channels: load at launch, keep the opened channel selected (#32, #34)

Assembling the channel rows is slow, so it now starts when the app launches
instead of when the view is first opened; opening the view usually finds the
rows already there, and a second pass is skipped while one is in flight or the
data is still fresh (#32).

Coming back from a channel page re-selects the channel that was opened, scrolling
its row back to it, instead of snapping to the first one (#34).

Also drops the custom focusRestorer fallback added for #29: handing back a
requester whose card had scrolled out of composition crashed the app with
"FocusRequester is not initialized" when focus re-entered a scrolled row (hit on
the Channels screen). The plain restorer keeps the #29 behaviour without it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

app/src/main/java/net/jeena/jtubetv/ui/player/PlayerSidebar.kt

@@ -190,64 +190,28 @@ private fun InfoColumn(
     }
 
     val descFocus = remember { FocusRequester() }
-    val firstLinkFocus = remember { FocusRequester() }
-    // Focus the description so the D-pad can scroll it right away (issue #23):
-    // a description with no links used to have nothing focusable, so a long
-    // text could never be scrolled down with the remote. Fall back to the
-    // first link when there is no description text.
+    // The description owns the focus for the whole panel: UP/DOWN scroll it and are
+    // always consumed, so scrolling can never strand focus somewhere it can't come
+    // back from (issue #23 review: "it loses focus and it's impossible to scroll up").
     LaunchedEffect(Unit) {
         kotlinx.coroutines.delay(150)
-        runCatching {
-            if (description.isNotBlank()) descFocus.requestFocus()
-            else firstLinkFocus.requestFocus()
-        }
+        runCatching { descFocus.requestFocus() }
     }
 
     Column(Modifier.fillMaxSize()) {
-        if (description.isNotBlank()) {
+        if (description.isBlank()) {
+            SidebarFallback("No description.", onDismiss)
+        } else {
             DescriptionScroll(
                 annotated = annotated,
                 focusRequester = descFocus,
                 onDismiss = onDismiss,
-                onLeaveBottom = {
-                    if (links.isNotEmpty()) {
-                        runCatching { firstLinkFocus.requestFocus() }.isSuccess
-                    } else false
-                },
+                // Links stay inline in the running text (issue #23 review) instead of
+                // being repeated in a list underneath; OK opens the first one.
+                onActivate = { links.firstOrNull()?.let { open(it) } },
                 modifier = Modifier.weight(1f, fill = false),
             )
         }
-        if (links.isNotEmpty()) {
-            Text(
-                text = "Links",
-                color = TextDim,
-                style = MaterialTheme.typography.labelMedium,
-                modifier = Modifier.padding(start = 20.dp, top = 10.dp, bottom = 2.dp),
-            )
-            LazyColumn(Modifier.heightIn(max = 220.dp)) {
-                links.forEachIndexed { index, url ->
-                    item(key = "l" + index + url) {
-                        SidebarRow(
-                            onLeft = onDismiss,
-                            onUp = if (index == 0 && description.isNotBlank()) {
-                                { runCatching { descFocus.requestFocus() } }
-                            } else null,
-                            atTop = index == 0 && description.isBlank(),
-                            atBottom = index == links.size - 1,
-                            focusRequester = if (index == 0) firstLinkFocus else null,
-                            onClick = { open(url) },
-                        ) {
-                            Text(
-                                text = linkLabel(url),
-                                color = TextMain,
-                                style = MaterialTheme.typography.bodySmall,
-                                maxLines = 1,
-                            )
-                        }
-                    }
-                }
-            }
-        }
     }
 }
 
