feat(android): Head-to-Head "Musik-Match" screen (parity with web)

Android CompareScreen mirroring the web feature: partner picker fed by
GET /scrobble/users, then GET /scrobble/compare?with= → a match-score ring
(Canvas arc), per-user totals, mirrored shared-artist bars, shared tracks,
and each side's unique top artists. Rows navigate to artist/album. Reuses the
one PlayLogClient HttpClient (fetchUsers/fetchCompare). Opened from Settings
"🎧 Musik-Match". Parity matrix updated (Android ✅).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CHANGELOG.md

@@ -57,7 +57,7 @@ Versioning: two-part `MAJOR.MINOR` — each release bumps the minor (features an
 | Timestamped play-log (own scrobble)  | ✅        | ✅      |
 | Listening statistics view            | ✅        | ✅      |
 | Stats cover art (artist/album)       | ✅        | ✅      |
-| Musik-Match (Head-to-Head)           | ✅        | 🔜      |
+| Musik-Match (Head-to-Head)           | ✅        | ✅      |
 | Yearly Wrapped                       | 🔜        | 🔜      |
 | Romaji / Japanese sort           | ✅        | ❌      |
 | Settings (Navidrome, ABS, etc.)  | ✅        | ✅      |

android/app/src/main/kotlin/com/novasonic/app/api/model/ScrobbleModels.kt

@@ -63,3 +63,66 @@ data class StatHour(
     val hour: Int = 0,
     val plays: Int = 0,
 )
+
+// ─── Head-to-Head "Musik-Match" ─────────────────────────────────────────────
+// GET /scrobble/users — distinct users in the log, for the partner picker.
+@Serializable
+data class ScrobbleUsersResponse(
+    val me: String = "",
+    val users: List<ScrobbleUser> = emptyList(),
+)
+
+@Serializable
+data class ScrobbleUser(
+    val user: String = "",
+    val plays: Int = 0,
+    val lastPlayedAt: Long? = null,
+)
+
+// GET /scrobble/compare?with= — taste comparison of the authed user (A) vs another (B).
+@Serializable
+data class CompareResult(
+    val userA: String = "",
+    val userB: String = "",
+    val matchScore: Int = 0,
+    val totalsA: CompareTotals = CompareTotals(),
+    val totalsB: CompareTotals = CompareTotals(),
+    val sharedArtists: List<SharedArtist> = emptyList(),
+    val sharedTracks: List<SharedTrack> = emptyList(),
+    val onlyA: List<UniqueArtist> = emptyList(),
+    val onlyB: List<UniqueArtist> = emptyList(),
+)
+
+@Serializable
+data class CompareTotals(
+    val plays: Int = 0,
+    val seconds: Long = 0,
+    val artists: Int = 0,
+)
+
+@Serializable
+data class SharedArtist(
+    val name: String? = null,
+    val artistId: String? = null,
+    val playsA: Int = 0,
+    val playsB: Int = 0,
+)
+
+@Serializable
+data class SharedTrack(
+    val songId: String? = null,
+    val title: String? = null,
+    val artist: String? = null,
+    val artistId: String? = null,
+    val albumId: String? = null,
+    val coverArt: String? = null,
+    val playsA: Int = 0,
+    val playsB: Int = 0,
+)
+
+@Serializable
+data class UniqueArtist(
+    val name: String? = null,
+    val artistId: String? = null,
+    val plays: Int = 0,
+)

android/app/src/main/kotlin/com/novasonic/app/data/MusicRepository.kt

@@ -62,6 +62,8 @@ class MusicRepository(private val context: Context) {
     suspend fun flushPlayLog()                          = playLog.flush()
     suspend fun fetchScrobbleStats(from: Long, to: Long, tz: Int, bucket: String, limit: Int) =
         playLog.fetchStats(from, to, tz, bucket, limit)
+    suspend fun fetchScrobbleUsers()                    = playLog.fetchUsers()
+    suspend fun fetchScrobbleCompare(with: String)      = playLog.fetchCompare(with)
     suspend fun getArtistInfo(id: String)               = api().getArtistInfo(id)
     suspend fun getTopSongs(artistName: String)         = api().getTopSongs(artistName)
     suspend fun getGenres()                             = api().getGenres()

android/app/src/main/kotlin/com/novasonic/app/data/PlayLogClient.kt

@@ -135,6 +135,33 @@ class PlayLogClient(context: Context) {
         }.getOrNull()
     }
 
