feat(satellites): fuzzy name search ignoring separators

The satellite search only matched exact continuous substrings, so names with
dashes, spaces or brackets (AO-7, ISS (ZARYA), FO-29) could not be found by
queries without those separators. Now the query is normalized (lowercased,
non-alphanumeric separators stripped) and split into space-separated tokens,
and every token must appear in the normalized satellite name. This makes
'ao7' match 'AO-7 (AMSAT-OSCAR 7)' and 'iss zarya' match 'ISS (ZARYA)'.
Numeric queries still match catnum exactly. Covered by 8 new unit tests.

app/src/main/java/com/rtbishop/look4sat/MainScreen.kt

@@ -81,6 +81,7 @@ import com.rtbishop.look4sat.core.presentation.Screen
 import com.rtbishop.look4sat.core.presentation.hasEnoughHeight
 import com.rtbishop.look4sat.core.presentation.hasEnoughWidth
 import com.rtbishop.look4sat.feature.map.MapDestination
+import com.rtbishop.look4sat.feature.map.MapFilterViewModel
 import com.rtbishop.look4sat.feature.mutual.MutualScreen
 import com.rtbishop.look4sat.feature.mutual.MutualViewModel
 import com.rtbishop.look4sat.feature.passes.PassesDestination
@@ -169,6 +170,12 @@ fun MainScreen(
         viewModelStoreOwner = context as ViewModelStoreOwner,
         factory = MutualViewModel.factory(container)
     )
+    // Activity-scoped so the map's award filter survives page switches;
+    // resets to VUCC only on cold start (fresh process).
+    val mapFilterViewModel: MapFilterViewModel = viewModel(
+        viewModelStoreOwner = context as ViewModelStoreOwner,
+        factory = MapFilterViewModel.factory()
+    )
 
     CompositionLocalProvider(
         LocalElevationThresholds provides ElevationThresholds(
@@ -237,7 +244,7 @@ fun MainScreen(
                             )
                         }
                         entry<Screen.Map> {
-                            MapDestination()
+                            MapDestination(mapFilterViewModel = mapFilterViewModel)
                         }
                         entry<Screen.Mutual> {
                             MutualScreen(

core/data/src/main/java/com/rtbishop/look4sat/core/data/repository/SelectionRepo.kt

@@ -111,12 +111,29 @@ class SelectionRepo(
     /**
      * Filters items by query. Uses toIntOrNull() instead of exception-based flow,
      * and lowercases the query once up front instead of per-item.
+     *
+     * Fuzzy search: the query is split into space-separated tokens and every
+     * token must appear in the satellite name after both sides are normalized
+     * (lowercased, non-alphanumeric separators such as dashes, spaces, brackets
+     * and dots stripped). This makes "ao7" match "AO-7 (AMSAT-OSCAR 7)" and
+     * "iss zarya" match "ISS (ZARYA)" — exact continuous-substring matching
+     * previously failed whenever the name contained a separator the query lacked.
      */
     private fun filterByQuery(items: List<SatItem>, query: String): List<SatItem> {
         if (query.isBlank()) return items
         val catnum = query.toIntOrNull()
         if (catnum != null) return items.filter { it.catnum == catnum }
-        val lowerQuery = query.lowercase()
-        return items.filter { it.name.lowercase().contains(lowerQuery) }
+        val tokens = query.split(' ')
+            .map { normalizeForSearch(it) }
+            .filter { it.isNotEmpty() }
+        if (tokens.isEmpty()) return items
+        return items.filter { item ->
+            val normalizedName = normalizeForSearch(item.name)
+            tokens.all { normalizedName.contains(it) }
+        }
     }
+
+    /** Lowercases and strips all non-alphanumeric chars for fuzzy matching. */
+    private fun normalizeForSearch(text: String): String =
+        text.lowercase().filter { it.isLetterOrDigit() }
 }

core/data/src/test/java/com/rtbishop/look4sat/core/data/repository/SelectionRepoSearchTest.kt

