feat!: replace Section.subtitle with a global viewMoreTitle option

Section.subtitle had exactly one renderer anywhere: the second line of
the row Android Auto appends under a section carrying a `path`. It was a
link label wearing a subtitle's name, and it made per-section copy
mandatory for a row most consumers never see drawn.

That row's title now comes from a global `viewMoreTitle` browser option,
defaulting to "View more". A callback rather than a string so it
re-resolves once per content generation: an app whose locale is its own
rather than the system's can switch language and pick the new copy up
via invalidateAllContent(), which a value frozen at configure time
cannot express.

Also drops the `display == GRID` gate in toMediaItems. No Android Auto
header is tappable at any display, so a pathed *list* section previously
swallowed its `path` — its destination unreachable, with no diagnostic.

CarPlay is unchanged: its tile rows already navigate on their own, and a
list section gets no invented row — Apple documents no "see all"
affordance for one, and it would spend an item from the template's cap.

Per-section wording stays available by authoring the link yourself:
leave `path` unset and append an ordinary browsable Track to the
section's `children`. The row is Android-only, so that is a platform
branch in the content you emit, not a new API.

Closes #137. Amends #134.

BREAKING CHANGE: `Section.subtitle` is removed. A section's view-all row
is titled by the `viewMoreTitle` browser option instead, and a section
with a `path` now gets that row at every `display`, not only grids.

Author: puckey

android/src/main/java/com/audiobrowser/AudioBrowser.kt

@@ -203,6 +203,7 @@ class AudioBrowser : HybridAudioBrowserSpec(), ServiceConnection {
       singleTrack = null,
       handleTrackLoad = null,
       androidControllerOfflineError = null,
+      viewMoreTitle = null,
       carPlayLoadingTitle = null,
       resolveAlbumPath = null,
       formatNavigationError = null,
@@ -369,6 +370,7 @@ class AudioBrowser : HybridAudioBrowserSpec(), ServiceConnection {
       routes = _configuration.routes,
       singleTrack = _configuration.singleTrack ?: false,
       androidControllerOfflineError = _configuration.androidControllerOfflineError ?: true,
+      viewMoreTitle = _configuration.viewMoreTitle,
     )
   }
 
@@ -1571,6 +1573,7 @@ private fun NativeBrowserConfiguration.strippingJSCallbacks() =
     requestResolver = null,
     browseResolver = null,
     handleTrackLoad = null,
+    viewMoreTitle = null,
     resolveAlbumPath = null,
     formatNavigationError = null,
     request = request?.strippingJSCallbacks(),

android/src/main/java/com/audiobrowser/browser/BrowserManager.kt

@@ -24,6 +24,7 @@ import com.margelo.nitro.audiobrowser.Section
 import com.margelo.nitro.audiobrowser.StyleDisplay
 import com.margelo.nitro.audiobrowser.Track
 import com.margelo.nitro.audiobrowser.TransformableRequestConfig
+import com.margelo.nitro.core.Promise
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.async
 import kotlinx.coroutines.awaitAll
@@ -133,6 +134,12 @@ class BrowserManager {
   private var resolvedRequestLayer: TransformableRequestConfig? = null
   private var resolvedBrowseLayer: TransformableRequestConfig? = null
 
+  // The "view more" row title, cached on the same generation as the layers above — see
+  // viewMoreTitle(). Kept separate from them because it is resolved lazily (only a browse that
+  // actually appends a row asks for it), not eagerly alongside every request.
+  private var resolvedViewMoreTitleGeneration = -1
+  private var resolvedViewMoreTitle = DEFAULT_VIEW_MORE_TITLE
+
   /** Test-only accessors for the resolver-layer cache state (see ensureLayersResolved). */
   internal val layerGenerationForTest: Int
     get() = layerGeneration
@@ -1129,6 +1136,14 @@ class BrowserManager {
 
     /** Internal path used for search */
     internal const val SEARCH_ROUTE_PATH = "__search__"
+
+    /**
+     * Title of the appended "view more" row when the consumer sets no
+     * [BrowserConfig.viewMoreTitle]. English in code, like [defaultFormattedError]'s error copy — a
+     * default that renders beats a section whose `path` is unreachable, and it still resolves when
+     * the JS runtime is gone.
+     */
+    internal const val DEFAULT_VIEW_MORE_TITLE = "View more"
   }
 
