feat: past tracks layer toggle + persist vessel/crew registry

Layers menu:
- Add "Past tracks" switch to layer picker sheet — hides/shows previous
  voyage polylines on the map, persisted across sessions via SharedPrefs

Vessel/crew registry:
- VesselRepository now takes a Context and persists all vessels and crew
  to SharedPreferences as JSON (Moshi, same pattern as BoatProfileRepository)
- Wire VesselRepository as a singleton in NavApplication so the Fragment
  and ViewModel share one instance — previously each created its own empty repo

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

8 files changed, 208 insertions, 12 deletions

diff --git a/android-app/app/src/main/kotlin/org/terst/nav/MainActivity.kt b/android-app/app/src/main/kotlin/org/terst/nav/MainActivity.kt
index da96e98..5e7ce82 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/MainActivity.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/MainActivity.kt
@@ -282,6 +282,12 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
                 layerManager.setParticlesEnabled(enabled)
                 particleWindView?.visibility = if (enabled) View.VISIBLE else View.GONE
             },
+            onPastTracksChanged = { enabled ->
+                layerManager.setPastTracksEnabled(enabled)
+                val style = loadedStyleFlow.value ?: return@LayerPickerSheet
+                val past = if (enabled) viewModel.pastTracks.value else emptyList()
+                mapHandler?.updateTrackLayer(style, viewModel.trackPoints.value, past)
+            },
             unitPrefs         = unitPrefs,
             onUnitsChanged    = { refreshUnits() }
         )
@@ -656,7 +662,10 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
             loadedStyleFlow.filterNotNull()
                 .combine(viewModel.trackPoints) { style, points -> style to points }
                 .combine(viewModel.pastTracks) { (style, active), past -> Triple(style, active, past) }
-                .collect { (style, active, past) -> mapHandler?.updateTrackLayer(style, active, past) }
+                .collect { (style, active, past) ->
+                    val visiblePast = if (layerManager.pastTracksEnabled) past else emptyList()
+                    mapHandler?.updateTrackLayer(style, active, visiblePast)
+                }
         }
     }
 
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/NavApplication.kt b/android-app/app/src/main/kotlin/org/terst/nav/NavApplication.kt
index cf3103d..0bec116 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/NavApplication.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/NavApplication.kt
@@ -19,6 +19,7 @@ class NavApplication : Application() {
         val logbookRepository = org.terst.nav.logbook.InMemoryLogbookRepository()
         lateinit var trackRepository: org.terst.nav.track.TrackRepository
         lateinit var boatProfileRepository: org.terst.nav.tripreport.BoatProfileRepository
+        lateinit var vesselRepository: org.terst.nav.vessel.VesselRepository
         var isTesting: Boolean = false
             get() {
                 if (field) return true
@@ -36,6 +37,7 @@ class NavApplication : Application() {
         featureFlags = FeatureFlags(this)
         trackRepository = org.terst.nav.track.TrackRepository(this)
         boatProfileRepository = org.terst.nav.tripreport.BoatProfileRepository(this)
+        vesselRepository = org.terst.nav.vessel.VesselRepository(this)
         FirebaseCrashlytics.getInstance().sendUnsentReports()
         installCrashLogger()
     }
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/ui/LayerPickerSheet.kt b/android-app/app/src/main/kotlin/org/terst/nav/ui/LayerPickerSheet.kt
index 78fd70f..bd84961 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/ui/LayerPickerSheet.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/ui/LayerPickerSheet.kt
@@ -19,6 +19,7 @@ class LayerPickerSheet(
     private val onBaseChanged: (MapBasePreset) -> Unit,
     private val onWindChanged: (Boolean) -> Unit,
     private val onParticlesChanged: (Boolean) -> Unit,
+    private val onPastTracksChanged: (Boolean) -> Unit,
     private val unitPrefs: UnitPrefs,
     private val onUnitsChanged: () -> Unit
 ) : BottomSheetDialogFragment() {
@@ -54,6 +55,11 @@ class LayerPickerSheet(
         particlesSwitch.isChecked = manager.particlesEnabled
         particlesSwitch.setOnCheckedChangeListener { _, checked -> onParticlesChanged(checked) }
 