@@ -0,0 +1,197 @@
+/*
+ * Look4Sat. Amateur radio satellite tracker and pass predictor.
+ * Copyright (C) 2019-2026 Arty Bishop and contributors.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ */
+package com.rtbishop.look4sat.core.data.repository
+
+import com.rtbishop.look4sat.core.domain.model.DataSourcesSettings
+import com.rtbishop.look4sat.core.domain.model.DatabaseState
+import com.rtbishop.look4sat.core.domain.model.OtherSettings
+import com.rtbishop.look4sat.core.domain.model.PassesSettings
+import com.rtbishop.look4sat.core.domain.model.RCSettings
+import com.rtbishop.look4sat.core.domain.model.RadioControlSettings
+import com.rtbishop.look4sat.core.domain.model.SatItem
+import com.rtbishop.look4sat.core.domain.model.SatRadio
+import com.rtbishop.look4sat.core.domain.predict.GeoPos
+import com.rtbishop.look4sat.core.domain.predict.OrbitalData
+import com.rtbishop.look4sat.core.domain.predict.OrbitalObject
+import com.rtbishop.look4sat.core.domain.repository.ISelectionRepo
+import com.rtbishop.look4sat.core.domain.repository.ISettingsRepo
+import com.rtbishop.look4sat.core.domain.source.ILocalSource
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.test.runTest
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+@OptIn(ExperimentalCoroutinesApi::class)
+class SelectionRepoSearchTest {
+
+    private val sampleItems = listOf(
+        SatItem(catnum = 25544, name = "ISS (ZARYA)"),
+        SatItem(catnum = 7530, name = "AO-7 (AMSAT-OSCAR 7)"),
+        SatItem(catnum = 39444, name = "AO-73 (FUNcube-1)"),
+        SatItem(catnum = 43803, name = "JO-97 (BIRDS-3)"),
+        SatItem(catnum = 99999, name = "FO-29"),
+    )
+
+    @Test
+    fun `query without separators matches name with dashes spaces brackets`() = runTest {
+        val repo = createRepo(sampleItems)
+        repo.setQuery("ao7")
+        val results = repo.getEntriesFlow().first()
+        // "ao7" is a substring of the normalized "AO-73 (FUNcube-1)" too, so a
+        // fuzzy search legitimately returns both AO-7 (first) and AO-73. The
+        // key guarantee is that AO-7 — which was unreachable before because of
+        // the dashes/brackets — is now found.
+        assertTrue(results.map { it.catnum }.contains(7530))
+        assertEquals(7530, results.first().catnum)
+    }
+
+    @Test
+    fun `query without separators matches name with only dashes`() = runTest {
+        val repo = createRepo(sampleItems)
+        repo.setQuery("fo29")
+        val results = repo.getEntriesFlow().first()
+        assertEquals(listOf(99999), results.map { it.catnum })
+    }
+
+    @Test
+    fun `space-separated tokens all must match in any order`() = runTest {
+        val repo = createRepo(sampleItems)
+        repo.setQuery("zarya iss")
+        val results = repo.getEntriesFlow().first()
+        assertEquals(listOf(25544), results.map { it.catnum })
+    }
+
+    @Test
+    fun `exact name query still matches`() = runTest {
+        val repo = createRepo(sampleItems)
+        repo.setQuery("AO-7 (AMSAT-OSCAR 7)")
+        val results = repo.getEntriesFlow().first()
+        assertEquals(listOf(7530), results.map { it.catnum })
+    }
+
+    @Test
+    fun `partial token query matches substring`() = runTest {
+        val repo = createRepo(sampleItems)
+        repo.setQuery("funcube")
+        val results = repo.getEntriesFlow().first()
+        assertEquals(listOf(39444), results.map { it.catnum })
+    }
+
+    @Test
+    fun `numeric query matches catnum exactly`() = runTest {
+        val repo = createRepo(sampleItems)
+        repo.setQuery("25544")
+        val results = repo.getEntriesFlow().first()
+        assertEquals(listOf(25544), results.map { it.catnum })
+    }
+
+    @Test
+    fun `no query returns all items`() = runTest {
+        val repo = createRepo(sampleItems)
+        repo.setQuery("")
+        val results = repo.getEntriesFlow().first()
+        assertEquals(sampleItems.size, results.size)
+    }
+
+    @Test
+    fun `unmatched query returns nothing`() = runTest {
+        val repo = createRepo(sampleItems)
+        repo.setQuery("zzzznomatch")
+        assertTrue(repo.getEntriesFlow().first().isEmpty())
+    }
+
+    private fun createRepo(items: List<SatItem>): ISelectionRepo {
+        return SelectionRepo(
+            dispatcher = Dispatchers.Unconfined,
+            localSource = FakeLocalSourceForSearch(items),
+            settingsRepo = FakeSettingsRepoForSearch()
+        )
+    }
+}
+
+private class FakeLocalSourceForSearch(private val items: List<SatItem>) : ILocalSource {
+    override suspend fun getEntriesTotal(): Int = items.size
+    override suspend fun getEntriesList(): List<SatItem> = items