   /**
@@ -1304,6 +1319,33 @@ class BrowserManager {
     return resolvedRequestLayer
   }
 
+  /**
+   * The title for the "view more" row appended to a pathed section on a surface whose header cannot
+   * be tapped (Android Auto).
+   *
+   * Resolved from [BrowserConfig.viewMoreTitle] once per content generation — the same generation
+   * the resolver layers use, so `invalidateAllContent()` re-reads it and an app that switched
+   * language mid-drive gets the new copy without reconfiguring. Falls back to
+   * [DEFAULT_VIEW_MORE_TITLE] when unset, blank, or throwing: a row with the default copy still
+   * reaches the section's page, an untitled one does not.
+   */
+  internal suspend fun viewMoreTitle(): String {
+    val generation = layerGeneration
+    if (resolvedViewMoreTitleGeneration == generation) return resolvedViewMoreTitle
+    val title =
+      try {
+        config.viewMoreTitle?.invoke()?.await()?.takeIf { it.isNotBlank() }
+      } catch (e: Exception) {
+        Timber.e(e, "viewMoreTitle callback failed; falling back to the default")
+        null
+      } ?: DEFAULT_VIEW_MORE_TITLE
+    // A newer generation started while awaiting — use this result, but don't cache it as current.
+    if (generation != layerGeneration) return title
+    resolvedViewMoreTitle = title
+    resolvedViewMoreTitleGeneration = generation
+    return title
+  }
+
   /**
    * Builds the HTTP request for an API-backed path by layering request (shared) → kind
    * (browse/search) → route configs. Each layer's transform receives the previous layer's output; a
@@ -1502,6 +1544,8 @@ data class BrowserConfig(
   // Behavior
   val singleTrack: Boolean = false,
   val androidControllerOfflineError: Boolean = true,
+  // Titles the "view more" row appended to a pathed section. See BrowserManager.viewMoreTitle.
+  val viewMoreTitle: (() -> Promise<String>)? = null,
 ) {
   /** Returns true if search functionality is configured (either callback or config). */
   val hasSearch: Boolean

android/src/main/java/com/audiobrowser/browser/JsonModels.kt

@@ -40,7 +40,6 @@ data class JsonTrackRequest(
 @Serializable
 data class JsonSection(
   val title: String? = null,
-  val subtitle: String? = null,
   val style: JsonElement? = null,
   val path: String? = null,
   val children: List<JsonTrack>,
@@ -150,7 +149,6 @@ private fun String?.toCarPlaySiriListButtonPosition(): CarPlaySiriListButtonPosi
 fun JsonSection.toNitro(): Section {
   return Section(
     title = title,
-    subtitle = subtitle,
     style = style.toSectionStyle(),
     path = path,
     children = children.map { it.toNitro() }.toTypedArray(),

android/src/main/java/com/audiobrowser/browser/SectionScope.kt

@@ -59,7 +59,7 @@ object SectionScope {
  * search results — ADR 0010).
  */
 fun untitledSection(children: Array<Track>): Section =
-  Section(title = null, subtitle = null, style = null, path = null, children = children)
+  Section(title = null, style = null, path = null, children = children)
 
 /**
  * The canonical sectioned shape: `sections` wins when present; plain `children` is authoring sugar