@@ -263,7 +227,7 @@ private fun DescriptionScroll(
     annotated: androidx.compose.ui.text.AnnotatedString,
     focusRequester: FocusRequester,
     onDismiss: () -> Unit,
-    onLeaveBottom: () -> Boolean,
+    onActivate: () -> Unit,
     modifier: Modifier = Modifier,
 ) {
     val scroll = androidx.compose.foundation.rememberScrollState()
@@ -281,19 +245,23 @@ private fun DescriptionScroll(
                 if (ke.type != KeyEventType.KeyDown) return@onPreviewKeyEvent false
                 val step = (viewportPx * 0.85f).coerceAtLeast(240f)
                 when (ke.nativeKeyEvent.keyCode) {
-                    KeyEvent.KEYCODE_DPAD_DOWN ->
-                        if (scroll.value < scroll.maxValue) {
-                            scope.launch { scroll.animateScrollBy(step) }
+                    // UP/DOWN are always consumed: they scroll while there is room and
+                    // otherwise do nothing, so focus stays here and the text can always
+                    // be scrolled back up (issue #23 review).
+                    KeyEvent.KEYCODE_DPAD_DOWN -> {
+                        if (scroll.value < scroll.maxValue) scope.launch { scroll.animateScrollBy(step) }
                         true
-                        } else onLeaveBottom()
-                    KeyEvent.KEYCODE_DPAD_UP ->
-                        if (scroll.value > 0) {
-                            scope.launch { scroll.animateScrollBy(-step) }
+                    }
+                    KeyEvent.KEYCODE_DPAD_UP -> {
+                        if (scroll.value > 0) scope.launch { scroll.animateScrollBy(-step) }
                         true
-                        } else true // nothing above the description; stay put
+                    }
                     KeyEvent.KEYCODE_DPAD_LEFT -> {
                         onDismiss(); true
                     }
+                    KeyEvent.KEYCODE_DPAD_CENTER, KeyEvent.KEYCODE_ENTER -> {
+                        onActivate(); true
+                    }
                     else -> false
                 }
             }

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

@@ -127,11 +127,17 @@ class ChannelsViewModel(private val store: TokenStore) : ViewModel() {
     // its shimmer placeholder rows until the (fast-path, few-request) load lands,
     // instead of painting a stale snapshot that reshuffled as stats streamed in.
 
+    /** Guards against a second pass while the first is still running (issue #32:
+     *  the load now starts at app launch, so opening the view can overlap it). */
+    private var inFlight = false
+
     fun load(force: Boolean = false) {
         // Re-entry (destination switch away + back) inside the freshness window:
         // repaint the in-memory rows and skip the network (issue #13) — rows are
         // never torn down on re-entry; an account switch builds a new ViewModel.
+        if (inFlight) return
         if (!force && userRows.isNotEmpty() && fresh()) return
+        inFlight = true
         loading = true
         error = null
         viewModelScope.launch {
@@ -160,6 +166,7 @@ class ChannelsViewModel(private val store: TokenStore) : ViewModel() {
                 error = e.message ?: "Could not load channels"
             } finally {
                 loading = false
+                inFlight = false
             }
         }
     }
@@ -310,6 +317,8 @@ fun ChannelsScreen(
     epoch: Int = 0,
     onOpenDrawer: () -> Unit = {},
     drawerPulse: Int = 0,
+    /** Channel opened last — gets the focus back on return (issue #34). */
+    focusHandle: String? = null,
     viewModel: ChannelsViewModel = viewModel(key = "channels$epoch", factory = ChannelsViewModel.factory),
 ) {
     LaunchedEffect(epoch) { viewModel.load() }
@@ -317,10 +326,8 @@ fun ChannelsScreen(
 
