compose: add shared composable foundations

EmptyState, SectionHeader, Shimmer placeholders; TopAppBar and
ScrollHint refinements to support the migrated screens.

app/src/main/java/com/aurora/store/compose/composable/EmptyState.kt

@@ -0,0 +1,77 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Aurora OSS
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+package com.aurora.store.compose.composable
+
+import androidx.annotation.DrawableRes
+import androidx.annotation.StringRes
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.size
+import androidx.compose.material3.FilledTonalButton
+import androidx.compose.material3.Icon
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.dimensionResource
+import androidx.compose.ui.res.painterResource
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.style.TextAlign
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.tooling.preview.PreviewWrapper
+import com.aurora.store.R
+import com.aurora.store.compose.preview.ThemePreviewProvider
+
+@Composable
+fun EmptyState(
+    modifier: Modifier = Modifier,
+    @DrawableRes icon: Int,
+    @StringRes message: Int,
+    @StringRes actionLabel: Int? = null,
+    onAction: () -> Unit = {}
+) {
+    Column(
+        modifier = modifier.fillMaxSize(),
+        horizontalAlignment = Alignment.CenterHorizontally,
+        verticalArrangement = Arrangement.spacedBy(
+            dimensionResource(R.dimen.margin_small),
+            Alignment.CenterVertically
+        )
+    ) {
+        Icon(
+            painter = painterResource(icon),
+            contentDescription = null,
+            modifier = Modifier.size(dimensionResource(R.dimen.icon_size_medium)),
+            tint = MaterialTheme.colorScheme.primary
+        )
+
+        Text(
+            text = stringResource(message),
+            style = MaterialTheme.typography.bodyLarge,
+            textAlign = TextAlign.Center,
+            color = MaterialTheme.colorScheme.onPrimary
+        )
+
+        if (actionLabel != null) {
+            FilledTonalButton(onClick = onAction) {
+                Text(stringResource(actionLabel))
+            }
+        }
+    }
+}
+
+@PreviewWrapper(ThemePreviewProvider::class)
+@Preview
+@Composable
+private fun EmptyStatePreview() {
+    EmptyState(
+        icon = R.drawable.ic_updates,
+        message = R.string.details_no_updates,
+        actionLabel = R.string.check_updates
+    )
+}

app/src/main/java/com/aurora/store/compose/composable/ScrollHint.kt

@@ -36,8 +36,8 @@ import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment.Companion.Center
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.alpha
+import androidx.compose.ui.res.dimensionResource
 import androidx.compose.ui.res.painterResource
-import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.IntOffset
 import androidx.compose.ui.unit.dp
 import com.aurora.store.R
@@ -48,7 +48,6 @@ import kotlinx.coroutines.launch
 fun ScrollHint(
     listState: LazyListState,
     modifier: Modifier = Modifier,
-    bottomPadding: Dp = 72.dp, // keep above bottom bar
     autoHideOnScroll: Boolean = true,
     enableBounce: Boolean = true,
     onClickScrollOffset: Float = 300f
@@ -88,7 +87,7 @@ fun ScrollHint(
         visible = visible,
         modifier = modifier
             .fillMaxWidth()
-            .padding(bottom = bottomPadding),
+            .padding(bottom = dimensionResource(R.dimen.scroll_hint_padding)),
         enter = fadeIn() + slideInVertically { it / 2 },
         exit = fadeOut()
     ) {

