>(
+        null,
+    )
+        private set
+
     override fun onChunkLoaded(chunk: List<VideoListItem>) {
         ImagePrefetcher.videoThumbnails(
             chunk.mapNotNull {
@@ -60,6 +71,15 @@ class VideoListViewModel(
         }
     }
 
+    fun loadChannelHeader(repository: PeerTubeRepository) {
+        val s = source
+        if (s is ListSource.Channel) {
+            viewModelScope.launch {
+                channelHeader = repository.videoChannel(s.handle).getOrNull()
+            }
+        }
+    }
+
     fun triggerSearch(raw: String) {
         query.value = raw
         activeSearch = raw.trim().ifBlank { null }

app/src/main/java/net/jeena/jtubetv/ui/screens/ChannelsScreen.kt

@@ -291,6 +291,10 @@ fun ChannelsScreen(
                 }
             }
         else -> {
+            // hand the initial focus to the first row exactly ONCE per screen visit:
+            // as stats stream in the rows re-sort, and re-focusing their first card
+            // would steal focus mid-navigation (user: "up jumps to the first row").
+            val focusHandedOut = remember { mutableStateOf(false) }
             LazyColumn(Modifier.fillMaxSize()) {
                 viewModel.userRows.forEach { group ->
                     item(key = "hdr-" + group.ownerName) {
@@ -304,7 +308,9 @@ fun ChannelsScreen(
                             group.channels,
                             onOpenChannel,
                             onOpenDrawer,
-                            firstFocused = group == viewModel.userRows.firstOrNull(),
+                            focused = !focusHandedOut.value &&
+                                group == viewModel.userRows.firstOrNull(),
+                            onFocused = { focusHandedOut.value = true },
                             stats = { viewModel.stats[it.name + "@" + it.host] },
                             platformName = { viewModel.platformNames[it.host ?: ""] },
                         )
@@ -355,7 +361,8 @@ private fun ChannelRow(
     channels: List<VideoChannelDto>,
     onOpenChannel: (String) -> Unit,
     onOpenDrawer: () -> Unit = {},
-    firstFocused: Boolean,
+    focused: Boolean,
+    onFocused: () -> Unit = {},
     stats: (VideoChannelDto) -> net.jeena.jtubetv.data.api.ChannelStats?,
     platformName: (VideoChannelDto) -> String?,
 ) {
@@ -373,9 +380,11 @@ private fun ChannelRow(
             if (notFullyVisible) rowState.animateScrollToItem(focusedIndex)
         }
     }
-    if (firstFocused) {
+    if (focused) {
         LaunchedEffect(channels.isNotEmpty()) {
-            if (channels.isNotEmpty()) runCatching { focusRequesters[0]?.requestFocus() }
+            if (channels.isNotEmpty()) {
+                if (runCatching { focusRequesters[0]?.requestFocus() }.isSuccess) onFocused()
+            }
         }
     }
 
@@ -448,13 +457,16 @@ fun ChannelCard(
                     .aspectRatio(16f / 9f)
                     .background(Color(0xFF222222)),
             ) {
+                // banner, or the newest video's thumbnail for bannerless channels
                 val banner = channel.banners.maxByOrNull { it.width }
-                if (banner != null) {
+                val coverUrl = banner?.let { absoluteBanner(it) }
+                    ?: stats?.latestThumbUrl
+                if (coverUrl != null) {
                     AsyncImage(
                         model = coil.request.ImageRequest.Builder(
                             androidx.compose.ui.platform.LocalContext.current,
                         )
-                            .data(absoluteBanner(banner))
+                            .data(coverUrl)
                             .size(480, 270) // same key as prefetch
                             .build(),
                         contentDescription = channel.displayName,

app/src/main/java/net/jeena/jtubetv/ui/screens/list/FocusKeys.kt

@@ -14,11 +14,16 @@ import androidx.compose.ui.input.key.onPreviewKeyEvent
  */
 fun Modifier.dpadCenterActivatable(onClick: () -> Unit): Modifier = composed {
     onPreviewKeyEvent { ke ->
-        if (ke.nativeKeyEvent.action == android.view.KeyEvent.ACTION_DOWN &&
-            ke.nativeKeyEvent.keyCode == android.view.KeyEvent.KEYCODE_DPAD_CENTER
-        ) {
-            onClick()
-            true
+        if (ke.nativeKeyEvent.action == android.view.KeyEvent.ACTION_DOWN) {
+            val code = ke.nativeKeyEvent.keyCode
+            val activates = code == android.view.KeyEvent.KEYCODE_DPAD_CENTER ||
+                code == android.view.KeyEvent.KEYCODE_ENTER ||
+                code == android.view.KeyEvent.KEYCODE_NUMPAD_ENTER ||
+                code == android.view.KeyEvent.KEYCODE_SPACE
+            if (activates) {
+                onClick()
+                true // consumed in preview -> the platform/card path never double-fires
+            } else false
         } else false
     }
 }