+    override suspend fun getEntriesWithIds(ids: List<Int>): List<OrbitalObject> = emptyList()
+    override suspend fun insertEntries(entries: List<OrbitalData>) = Unit
+    override suspend fun deleteEntries() = Unit
+    override suspend fun getIdsWithModes(modes: List<String>): List<Int> = emptyList()
+    override suspend fun getRadiosTotal(): Int = 0
+    override suspend fun getRadiosWithId(id: Int): List<SatRadio> = emptyList()
+    override suspend fun insertRadios(radios: List<SatRadio>, isCustom: Boolean) = Unit
+    override suspend fun deleteManagedRadios() = Unit
+    override suspend fun deleteRadios() = Unit
+}
+
+private class FakeSettingsRepoForSearch : ISettingsRepo {
+    override val appVersionName: String = "test"
+    override val selectedIds: StateFlow<List<Int>> = MutableStateFlow(emptyList())
+    override val selectedTypes: StateFlow<List<String>> = MutableStateFlow(emptyList())
+    override val passesSettings: StateFlow<PassesSettings> = MutableStateFlow(
+        PassesSettings(hoursAhead = 24, minElevation = 0.0, selectedModes = emptyList())
+    )
+    override val stationPosition: StateFlow<GeoPos> = MutableStateFlow(GeoPos(0.0, 0.0))
+    override val databaseState: MutableStateFlow<DatabaseState> = MutableStateFlow(DatabaseState(0, 0, 0L))
+    override val rcSettings: StateFlow<RCSettings> = MutableStateFlow(
+        RCSettings(false, "", "", "", false, "", "", "", 0L, false, "", "", "", false, "", "")
+    )
+    override val otherSettings: StateFlow<OtherSettings> = MutableStateFlow(
+        OtherSettings(
+            false, false, false, false, false, false, false,
+            shouldSeeWarning = false, shouldSeeWhatsNew = false
+        )
+    )
+    override val dataSourcesSettings: MutableStateFlow<DataSourcesSettings> =
+        MutableStateFlow(DataSourcesSettings(satelliteUrls = emptyList(), transceiversUrls = emptyList()))
+    override val dataSourcesStatus: StateFlow<Map<String, Int>> = MutableStateFlow(emptyMap())
+    override val radioControlSettings: StateFlow<RadioControlSettings> = MutableStateFlow(
+        RadioControlSettings(false, RadioControlSettings.MODEL_YAESU_FT817, "", "", "", "", 9600)
+    )
+    override val wavelogSettings: StateFlow<com.rtbishop.look4sat.core.domain.model.WavelogSettings> =
+        MutableStateFlow(com.rtbishop.look4sat.core.domain.model.WavelogSettings())
+    override val lotwSettings: StateFlow<com.rtbishop.look4sat.core.domain.model.LoTWSettings> =
+        MutableStateFlow(com.rtbishop.look4sat.core.domain.model.LoTWSettings())
+
+    override fun setSelectedIds(ids: List<Int>) = Unit
+    override fun setSelectedTypes(types: List<String>) = Unit
+    override fun setPassesSettings(settings: PassesSettings) = Unit
+    override fun setStationPosition(latitude: Double, longitude: Double, altitude: Double): Boolean = true
+    override fun setStationPosition(): Boolean = true
+    override fun setStationPosition(locator: String): Boolean = true
+    override fun getSatelliteTypesIds(types: List<String>): List<Int> = emptyList()
+    override fun setSatelliteTypeIds(type: String, ids: List<Int>) = Unit
+    override fun updateDatabaseState(state: DatabaseState) = Unit
+    override fun updateRCSettings(settings: RCSettings) = Unit
+    override fun updateOtherSettings(transform: (OtherSettings) -> OtherSettings) = Unit
+    override fun updateDataSourcesSettings(settings: DataSourcesSettings) = Unit
+    override fun updateDataSourcesStatus(status: Map<String, Int>) = Unit
+    override fun updateRadioControlSettings(settings: RadioControlSettings) = Unit
+    override fun getSatelliteOffset(catnum: Int): String = ""
+    override fun setSatelliteOffset(catnum: Int, offset: String) = Unit
+    override fun getAmSatCallsign(): String = ""
+    override fun setAmSatCallsign(callsign: String) = Unit
+    override fun updateWavelogSettings(settings: com.rtbishop.look4sat.core.domain.model.WavelogSettings) = Unit
+    override fun getWorkedGrids(): Set<String> = emptySet()
+    override fun setWorkedGrids(grids: Set<String>) = Unit
+    override fun getWorkedGridQsos(): Map<String, List<com.rtbishop.look4sat.core.domain.model.GridQso>> = emptyMap()
+    override fun setWorkedGridQsos(qsos: Map<String, List<com.rtbishop.look4sat.core.domain.model.GridQso>>) = Unit
+    override fun getRoamedGrids(): Set<String> = emptySet()
+    override fun setRoamedGrids(grids: Set<String>) = Unit
+    override fun updateLoTWSettings(settings: com.rtbishop.look4sat.core.domain.model.LoTWSettings) = Unit
+    override fun getLastLotwSyncDate(): String = ""
+    override fun setLastLotwSyncDate(date: String) = Unit
+    override fun getLastLotwSyncCallsign(): String = ""
+    override fun setLastLotwSyncCallsign(callsign: String) = Unit
+}

