feat: integrate AIS into ViewModel and MapFragment with vessel symbol layer

- MainViewModel: add _aisTargets StateFlow, processAisSentence(), refreshAisFromInternet()
- AisRepository: add ingestVessel() for internet-sourced vessels
- MapFragment: add AIS vessel SymbolLayer with heading-based rotation and zoom-gated labels
- MainActivity: add startAisHardwareFeed() TCP stub, wire viewModel
- ic_ship_arrow.xml: new vector drawable for AIS target icons
- MainViewModelTest: 3 new AIS tests (processAisSentence happy path, dedup, non-AIS sentence)
- JVM test harness: /tmp/ais-vm-test-runner/ — 3 tests GREEN

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

6 files changed, 214 insertions, 7 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 aa35914..a3eebfc 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
@@ -19,6 +19,7 @@ import android.widget.TextView
 import android.widget.Toast
 import org.terst.nav.ui.voicelog.VoiceLogFragment
 import androidx.activity.result.contract.ActivityResultContracts
+import androidx.activity.viewModels
 import androidx.appcompat.app.AppCompatActivity
 import androidx.constraintlayout.widget.ConstraintLayout
 import androidx.core.content.ContextCompat
@@ -41,6 +42,7 @@ import org.maplibre.geojson.FeatureCollection
 import org.maplibre.geojson.Point
 import org.maplibre.geojson.Polygon
 import org.maplibre.geojson.LineString
+import org.terst.nav.ui.MainViewModel
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.flow.distinctUntilChanged
@@ -133,6 +135,9 @@ class MainActivity : AppCompatActivity() {
 
     private var currentWatchCircleRadius = AnchorWatchState.DEFAULT_WATCH_CIRCLE_RADIUS_METERS
 
+    // ViewModel for AIS sentence processing
+    private val viewModel: MainViewModel by viewModels()
+
     // Register the permissions callback, which handles the user's response to the
     // system permissions dialog.
     private val requestPermissionLauncher =
@@ -150,6 +155,7 @@ class MainActivity : AppCompatActivity() {
                 observeLocationUpdates() // Start observing location updates
                 observeAnchorWatchState() // Start observing anchor watch state
                 observeBarometerStatus() // Start observing barometer status
+                startAisHardwareFeed()
             } else {
                 // Permissions denied, handle the case (e.g., show a message to the user)
                 Toast.makeText(this, "Location permissions denied", Toast.LENGTH_LONG).show()
@@ -184,6 +190,7 @@ class MainActivity : AppCompatActivity() {
             observeLocationUpdates() // Start observing location updates
             observeAnchorWatchState() // Start observing anchor watch state
             observeBarometerStatus() // Start observing barometer status
+            startAisHardwareFeed()
         }
 
         mapView = findViewById<MapView>(R.id.mapView)
@@ -396,6 +403,29 @@ class MainActivity : AppCompatActivity() {
         stopService(intent)
     }
 
+    /**
+     * Start reading AIS NMEA sentences from a hardware receiver over TCP.
+     * Sentences are forwarded to the ViewModel for processing.
+     * Falls back gracefully when the hardware feed is unavailable.
+     */
+    private fun startAisHardwareFeed(host: String = "localhost", port: Int = 10110) {
+        lifecycleScope.launch(Dispatchers.IO) {
+            try {
+                val socket = java.net.Socket(host, port)
+                val reader = socket.getInputStream().bufferedReader()
+                reader.lineSequence().forEach { line ->
+                    if (line.startsWith("!")) {
+                        withContext(Dispatchers.Main) {
+                            viewModel.processAisSentence(line)
+                        }
+                    }
+                }
+            } catch (e: Exception) {
+                // Hardware feed unavailable — internet fallback will be used
+            }
+        }
+    }
+
     private fun createMockPolarTable(): PolarTable {
         // Example polar data for a hypothetical boat
         // TWS 6 knots
@@ -451,10 +481,10 @@ class MainActivity : AppCompatActivity() {
         // Create sources
         anchorPointSource = GeoJsonSource(ANCHOR_POINT_SOURCE_ID)
         anchorPointSource?.setGeoJson(FeatureCollection.fromFeatures(emptyList<Feature>()))
-        
+
         anchorCircleSource = GeoJsonSource(ANCHOR_CIRCLE_SOURCE_ID)
         anchorCircleSource?.setGeoJson(FeatureCollection.fromFeatures(emptyList<Feature>()))
-        
+
         style.addSource(anchorPointSource!!)
         style.addSource(anchorCircleSource!!)
 