+        // ── Past tracks switch ────────────────────────────────────────────────
+        val pastTracksSwitch = view.findViewById<SwitchMaterial>(R.id.switch_past_tracks)
+        pastTracksSwitch.isChecked = manager.pastTracksEnabled
+        pastTracksSwitch.setOnCheckedChangeListener { _, checked -> onPastTracksChanged(checked) }
+
         // ── Temperature chips ─────────────────────────────────────────────────
         val chipTemp = view.findViewById<ChipGroup>(R.id.chip_group_temp)
         chipTemp.check(when (unitPrefs.tempUnit) {
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/ui/MainViewModel.kt b/android-app/app/src/main/kotlin/org/terst/nav/ui/MainViewModel.kt
index f05da21..88689e0 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/ui/MainViewModel.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/ui/MainViewModel.kt
@@ -19,7 +19,6 @@ import org.terst.nav.settings.FeatureFlags
 import org.terst.nav.settings.HardwareSource
 import org.terst.nav.vessel.CrewMember
 import org.terst.nav.vessel.Vessel
-import org.terst.nav.vessel.VesselRepository
 import org.terst.nav.data.model.ForecastItem
 import org.terst.nav.data.model.MarineConditions
 import org.terst.nav.data.model.WindArrow
@@ -90,7 +89,7 @@ class MainViewModel(
 
     private val trackRepository = org.terst.nav.NavApplication.trackRepository
 
-    val vesselRepository = VesselRepository()
+    val vesselRepository get() = org.terst.nav.NavApplication.vesselRepository
 
     private val _thermalState = MutableStateFlow(ThermalState.OK)
     val thermalState: StateFlow<ThermalState> = _thermalState.asStateFlow()
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/ui/MapLayerManager.kt b/android-app/app/src/main/kotlin/org/terst/nav/ui/MapLayerManager.kt
index 855233f..1c46248 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/ui/MapLayerManager.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/ui/MapLayerManager.kt
@@ -29,6 +29,9 @@ class MapLayerManager(context: Context) {
     var particlesEnabled: Boolean = prefs.getBoolean(KEY_PARTICLES, true)
         private set
 
+    var pastTracksEnabled: Boolean = prefs.getBoolean(KEY_PAST_TRACKS, true)
+        private set
+
     // ── Source / Layer IDs ────────────────────────────────────────────────────
 
     companion object {
@@ -42,9 +45,10 @@ class MapLayerManager(context: Context) {
         const val LAYER_WIND        = "wind-layer"
         const val LAYER_SEAMARKS    = "openseamap-layer"
 
-        private const val KEY_BASE      = "base_preset"
-        private const val KEY_WIND      = "wind_enabled"
-        private const val KEY_PARTICLES = "particles_enabled"
+        private const val KEY_BASE        = "base_preset"
+        private const val KEY_WIND        = "wind_enabled"
+        private const val KEY_PARTICLES   = "particles_enabled"
+        private const val KEY_PAST_TRACKS = "past_tracks_enabled"
 
         // Tile URLs
         private const val URL_SATELLITE =
@@ -116,6 +120,11 @@ class MapLayerManager(context: Context) {
         prefs.edit().putBoolean(KEY_PARTICLES, enabled).apply()
     }
 
+    fun setPastTracksEnabled(enabled: Boolean) {
+        pastTracksEnabled = enabled
+        prefs.edit().putBoolean(KEY_PAST_TRACKS, enabled).apply()
+    }
+
     /** Toggle wind overlay on a live style. */
     fun setWindEnabled(style: Style, enabled: Boolean) {
         windEnabled = enabled
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/ui/vessel/VesselRegistryFragment.kt b/android-app/app/src/main/kotlin/org/terst/nav/ui/vessel/VesselRegistryFragment.kt
index d0d8515..f359962 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/ui/vessel/VesselRegistryFragment.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/ui/vessel/VesselRegistryFragment.kt
@@ -12,15 +12,15 @@ import androidx.fragment.app.Fragment
 import com.google.android.material.button.MaterialButton
 import com.google.android.material.textfield.TextInputEditText
 import com.google.android.material.textfield.TextInputLayout
+import org.terst.nav.NavApplication
 import org.terst.nav.R
 import org.terst.nav.vessel.CrewMember
 import org.terst.nav.vessel.CrewRole
 import org.terst.nav.vessel.Vessel
-import org.terst.nav.vessel.VesselRepository
 
 class VesselRegistryFragment : Fragment() {
 
-    private val repo = VesselRepository()
+    private val repo get() = NavApplication.vesselRepository
 
     private lateinit var tvOwnVesselName: TextView
     private lateinit var tvOwnVesselDetails: TextView
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/vessel/VesselRepository.kt b/android-app/app/src/main/kotlin/org/terst/nav/vessel/VesselRepository.kt
index b65a816..7ebd2f6 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/vessel/VesselRepository.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/vessel/VesselRepository.kt
@@ -1,11 +1,33 @@
 package org.terst.nav.vessel
 