     when {
         viewModel.loading && viewModel.userRows.isEmpty() ->
-            // Placeholder rows while the channels load (issue #19): header stub
-            // + a row of shimmer card-shaped placeholders, twice.
+            // One row header stub + a single loading card, not a fake grid (#31).
             androidx.compose.foundation.layout.Column {
-                repeat(2) {
                 Box(Modifier.padding(start = 16.dp, top = 12.dp, bottom = 4.dp)) {
                     Box(
                         Modifier
@@ -330,8 +337,7 @@ fun ChannelsScreen(
                             .background(Color(0xFF232323)),
                     )
                 }
-                    ShimmerRow()
-                }
+                ShimmerRow(size = 1)
             }
         viewModel.error != null && viewModel.userRows.isEmpty() ->
             Box(Modifier.fillMaxSize(), contentAlignment = Alignment.Center) {
@@ -361,13 +367,22 @@ fun ChannelsScreen(
                         )
                     }
                     item(key = "row-" + group.ownerName) {
+                        // Coming back from a channel page, focus the card we opened
+                        // instead of the very first one (issue #34).
+                        val target = group.channels.indexOfFirst {
+                            it.name + "@" + it.host == focusHandle
+                        }
+                        val isTargetRow = target >= 0
                         ChannelRow(
                             group.channels,
                             onOpenChannel,
                             onOpenDrawer,
                             drawerPulse = drawerPulse,
-                            focused = !focusHandedOut.value &&
-                                group == viewModel.userRows.firstOrNull(),
+                            focused = !focusHandedOut.value && (
+                                if (focusHandle != null) isTargetRow
+                                else group == viewModel.userRows.firstOrNull()
+                            ),
+                            focusIndex = if (isTargetRow) target else 0,
                             onFocused = { focusHandedOut.value = true },
                             stats = { viewModel.stats[it.name + "@" + it.host] },
                             platformName = { viewModel.platformNames[it.host ?: ""] },
@@ -422,6 +437,8 @@ private fun ChannelRow(
     onOpenDrawer: () -> Unit = {},
     drawerPulse: Int = 0,
     focused: Boolean,
+    /** Which card to hand the initial focus to (issue #34). */
+    focusIndex: Int = 0,
     onFocused: () -> Unit = {},
     stats: (VideoChannelDto) -> net.jeena.jtubetv.data.api.ChannelStats?,
     platformName: (VideoChannelDto) -> String?,
@@ -448,17 +465,30 @@ private fun ChannelRow(
         }
     }
     if (focused) {
-        LaunchedEffect(channels.isNotEmpty()) {
+        LaunchedEffect(channels.isNotEmpty(), focusIndex) {
             if (channels.isNotEmpty()) {
-                if (runCatching { focusRequesters[0]?.requestFocus() }.isSuccess) onFocused()
+                val target = focusIndex.coerceIn(0, channels.size - 1)
+                // Bring it on screen first; a card further right isn't composed yet,
+                // so retry until its focus requester is attached (issue #34).
+                if (target > 0) runCatching { rowState.scrollToItem(target) }
+                repeat(8) {
+                    delay(80)
+                    val ok = runCatching { focusRequesters[target]?.requestFocus() }.getOrNull()
+                    if (ok != null) {
+                        onFocused()
+                        return@LaunchedEffect
+                    }
+                }
             }
         }
     }
 
     LazyRow(
         state = rowState,
-        // Land on the last-focused card when moving between rows (issue #29).
-        modifier = Modifier.focusRestorer { focusRequesters[focusedIndex.coerceAtLeast(0)] ?: FocusRequester.Default },
+        // Land on the last-focused card when moving between rows (issue #29). No
+        // custom fallback: a requester whose card has scrolled out of composition
+        // crashed with "FocusRequester is not initialized".
+        modifier = Modifier.focusRestorer(),
         contentPadding = PaddingValues(horizontal = 12.dp),
         horizontalArrangement = Arrangement.spacedBy(4.dp),
     ) {

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

@@ -457,8 +457,10 @@ fun FocusScrollRow(
         state = rowState,
         // Jumping between rows lands on the card this row last had focus on, not
         // the geometrically-nearest one (issue #29): the rows stop shifting
-        // left/right as you move up and down between them.
-        modifier = Modifier.focusRestorer { focusRequesters[focusedIndex.coerceAtLeast(0)] ?: FocusRequester.Default },
+        // left/right as you move up and down between them. No custom fallback —
+        // handing back a requester whose card has scrolled out of composition
+        // crashed with "FocusRequester is not initialized".
+        modifier = Modifier.focusRestorer(),
         contentPadding = PaddingValues(horizontal = 12.dp),
         horizontalArrangement = Arrangement.spacedBy(4.dp),
     ) {

