loading: placeholder cards with a faint shimmer; thumbnail while buffering

Rows that were still loading kept silent or a bare "Loading…" line.
Every list row (continue, new videos, subscriptions) now shows dummy
cards shaped like the real thing — gray rectangles with a very faint
sweeping sheen — because that says what is coming and that it is
moving; the spinner only survives where there is nothing to shape.

Fullscreen video loading shows the video's own thumbnail dimmed under
the circle loader instead of black, at least until the detail response
has the thumbnail; before that only the circle exists (issue #19).

The shimmer is a linear sheen at 8% alpha looping over 1.6s on a
near-black base, subtle per the report.

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

@@ -78,7 +78,9 @@ class HomeRowsViewModel(private val repository: PeerTubeRepository) : ViewModel(
     private var subsInFlight = false
     var subsExhausted by mutableStateOf(false)
         private set
-    private var subsLoading = false
+    /** Exposed for the shimmer placeholders (issue #19). */
+    var subsLoading = false
+        private set
 
     val recent = RecentVideosViewModel(repository)
 
@@ -310,10 +312,14 @@ fun HomeRowsScreen(
             )
         }
         item {
-            if (viewModel.continueItems.isEmpty()) {
+            if (viewModel.continueLoading && viewModel.continueItems.isEmpty()) {
+                // Dummy cards with the faint shimmer while the row loads (#19);
+                // "Watch something first" only when there is genuinely no history.
+                ShimmerRow()
+            } else if (viewModel.continueItems.isEmpty()) {
                 Box(Modifier.fillParentMaxWidth(0f).padding(start = 16.dp)) {
                     Text(
-                        text = if (viewModel.continueLoading) "Loading…" else "Watch something first",
+                        text = "Watch something first",
                         style = MaterialTheme.typography.bodySmall,
                         color = Color(0xFF8A8A8A),
                     )
@@ -350,13 +356,7 @@ fun HomeRowsScreen(
         item {
             if (recentItems.isEmpty()) {
                 LaunchedEffect("kick-recent") { viewModel.recent.loadMore() }
-                Row(Modifier.padding(start = 16.dp)) {
+                ShimmerRow()
-                    Text(
-                        text = "Loading…",
-                        style = MaterialTheme.typography.bodySmall,
-                        color = Color(0xFF8A8A8A),
-                    )
-                }
             } else {
                 FocusScrollRow(
                     videos = recentItems,
@@ -373,7 +373,7 @@ fun HomeRowsScreen(
                 }
             }
         }
-        if (viewModel.subItems.isNotEmpty()) {
+        if (viewModel.subItems.isNotEmpty() || viewModel.subsLoading) {
             item {
                 Text(
                     text = "New from your subscriptions",
@@ -383,6 +383,9 @@ fun HomeRowsScreen(
                 )
             }
             item {
+                if (viewModel.subItems.isEmpty() && viewModel.subsLoading) {
+                    ShimmerRow()
+                } else {
                 FocusScrollRow(
                     videos = viewModel.subItems,
                     progressOf = { null },
@@ -396,10 +399,27 @@ fun HomeRowsScreen(
                         LaunchedEffect(index) { viewModel.subsMore() }
                     }
                 }
+                }
             }
         }
     }
 }
+
+/** Placeholder row of dummy cards (issue #19). */
+@Composable
+private fun ShimmerRow(size: Int = 4) {
+    Row(Modifier.padding(horizontal = 12.dp)) {
+        androidx.compose.foundation.layout.Row {
+        }
+        repeat(size) {
+            net.jeena.jtubetv.ui.screens.list.ShimmerCard(
+                modifier = Modifier
+                    .padding(horizontal = 4.dp)
+                    .width(rowCardWidth()),
+            )
+        }
+    }
+}
 /**
  * Horizontal card row with eased scrolling: when focus moves to a card outside the
  * viewport, the row animates it to the left edge (SmartTube behaviour) instead of