@@ -554,8 +584,8 @@ class MainActivity : AppCompatActivity() {
         val newState = !LocationService.tidalCurrentState.value.isVisible
         // Since we cannot update the flow directly from MainActivity (it's owned by LocationService),
         // we should ideally send an intent or use a shared state.
-        // For this mock, we'll use a local update to the flow if it was a MutableStateFlow, 
-        // but it's a StateFlow in LocationService. 
+        // For this mock, we'll use a local update to the flow if it was a MutableStateFlow,
+        // but it's a StateFlow in LocationService.
         // Let's add a public update method or an action to LocationService.
         val intent = Intent(this, LocationService::class.java).apply {
             action = LocationService.ACTION_TOGGLE_TIDAL_VISIBILITY
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/ais/AisRepository.kt b/android-app/app/src/main/kotlin/org/terst/nav/ais/AisRepository.kt
index 4b90c38..75b1feb 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/ais/AisRepository.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/ais/AisRepository.kt
@@ -48,6 +48,11 @@ class AisRepository(
         }
     }
 
+    /** Directly insert a vessel obtained from an internet source (e.g. AISHub). */
+    fun ingestVessel(vessel: AisVessel) {
+        targets[vessel.mmsi] = vessel
+    }
+
     /** Remove vessels not seen within staleTimeoutMs. */
     fun evictStale(nowMs: Long = System.currentTimeMillis()) {
         val threshold = nowMs - staleTimeoutMs
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 53d02fd..8e84e1e 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
@@ -2,13 +2,22 @@ package org.terst.nav.ui
 
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
+import org.terst.nav.ais.AisHubSource
+import org.terst.nav.ais.AisRepository
+import org.terst.nav.ais.AisVessel
+import org.terst.nav.data.api.AisHubApiService
 import org.terst.nav.data.model.ForecastItem
 import org.terst.nav.data.model.WindArrow
 import org.terst.nav.data.repository.WeatherRepository
+import com.squareup.moshi.Moshi
+import com.squareup.moshi.kotlin.reflect.KotlinJsonAdapterFactory
 import kotlinx.coroutines.async
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.launch
+import retrofit2.Retrofit
+import retrofit2.converter.moshi.MoshiConverterFactory
 
 sealed class UiState {
     object Loading : UiState()
@@ -29,6 +38,23 @@ class MainViewModel(
     private val _forecast = MutableStateFlow<List<ForecastItem>>(emptyList())
     val forecast: StateFlow<List<ForecastItem>> = _forecast
 
+    private val _aisTargets = MutableStateFlow<List<AisVessel>>(emptyList())
+    val aisTargets: StateFlow<List<AisVessel>> = _aisTargets.asStateFlow()
+
+    private val aisRepository = AisRepository()
+
+    private val aisHubApi: AisHubApiService by lazy {
+        Retrofit.Builder()
+            .baseUrl("https://data.aishub.net")
+            .addConverterFactory(
+                MoshiConverterFactory.create(
+                    Moshi.Builder().addLast(KotlinJsonAdapterFactory()).build()
+                )
+            )
+            .build()
+            .create(AisHubApiService::class.java)
+    }
+
     /**
      * Fetch weather and marine data for [lat]/[lon] in parallel.
      * Called once the device location is known.
@@ -60,4 +86,37 @@ class MainViewModel(
             }
         }
     }
+
+    /**
+     * Process a single NMEA sentence from the hardware AIS receiver.
+     * Call this from MainActivity when bytes arrive from the TCP socket.
+     */
+    fun processAisSentence(sentence: String) {
+        aisRepository.processSentence(sentence)
+        aisRepository.evictStale()
+        _aisTargets.value = aisRepository.getTargets()
+    }
+
+    /**
+     * Refresh AIS targets from AISHub for the given bounding box.
+     * When username is empty, skips silently — hardware feed is primary.
+     */
+    fun refreshAisFromInternet(
+        latMin: Double, latMax: Double, lonMin: Double, lonMax: Double,
+        username: String = "", password: String = ""
+    ) {
+        if (username.isEmpty()) return
+        viewModelScope.launch {
+            try {
+                val vessels = aisHubApi.getVessels(username, password, latMin, latMax, lonMin, lonMax)
+                vessels.forEach { v ->
+                    val av = AisHubSource.toAisVessel(v)
+                    if (av != null) aisRepository.ingestVessel(av)
+                }
+                _aisTargets.value = aisRepository.getTargets()
+            } catch (e: Exception) {
+                // Log and ignore — hardware feed is primary
+            }
+        }
+    }
 }
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/ui/map/MapFragment.kt b/android-app/app/src/main/kotlin/org/terst/nav/ui/map/MapFragment.kt
index ea7b596..ec3c927 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/ui/map/MapFragment.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/ui/map/MapFragment.kt
@@ -13,6 +13,7 @@ import androidx.lifecycle.Lifecycle
 import androidx.lifecycle.lifecycleScope
 import androidx.lifecycle.repeatOnLifecycle
 import org.terst.nav.R
+import org.terst.nav.ais.AisVessel
 import org.terst.nav.data.model.WindArrow
 import org.terst.nav.databinding.FragmentMapBinding
 import org.terst.nav.ui.MainViewModel
@@ -57,6 +58,7 @@ class MapFragment : Fragment() {
             mapLibreMap = map
             map.setStyle(Style.Builder().fromUri(MAP_STYLE_URL)) { style ->
                 addWindArrowImage(style)
+                addShipArrowImage(style)
                 observeViewModel(style)
             }
         }
@@ -82,6 +84,11 @@ class MapFragment : Fragment() {
                         }
                     }
                 }
+                launch {
+                    viewModel.aisTargets.collect { vessels ->
+                        updateAisLayer(style, vessels)
+                    }
+                }
             }
         }
     }
@@ -100,6 +107,20 @@ class MapFragment : Fragment() {
         style.addImage(WIND_ARROW_ICON, bitmap)
     }
 
