feat(android): QuarantineRepository.flag + HideTrackSheet

Adds the hide-track capability. Repository wraps QuarantineApi.flag
with the QUARANTINE_FLAG mutation-queue fallback mirroring the
existing unflag pattern. Sheet collects reason (FilterChip row) +
optional notes (OutlinedTextField); reason vocabulary matches the
server wire values (bad_rip / wrong_file / wrong_tags / duplicate /
other) exactly.

Not yet reachable from a user surface — TrackActionsSheet wires it
in the next commit.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

android/app/src/main/java/com/fabledsword/minstrel/quarantine/data/QuarantineRepository.kt

@@ -1,5 +1,6 @@
 package com.fabledsword.minstrel.quarantine.data
 
+import com.fabledsword.minstrel.api.endpoints.FlagRequest
 import com.fabledsword.minstrel.api.endpoints.QuarantineApi
 import com.fabledsword.minstrel.cache.mutations.MutationQueue
 import com.fabledsword.minstrel.models.QuarantineRef
@@ -16,13 +17,17 @@ import javax.inject.Singleton
  */
 enum class UnflagOutcome { ACCEPTED, QUEUED }
 
+/**
+ * Outcome of a `flag` call. Same semantics as [UnflagOutcome] —
+ * ACCEPTED = server confirmed; QUEUED = the call landed in the
+ * MutationQueue for later replay.
+ */
+enum class FlagOutcome { ACCEPTED, QUEUED }
+
 /**
  * Read-through accessor for the caller's quarantine list + offline-
- * first unflag write. No Room caching for v1 (same shape as Requests/
- * History — offline-snapshot mirror lands with Phase 13). Flag is
- * deferred to the AlbumDetail/ArtistDetail/PlaylistDetail per-track
- * actions phase since there's no surface to flag from in the current
- * screens.
+ * first flag / unflag writes. No Room caching for v1 (same shape as
+ * Requests/History — offline-snapshot mirror lands with Phase 13).
  */
 @Singleton
 class QuarantineRepository @Inject constructor(
@@ -33,6 +38,24 @@ class QuarantineRepository @Inject constructor(
 
     suspend fun listMine(): List<QuarantineRef> = api.listMine().map { it.toDomain() }
 
+    /**
+     * Flag a track for quarantine with [reason] (one of bad_rip,
+     * wrong_file, wrong_tags, duplicate, other) and an optional
+     * [notes] string visible to admins. On transport failure the
+     * call is enqueued via MutationQueue for later replay; server-
+     * side re-flagging the same (user, track) pair is idempotent.
+     */
+    suspend fun flag(trackId: String, reason: String, notes: String): FlagOutcome = try {
+        api.flag(FlagRequest(trackId = trackId, reason = reason, notes = notes))
+        FlagOutcome.ACCEPTED
+    } catch (
+        @Suppress("TooGenericExceptionCaught", "SwallowedException") e: Throwable,
+    ) {
+        // Intentional swallow: queue the flag for later replay.
+        mutationQueue.enqueueQuarantineFlag(trackId, reason, notes)
+        FlagOutcome.QUEUED
+    }
+
     suspend fun unflag(trackId: String): UnflagOutcome = try {
         api.unflag(trackId)
         UnflagOutcome.ACCEPTED

android/app/src/main/java/com/fabledsword/minstrel/shared/widgets/track_actions/HideTrackSheet.kt

@@ -0,0 +1,109 @@
+package com.fabledsword.minstrel.shared.widgets.track_actions
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.ExperimentalLayoutApi
+import androidx.compose.foundation.layout.FlowRow
+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.material3.Button
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.FilterChip
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.ModalBottomSheet
+import androidx.compose.material3.OutlinedTextField
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.material3.rememberModalBottomSheetState
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.unit.dp
+
+private data class HideReason(val wire: String, val label: String)
+
+private val HIDE_REASONS = listOf(
+    HideReason("bad_rip", "Bad rip"),
+    HideReason("wrong_file", "Wrong file"),
+    HideReason("wrong_tags", "Wrong tags"),
+    HideReason("duplicate", "Duplicate"),
+    HideReason("other", "Other"),
+)
+
+/**
+ * ModalBottomSheet that collects a hide reason + optional notes and
+ * pops back via [onSubmit]. Mirrors Flutter's `HideTrackSheet`. The
+ * reason vocabulary matches the server wire values exactly.
+ */
+@OptIn(ExperimentalMaterial3Api::class, ExperimentalLayoutApi::class)
+@Composable
+fun HideTrackSheet(
+    onSubmit: (reason: String, notes: String) -> Unit,
+    onDismiss: () -> Unit,
+) {
+    val sheetState = rememberModalBottomSheetState(skipPartiallyExpanded = true)
+    var reason by remember { mutableStateOf(HIDE_REASONS.first().wire) }
+    var notes by remember { mutableStateOf("") }
+    ModalBottomSheet(
+        onDismissRequest = onDismiss,
+        sheetState = sheetState,
+    ) {
+        Column(
+            modifier = Modifier
+                .fillMaxWidth()
+                .padding(horizontal = 20.dp, vertical = 8.dp),
+        ) {
+            Text(
+                text = "Hide this track",
+                style = MaterialTheme.typography.titleLarge,
+                color = MaterialTheme.colorScheme.onSurface,
+            )
+            Spacer(Modifier.height(8.dp))
+            Text(
+                text = "Pick a reason. Optional notes are visible to admins.",
+                style = MaterialTheme.typography.bodyMedium,
+                color = MaterialTheme.colorScheme.onSurfaceVariant,
+            )
+            Spacer(Modifier.height(12.dp))
+            FlowRow(
+                horizontalArrangement = Arrangement.spacedBy(8.dp),
+                verticalArrangement = Arrangement.spacedBy(8.dp),
+                modifier = Modifier.fillMaxWidth(),
+            ) {
+                HIDE_REASONS.forEach { r ->
+                    FilterChip(
+                        selected = reason == r.wire,
+                        onClick = { reason = r.wire },
+                        label = { Text(r.label) },
+                    )
+                }
+            }
+            Spacer(Modifier.height(12.dp))
+            OutlinedTextField(
+                value = notes,
+                onValueChange = { notes = it },
+                label = { Text("Notes (optional)") },
+                modifier = Modifier.fillMaxWidth(),
+                maxLines = 2,
+            )
+            Spacer(Modifier.height(16.dp))
+            Row(
+                modifier = Modifier.fillMaxWidth(),
+                horizontalArrangement = Arrangement.End,
+            ) {
+                TextButton(onClick = onDismiss) { Text("Cancel") }
+                Spacer(Modifier.padding(horizontal = 4.dp))
+                Button(onClick = { onSubmit(reason, notes.trim()) }) {
+                    Text("Hide")
+                }
+            }
+            Spacer(Modifier.height(8.dp))
+        }
+    }
+}