android/app/src/main/java/com/fabledsword/minstrel/MainActivity.kt

@@ -4,15 +4,34 @@ import android.os.Bundle
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
-import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.Icon
+import androidx.compose.material3.NavigationBar
+import androidx.compose.material3.NavigationBarItem
 import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
 import androidx.compose.ui.Modifier
-import com.fabledsword.minstrel.library.ui.LibraryScreen
+import androidx.compose.ui.graphics.vector.ImageVector
+import androidx.navigation.NavDestination.Companion.hasRoute
+import androidx.navigation.NavHostController
+import androidx.navigation.compose.currentBackStackEntryAsState
+import androidx.navigation.compose.rememberNavController
+import com.composables.icons.lucide.House
+import com.composables.icons.lucide.LibraryBig
+import com.composables.icons.lucide.Lucide
+import com.composables.icons.lucide.Search
+import com.composables.icons.lucide.Settings
+import com.fabledsword.minstrel.nav.Home
+import com.fabledsword.minstrel.nav.Library
+import com.fabledsword.minstrel.nav.MinstrelNavGraph
+import com.fabledsword.minstrel.nav.Search as SearchRoute
+import com.fabledsword.minstrel.nav.Settings as SettingsRoute
 import com.fabledsword.minstrel.theme.MinstrelTheme
 import dagger.hilt.android.AndroidEntryPoint
+import kotlin.reflect.KClass
 
 @AndroidEntryPoint
 class MainActivity : ComponentActivity() {
@@ -27,12 +46,44 @@ class MainActivity : ComponentActivity() {
 
 @Composable
 private fun App() {
-    // Bottom-bar nav-graph wiring lands in Phase 5.5. For now render
-    // LibraryScreen directly so the new UI is reachable end-to-end.
-    // onArtistClick / onAlbumClick are no-op until the nav graph lands.
-    Scaffold(modifier = Modifier.fillMaxSize()) { inner ->
-        Box(modifier = Modifier.padding(inner)) {
-            LibraryScreen()
+    val navController = rememberNavController()
+    Scaffold(
+        modifier = Modifier.fillMaxSize(),
+        bottomBar = { MinstrelBottomBar(navController) },
+    ) { inner ->
+        MinstrelNavGraph(
+            navController = navController,
+            modifier = Modifier.padding(inner),
+        )
+    }
+}
+
+private data class BottomBarTab(
+    val label: String,
+    val icon: ImageVector,
+    val routeClass: KClass<*>,
+    val navigate: NavHostController.() -> Unit,
+)
+
+@Composable
+private fun MinstrelBottomBar(navController: NavHostController) {
+    val tabs = listOf(
+        BottomBarTab("Home", Lucide.House, Home::class) { navigate(Home) },
+        BottomBarTab("Library", Lucide.LibraryBig, Library::class) { navigate(Library) },
+        BottomBarTab("Search", Lucide.Search, SearchRoute::class) { navigate(SearchRoute) },
+        BottomBarTab("Settings", Lucide.Settings, SettingsRoute::class) { navigate(SettingsRoute) },
+    )
+    val backStackEntry by navController.currentBackStackEntryAsState()
+    val currentDestination = backStackEntry?.destination
+    NavigationBar {
+        tabs.forEach { tab ->
+            val selected = currentDestination?.hasRoute(tab.routeClass) == true
+            NavigationBarItem(
+                selected = selected,
+                onClick = { tab.navigate(navController) },
+                icon = { Icon(tab.icon, contentDescription = tab.label) },
+                label = { Text(tab.label) },
+            )
         }
     }
 }

android/app/src/main/java/com/fabledsword/minstrel/nav/MinstrelNavGraph.kt

@@ -0,0 +1,88 @@
+package com.fabledsword.minstrel.nav
+
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Modifier
+import androidx.navigation.NavHostController
+import androidx.navigation.compose.NavHost
+import androidx.navigation.compose.composable
+import androidx.navigation.toRoute
+import com.fabledsword.minstrel.library.ui.LibraryScreen
+import com.fabledsword.minstrel.shared.widgets.EmptyState
+
+/**
+ * Single NavHost for the whole app. Top-level tabs (Home / Library /
+ * Search / Settings) are direct destinations; detail screens push on
+ * top with their argument types passed via the @Serializable route
+ * classes' fields.
+ *
+ * Stub composables call EmptyState — the real screens land in their
+ * respective feature phases.
+ */
+@Composable
+fun MinstrelNavGraph(
+    navController: NavHostController,
+    modifier: Modifier = Modifier,
+) {
+    NavHost(
+        navController = navController,
+        startDestination = Library,
+        modifier = modifier.fillMaxSize(),
+    ) {
+        // ── Top-level tabs ────────────────────────────────────────────────
+
+        composable<Home> { ComingSoon(title = "Home", body = "Lands in Phase 6.") }
+
+        composable<Library> {
+            LibraryScreen(
+                onArtistClick = { artist -> navController.navigate(ArtistDetail(artist.id)) },
+                onAlbumClick = { album -> navController.navigate(AlbumDetail(album.id)) },
+            )
+        }
+
+        composable<Search> { ComingSoon(title = "Search", body = "Lands in a later phase.") }
+
+        composable<Settings> { ComingSoon(title = "Settings", body = "Lands in Phase 11.") }
+
+        // ── Detail / overlay screens ──────────────────────────────────────
+
+        composable<AlbumDetail> { backStackEntry ->
+            val route: AlbumDetail = backStackEntry.toRoute()
+            ComingSoon(
+                title = "Album",
+                body = "Album detail for ${route.id} — lands in a later 5.x slice.",
+            )
+        }
+
+        composable<ArtistDetail> { backStackEntry ->
+            val route: ArtistDetail = backStackEntry.toRoute()
+            ComingSoon(
+                title = "Artist",
+                body = "Artist detail for ${route.id} — lands in a later 5.x slice.",
+            )
+        }
+
+        composable<PlaylistDetail> { backStackEntry ->
+            val route: PlaylistDetail = backStackEntry.toRoute()
+            ComingSoon(
+                title = "Playlist",
+                body = "Playlist detail for ${route.id} — lands in Phase 7.",
+            )
+        }
+
+        composable<NowPlaying> { ComingSoon(title = "Now playing", body = "Lands in Phase 6.4.") }
+        composable<Queue> { ComingSoon(title = "Queue", body = "Lands in Phase 6.") }
+        composable<Login> { ComingSoon(title = "Sign in", body = "Lands in a later phase.") }
+    }
+}
+
+@Composable
+private fun ComingSoon(title: String, body: String) {
+    // Reuse EmptyState as a generic placeholder for unbuilt screens —
+    // keeps the design system intact rather than ad-hoc Text.
+    EmptyState(
+        title = title,
+        body = body,
+        modifier = Modifier.fillMaxSize(),
+    )
+}

android/app/src/main/java/com/fabledsword/minstrel/nav/Routes.kt

@@ -0,0 +1,20 @@
+package com.fabledsword.minstrel.nav
+
+import kotlinx.serialization.Serializable
+
+// Top-level destinations (bottom-bar tabs).
+
+@Serializable data object Home
+@Serializable data object Library
+@Serializable data object Search
+@Serializable data object Settings
+
+// Push-on-top destinations (no bottom-bar entry).
+
+@Serializable data class AlbumDetail(val id: String)
+@Serializable data class ArtistDetail(val id: String)
+@Serializable data class PlaylistDetail(val id: String)
+
+@Serializable data object NowPlaying
+@Serializable data object Queue
+@Serializable data object Login