app/src/main/java/com/aurora/store/compose/composable/SectionHeader.kt

@@ -0,0 +1,116 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Aurora OSS
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+package com.aurora.store.compose.composable
+
+import androidx.compose.foundation.clickable
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
+import androidx.compose.material3.Icon
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.dimensionResource
+import androidx.compose.ui.res.painterResource
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.tooling.preview.PreviewWrapper
+import com.aurora.store.R
+import com.aurora.store.compose.preview.ThemePreviewProvider
+
+/**
+ * Section header row with optional right-chevron for navigation (replaces HeaderView).
+ * When [browseUrl] is non-null and non-blank the row is clickable and shows a chevron.
+ */
+@Composable
+fun SectionHeader(
+    modifier: Modifier = Modifier,
+    title: String,
+    browseUrl: String? = null,
+    onClick: () -> Unit = {}
+) {
+    val hasLink = !browseUrl.isNullOrBlank()
+    Row(
+        modifier = modifier
+            .fillMaxWidth()
+            .then(if (hasLink) Modifier.clickable(onClick = onClick) else Modifier)
+            .padding(all = dimensionResource(R.dimen.padding_medium)),
+        verticalAlignment = Alignment.CenterVertically
+    ) {
+        Text(
+            text = title,
+            style = MaterialTheme.typography.titleMedium,
+            fontWeight = FontWeight.SemiBold,
+            maxLines = 1,
+            overflow = TextOverflow.Ellipsis,
+            modifier = Modifier.weight(1f)
+        )
+        if (hasLink) {
+            Spacer(Modifier.width(dimensionResource(R.dimen.margin_small)))
+            Icon(
+                painter = painterResource(R.drawable.ic_arrow_right),
+                contentDescription = null,
+                modifier = Modifier.size(dimensionResource(R.dimen.icon_size_default)),
+                tint = MaterialTheme.colorScheme.primary
+            )
+        }
+    }
+}
+
+/**
+ * Section header row with a right-aligned action button (replaces UpdateHeaderView).
+ */
+@Composable
+fun SectionHeaderWithAction(
+    modifier: Modifier = Modifier,
+    title: String,
+    action: String,
+    onAction: () -> Unit = {}
+) {
+    Row(
+        modifier = modifier
+            .fillMaxWidth()
+            .padding(
+                start = dimensionResource(R.dimen.padding_small),
+                top = dimensionResource(R.dimen.padding_xxsmall),
+                bottom = dimensionResource(R.dimen.padding_xxsmall)
+            ),
+        verticalAlignment = Alignment.CenterVertically
+    ) {
+        Text(
+            text = title,
+            style = MaterialTheme.typography.titleMedium,
+            fontWeight = FontWeight.SemiBold,
+            maxLines = 1,
+            overflow = TextOverflow.Ellipsis,
+            modifier = Modifier.weight(1f)
+        )
+        TextButton(onClick = onAction) {
+            Text(action)
+        }
+    }
+}
+
+@PreviewWrapper(ThemePreviewProvider::class)
+@Preview(showBackground = true)
+@Composable
+private fun SectionHeaderPreview() {
+    SectionHeader(title = "Top Charts", browseUrl = "https://example.com")
+}
+
+@PreviewWrapper(ThemePreviewProvider::class)
+@Preview(showBackground = true)
+@Composable
+private fun SectionHeaderWithActionPreview() {
+    SectionHeaderWithAction(title = "3 updates available", action = "Update all")
+}