+    /** Head-to-Head: list the users in the log (for the partner picker). Null on failure. */
+    suspend fun fetchUsers(): com.novasonic.app.api.model.ScrobbleUsersResponse? {
+        val s = prefs.appSettings.first()
+        val base = s.scrobbleUrl.trimEnd('/')
+        if (base.isBlank() || s.username.isBlank() || s.password.isBlank()) return null
+        val auth = authParams(s.username, s.password)
+        return runCatching {
+            val resp = http.get("$base/scrobble/users?$auth")
+            if (!resp.status.isSuccess()) return null
+            json.decodeFromString<com.novasonic.app.api.model.ScrobbleUsersResponse>(resp.bodyAsText())
+        }.getOrNull()
+    }
+
+    /** Head-to-Head: compare the authed user against [with]. Null on failure. */
+    suspend fun fetchCompare(with: String): com.novasonic.app.api.model.CompareResult? {
+        val s = prefs.appSettings.first()
+        val base = s.scrobbleUrl.trimEnd('/')
+        if (base.isBlank() || s.username.isBlank() || s.password.isBlank()) return null
+        val auth = authParams(s.username, s.password)
+        val url = "$base/scrobble/compare?$auth&with=${with.encodeURLParameter()}"
+        return runCatching {
+            val resp = http.get(url)
+            if (!resp.status.isSuccess()) return null
+            json.decodeFromString<com.novasonic.app.api.model.CompareResult>(resp.bodyAsText())
+        }.getOrNull()
+    }
+
     private fun readQueue(): List<PlayEntry> =
         runCatching {
             if (!queueFile.exists()) emptyList()

android/app/src/main/kotlin/com/novasonic/app/ui/AppNavigation.kt

@@ -388,7 +388,10 @@ fun AppNavigation() {
                     }
                 }
                 composable(TopLevel.SETTINGS.route) {
-                    SettingsScreen(onOpenStats = { navController.navigate("stats") })
+                    SettingsScreen(
+                        onOpenStats = { navController.navigate("stats") },
+                        onOpenCompare = { navController.navigate("compare") },
+                    )
                 }
                 composable("stats") {
                     StatsScreen(
@@ -398,6 +401,14 @@ fun AppNavigation() {
                         onAlbumClick  = { id -> navController.navigate("album/$id") },
                     )
                 }
+                composable("compare") {
+                    CompareScreen(
+                        coverUrl      = { id -> coverUrl(id) },
+                        onBack        = { navController.popBackStack() },
+                        onArtistClick = { id -> navController.navigate("artist/$id") },
+                        onAlbumClick  = { id -> navController.navigate("album/$id") },
+                    )
+                }
 