android/src/main/java/com/audiobrowser/player/MediaSessionCallback.kt

@@ -32,7 +32,6 @@ import com.margelo.nitro.audiobrowser.PlayerCapabilities
 import com.margelo.nitro.audiobrowser.RemoteButtonLayout
 import com.margelo.nitro.audiobrowser.SearchParams
 import com.margelo.nitro.audiobrowser.Section
-import com.margelo.nitro.audiobrowser.StyleDisplay
 import com.margelo.nitro.audiobrowser.Track
 import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.CoroutineScope
@@ -419,41 +418,41 @@ class MediaSessionCallback(private val player: Player) :
   /**
    * Flattens a page's sections to MediaItems for browse delivery — the Media3 boundary where
    * sections die (ADR 0010): the MediaBrowser protocol has no section node, so each child is
-   * stamped with its owning section's title/style hints. A grid-displayed section with a `path`
-   * gains a browsable "view all" link under the same header. Http(s) artwork routes through the
-   * content:// provider so Android Auto can load it via the ArtworkContentProvider.
+   * stamped with its owning section's title/style hints. A section with a `path` gains a browsable
+   * "view more" row under the same header — at every `display`, because no Android Auto header is
+   * tappable at any of them, so the row is the section's only "view all" affordance here. Http(s)
+   * artwork routes through the content:// provider so Android Auto can load it via the
+   * ArtworkContentProvider.
    */
-  private fun toMediaItems(sections: List<Section>): List<MediaItem> {
+  private suspend fun toMediaItems(sections: List<Section>): List<MediaItem> {
     val registry = player.browseArtworkRegistry
     val authority = com.audiobrowser.util.ArtworkUris.authorityFor(player.context.packageName)
     return sections.flatMap { section ->
       // Android Auto has no disabled affordance, so an unavailable track hides
       // — never a normal-looking dead row (Track.disabled's rendering ladder).
-      val visibleChildren = section.children.filter { it.disabled != true }
-      val items =
-        visibleChildren.map { TrackFactory.toBrowseMediaItem(it, registry, authority, section) }
-      val isTileSection = section.style?.display == StyleDisplay.GRID
-      // No "view all" under an empty section — CarPlay skips empty sections
+      val children = section.children.filter { it.disabled != true }
+      val items = children.map { TrackFactory.toBrowseMediaItem(it, registry, authority, section) }
+      // No "view more" under an empty section — CarPlay skips empty sections
       // outright, and a lone navigation tile under a header is a dead end.
-      if (isTileSection && section.path != null && visibleChildren.isNotEmpty()) {
-        items +
-          TrackFactory.toBrowseMediaItem(
-            TrackFactory.navigationTrack(section),
-            registry,
-            authority,
-            section,
-          )
-      } else {
-        items
-      }
+      if (section.path == null || children.isEmpty()) return@flatMap items
+      // The browser is already up at every call site, so awaiting it here is a field read, and
+      // viewMoreTitle is memoized per content generation — both are free after the first row.
+      val title = player.awaitBrowser().browserManager.viewMoreTitle()
+      items +
+        TrackFactory.toBrowseMediaItem(
+          TrackFactory.navigationTrack(section, title),
+          registry,
+          authority,
+          section,
+        )
     }
   }
 
   /**
    * Flat lists (tabs, search results) convert as one untitled list section — which contributes no
    * group or style hints — so exactly one Track→MediaItem path exists at the Media3 boundary.
    */
-  private fun toFlatMediaItems(tracks: List<Track>): List<MediaItem> =
+  private suspend fun toFlatMediaItems(tracks: List<Track>): List<MediaItem> =
     toMediaItems(listOf(untitledSection(tracks.toTypedArray())))
 
   override fun onGetItem(

android/src/main/java/com/audiobrowser/util/TrackFactory.kt

@@ -25,22 +25,25 @@ object TrackFactory {
   }
 
   /**
-   * A synthetic browsable Track for a section's "view all" surface — the section has a path, title,
-   * and label, but no Track (ADR 0010). It carries the section's declared item block as its own,
+   * A synthetic browsable Track for a section's "view more" row — the section has a path but no
+   * Track to hang it on (ADR 0010). It carries the section's declared item block as its own,
    * `display` included: the section's declaration about this content's layout is the only declared
    * promise the "view all" page can ever have (there is no consumer-authored handle to declare one
    * on), and without it Android Auto would always render that page as a list.
+   *
+   * [title] is the consumer's `viewMoreTitle`, one string for every section — not the section's own
+   * title, which the group header above the row already shows.
    */
-  fun navigationTrack(section: Section): Track =
+  fun navigationTrack(section: Section, title: String): Track =
     Track(
       id = null,
       path = section.path,
       src = null,
       artwork = null,
       artworkSource = null,
       request = null,
-      title = section.title ?: "",
-      subtitle = section.subtitle,
+      title = title,
+      subtitle = null,
       artist = null,
       albumPath = null,
       album = null,