+import android.content.Context
+import com.squareup.moshi.JsonClass
+import com.squareup.moshi.Moshi
+import com.squareup.moshi.Types
+import com.squareup.moshi.kotlin.reflect.KotlinJsonAdapterFactory
 import java.util.UUID
 
-class VesselRepository {
+class VesselRepository(context: Context) {
+
+    private val prefs = context.getSharedPreferences("vessel_registry", Context.MODE_PRIVATE)
+    private val moshi = Moshi.Builder().add(KotlinJsonAdapterFactory()).build()
+
+    private val vesselListType = Types.newParameterizedType(List::class.java, VesselJson::class.java)
+    private val crewListType   = Types.newParameterizedType(List::class.java, CrewJson::class.java)
+    private val vesselAdapter  = moshi.adapter<List<VesselJson>>(vesselListType)
+    private val crewAdapter    = moshi.adapter<List<CrewJson>>(crewListType)
 
     private val vessels = mutableListOf<Vessel>()
-    private val crew = mutableListOf<CrewMember>()
+    private val crew    = mutableListOf<CrewMember>()
+
+    init {
+        prefs.getString(KEY_VESSELS, null)
+            ?.let { runCatching { vesselAdapter.fromJson(it) }.getOrNull() }
+            ?.forEach { vessels.add(it.toDomain()) }
+        prefs.getString(KEY_CREW, null)
+            ?.let { runCatching { crewAdapter.fromJson(it) }.getOrNull() }
+            ?.forEach { crew.add(it.toDomain()) }
+    }
 
     // --- Vessel CRUD ---
 
@@ -13,6 +35,7 @@ class VesselRepository {
         val v = if (vessel.id.isBlank()) vessel.copy(id = UUID.randomUUID().toString()) else vessel
         vessels.removeAll { it.id == v.id }
         vessels.add(v)
+        saveVessels()
         return v
     }
 
@@ -20,10 +43,15 @@ class VesselRepository {
         val idx = vessels.indexOfFirst { it.id == vessel.id }
         if (idx < 0) return false
         vessels[idx] = vessel
+        saveVessels()
         return true
     }
 
-    fun removeVessel(id: String): Boolean = vessels.removeAll { it.id == id }
+    fun removeVessel(id: String): Boolean {
+        val removed = vessels.removeAll { it.id == id }
+        if (removed) saveVessels()
+        return removed
+    }
 
     fun getVessel(id: String): Vessel? = vessels.find { it.id == id }
 
@@ -37,6 +65,7 @@ class VesselRepository {
         val m = if (member.id.isBlank()) member.copy(id = UUID.randomUUID().toString()) else member
         crew.removeAll { it.id == m.id }
         crew.add(m)
+        saveCrew()
         return m
     }
 
@@ -44,10 +73,15 @@ class VesselRepository {
         val idx = crew.indexOfFirst { it.id == member.id }
         if (idx < 0) return false
         crew[idx] = member
+        saveCrew()
         return true
     }
 
-    fun removeCrewMember(id: String): Boolean = crew.removeAll { it.id == id }
+    fun removeCrewMember(id: String): Boolean {
+        val removed = crew.removeAll { it.id == id }
+        if (removed) saveCrew()
+        return removed
+    }
 
     fun getCrewMember(id: String): CrewMember? = crew.find { it.id == id }
 
@@ -56,4 +90,106 @@ class VesselRepository {
     fun getCrewByRole(role: CrewRole): List<CrewMember> = crew.filter { it.role == role }
 