app/src/main/java/com/aurora/store/compose/composable/Shimmer.kt

@@ -0,0 +1,274 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Aurora OSS
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+package com.aurora.store.compose.composable
+
+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.foundation.background
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.requiredSize
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.graphics.Brush
+import androidx.compose.ui.res.dimensionResource
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.tooling.preview.PreviewWrapper
+import androidx.compose.ui.unit.dp
+import com.aurora.store.R
+import com.aurora.store.compose.preview.ThemePreviewProvider
+
+@Composable
+fun shimmerBrush(): Brush {
+    val base = MaterialTheme.colorScheme.onSurface
+    val colors = listOf(
+        base.copy(alpha = 0.08f),
+        base.copy(alpha = 0.20f),
+        base.copy(alpha = 0.08f)
+    )
+    val transition = rememberInfiniteTransition(label = "shimmer")
+    val offset by transition.animateFloat(
+        initialValue = 0f,
+        targetValue = 1f,
+        animationSpec = infiniteRepeatable(
+            animation = tween(1000, easing = LinearEasing),
+            repeatMode = RepeatMode.Restart
+        ),
+        label = "shimmer_offset"
+    )
+    val x = offset * 1200f
+    return Brush.linearGradient(
+        colors = colors,
+        start = Offset(x - 400f, 0f),
+        end = Offset(x, 400f)
+    )
+}
+
+@Composable
+internal fun ShimmerCategoryRow() {
+    val brush = shimmerBrush()
+    Row(
+        modifier = Modifier
+            .fillMaxWidth()
+            .padding(
+                horizontal = dimensionResource(R.dimen.padding_medium),
+                vertical = dimensionResource(R.dimen.padding_small)
+            ),
+        verticalAlignment = Alignment.CenterVertically,
+        horizontalArrangement = Arrangement.spacedBy(dimensionResource(R.dimen.padding_large))
+    ) {
+        Box(
+            modifier = Modifier
+                .requiredSize(dimensionResource(R.dimen.icon_size_category))
+                .clip(RoundedCornerShape(dimensionResource(R.dimen.radius_small)))
+                .background(brush)
+        )
+
+        Box(
+            modifier = Modifier
+                .weight(1f)
+                .height(24.dp)
+                .clip(RoundedCornerShape(dimensionResource(R.dimen.radius_small)))
+                .background(brush)
+        )
+    }
+}
+
+@Composable
+internal fun ShimmerAppRow() {
+    val brush = shimmerBrush()
+    Row(
+        modifier = Modifier
+            .fillMaxWidth()
+            .padding(
+                horizontal = dimensionResource(R.dimen.padding_small),
+                vertical = dimensionResource(R.dimen.padding_xsmall)
+            ),
+        verticalAlignment = Alignment.CenterVertically
+    ) {
+        Box(
+            modifier = Modifier
+                .requiredSize(dimensionResource(R.dimen.icon_size_medium))
+                .clip(RoundedCornerShape(dimensionResource(R.dimen.radius_small)))
+                .background(brush)
+        )
+        Column(
+            modifier = Modifier.padding(horizontal = dimensionResource(R.dimen.margin_small))
+        ) {
+            repeat(3) { i ->
+                Box(
+                    modifier = Modifier
+                        .fillMaxWidth(if (i == 0) 0.75f else 0.5f)
+                        .height(14.dp)
+                        .clip(RoundedCornerShape(dimensionResource(R.dimen.radius_small)))
+                        .background(brush)
+                )
+                if (i < 2) Spacer(Modifier.height(dimensionResource(R.dimen.padding_xxsmall)))
+            }
+        }
+    }
+}
+
+@Composable
+internal fun ShimmerUpdateItem() {
+    val brush = shimmerBrush()
+    Row(
+        modifier = Modifier
+            .fillMaxWidth()
+            .padding(
+                horizontal = dimensionResource(R.dimen.padding_small),
+                vertical = dimensionResource(R.dimen.padding_xsmall)
+            ),
+        verticalAlignment = Alignment.CenterVertically,
+        horizontalArrangement = Arrangement.spacedBy(dimensionResource(R.dimen.padding_small))
+    ) {
+        Box(
+            modifier = Modifier
+                .requiredSize(dimensionResource(R.dimen.icon_size_medium))
+                .clip(RoundedCornerShape(dimensionResource(R.dimen.radius_small)))
+                .background(brush)
+        )
+
+        Column(modifier = Modifier.weight(1f)) {
+            repeat(3) { i ->
+                Box(
+                    modifier = Modifier
+                        .fillMaxWidth(if (i == 0) 0.7f else 0.5f)
+                        .height(14.dp)
+                        .clip(RoundedCornerShape(dimensionResource(R.dimen.radius_small)))
+                        .background(brush)
+                )
+                if (i < 2) Spacer(Modifier.height(dimensionResource(R.dimen.padding_xxsmall)))
+            }
+        }
+
+        Box(
+            modifier = Modifier
+                .width(80.dp)
+                .height(36.dp)
+                .clip(RoundedCornerShape(50))
+                .background(brush)
+        )
+    }
+}
+
+@Composable
+internal fun ShimmerCarouselSection() {
+    val brush = shimmerBrush()
+    Column(
+        modifier = Modifier
+            .fillMaxWidth()
+            .padding(all = dimensionResource(R.dimen.padding_small)),
+        verticalArrangement = Arrangement.spacedBy(dimensionResource(R.dimen.padding_small))
+    ) {
+        Box(
+            modifier = Modifier
+                .fillMaxWidth(0.42f)
+                .height(16.dp)
+                .clip(RoundedCornerShape(dimensionResource(R.dimen.radius_small)))
+                .background(brush)
+        )
+
+        Row(
+            modifier = Modifier.fillMaxWidth(),
+            horizontalArrangement = Arrangement.spacedBy(dimensionResource(R.dimen.padding_small))
+        ) {
+            repeat(5) {
+                Column(
+                    verticalArrangement = Arrangement.spacedBy(
+                        dimensionResource(R.dimen.padding_xsmall)
+                    )
+                ) {
+                    Box(
+                        modifier = Modifier
+                            .size(dimensionResource(R.dimen.icon_size_cluster))
+                            .clip(RoundedCornerShape(dimensionResource(R.dimen.radius_medium)))
+                            .background(brush)
+                    )
+                    Box(
+                        modifier = Modifier
+                            .width(dimensionResource(R.dimen.icon_size_cluster) * 0.75f)
+                            .height(11.dp)
+                            .clip(RoundedCornerShape(dimensionResource(R.dimen.radius_small)))
+                            .background(brush)
+                    )
+                    Box(
+                        modifier = Modifier
+                            .width(dimensionResource(R.dimen.icon_size_cluster) * 0.5f)
+                            .height(11.dp)
+                            .clip(RoundedCornerShape(dimensionResource(R.dimen.radius_small)))
+                            .background(brush)
+                    )
+                }
+            }
+        }
+    }
+}
+
+@Composable
+internal fun ShimmerAppListItem() {
+    val brush = shimmerBrush()
+    Box(
+        modifier = Modifier
+            .padding(dimensionResource(R.dimen.padding_xsmall))
+            .size(dimensionResource(R.dimen.icon_size_cluster))
+            .clip(RoundedCornerShape(dimensionResource(R.dimen.radius_medium)))
+            .background(brush)
+    )
+}
+
+@PreviewWrapper(ThemePreviewProvider::class)
+@Preview(showBackground = true)
+@Composable
+private fun ShimmerCategoryRowPreview() {
+    ShimmerCategoryRow()
+}
+
+@PreviewWrapper(ThemePreviewProvider::class)
+@Preview(showBackground = true)
+@Composable
+private fun ShimmerAppRowPreview() {
+    ShimmerAppRow()
+}
+
+@PreviewWrapper(ThemePreviewProvider::class)
+@Preview(showBackground = true)
+@Composable
+private fun ShimmerUpdateItemPreview() {
+    ShimmerUpdateItem()
+}
+
+@PreviewWrapper(ThemePreviewProvider::class)
+@Preview(showBackground = true)
+@Composable
+private fun ShimmerCarouselSectionPreview() {
+    ShimmerCarouselSection()
+}
+
+@PreviewWrapper(ThemePreviewProvider::class)
+@Preview(showBackground = true)
+@Composable
+private fun ShimmerAppListItemPreview() {
+    ShimmerAppListItem()
+}