                 composable(
                     "album/{albumId}",

android/app/src/main/kotlin/com/novasonic/app/ui/screen/CompareScreen.kt

@@ -0,0 +1,345 @@
+package com.novasonic.app.ui.screen
+
+import androidx.compose.foundation.Canvas
+import androidx.compose.foundation.background
+import androidx.compose.foundation.clickable
+import androidx.compose.foundation.layout.*
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.shape.CircleShape
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.foundation.verticalScroll
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.ArrowBack
+import androidx.compose.material3.CircularProgressIndicator
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.Text
+import androidx.compose.runtime.*
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.geometry.Size
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.layout.ContentScale
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextAlign
+import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.unit.sp
+import androidx.compose.ui.graphics.drawscope.Stroke
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import androidx.lifecycle.viewmodel.compose.viewModel
+import coil.compose.AsyncImage
+import com.novasonic.app.api.model.CompareResult
+import com.novasonic.app.api.model.SharedArtist
+import com.novasonic.app.api.model.SharedTrack
+import com.novasonic.app.api.model.UniqueArtist
+import com.novasonic.app.ui.theme.*
+import com.novasonic.app.viewmodel.CompareViewModel
+
+@Composable
+fun CompareScreen(
+    coverUrl: (String?) -> String?,
+    onBack: () -> Unit,
+    onArtistClick: (String) -> Unit = {},
+    onAlbumClick: (String) -> Unit = {},
+    vm: CompareViewModel = viewModel(),
+) {
+    val state by vm.state.collectAsStateWithLifecycle()
+
+    Column(Modifier.fillMaxSize().background(NsBackground)) {
+        // ── Top bar ──
+        Row(
+            verticalAlignment = Alignment.CenterVertically,
+            modifier = Modifier.fillMaxWidth().padding(start = 4.dp, top = 8.dp, end = 12.dp),
+        ) {
+            IconButton(onClick = onBack) {
+                Icon(Icons.Default.ArrowBack, contentDescription = "Zurück", tint = NsOnSurface)
+            }
+            Text(
+                "Musik-Match",
+                fontFamily = Outfit, fontWeight = FontWeight.Bold, fontSize = 22.sp,
+                color = NsOnSurface, modifier = Modifier.weight(1f),
+            )
+            // Show "wechseln" once a partner is picked so you can go back to the list.
+            if (state.partner != null) {
+                Text(
+                    "↺ Wechseln",
+                    fontFamily = Outfit, fontSize = 13.sp, fontWeight = FontWeight.SemiBold,
+                    color = NsOnSurface2,
+                    modifier = Modifier
+                        .clip(RoundedCornerShape(8.dp))
+                        .clickable { vm.clearPartner() }
+                        .padding(horizontal = 8.dp, vertical = 6.dp),
+                )
+            }
+        }
+
+        when {
+            state.loading -> CenterBox { CircularProgressIndicator(color = NsAccent) }
+            !state.configured -> CenterMsg(
+                "Kein Scrobble-Dienst konfiguriert.\nTrage die Scrobble-URL in den Einstellungen ein.",
+            )
+            state.error != null -> CenterMsg(state.error!!, NsError)
+            state.partner == null -> PartnerPicker(state.me, state.users, vm::choosePartner)
+            state.result != null -> CompareContent(state.result!!, coverUrl, onArtistClick, onAlbumClick)
+            else -> CenterBox { CircularProgressIndicator(color = NsAccent) }
+        }
+    }
+}
+
+@Composable
+private fun PartnerPicker(
+    me: String,
+    users: List<com.novasonic.app.api.model.ScrobbleUser>,
+    onPick: (String) -> Unit,
+) {
+    if (users.isEmpty()) {