     fun getSkipper(): CrewMember? = crew.find { it.role == CrewRole.SKIPPER }
+
+    // --- Persistence ---
+
+    private fun saveVessels() {
+        prefs.edit().putString(KEY_VESSELS, vesselAdapter.toJson(vessels.map { VesselJson.from(it) })).apply()
+    }
+
+    private fun saveCrew() {
+        prefs.edit().putString(KEY_CREW, crewAdapter.toJson(crew.map { CrewJson.from(it) })).apply()
+    }
+
+    // --- JSON transfer objects ---
+
+    @JsonClass(generateAdapter = true)
+    data class VesselJson(
+        val id: String,
+        val name: String,
+        val mmsi: String,
+        val callsign: String,
+        val flag: String,
+        val homePort: String,
+        val hullType: String,
+        val loaMeters: Double,
+        val beamMeters: Double,
+        val draftMeters: Double,
+        val displacementKg: Double,
+        val engineHp: Int,
+        val notes: String,
+        val isOwnVessel: Boolean
+    ) {
+        fun toDomain() = Vessel(
+            id             = id,
+            name           = name,
+            mmsi           = mmsi,
+            callsign       = callsign,
+            flag           = flag,
+            homePort       = homePort,
+            hullType       = runCatching { HullType.valueOf(hullType) }.getOrDefault(HullType.MONOHULL),
+            loaMeters      = loaMeters,
+            beamMeters     = beamMeters,
+            draftMeters    = draftMeters,
+            displacementKg = displacementKg,
+            engineHp       = engineHp,
+            notes          = notes,
+            isOwnVessel    = isOwnVessel
+        )
+        companion object {
+            fun from(v: Vessel) = VesselJson(
+                id             = v.id,
+                name           = v.name,
+                mmsi           = v.mmsi,
+                callsign       = v.callsign,
+                flag           = v.flag,
+                homePort       = v.homePort,
+                hullType       = v.hullType.name,
+                loaMeters      = v.loaMeters,
+                beamMeters     = v.beamMeters,
+                draftMeters    = v.draftMeters,
+                displacementKg = v.displacementKg,
+                engineHp       = v.engineHp,
+                notes          = v.notes,
+                isOwnVessel    = v.isOwnVessel
+            )
+        }
+    }
+
+    @JsonClass(generateAdapter = true)
+    data class CrewJson(
+        val id: String,
+        val name: String,
+        val role: String,
+        val emergencyContact: String,
+        val emergencyPhone: String,
+        val certifications: List<String>,
+        val notes: String
+    ) {
+        fun toDomain() = CrewMember(
+            id               = id,
+            name             = name,
+            role             = runCatching { CrewRole.valueOf(role) }.getOrDefault(CrewRole.CREW),
+            emergencyContact = emergencyContact,
+            emergencyPhone   = emergencyPhone,
+            certifications   = certifications,
+            notes            = notes
+        )
+        companion object {
+            fun from(m: CrewMember) = CrewJson(
+                id               = m.id,
+                name             = m.name,
+                role             = m.role.name,
+                emergencyContact = m.emergencyContact,
+                emergencyPhone   = m.emergencyPhone,
+                certifications   = m.certifications,
+                notes            = m.notes
+            )
+        }
+    }
+
+    companion object {
+        private const val KEY_VESSELS = "vessels"
+        private const val KEY_CREW    = "crew"
+    }
 }
diff --git a/android-app/app/src/main/res/layout/layout_layer_picker_sheet.xml b/android-app/app/src/main/res/layout/layout_layer_picker_sheet.xml
index fdfbb7a..2e6f982 100644
--- a/android-app/app/src/main/res/layout/layout_layer_picker_sheet.xml
+++ b/android-app/app/src/main/res/layout/layout_layer_picker_sheet.xml
@@ -141,6 +141,41 @@
 
         </LinearLayout>
 
+        <!-- Past tracks toggle -->
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="horizontal"
+            android:gravity="center_vertical"
+            android:layout_marginTop="4dp"
+            android:layout_marginBottom="8dp">
+
+            <LinearLayout
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:orientation="vertical">
+                <TextView
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="Past tracks"
+                    android:textSize="15sp"
+                    android:textColor="@color/instrument_text_normal" />
+                <TextView
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="Show previous voyages on map"
+                    android:textSize="12sp"
+                    android:textColor="@color/instrument_text_secondary" />
+            </LinearLayout>
+
+            <com.google.android.material.switchmaterial.SwitchMaterial
+                android:id="@+id/switch_past_tracks"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content" />
+
+        </LinearLayout>
+
         <!-- ── UNITS ───────────────────────────────────────────────── -->
 
         <View