feature/map/src/main/java/com/rtbishop/look4sat/feature/map/MapFilterViewModel.kt

@@ -0,0 +1,39 @@
+package com.rtbishop.look4sat.feature.map
+
+import androidx.compose.runtime.MutableState
+import androidx.compose.runtime.mutableStateOf
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewmodel.initializer
+import androidx.lifecycle.viewmodel.viewModelFactory
+import com.rtbishop.look4sat.core.domain.model.AwardType
+
+/**
+ * Session-scoped holder for the map's award filter selection.
+ *
+ * Scoped to the Activity (not the navigation entry) so the selection survives
+ * switching to another page and back; it resets to VUCC only when the process
+ * starts fresh (cold start), which is what the user expects as the default.
+ */
+class MapFilterViewModel : ViewModel() {
+
+    /** Last chosen award chip; null means "All". Initialized to VUCC once per process. */
+    val selectedAward: MutableState<AwardType?> = mutableStateOf(AwardType.VUCC)
+
+    /** Last map viewport (center + zoom), saved when leaving the page. Null until first visit. */
+    var mapCenterLat: Double? = null
+    var mapCenterLon: Double? = null
+    var mapZoom: Double? = null
+
+    /** Persists the current viewport so a later re-entry restores exactly where the user left off. */
+    fun saveMapViewState(centerLat: Double, centerLon: Double, zoom: Double) {
+        mapCenterLat = centerLat
+        mapCenterLon = centerLon
+        mapZoom = zoom
+    }
+
+    companion object {
+        fun factory() = viewModelFactory {
+            initializer { MapFilterViewModel() }
+        }
+    }
+}

feature/map/src/main/java/com/rtbishop/look4sat/feature/map/MapScreen.kt

@@ -144,13 +144,30 @@ private val moonIconPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
 }
 
