Fixed unfavorite list jump

.idea/deploymentTargetSelector.xml

@@ -4,10 +4,10 @@
     <selectionStates>
       <SelectionState runConfigName="app">
         <option name="selectionMode" value="DROPDOWN" />
-        <DropdownSelection timestamp="2026-06-23T09:15:42.913635127Z">
+        <DropdownSelection timestamp="2026-06-23T09:36:00.583173984Z">
           <Target type="DEFAULT_BOOT">
             <handle>
-              <DeviceId pluginId="PhysicalDevice" identifier="serial=RFCY20YA30P" />
+              <DeviceId pluginId="LocalEmulator" identifier="path=/home/sylar/.android/avd/Medium_Phone.avd" />
             </handle>
           </Target>
         </DropdownSelection>

app/src/main/java/com/keylightpiano/pianotimeline/ui/RecordingListScreen.kt

@@ -45,8 +45,10 @@ import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
+import androidx.compose.runtime.withFrameNanos
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.input.nestedscroll.nestedScroll
@@ -56,6 +58,8 @@ import androidx.compose.ui.unit.dp
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.lifecycle.viewmodel.compose.viewModel
 import com.keylightpiano.pianotimeline.R
+import kotlinx.coroutines.launch
+import com.keylightpiano.pianotimeline.domain.Recording
 
 @OptIn(ExperimentalMaterial3Api::class, ExperimentalLayoutApi::class)
 @Composable
@@ -93,6 +97,22 @@ fun RecordingListScreen(
         wasRefreshing = isRefreshing
     }
 
+    // Preserve scroll position across a favorite toggle (which reorders the list).
+    // When the user stars/unstars an item, we snapshot the current top item's
+    // index+offset, then restore it after the list settles so the viewport
+    // doesn't jump to follow the moved item.
+    val coroutineScope = rememberCoroutineScope()
+    val onFavoriteToggle: (Recording) -> Unit = { recording ->
+        val anchorIndex = listState.firstVisibleItemIndex
+        val anchorOffset = listState.firstVisibleItemScrollOffset
+        vm.toggleFavorite(recording)
+        coroutineScope.launch {
+            // Wait one frame for the reordered list to be applied, then restore.
+            withFrameNanos { }
+            listState.scrollToItem(anchorIndex, anchorOffset)
+        }
+    }
+
     val scrollBehavior = TopAppBarDefaults.pinnedScrollBehavior()
     val hasActiveFilter = searchQuery.isNotEmpty() || hiddenArtists.isNotEmpty()
 
@@ -269,7 +289,7 @@ fun RecordingListScreen(
                                 RecordingItem(
                                     recording = recording,
                                     onPlayClick = { vm.onPlay(recording) },
-                                    onFavoriteClick = { vm.toggleFavorite(recording) },
+                                    onFavoriteClick = { onFavoriteToggle(recording) },
                                     onNotesClick = if (recording.hasMidi) {
                                         { /* TODO: open falling notes */ }
                                     } else null