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

@@ -554,9 +554,10 @@ private fun PlayerSurface(
                 .fillMaxSize()
                 .padding(end = if (sidebar != null) SIDEBAR_WIDTH else 0.dp),
         )
-        // Cover the picture with the loading indicator until the player is really
+        // Cover the picture with a loading state until the player is really
         // ready to render — metadata resolution alone (the Loading state) is not
-        // enough (issue #8).
+        // enough (issue #8). Fullscreen loading shows the video's own thumbnail
+        // dimmed under the circle loader (issue #19) instead of plain black.
         if (buffering) {
             Box(
                 Modifier
@@ -564,7 +565,18 @@ private fun PlayerSurface(
                     .background(Color.Black)
                     .pointerInput(Unit) {}, // swallow taps/clicks while covering
                 contentAlignment = Alignment.Center,
-            ) { CircularProgressIndicator() }
+            ) {
+                s.detail.thumbnailPath?.let { thumbPath ->
+                    coil.compose.AsyncImage(
+                        model = AppGraph.repository.absoluteUrl(thumbPath),
+                        contentDescription = null,
+                        contentScale = ContentScale.Crop,
+                        modifier = Modifier.fillMaxSize(),
+                    )
+                    Box(Modifier.fillMaxSize().background(Color(0xB3000000)))
+                }
+                CircularProgressIndicator()
+            }
         }
         // Controls: SmartTube-style (title + channel above, then the seek bar +
         // action row). Persistent when paused, transient while playing.

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

@@ -4,6 +4,17 @@ import androidx.compose.material.icons.filled.PlayArrow
 import androidx.compose.foundation.layout.size
 
 import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.fillMaxHeight
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.animation.core.LinearEasing
+import androidx.compose.animation.core.RepeatMode
+import androidx.compose.animation.core.animateFloat
+import androidx.compose.animation.core.infiniteRepeatable
+import androidx.compose.animation.core.rememberInfiniteTransition
+import androidx.compose.animation.core.tween
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.graphics.Brush
+import androidx.compose.ui.draw.drawBehind
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.aspectRatio
@@ -267,3 +278,56 @@ internal fun formatAge(iso: String?): String {
         ""
     }
 }
+/**
+ * Dummy card while a row/grid loads: gray rectangles in the card's shape with
+ * a very faint sweeping sheen instead of a spinner (issue #19 — the spinner
+ * says nothing about what's coming).
+ */
+@Composable
+fun ShimmerCard(modifier: Modifier = Modifier) {
+    val sweep = rememberInfiniteTransition()
+    val x by sweep.animateFloat(
+        initialValue = 0f,
+        targetValue = 1f,
+        animationSpec = infiniteRepeatable(tween(1600, easing = LinearEasing)),
+    )
+    val base = Color(0xFF232323)
+    Column(modifier) {
+        Box(
+            Modifier
+                .fillMaxWidth()
+                .height(158.dp)
+                .background(base, RoundedCornerShape(8.dp))
+                .shimmer(x),
+        )
+        Box(
+            Modifier
+                .padding(top = 10.dp)
+                .height(13.dp)
+                .fillMaxWidth(0.85f)
+                .background(base, RoundedCornerShape(4.dp))
+                .shimmer(x),
+        )
+        Box(
+            Modifier
+                .padding(top = 6.dp)
+                .height(10.dp)
+                .fillMaxWidth(0.55f)
+                .background(base, RoundedCornerShape(4.dp))
+                .shimmer(x),
+        )
+    }
+}
+
+/** Very faint metallic sheen sweeping per [progress] (0..1); barely stronger than the base. */
+fun Modifier.shimmer(progress: Float): Modifier = drawBehind {
+    drawRect(
+        Brush.linearGradient(
+            0f to Color.Transparent,
+            0.5f to Color(0x14FFFFFF),
+            1f to Color.Transparent,
+            start = Offset(size.width * (progress * 2f - 1f), size.height),
+            end = Offset(size.width * (progress * 2f), 0f),
+        ),
+    )
+}