+        CenterMsg("Noch niemand sonst hat Wiedergaben aufgezeichnet.\nSobald eine andere Person NovaSonic nutzt, könnt ihr euch hier vergleichen.")
+        return
+    }
+    Column(
+        Modifier.fillMaxSize().verticalScroll(rememberScrollState())
+            .padding(horizontal = 16.dp).padding(bottom = 24.dp),
+    ) {
+        Text(
+            "Mit wem willst du dich vergleichen?",
+            fontFamily = Outfit, fontSize = 13.sp, color = NsOnSurface2,
+            modifier = Modifier.padding(vertical = 6.dp),
+        )
+        users.forEach { u ->
+            Row(
+                verticalAlignment = Alignment.CenterVertically,
+                modifier = Modifier.fillMaxWidth()
+                    .padding(vertical = 5.dp)
+                    .clip(RoundedCornerShape(12.dp))
+                    .background(NsSurface2)
+                    .clickable { onPick(u.user) }
+                    .padding(12.dp),
+            ) {
+                Box(
+                    Modifier.size(40.dp).clip(CircleShape).background(NsAccent),
+                    contentAlignment = Alignment.Center,
+                ) {
+                    Text(
+                        (u.user.firstOrNull()?.uppercase() ?: "?"),
+                        fontFamily = Outfit, fontWeight = FontWeight.Bold, fontSize = 18.sp, color = Color.Black,
+                    )
+                }
+                Column(Modifier.weight(1f).padding(horizontal = 12.dp)) {
+                    Text(u.user, fontFamily = Outfit, fontWeight = FontWeight.Bold, fontSize = 15.sp,
+                        color = NsOnSurface, maxLines = 1, overflow = TextOverflow.Ellipsis)
+                    Text("${u.plays} Plays", fontFamily = Outfit, fontSize = 12.sp, color = NsOnSurface2)
+                }
+                Text("›", fontFamily = Outfit, fontSize = 20.sp, color = NsOnSurface2)
+            }
+        }
+    }
+}
+
+@Composable
+private fun CompareContent(
+    d: CompareResult,
+    coverUrl: (String?) -> String?,
+    onArtistClick: (String) -> Unit,
+    onAlbumClick: (String) -> Unit,
+) {
+    Column(
+        Modifier.fillMaxSize().verticalScroll(rememberScrollState())
+            .padding(horizontal = 16.dp).padding(bottom = 24.dp),
+    ) {
+        ScoreRing(d)
+        Spacer(Modifier.height(20.dp))
+        Totals(d)
+        Spacer(Modifier.height(22.dp))
+
+        SectionHeader("Gemeinsame Künstler")
+        if (d.sharedArtists.isEmpty()) {
+            EmptyLine("Keine gemeinsamen Künstler in diesem Zeitraum.")
+        } else {
+            val max = (d.sharedArtists.maxOfOrNull { maxOf(it.playsA, it.playsB) } ?: 1).coerceAtLeast(1)
+            d.sharedArtists.take(15).forEach { a ->
+                SharedArtistRow(a, max, a.artistId?.let { id -> { onArtistClick(id) } })
+            }
+        }
+        Spacer(Modifier.height(22.dp))
+
+        if (d.sharedTracks.isNotEmpty()) {
+            SectionHeader("Gemeinsame Songs")
+            d.sharedTracks.take(12).forEach { t ->
+                SharedTrackRow(t, coverUrl(t.coverArt ?: t.albumId ?: t.songId),
+                    t.albumId?.let { id -> { onAlbumClick(id) } })
+            }
+            Spacer(Modifier.height(22.dp))
+        }
+
+        SectionHeader("Nur bei…")
+        Row(horizontalArrangement = Arrangement.spacedBy(18.dp)) {
+            UniqueColumn("Nur ${d.userA}", d.onlyA, onArtistClick, Modifier.weight(1f))
+            UniqueColumn("Nur ${d.userB}", d.onlyB, onArtistClick, Modifier.weight(1f))
+        }
+    }
+}
+
+@Composable
+private fun ScoreRing(d: CompareResult) {
+    val score = d.matchScore.coerceIn(0, 100)
+    val verdict = when {
+        score >= 80 -> "Seelenverwandte 🎯"
+        score >= 60 -> "Starkes Match 🔥"
+        score >= 40 -> "Solide Überschneidung 👍"
+        score >= 20 -> "Ein paar Gemeinsamkeiten 🙂"