 @Composable
-fun MapDestination() {
+fun MapDestination(
+    mapFilterViewModel: MapFilterViewModel
+) {
     val context = LocalContext.current
     val container = (context.applicationContext as IContainerProvider).getMainContainer()
     val viewModel: MapViewModel = viewModel(factory = MapViewModel.factory(container))
     val uiState by viewModel.uiState.collectAsStateWithLifecycle()
-    val mapView = rememberMapViewWithLifecycle()
+    val mapView = rememberMapViewWithLifecycle(mapFilterViewModel, restoreViewport = uiState.isGridMode)
     val lifecycle = LocalLifecycleOwner.current.lifecycle
+    // Save the viewport when leaving the page, but only in grid mode: the
+    // satellite mode intentionally keeps its original behavior (default center,
+    // follow the selected satellite), so a satellite-mode exit must not
+    // overwrite the last grid-mode viewport.
+    DisposableEffect(mapView, uiState.isGridMode) {
+        onDispose {
+            if (uiState.isGridMode) {
+                mapFilterViewModel.saveMapViewState(
+                    mapView.mapCenter.latitude,
+                    mapView.mapCenter.longitude,
+                    mapView.zoomLevelDouble
+                )
+            }
+        }
+    }
     DisposableEffect(lifecycle) {
         val observer = LifecycleEventObserver { _, event ->
             when (event) {
@@ -165,11 +182,16 @@ fun MapDestination() {
             viewModel.onAction(MapAction.SetVisible(false))
         }
     }
-    MapScreen(uiState, viewModel::onAction, mapView)
+    MapScreen(uiState, viewModel::onAction, mapView, mapFilterViewModel)
 }
 
 @Composable
-private fun MapScreen(uiState: MapState, onAction: (MapAction) -> Unit, mapView: MapView) {
+private fun MapScreen(
+    uiState: MapState,
+    onAction: (MapAction) -> Unit,
+    mapView: MapView,
+    mapFilterViewModel: MapFilterViewModel
+) {
     val rotateMod = Modifier.rotate(180f)
     val timeString = uiState.mapData?.aosTime ?: "00:00:00"
     val isTimeAos = uiState.mapData?.isTimeAos ?: true
@@ -177,9 +199,9 @@ private fun MapScreen(uiState: MapState, onAction: (MapAction) -> Unit, mapView:
     // Tapped worked grid -> centered QSO dialog. Local UI state: the map is the
     // only consumer and it resets when leaving the page.
     var selectedGrid by remember { mutableStateOf<String?>(null) }
-    // Selected award filter. Entering grid mode defaults to VUCC (the plain
-    // worked-grid view); the reset effect below re-asserts that on every entry.
-    var selectedAward by remember { mutableStateOf<AwardType?>(AwardType.VUCC) }
+    // Selected award filter. Lives in an Activity-scoped ViewModel so it
+    // survives page switches; defaults to VUCC only once per process (cold start).
+    var selectedAward by mapFilterViewModel.selectedAward
     // Six-award progress derived from the confirmed QSO store; recomputed when
     // the store changes (LoTW/Wavelog sync).
     // Per operated-grid VUCC breakdown: myGrid -> set of worked grids worked from it.
@@ -215,6 +237,14 @@ private fun MapScreen(uiState: MapState, onAction: (MapAction) -> Unit, mapView:
         else vuccByMyGrid[selectedMyGrid] ?: emptySet()
     }
     val isGridMode = uiState.isGridMode
+    // True when this composition restored a saved viewport. Only grid mode
+    // restores the viewport the user left (satellite mode keeps its original
+    // follow-the-satellite behavior); this implies grid mode was already on
+    // when re-entering, which is why the grid-mode auto-centering below can
+    // treat the entry as already centered.
+    val restoredViewport = remember {
+        isGridMode && mapFilterViewModel.mapCenterLat != null && mapFilterViewModel.mapZoom != null
+    }
     DisposableEffect(isGridMode, workedGrids) {
         val receiver = object : org.osmdroid.events.MapEventsReceiver {
             override fun singleTapConfirmedHelper(p: GeoPoint?): Boolean {
@@ -240,12 +270,6 @@ private fun MapScreen(uiState: MapState, onAction: (MapAction) -> Unit, mapView:
         (mapView.overlays.getOrNull(OVERLAY_GRID) as? MaidenheadGridOverlay)?.selectedGrid = selectedGrid
         mapView.invalidate()
     }
-    // Re-assert the VUCC default each time grid mode is entered; while already
-    // in grid mode the user's chip choice is preserved.
-    LaunchedEffect(uiState.isGridMode) {
-        if (uiState.isGridMode) selectedAward = AwardType.VUCC
-    }
-
     LaunchedEffect(uiState.track) {
         // In grid mode the map is centered on the local grid square; following
         // the satellite subpoint here would override that centering on every
@@ -281,9 +305,14 @@ private fun MapScreen(uiState: MapState, onAction: (MapAction) -> Unit, mapView:
         }
         ElevatedCard(modifier = Modifier.weight(1f)) {
             Box(contentAlignment = Alignment.BottomCenter) {
-                // Track grid-mode transitions; initial value false so that entering
-                // the map page with grid mode already ON also centers the map.
-                var prevGridMode by remember { mutableStateOf(false) }
+                // Track grid-mode transitions. When the map was just restored to
+                // the viewport the user left (re-entry after a page switch) and
+                // grid mode is already on, treat the entry as already centered so
+                // the restored position survives. Cold-start entries and in-page
+                // toggles still center on the station grid as before.
+                var prevGridMode by remember {
+                    mutableStateOf(restoredViewport && uiState.isGridMode)
+                }
                 AndroidView({ mapView }) { view ->
                     // Award filter mode: show the selected award's regions with
                     // worked ones filled green; hide satellite layers like grid mode.
@@ -297,6 +326,10 @@ private fun MapScreen(uiState: MapState, onAction: (MapAction) -> Unit, mapView:
                         prevGridMode = uiState.isGridMode
                     } else {
                         // Center on the station grid whenever entering grid mode.
+                        // (prevGridMode is initialized to "already centered" when
+                        // the map was just restored to the viewport the user left,
+                        // so a re-entry keeps the restored position; in-page
+                        // toggles still center normally.)
                         // Only mark the transition as consumed once a real position
                         // was available; otherwise a first frame with a null
                         // stationPosition would swallow the centering forever.
@@ -1173,7 +1206,10 @@ private fun setMoonPosition(moonLatDeg: Double, moonLonDeg: Double, mapView: Map
 