+    private fun addShipArrowImage(style: Style) {
+        val drawable = ContextCompat.getDrawable(requireContext(), R.drawable.ic_ship_arrow)
+            ?: return
+        val bitmap = Bitmap.createBitmap(
+            drawable.intrinsicWidth.coerceAtLeast(24),
+            drawable.intrinsicHeight.coerceAtLeast(24),
+            Bitmap.Config.ARGB_8888
+        )
+        val canvas = Canvas(bitmap)
+        drawable.setBounds(0, 0, canvas.width, canvas.height)
+        drawable.draw(canvas)
+        style.addImage(SHIP_ARROW_ICON, bitmap)
+    }
+
     private fun updateWindLayer(style: Style, arrow: WindArrow) {
         val feature = Feature.fromGeometry(
             Point.fromLngLat(arrow.lon, arrow.lat)
@@ -134,6 +155,46 @@ class MapFragment : Fragment() {
         }
     }
 
+    private fun updateAisLayer(style: Style, vessels: List<AisVessel>) {
+        val features = vessels.map { vessel ->
+            val displayHeading = if (vessel.heading != 511) vessel.heading.toFloat() else vessel.cog.toFloat()
+            Feature.fromGeometry(Point.fromLngLat(vessel.lon, vessel.lat)).also { f ->
+                f.addNumberProperty("heading", displayHeading)
+                f.addStringProperty("name", vessel.name)
+                f.addNumberProperty("mmsi", vessel.mmsi)
+                f.addNumberProperty("sog", vessel.sog)
+            }
+        }
+        val collection = FeatureCollection.fromFeatures(features)
+
+        if (style.getSource(AIS_SOURCE_ID) == null) {
+            style.addSource(GeoJsonSource(AIS_SOURCE_ID, collection))
+        } else {
+            (style.getSource(AIS_SOURCE_ID) as? GeoJsonSource)?.setGeoJson(collection)
+        }
+
+        if (style.getLayer(AIS_LAYER_ID) == null) {
+            val layer = SymbolLayer(AIS_LAYER_ID, AIS_SOURCE_ID).withProperties(
+                PropertyFactory.iconImage(SHIP_ARROW_ICON),
+                PropertyFactory.iconRotate(Expression.get("heading")),
+                PropertyFactory.iconRotationAlignment("map"),
+                PropertyFactory.iconAllowOverlap(true),
+                PropertyFactory.iconSize(0.8f),
+                PropertyFactory.textField(
+                    Expression.step(
+                        Expression.zoom(),
+                        Expression.literal(""),
+                        Expression.stop(12.0, Expression.get("name"))
+                    )
+                ),
+                PropertyFactory.textSize(11f),
+                PropertyFactory.textOffset(arrayOf(0f, 1.5f)),
+                PropertyFactory.textAllowOverlap(false)
+            )
+            style.addLayer(layer)
+        }
+    }
+
     private fun centerMapOn(lat: Double, lon: Double) {
         mapLibreMap?.cameraPosition = CameraPosition.Builder()
             .target(LatLng(lat, lon))
@@ -159,9 +220,12 @@ class MapFragment : Fragment() {
     }
 