+        else -> "Ziemlich unterschiedlich 🌗"
+    }
+    Column(Modifier.fillMaxWidth(), horizontalAlignment = Alignment.CenterHorizontally) {
+        Box(Modifier.size(132.dp), contentAlignment = Alignment.Center) {
+            val accent = NsAccent
+            val track = NsSurface2
+            Canvas(Modifier.fillMaxSize()) {
+                val stroke = 14.dp.toPx()
+                val inset = stroke / 2
+                val arcSize = Size(size.width - stroke, size.height - stroke)
+                drawArc(
+                    color = track, startAngle = 0f, sweepAngle = 360f, useCenter = false,
+                    topLeft = androidx.compose.ui.geometry.Offset(inset, inset), size = arcSize,
+                    style = Stroke(width = stroke),
+                )
+                drawArc(
+                    color = accent, startAngle = -90f, sweepAngle = score * 3.6f, useCenter = false,
+                    topLeft = androidx.compose.ui.geometry.Offset(inset, inset), size = arcSize,
+                    style = Stroke(width = stroke),
+                )
+            }
+            Column(horizontalAlignment = Alignment.CenterHorizontally) {
+                Text("$score%", fontFamily = Outfit, fontWeight = FontWeight.Bold, fontSize = 30.sp, color = NsOnSurface)
+                Text("Match", fontFamily = Outfit, fontSize = 11.sp, color = NsOnSurface2)
+            }
+        }
+        Spacer(Modifier.height(10.dp))
+        Text(verdict, fontFamily = Outfit, fontWeight = FontWeight.Bold, fontSize = 15.sp, color = NsOnSurface)
+        Spacer(Modifier.height(4.dp))
+        Text("${d.userA}  ⟷  ${d.userB}", fontFamily = Outfit, fontSize = 13.sp, color = NsOnSurface2)
+    }
+}
+
+@Composable
+private fun Totals(d: CompareResult) {
+    Row(horizontalArrangement = Arrangement.spacedBy(10.dp)) {
+        TotalCard(d.userA, d.totalsA.plays, d.totalsA.artists, Modifier.weight(1f))
+        TotalCard(d.userB, d.totalsB.plays, d.totalsB.artists, Modifier.weight(1f))
+    }
+}
+
+@Composable
+private fun TotalCard(name: String, plays: Int, artists: Int, modifier: Modifier) {
+    Column(modifier.clip(RoundedCornerShape(12.dp)).background(NsSurface2).padding(14.dp)) {
+        Text(name, fontFamily = Outfit, fontWeight = FontWeight.Bold, fontSize = 15.sp,
+            color = NsOnSurface, maxLines = 1, overflow = TextOverflow.Ellipsis)
+        Spacer(Modifier.height(6.dp))
+        Text("$plays Plays · $artists Künstler", fontFamily = Outfit, fontSize = 12.sp, color = NsOnSurface2)
+    }
+}
+
+@Composable
+private fun SharedArtistRow(a: SharedArtist, max: Int, onClick: (() -> Unit)?) {
+    Row(
+        verticalAlignment = Alignment.CenterVertically,
+        modifier = Modifier.fillMaxWidth()
+            .then(if (onClick != null) Modifier.clickable(onClick = onClick) else Modifier)
+            .padding(vertical = 7.dp),
+    ) {
+        Text("${a.playsA}", fontFamily = Outfit, fontWeight = FontWeight.Bold, fontSize = 12.sp,
+            color = NsOnSurface2, textAlign = TextAlign.End, modifier = Modifier.width(30.dp))
+        // left (A) bar grows toward the centre
+        Box(Modifier.weight(1f), contentAlignment = Alignment.CenterEnd) {
+            Box(Modifier.fillMaxWidth(a.playsA.toFloat() / max).height(6.dp)
+                .clip(RoundedCornerShape(3.dp)).background(NsAccent))
+        }
+        Text(
+            a.name ?: "—", fontFamily = Outfit, fontWeight = FontWeight.SemiBold, fontSize = 13.sp,
+            color = NsOnSurface, maxLines = 1, overflow = TextOverflow.Ellipsis, textAlign = TextAlign.Center,
+            modifier = Modifier.weight(1.6f).padding(horizontal = 6.dp),
+        )
+        // right (B) bar grows from the centre
+        Box(Modifier.weight(1f), contentAlignment = Alignment.CenterStart) {
+            Box(Modifier.fillMaxWidth(a.playsB.toFloat() / max).height(6.dp)