 // region MapView lifecycle
 @Composable
-private fun rememberMapViewWithLifecycle(): MapView {
+private fun rememberMapViewWithLifecycle(
+    mapFilterViewModel: MapFilterViewModel,
+    restoreViewport: Boolean
+): MapView {
     val tileSource = XYTileSource("tiles", 0, 6, 256, ".webp", emptyArray<String>())
     val context = LocalContext.current
     val isVertical = isVerticalLayout()
@@ -1189,8 +1225,19 @@ private fun rememberMapViewWithLifecycle(): MapView {
             setTileSource(tileSource)
             minZoomLevel = getMinZoom(resources.displayMetrics.heightPixels, isVertical)
             maxZoomLevel = 7.0
-            controller.setCenter(GeoPoint(48.8575, 6.3514))
-            controller.setZoom(minZoomLevel + 2)
+            // Restore the viewport the user left on the previous visit, but only
+            // in grid mode: satellite mode intentionally keeps its original
+            // behavior (default center, then follows the selected satellite).
+            val savedLat = mapFilterViewModel.mapCenterLat
+            val savedLon = mapFilterViewModel.mapCenterLon
+            val savedZoom = mapFilterViewModel.mapZoom
+            if (restoreViewport && savedLat != null && savedLon != null && savedZoom != null) {
+                controller.setCenter(GeoPoint(savedLat, savedLon))
+                controller.setZoom(savedZoom)
+            } else {
+                controller.setCenter(GeoPoint(48.8575, 6.3514))
+                controller.setZoom(minZoomLevel + 2)
+            }
             zoomController.setVisibility(CustomZoomButtonsController.Visibility.NEVER)
             overlayManager.tilesOverlay.loadingBackgroundColor = Color.TRANSPARENT
             overlayManager.tilesOverlay.loadingLineColor = Color.TRANSPARENT
@@ -1208,6 +1255,7 @@ private fun rememberMapViewWithLifecycle(): MapView {
     }
     // The overlay caches below are file-level (shared across MapView instances), so they must be
     // released with the MapView or they keep the Activity and its bitmaps alive after disposal.
+    // (The viewport save lives in MapDestination, where the grid/satellite mode is known.)
     DisposableEffect(mapView) {
         onDispose { clearMapCaches() }
     }

feature/mutual/src/main/java/com/rtbishop/look4sat/feature/mutual/MutualScreen.kt

