give the album detail artist line a full touch target

The subtitle was a bare bodyMedium line: 20dp tall and only as wide as the text. It now
sits in a full-width target spanning the 4dp lead-in and the 20dp gap below it, so the
row clears 48dp while the text stays where it was. The album title is deliberately not
part of it, unlike now playing: it can wrap to two lines, so tapping it should not jump
to the artist. The controls row moves down 4dp, the only layout delta.

AlbumDetailTapsTest covers the tap, the 48dp minimum (fails on a 20dp node) and that the
title carries no click action.

app/src/main/kotlin/com/subtracks/ui/components/HeroDetailScaffold.kt

@@ -14,6 +14,7 @@ import androidx.compose.foundation.layout.WindowInsets
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.heightIn
 import androidx.compose.foundation.layout.navigationBars
 import androidx.compose.foundation.layout.offset
 import androidx.compose.foundation.layout.padding
@@ -187,6 +188,22 @@ fun HeroDetailScaffold(
     }
 }
 
+@Composable
+private fun HeroSubtitle(
+    text: String,
+    modifier: Modifier = Modifier,
+) {
+    Text(
+        text = text,
+        style = MaterialTheme.typography.bodyMedium,
+        color = MaterialTheme.colorScheme.onSurfaceVariant,
+        textAlign = TextAlign.Center,
+        maxLines = 2,
+        overflow = TextOverflow.Ellipsis,
+        modifier = modifier,
+    )
+}
+
 @Composable
 fun HeroHeader(
     art: CoverArtRef?,
@@ -227,30 +244,30 @@ fun HeroHeader(
             maxLines = 2,
             overflow = TextOverflow.Ellipsis,
         )
-        if (subtitle.isNotEmpty()) {
+        val subtitleIsTarget = onSubtitleClick != null && subtitle.isNotEmpty() && comment.isNullOrBlank()
+        if (subtitleIsTarget) {
+            // The target spans the 4dp lead-in and the 20dp gap that would sit below the
+            // line, so the text stays put and the row clears 48dp; without those the
+            // subtitle alone is a single 20dp line.
+            Box(
+                modifier =
+                    Modifier
+                        .fillMaxWidth()
+                        .heightIn(min = 48.dp)
+                        .clickable(onClickLabel = "Open artist") { onSubtitleClick?.invoke() },
+                contentAlignment = Alignment.TopCenter,
+            ) {
+                HeroSubtitle(subtitle, Modifier.padding(top = 4.dp))
+            }
+        } else if (subtitle.isNotEmpty()) {
             Spacer(Modifier.height(4.dp))
-            Text(
-                text = subtitle,
-                style = MaterialTheme.typography.bodyMedium,
-                color = MaterialTheme.colorScheme.onSurfaceVariant,
-                textAlign = TextAlign.Center,
-                maxLines = 2,
-                overflow = TextOverflow.Ellipsis,
-                modifier = if (onSubtitleClick != null) Modifier.clickable { onSubtitleClick() } else Modifier,
-            )
+            HeroSubtitle(subtitle)
         }
         if (!comment.isNullOrBlank()) {
             Spacer(Modifier.height(4.dp))
-            Text(
-                text = comment,
-                style = MaterialTheme.typography.bodyMedium,
-                color = MaterialTheme.colorScheme.onSurfaceVariant,
-                textAlign = TextAlign.Center,
-                maxLines = 2,
-                overflow = TextOverflow.Ellipsis,
-            )
+            HeroSubtitle(comment)
         }
-        Spacer(Modifier.height(20.dp))
+        if (!subtitleIsTarget) Spacer(Modifier.height(20.dp))
         Row(
             modifier = controlsModifier.fillMaxWidth(),
             verticalAlignment = Alignment.CenterVertically,

app/src/test/kotlin/com/subtracks/ui/library/AlbumDetailTapsTest.kt

@@ -0,0 +1,84 @@
+package com.subtracks.ui.library
+
+import androidx.activity.ComponentActivity
+import androidx.compose.ui.test.assertCountEquals
+import androidx.compose.ui.test.assertHeightIsAtLeast
+import androidx.compose.ui.test.filter
+import androidx.compose.ui.test.hasClickAction
+import androidx.compose.ui.test.junit4.v2.createAndroidComposeRule
+import androidx.compose.ui.test.onAllNodesWithText
+import androidx.compose.ui.test.onNodeWithText
+import androidx.compose.ui.test.performClick
+import androidx.compose.ui.unit.dp
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.subtracks.data.model.Album
+import com.subtracks.data.model.CoverArtRef
+import com.subtracks.ui.theme.SubtracksTheme
+import org.junit.Assert.assertTrue
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.annotation.GraphicsMode
+
+@RunWith(AndroidJUnit4::class)
+@GraphicsMode(GraphicsMode.Mode.NATIVE)
+class AlbumDetailTapsTest {
+    @get:Rule
+    val composeRule = createAndroidComposeRule<ComponentActivity>()
+
+    private val album =
+        Album(
+            sourceId = 1,
+            id = "al-kid-a",
+            artistId = "ar-radiohead",
+            name = "Kid A",
+            albumArtist = "Radiohead",
+            created = 0,
+            coverArt = "art-al-kid-a",
+            genre = null,
+            year = 2000,
+            starred = null,
+            songCount = 1,
+        )
+
+    private fun render(onArtistClick: (() -> Unit)? = null) {
+        composeRule.setContent {
+            SubtracksTheme {
+                AlbumDetailScreen(
+                    album = album,
+                    songs = emptyList(),
+                    coverArt = { id, _ -> id?.let { CoverArtRef(it, "test:$it") } },
+                    artwork = null,
+                    onBack = {},
+                    onSongClick = {},
+                    onArtistClick = onArtistClick,
+                )
+            }
+        }
+    }
+
+    @Test
+    fun tappingTheArtistOpensTheArtist() {
+        var opened = false
+        render(onArtistClick = { opened = true })
+
+        composeRule.onNodeWithText("Radiohead \u00B7 2000").performClick()
+
+        assertTrue("the artist name should open the artist", opened)
+    }
+
+    @Test
+    fun theArtistTargetIsAtLeastTheMinimumTouchSize() {
+        render(onArtistClick = {})
+
+        composeRule.onNodeWithText("Radiohead \u00B7 2000").assertHeightIsAtLeast(48.dp)
+    }
+
+    @Test
+    fun theAlbumTitleIsNotATapTarget() {
+        render(onArtistClick = {})
+
+        // The app bar repeats the album name, so match the hero title by having no click.
+        composeRule.onAllNodesWithText("Kid A").filter(hasClickAction().not()).assertCountEquals(1)
+    }
+}