+                .clip(RoundedCornerShape(3.dp)).background(NsAccent.copy(alpha = 0.55f)))
+        }
+        Text("${a.playsB}", fontFamily = Outfit, fontWeight = FontWeight.Bold, fontSize = 12.sp,
+            color = NsOnSurface2, textAlign = TextAlign.Start, modifier = Modifier.width(30.dp))
+    }
+}
+
+@Composable
+private fun SharedTrackRow(t: SharedTrack, cover: String?, onClick: (() -> Unit)?) {
+    Row(
+        verticalAlignment = Alignment.CenterVertically,
+        modifier = Modifier.fillMaxWidth()
+            .then(if (onClick != null) Modifier.clickable(onClick = onClick) else Modifier)
+            .padding(vertical = 5.dp),
+    ) {
+        Box(Modifier.size(44.dp).clip(RoundedCornerShape(6.dp)).background(NsSurface2)) {
+            AsyncImage(model = cover, contentDescription = null, contentScale = ContentScale.Crop,
+                modifier = Modifier.fillMaxSize())
+        }
+        Column(Modifier.weight(1f).padding(horizontal = 12.dp)) {
+            Text(t.title ?: "—", fontFamily = Outfit, fontWeight = FontWeight.SemiBold, fontSize = 14.sp,
+                color = NsOnSurface, maxLines = 1, overflow = TextOverflow.Ellipsis)
+            if (!t.artist.isNullOrBlank()) {
+                Text(t.artist, fontFamily = Outfit, fontSize = 12.sp, color = NsOnSurface2,
+                    maxLines = 1, overflow = TextOverflow.Ellipsis)
+            }
+        }
+        Text("${t.playsA} · ${t.playsB}", fontFamily = Outfit, fontWeight = FontWeight.SemiBold,
+            fontSize = 13.sp, color = NsOnSurface2)
+    }
+}
+
+@Composable
+private fun UniqueColumn(title: String, items: List<UniqueArtist>, onArtistClick: (String) -> Unit, modifier: Modifier) {
+    Column(modifier) {
+        Text(title, fontFamily = Outfit, fontWeight = FontWeight.Bold, fontSize = 12.sp,
+            color = NsOnSurface2, maxLines = 1, overflow = TextOverflow.Ellipsis,
+            modifier = Modifier.padding(bottom = 6.dp))
+        if (items.isEmpty()) {
+            Text("—", fontFamily = Outfit, fontSize = 13.sp, color = NsOnSurface2, modifier = Modifier.padding(vertical = 4.dp))
+        } else {
+            items.take(6).forEach { a ->
+                Row(
+                    verticalAlignment = Alignment.CenterVertically,
+                    modifier = Modifier.fillMaxWidth()
+                        .then(if (a.artistId != null) Modifier.clickable { onArtistClick(a.artistId) } else Modifier)
+                        .padding(vertical = 4.dp),
+                ) {
+                    Text(a.name ?: "—", fontFamily = Outfit, fontSize = 13.sp, color = NsOnSurface,
+                        maxLines = 1, overflow = TextOverflow.Ellipsis, modifier = Modifier.weight(1f))
+                    Text("${a.plays}", fontFamily = Outfit, fontWeight = FontWeight.SemiBold, fontSize = 12.sp,
+                        color = NsOnSurface2, modifier = Modifier.padding(start = 6.dp))
+                }
+            }
+        }
+    }
+}
+
+@Composable
+private fun SectionHeader(t: String) {
+    Text(t.uppercase(), fontFamily = Outfit, fontWeight = FontWeight.Bold, fontSize = 12.sp,
+        letterSpacing = 0.6.sp, color = NsOnSurface2, modifier = Modifier.padding(bottom = 8.dp))
+}
+
+@Composable
+private fun EmptyLine(msg: String) {
+    Text(msg, fontFamily = Outfit, fontSize = 13.sp, color = NsOnSurface2, modifier = Modifier.padding(vertical = 8.dp))
+}
+
+@Composable
+private fun CenterBox(content: @Composable BoxScope.() -> Unit) {
+    Box(Modifier.fillMaxSize(), contentAlignment = Alignment.Center, content = content)
+}
+
+@Composable
+private fun CenterMsg(msg: String, color: Color = NsOnSurface2) {
+    Box(Modifier.fillMaxSize().padding(32.dp), contentAlignment = Alignment.Center) {
+        Text(msg, fontFamily = Outfit, fontSize = 14.sp, color = color, textAlign = TextAlign.Center)
+    }
+}