@@ -32,6 +32,7 @@ import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.lazy.LazyListState
 import androidx.compose.foundation.lazy.itemsIndexed
 import androidx.compose.foundation.text.KeyboardOptions
 import androidx.compose.material3.Button
@@ -49,11 +50,13 @@ import androidx.compose.material3.Slider
 import androidx.compose.material3.Surface
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableFloatStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
+import androidx.compose.runtime.snapshotFlow
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.res.painterResource
@@ -74,6 +77,7 @@ import java.text.SimpleDateFormat
 import java.util.Date
 import java.util.Locale
 import java.util.TimeZone
+import kotlinx.coroutines.flow.distinctUntilChanged
 
 @Composable
 fun MutualScreen(
@@ -150,6 +154,7 @@ fun MutualScreen(
         }
     ) { isVertical ->
         MutualContent(
+            viewModel = viewModel,
             state = state,
             isVertical = isVertical,
             onQuery = viewModel::queryMutualPasses,
@@ -172,6 +177,7 @@ fun MutualScreen(
 
 @Composable
 private fun MutualContent(
+    viewModel: MutualViewModel,
     state: MutualUiState,
     isVertical: Boolean,
     onQuery: () -> Unit,
@@ -195,8 +201,28 @@ private fun MutualContent(
         }
     }
 
+    // List state survives page switches via the Activity-scoped ViewModel: the
+    // initial position is restored from the VM, and scrolling writes back to it,
+    // so returning to this page keeps exactly where the user left off. A new
+    // query (queryGeneration bump) rebuilds the state at the top.
+    val listState = remember(viewModel.queryGeneration) {
+        LazyListState(
+            firstVisibleItemIndex = viewModel.listScrollIndex,
+            firstVisibleItemScrollOffset = viewModel.listScrollOffset
+        )
+    }
+    LaunchedEffect(listState) {
+        snapshotFlow { listState.firstVisibleItemIndex to listState.firstVisibleItemScrollOffset }
+            .distinctUntilChanged()
+            .collect { (index, offset) ->
+                viewModel.listScrollIndex = index
+                viewModel.listScrollOffset = offset
+            }
+    }
+
     LazyColumn(
         modifier = Modifier.fillMaxSize(),
+        state = listState,
         verticalArrangement = Arrangement.spacedBy(6.dp)
     ) {
         // Error message

feature/mutual/src/main/java/com/rtbishop/look4sat/feature/mutual/MutualViewModel.kt

@@ -69,6 +69,15 @@ class MutualViewModel(
     private val _uiState = MutableStateFlow(MutualUiState())
     val uiState: StateFlow<MutualUiState> = _uiState.asStateFlow()
 
+    // Session-scoped scroll position of the pass list (Activity-scoped VM, so it
+    // survives switching to another page and back). Reset to the top whenever a
+    // new query replaces the results.
+    var listScrollIndex: Int = 0
+    var listScrollOffset: Int = 0
+
+    /** Bumped on every new query so the list scrolls back to the top. */
+    var queryGeneration: Int = 0
+
     init {
         // Pre-fill station A with the user's current station position (as grid),
         // and default min elevation to the same value used by the main radar passes
@@ -201,6 +210,11 @@ class MutualViewModel(
                 selectedPassIndex = -1
             )
         }
+        // The results list is about to be replaced, so the scroll position must
+        // not leak from the previous query's list.
+        listScrollIndex = 0
+        listScrollOffset = 0
+        queryGeneration += 1
 
         viewModelScope.launch {
             val time = System.currentTimeMillis()

gradle/libs.versions.toml

@@ -1,8 +1,8 @@
 [versions]
 #noinspection UnusedVersionCatalogEntry
-appVersionCode = "478"
+appVersionCode = "480"
 #noinspection UnusedVersionCatalogEntry
-appVersionName = "4.4.7-ba7opf.8"
+appVersionName = "4.4.7-ba7opf.10"
 #noinspection UnusedVersionCatalogEntry
 compileSdk = "37"
 #noinspection UnusedVersionCatalogEntry