android/src/main/res/values/strings.xml

@@ -1,10 +1,45 @@
 <?xml version="1.0" encoding="utf-8"?>
+<!--
+  Default copy for the two error tiles the library invents in the Android Auto
+  browse list. These rows have no consumer-authored Track behind them, so there
+  is nothing in the browse tree to read a title from; English here because a
+  default that renders beats a blank row.
+
+  Resources rather than a browser-config option — the route the library's
+  cross-platform copy takes (`formatNavigationError`, `carPlayLoadingTitle`,
+  `viewMoreTitle`) — because these two are not cross-platform. They exist only
+  because Media3 drops the message from `LibraryResult.ofError` on the legacy
+  browse bridge, so a row is the sole signal available; CarPlay has no
+  counterpart, stating failures in the list's centered empty view instead
+  (CarPlayController.showMessage). Android-only copy in the Android-idiomatic
+  place: an app re-skins either by declaring the same name in its own
+  strings.xml, and a `values-<locale>/` file can add translations later without
+  touching the API.
+-->
 <resources>
-    <!-- Error message shown in Android Auto when network is offline -->
+    <!--
+      The offline tile: shown in place of a page's contents when the device is
+      offline and the consumer left `androidControllerOfflineError` on. Distinct
+      from the browse-error tile below — this one is used only when the network
+      monitor says we are actually offline, so it may name the cause. The
+      subtitle is the tile's second line.
+    -->
     <string name="audio_browser_offline_error">No internet connection</string>
     <string name="audio_browser_offline_error_subtitle">Check your connection and try again</string>
 
-    <!-- Generic error message shown in Android Auto when browsing fails -->
+    <!--
+      The browse-error tile: shown when a browse fails while ONLINE — a server
+      error, a bad status, a timeout waiting for the JS browser. Deliberately
+      vague, and deliberately not "no internet connection": the genuinely-offline
+      case is caught earlier and gets the tile above, so anything reaching this
+      one has a working connection and would be misdiagnosed by that wording.
+
+      A tile rather than an error dialog because Media3 drops the message from
+      `LibraryResult.ofError` on the legacy browse bridge, which would leave a
+      bare "No items" screen. Verified on a head unit (2026-06): the Android Auto
+      browse list never renders error text by any other route, so tiles are the
+      only in-browse signal the library controls.
+    -->
     <string name="audio_browser_browse_error">Something went wrong</string>
     <string name="audio_browser_browse_error_subtitle">Please try again later</string>
 </resources>

android/src/test/java/com/audiobrowser/TestFixtures.kt

@@ -61,10 +61,9 @@ object TestFixtures {
   fun section(
     children: Array<Track> = emptyArray(),
     title: String? = null,
-    subtitle: String? = null,
     style: SectionStyle? = null,
     path: String? = null,
-  ) = Section(title = title, subtitle = subtitle, style = style, path = path, children = children)
+  ) = Section(title = title, style = style, path = path, children = children)
 
   fun transformableConfig(
     baseUrl: String? = null,

android/src/test/java/com/audiobrowser/browser/BrowserManagerLayerResolutionTest.kt

@@ -144,4 +144,13 @@ class BrowserManagerLayerResolutionTest {
     assertSame(request, browserManager.resolvedRequestLayerForTest)
     assertNull(browserManager.resolvedBrowseLayerForTest)
   }
+
+  @Test
+  fun `viewMoreTitle falls back to the in-code default when unconfigured`() = runTest {
+    // The only viewMoreTitle path a JVM test can reach — a configured callback returns a Nitro
+    // Promise, see the resolver-thunk gap noted above.
+    browserManager.config = BrowserConfig()
+
+    assertEquals(BrowserManager.DEFAULT_VIEW_MORE_TITLE, browserManager.viewMoreTitle())
+  }
 }

android/src/test/java/com/audiobrowser/util/MediaExtrasBuilderTest.kt

@@ -130,8 +130,9 @@ class MediaExtrasBuilderTest {
         path = "/popular",
         style = sectionStyle(display = StyleDisplay.GRID, artworkRendering = null, gridWrap = false),
       )
-    val navigation = TrackFactory.navigationTrack(section)
+    val navigation = TrackFactory.navigationTrack(section, "View more")
     assertEquals(StyleDisplay.GRID, navigation.style?.display)
+    assertEquals("View more", navigation.title)
 
     val extras = MediaExtrasBuilder.build(navigation)
     assertEquals(