Fix wind particles never appearing

Two bugs prevented wind particles from rendering:

1. Retrofit URL-encoded commas in the batch lat/lon query strings
   (%2C instead of ,), so Open-Meteo rejected every grid fetch silently.
   Fixed with encoded=true on the @Query annotations.

2. loadWindGrid() was only called from onCameraIdleListener, so particles
   never started unless the user manually panned. Added an eager trigger
   on the first GPS fix using the map's current visible region.

Also added a log warning when fetchWindGrid fails so future failures are
visible in logcat.

https://claude.ai/code/session_017TwkSjhzhmTcHKmVG5MWUa

3 files changed, 20 insertions, 3 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 0a37eaf..94b9c81 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
@@ -38,6 +38,7 @@ import kotlinx.coroutines.delay
 import kotlinx.coroutines.launch
 import java.util.Locale
 import org.maplibre.android.MapLibre
+import org.maplibre.android.maps.MapLibreMap
 import org.maplibre.android.maps.MapView
 import org.maplibre.android.maps.Style
 import org.maplibre.android.style.layers.RasterLayer
@@ -71,10 +72,12 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
     private var mobHandler: MobHandler? = null
     private var instrumentHandler: InstrumentHandler? = null
     private var mapHandler: MapHandler? = null
+    private var cachedMap: MapLibreMap? = null
     private val loadedStyleFlow = MutableStateFlow<Style?>(null)
     private lateinit var layerManager: MapLayerManager
     private var particleWindView: ParticleWindView? = null
     private var weatherLoaded = false
+    private var windGridLoaded = false
     private var cameraIdleJob: Job? = null
 
     private lateinit var bottomSheetBehavior: BottomSheetBehavior<View>
@@ -624,6 +627,7 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
         mapView?.onCreate(null)
         mapView?.getMapAsync { maplibreMap ->
             mapHandler = MapHandler(maplibreMap)
+            cachedMap = maplibreMap
             particleWindView?.attachMap(maplibreMap)
 
             lifecycleScope.launch {
@@ -768,6 +772,17 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
                     weatherLoaded = true
                     viewModel.loadWeather(gpsData.latitude, gpsData.longitude)
                 }
+                if (!windGridLoaded) {
+                    windGridLoaded = true
+                    val r = cachedMap?.projection?.visibleRegion
+                    val corners = listOfNotNull(r?.nearLeft, r?.nearRight, r?.farLeft, r?.farRight)
+                    if (corners.size == 4) {
+                        viewModel.loadWindGrid(
+                            corners.minOf { it.latitude }, corners.maxOf { it.latitude },
+                            corners.minOf { it.longitude }, corners.maxOf { it.longitude }
+                        )
+                    }
+                }
             }
         }
         lifecycleScope.launch {
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/data/api/WeatherApiService.kt b/android-app/app/src/main/kotlin/org/terst/nav/data/api/WeatherApiService.kt
index bce3534..db5caee 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/data/api/WeatherApiService.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/data/api/WeatherApiService.kt
@@ -19,8 +19,8 @@ interface WeatherApiService {
     /** Batch endpoint: comma-separated lat/lon → JSON array of WeatherResponse. */
     @GET("v1/forecast")
     suspend fun getWeatherForecastBatch(
-        @Query("latitude")        latitudes: String,
-        @Query("longitude")       longitudes: String,
+        @Query(value = "latitude",  encoded = true) latitudes: String,
+        @Query(value = "longitude", encoded = true) longitudes: String,
         @Query("hourly")          hourly: String = "windspeed_10m,winddirection_10m",
         @Query("forecast_days")   forecastDays: Int = 1,
         @Query("wind_speed_unit") windSpeedUnit: String = "kn"
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 7d0ab33..288fef4 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
@@ -381,7 +381,9 @@ class MainViewModel(
         windGridThrottle.update(centerLat, centerLon)
         viewModelScope.launch {
             val points = buildGrid(latMin, latMax, lonMin, lonMax, cols = 4, rows = 5)
-            repository.fetchWindGrid(points).getOrNull()?.let { _windGrid.value = it }
+            val result = repository.fetchWindGrid(points)
+            result.onFailure { NavLogger.w("windGrid", "fetchWindGrid failed: ${it.message}") }
+            result.getOrNull()?.let { _windGrid.value = it }
         }
     }