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

@@ -87,6 +87,16 @@ fun HomeScreen(viewModel: AppViewModel = androidx.lifecycle.viewmodel.compose.vi
     var destination by rememberSaveable { mutableStateOf(Destination.Home) }
     var channelDetails by rememberSaveable { mutableStateOf<String?>(null) } // handle
     var channelName by rememberSaveable { mutableStateOf<String?>(null) }   // display name
+    // Last channel opened from the Channels screen — refocused on return (#34).
+    var lastOpenedChannel by rememberSaveable { mutableStateOf<String?>(null) }
+    // Channels are expensive to assemble, so start that work at app launch rather
+    // than when the view is first opened (issue #32); the view then usually finds
+    // the rows already there, and load() no-ops while fresh.
+    val channelsViewModel: ChannelsViewModel = androidx.lifecycle.viewmodel.compose.viewModel(
+        key = "channels$epoch",
+        factory = ChannelsViewModel.factory,
+    )
+    LaunchedEffect(epoch) { channelsViewModel.load() }
     // NOT saveable: launching the app should never resume a half-watched player session.
     var playingVideo by rememberSaveable { mutableStateOf<String?>(null) }  // shortUUID
     // Non-null while the playing video lives on ANOTHER instance (vidiverse results).
@@ -220,10 +230,16 @@ fun HomeScreen(viewModel: AppViewModel = androidx.lifecycle.viewmodel.compose.vi
                             drawerPulse = drawerPulse,
                         )
                     Destination.Channels -> ChannelsScreen(
-                        onOpenChannel = { handle -> channelDetails = handle },
+                        onOpenChannel = { handle ->
+                            channelDetails = handle
+                            lastOpenedChannel = handle
+                        },
                         epoch = epoch,
                         onOpenDrawer = { drawerOpen = true },
                         drawerPulse = drawerPulse,
+                        // Back from a channel page re-selects it (issue #34).
+                        focusHandle = lastOpenedChannel,
+                        viewModel = channelsViewModel,
                     )
                     Destination.Search ->
                         VideoListScreen(

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

@@ -438,7 +438,10 @@ private fun PlayerSurface(
             }
 
             override fun onPlaybackStateChanged(playbackState: Int) {
-                bufferingPending = playbackState != Player.STATE_READY
+                // Only real buffering shows the overlay (issue #33): STATE_ENDED used
+                // to count as "not ready" and brought the thumbnail + spinner back
+                // over the last frame. The initial load is covered by !firstFrame.
+                bufferingPending = playbackState == Player.STATE_BUFFERING
             }
 
             override fun onRenderedFirstFrame() {
@@ -643,9 +646,9 @@ private fun PlayerSurface(
                     closeSidebar()
                 },
                 onOpenVideo = onOpenVideo,
-                modifier = Modifier
-                    .align(Alignment.CenterEnd)
-                    .padding(top = 48.dp),
+                // Full height from the very top — the old top padding left a black
+                // strip above the panel (issues #23/#24).
+                modifier = Modifier.align(Alignment.TopEnd),
             )
         }
     }

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

@@ -1,5 +1,6 @@
 package net.jeena.jtubetv.ui.screens.list
 import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.AccountCircle
 import androidx.compose.material.icons.filled.Add
 import androidx.compose.material.icons.filled.CalendarMonth
 import androidx.compose.material.icons.filled.Check
@@ -108,6 +109,15 @@ fun VideoListScreen(
     if (source is ListSource.Channel) {
         // Fetch the banner/avatar/counts for the channel page header.
         LaunchedEffect(source) { viewModel.loadChannelHeader(AppGraph.repository) }
+        // Focusing the first card nudges the grid down far enough to clip the
+        // header's top (and its Subscribe button); the header and the first row
+        // both fit, so park the grid back at the top when the page opens.
+        LaunchedEffect(items.isNotEmpty(), source) {
+            if (items.isNotEmpty()) {
+                kotlinx.coroutines.delay(150)
+                runCatching { gridState.scrollToItem(0) }
+            }
+        }
     }
 
     // Row starts of the grid: LEFT from a row's first card opens the drawer
@@ -162,29 +172,27 @@ fun VideoListScreen(
         return
     }
 