app/src/main/java/com/aurora/store/compose/composable/TopAppBar.kt

@@ -5,11 +5,15 @@
 
 package com.aurora.store.compose.composable
 
+import androidx.activity.ComponentActivity
+import androidx.activity.compose.LocalActivity
 import androidx.compose.foundation.layout.RowScope
+import androidx.compose.foundation.layout.WindowInsets
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
 import androidx.compose.material3.Text
 import androidx.compose.material3.TopAppBar
+import androidx.compose.material3.TopAppBarDefaults
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.painter.Painter
@@ -25,7 +29,7 @@ import com.aurora.store.compose.preview.ThemePreviewProvider
  * @param modifier The modifier to be applied to the composable
  * @param title Title of the screen
  * @param navigationIcon Icon for the navigation button
- * @param onNavigateUp Action when user clicks the navigation icon
+ * @param showNavigationIcon Whether to show the navigation (back) icon button
  * @param actions Actions to display on the top app bar (for e.g. menu)
  */
 @Composable
@@ -33,15 +37,17 @@ fun TopAppBar(
     modifier: Modifier = Modifier,
     title: String? = null,
     navigationIcon: Painter = painterResource(R.drawable.ic_arrow_back),
-    onNavigateUp: (() -> Unit)? = null,
+    showNavigationIcon: Boolean = true,
+    windowInsets: WindowInsets = TopAppBarDefaults.windowInsets,
     actions: @Composable (RowScope.() -> Unit) = {}
 ) {
+    val activity = LocalActivity.current as? ComponentActivity
     TopAppBar(
         modifier = modifier,
         title = { if (title != null) Text(text = title) },
         navigationIcon = {
-            if (onNavigateUp != null) {
+            if (showNavigationIcon) {
-                IconButton(onClick = onNavigateUp) {
+                IconButton(onClick = { activity?.onBackPressedDispatcher?.onBackPressed() }) {
                     Icon(
                         painter = navigationIcon,
                         contentDescription = stringResource(R.string.action_back)
@@ -49,6 +55,7 @@ fun TopAppBar(
                 }
             }
         },
+        windowInsets = windowInsets,
         actions = actions
     )
 }
@@ -58,7 +65,6 @@ fun TopAppBar(
 @Composable
 private fun TopAppBarPreview() {
     TopAppBar(
-        title = stringResource(R.string.title_about),
+        title = stringResource(R.string.title_about)
-        onNavigateUp = {}
     )
 }