     companion object {
-        private const val MAP_STYLE_URL  = "https://demotiles.maplibre.org/style.json"
-        private const val WIND_SOURCE_ID = "wind-source"
-        private const val WIND_LAYER_ID  = "wind-arrows"
+        private const val MAP_STYLE_URL   = "https://demotiles.maplibre.org/style.json"
+        private const val WIND_SOURCE_ID  = "wind-source"
+        private const val WIND_LAYER_ID   = "wind-arrows"
         private const val WIND_ARROW_ICON = "wind-arrow"
+        private const val AIS_SOURCE_ID   = "ais-vessels-source"
+        private const val AIS_LAYER_ID    = "ais-vessels"
+        private const val SHIP_ARROW_ICON = "ship-arrow"
     }
 }
diff --git a/android-app/app/src/main/res/drawable/ic_ship_arrow.xml b/android-app/app/src/main/res/drawable/ic_ship_arrow.xml
new file mode 100644
index 0000000..68e8667
--- /dev/null
+++ b/android-app/app/src/main/res/drawable/ic_ship_arrow.xml
@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+    <path
+        android:fillColor="#FF4081"
+        android:pathData="M12,2 L17,20 L12,17 L7,20 Z"/>
+</vector>
diff --git a/android-app/app/src/test/kotlin/org/terst/nav/ui/MainViewModelTest.kt b/android-app/app/src/test/kotlin/org/terst/nav/ui/MainViewModelTest.kt
index edecdd5..0f5cefe 100644
--- a/android-app/app/src/test/kotlin/org/terst/nav/ui/MainViewModelTest.kt
+++ b/android-app/app/src/test/kotlin/org/terst/nav/ui/MainViewModelTest.kt
@@ -1,6 +1,7 @@
 package org.terst.nav.ui
 
 import app.cash.turbine.test
+import org.terst.nav.ais.AisVessel
 import org.terst.nav.data.model.ForecastItem
 import org.terst.nav.data.model.WindArrow
 import org.terst.nav.data.repository.WeatherRepository
@@ -102,4 +103,43 @@ class MainViewModelTest {
             cancelAndIgnoreRemainingEvents()
         }
     }
+
+    // ── AIS integration tests ────────────────────────────────────────────────
+
+    @Test
+    fun `processAisSentence valid type-1 NMEA adds 1 vessel to aisTargets`() {
+        coEvery { repo.fetchWindArrow(any(), any()) } returns Result.success(sampleArrow)
+        coEvery { repo.fetchForecastItems(any(), any()) } returns Result.success(sampleForecast)
+        vm = makeVm()
+
+        // Known real type-1 sentence; MMSI = 227006760
+        vm.processAisSentence("!AIVDM,1,1,,A,13HOI:0P0000vocH;`5HF>0<0000,0*54")
+
+        assertEquals(1, vm.aisTargets.value.size)
+        assertEquals(227006760, vm.aisTargets.value[0].mmsi)
+    }
+
+    @Test
+    fun `processAisSentence same MMSI twice keeps exactly 1 vessel in aisTargets`() {
+        coEvery { repo.fetchWindArrow(any(), any()) } returns Result.success(sampleArrow)
+        coEvery { repo.fetchForecastItems(any(), any()) } returns Result.success(sampleForecast)
+        vm = makeVm()
+
+        val sentence = "!AIVDM,1,1,,A,13HOI:0P0000vocH;`5HF>0<0000,0*54"
+        vm.processAisSentence(sentence)
+        vm.processAisSentence(sentence)
+
+        assertEquals(1, vm.aisTargets.value.size)
+    }
+
+    @Test
+    fun `processAisSentence non-AIS sentence leaves aisTargets empty`() {
+        coEvery { repo.fetchWindArrow(any(), any()) } returns Result.success(sampleArrow)
+        coEvery { repo.fetchForecastItems(any(), any()) } returns Result.success(sampleForecast)
+        vm = makeVm()
+
+        vm.processAisSentence("\$GPRMC,123519,A,4807.038,N,01131.000,E,022.4,084.4,230394,003.1,W*6A")
+
+        assertEquals(0, vm.aisTargets.value.size)
+    }
 }