-    androidx.compose.foundation.layout.Column(Modifier.fillMaxSize()) {
-    // Channel page: the header is PINNED above the grid (issue #27) rather than
-    // scrolling away as the first grid item — auto-focusing the first video card
-    // no longer hides the banner, and the Subscribe button on it stays reachable.
-    if (source is ListSource.Channel) {
-        ChannelHeader(
+    LazyVerticalGrid(
+        // Same card size as the Home rows: ~4 fit per row (user request).
+        columns = GridCells.Adaptive(rowCardWidth() - 12.dp),
+        state = gridState,
+        modifier = Modifier.fillMaxSize().padding(vertical = 8.dp),
+    ) {
+        // Page headers scroll WITH the content (issue #27 review: a pinned header
+        // stayed put and the videos slid behind it). The header is compact enough
+        // that it's still fully visible when the first card takes focus.
+        if (source is ListSource.Search || source is ListSource.Channel) {
+            item(key = "page-header", span = { androidx.compose.foundation.lazy.grid.GridItemSpan(maxLineSpan) }) {
+                when (source) {
+                    is ListSource.Search -> SearchHeader(viewModel, onOpenDrawer)
+                    is ListSource.Channel -> ChannelHeader(
                         channelHeader = viewModel.channelHeader,
                         videoTotal = viewModel.videoTotal,
                         handle = source.handle,
                         onLeftEdge = onOpenDrawer,
                     )
+                    else -> {}
                 }
-    LazyVerticalGrid(
-        // Same card size as the Home rows: ~4 fit per row (user request).
-        columns = GridCells.Adaptive(rowCardWidth() - 12.dp),
-        state = gridState,
-        modifier = Modifier.fillMaxWidth().weight(1f).padding(vertical = 8.dp),
-    ) {
-        // Search field still scrolls with its results (its own header item);
-        // the channel banner is pinned above the grid instead (issue #27).
-        if (source is ListSource.Search) {
-            item(key = "page-header", span = { androidx.compose.foundation.lazy.grid.GridItemSpan(maxLineSpan) }) {
-                SearchHeader(viewModel, onOpenDrawer)
             }
         }
         if (source is ListSource.Search && items.isEmpty() && !viewModel.loadingInitial) {
@@ -211,21 +219,14 @@ fun VideoListScreen(
             // VideoListScreen (My videos, Search, Subscriptions, History, channel pages).
             item(key = "initial-placeholders", span = { androidx.compose.foundation.lazy.grid.GridItemSpan(maxLineSpan) }) {
                 LaunchedEffect(source) { viewModel.loadMore(force = true) }
-                androidx.compose.foundation.layout.Column {
-                    repeat(2) {
-                        androidx.compose.foundation.layout.Row {
-                            repeat(cardsPerRow) {
+                // A single loading card, not a full fake grid (issue #31).
                 ShimmerCard(
                     modifier = Modifier
                         .padding(6.dp)
-                                        .width(rowCardWidth()),
+                        .width(rowCardWidth() - 12.dp),
                 )
             }
         }
-                    }
-                }
-            }
-        }
         itemsIndexed(items, key = { _, item -> itemStableKey(item) }) { index, item ->
             val video: VideoDto = when (item) {
                 is VideoListItem.HistoryEntry -> item.history.video
@@ -260,7 +261,6 @@ fun VideoListScreen(
             }
         }
     }
-    }
 }
 