android/app/src/main/kotlin/com/novasonic/app/ui/screen/SettingsScreen.kt

@@ -41,7 +41,7 @@ private val SCROBBLE_OPTIONS = listOf(
 
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
-fun SettingsScreen(onOpenStats: () -> Unit = {}) {
+fun SettingsScreen(onOpenStats: () -> Unit = {}, onOpenCompare: () -> Unit = {}) {
     val vm: SettingsViewModel = viewModel()
     val state by vm.state.collectAsStateWithLifecycle()
 
@@ -88,6 +88,14 @@ fun SettingsScreen(onOpenStats: () -> Unit = {}) {
             Text("📊 Meine Statistiken", color = NsOnSurface, fontFamily = Outfit, fontWeight = FontWeight.SemiBold)
         }
 
+        Spacer(Modifier.height(8.dp))
+        OutlinedButton(
+            onClick = onOpenCompare,
+            modifier = Modifier.fillMaxWidth().height(48.dp),
+        ) {
+            Text("🎧 Musik-Match", color = NsOnSurface, fontFamily = Outfit, fontWeight = FontWeight.SemiBold)
+        }
+
         // ── Save button (TOP) ────────────────────────────────────────────────
         SaveButton(vm, state.isSaving, state.savedOk, state.error)
 

android/app/src/main/kotlin/com/novasonic/app/viewmodel/CompareViewModel.kt

@@ -0,0 +1,68 @@
+package com.novasonic.app.viewmodel
+
+import android.app.Application
+import androidx.lifecycle.AndroidViewModel
+import androidx.lifecycle.viewModelScope
+import com.novasonic.app.api.model.CompareResult
+import com.novasonic.app.api.model.ScrobbleUser
+import com.novasonic.app.app
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.launch
+
+data class CompareUiState(
+    val loading: Boolean = true,
+    val configured: Boolean = true,
+    val error: String? = null,
+    val me: String = "",
+    val users: List<ScrobbleUser> = emptyList(),   // candidates (excludes me)
+    val partner: String? = null,                   // chosen userB; null → show picker
+    val result: CompareResult? = null,
+)
+
+/** Head-to-Head "Musik-Match": pick a partner from the play-log, then compare. */
+class CompareViewModel(app: Application) : AndroidViewModel(app) {
+
+    private val repo = app.app.repository
+    private val _state = MutableStateFlow(CompareUiState())
+    val state: StateFlow<CompareUiState> = _state
+
+    init { loadUsers() }
+
+    fun loadUsers() {
+        viewModelScope.launch {
+            _state.value = CompareUiState(loading = true)
+            val settings = repo.appSettingsFlow().first()
+            if (settings.scrobbleUrl.isBlank()) {
+                _state.value = _state.value.copy(loading = false, configured = false)
+                return@launch
+            }
+            val resp = repo.fetchScrobbleUsers()
+            _state.value = if (resp == null)
+                _state.value.copy(loading = false, error = "Scrobble-Dienst nicht erreichbar")
+            else
+                _state.value.copy(
+                    loading = false, configured = true, error = null,
+                    me = resp.me,
+                    users = resp.users.filter { it.user != resp.me },
+                )
+        }
+    }
+
+    /** Back to the partner picker. */
+    fun clearPartner() {
+        _state.value = _state.value.copy(partner = null, result = null, error = null)
+    }
+
+    fun choosePartner(name: String) {
+        _state.value = _state.value.copy(partner = name, loading = true, error = null, result = null)
+        viewModelScope.launch {
+            val res = repo.fetchScrobbleCompare(name)
+            _state.value = if (res == null)
+                _state.value.copy(loading = false, error = "Scrobble-Dienst nicht erreichbar")
+            else
+                _state.value.copy(loading = false, result = res, error = null)
+        }
+    }
+}