 @Composable
@@ -406,8 +406,11 @@ private fun ScopeChip(
 /**
  * Channel page header (issue #27): the banner is the backdrop of a fixed-height
  * header, darkened with a bottom-up gradient, with the channel identity + stats
- * and a reachable Subscribe button laid over it. It's pinned above the grid so
- * it never scrolls away, and the video cards start directly beneath it.
+ * and a reachable Subscribe button laid over it. It scrolls with the video grid.
+ *
+ * Its height is the same before and after the channel loads, so the cards never
+ * get pushed down when it arrives (issue #27 review), and a channel with no
+ * banner gets a colour gradient derived from its handle instead of flat black.
  */
 @Composable
 private fun ChannelHeader(
@@ -416,10 +419,10 @@ private fun ChannelHeader(
     handle: String,
     onLeftEdge: () -> Unit = {},
 ) {
-    if (channelHeader == null) return
     val metaColor = Color(0xFFCFCFCF)
-    val banner = channelHeader.banners.maxByOrNull { it.width }
-    val description = channelHeader.description?.takeIf { it.isNotBlank() }
+    val banner = channelHeader?.banners?.maxByOrNull { it.width }
+    val description = channelHeader?.description?.takeIf { it.isNotBlank() }
+    val accent = remember(handle) { channelAccent(handle) }
     androidx.compose.foundation.layout.Column(
         Modifier
             .fillMaxWidth()
@@ -428,13 +431,12 @@ private fun ChannelHeader(
             .background(Color.Black),
     ) {
     // Banner area: a fixed height with the identity + stats anchored to its
-    // bottom. A long description flows into the black strip BELOW it rather than
-    // being pushed up over the banner or clipped (user request).
+    // bottom; the description sits in the black strip below it.
     Box(
         Modifier
             .fillMaxWidth()
             .height(178.dp)
-            .background(Color(0xFF1C1C1C)),
+            .background(androidx.compose.ui.graphics.Brush.linearGradient(accent)),
     ) {
         if (banner != null) {
             ShimmerAsyncImage(
@@ -458,7 +460,9 @@ private fun ChannelHeader(
                 ),
         )
         // Identity + stats, bottom-left. The avatar sits beside the title (as it
-        // did before the redesign — user request).
+        // did before the redesign — user request). Only once the channel loaded;
+        // the box above keeps the height reserved in the meantime.
+        if (channelHeader != null) {
         Column(
             modifier = Modifier
                 .align(Alignment.BottomStart)
@@ -476,6 +480,22 @@ private fun ChannelHeader(
                             .size(56.dp)
                             .clip(androidx.compose.foundation.shape.CircleShape),
                     )
+                } else {
+                    // A channel with no icon gets a stand-in, not a gap (#27 review).
+                    Box(
+                        Modifier
+                            .size(56.dp)
+                            .clip(androidx.compose.foundation.shape.CircleShape)
+                            .background(Color(0x40FFFFFF)),
+                        contentAlignment = Alignment.Center,
+                    ) {
+                        androidx.compose.material3.Icon(
+                            imageVector = Icons.Filled.AccountCircle,
+                            contentDescription = null,
+                            tint = Color(0xFFE8E8E8),
+                            modifier = Modifier.size(42.dp),
+                        )
+                    }
                 }
                 Column(modifier = Modifier.padding(start = 14.dp)) {
                     Text(
@@ -531,19 +551,39 @@ private fun ChannelHeader(
                 .padding(16.dp),
         )
         }
-    // Description in the black beneath the banner: a long one grows the header
-    // downward, fading out of the banner that already darkens into black.
+    }
+    // Description strip in the black beneath the banner. Fixed height so the
+    // header measures the same before and after the channel loads (#27 review).
+    Box(
+        Modifier
+            .fillMaxWidth()
+            .height(42.dp)
+            .padding(start = 16.dp, end = 16.dp, top = 6.dp),
+    ) {
         if (description != null) {
             Text(
                 text = description,
                 color = Color(0xFFCCCCCC),
                 style = MaterialTheme.typography.bodySmall,
-            maxLines = 3,
+                maxLines = 2,
                 overflow = androidx.compose.ui.text.style.TextOverflow.Ellipsis,
-            modifier = Modifier.padding(start = 16.dp, end = 16.dp, top = 6.dp, bottom = 12.dp),
             )
         }
     }
+    }
+}
+
+/**
+ * Deterministic backdrop colours for a channel without a banner (#27 review):
+ * the handle's hash picks a hue, so every channel keeps the same recognisable
+ * gradient instead of a flat black header.
+ */
+private fun channelAccent(handle: String): List<Color> {
+    val hue = ((handle.hashCode() ushr 8) % 360 + 360) % 360
+    return listOf(
+        Color.hsv(hue.toFloat(), 0.45f, 0.42f),
+        Color.hsv(((hue + 38) % 360).toFloat(), 0.55f, 0.16f),
+    )
 }
 
 /**