chore: bump version to 4.4.6

Next release: versionCode 445 -> 446, versionName 4.4.5 -> 4.4.6. Adds the Roaming page (QTH定位器-style 3x3 Maidenhead grid) between Match and Settings, credits BG7NTA & the original author in the thanks title, and caps local Gradle heap for the 2GB build server.

.github/workflows/release.yml

@@ -4,10 +4,15 @@ on:
   push:
     tags:
       - v**
+  workflow_dispatch:
+    inputs:
+      tag_name:
+        description: 'Release tag name (e.g. v4.4.3)'
+        required: false
+        default: ''
 
 env:
-  TAG_NAME: ${{ github.ref_name }}
+  TAG_NAME: ${{ github.event.inputs.tag_name || github.ref_name }}
-  GITHUB_TOKEN: ${{ secrets.RELEASE_TOKEN }}
 
 jobs:
   release:
@@ -16,19 +21,19 @@ jobs:
       contents: write
     steps:
       - name: Checkout Repository
-        uses: actions/checkout@v7
+        uses: actions/checkout@v4
 
       - name: Setup Java
-        uses: actions/setup-java@v5
+        uses: actions/setup-java@v4
         with:
           distribution: 'temurin'
           java-version: '21'
 
       - name: Setup Gradle
-        uses: gradle/actions/setup-gradle@v6
+        uses: gradle/actions/setup-gradle@v4
 
-      - name: Assemble Artifacts
+      - name: Assemble APK
-        run: ./gradlew assembleRelease bundleRelease
+        run: ./gradlew assembleRelease
 
       - name: Sign APK
         run: |
@@ -44,38 +49,9 @@ jobs:
             "$APK"
           rm keystore.jks
 
-      - name: Sign Bundle
-        run: |
-          echo "${{ secrets.KEY_STORE }}" | base64 -d > keystore.jks
-          AAB=$(find app/build/outputs/bundle/release -name "*.aab" | head -1)
-          jarsigner -verbose -sigalg SHA256withRSA -digestalg SHA-256 \
-            -keystore keystore.jks \
-            -storepass ${{ secrets.KEY_STORE_PASSWORD }} \
-            -keypass ${{ secrets.KEY_PASSWORD }} \
-            "$AAB" ${{ secrets.KEY_ALIAS }}
-          rm keystore.jks
-
-      - name: Setup Ruby
-        uses: ruby/setup-ruby@v1
-        with:
-          ruby-version: '3.4'
-
-      - name: Deploy Bundle to Google Play
-        run: |
-          gem install multi_json
-          gem install fastlane --no-document
-          AAB=$(find app/build/outputs/bundle/release -name "*.aab" | head -1)
-          echo '${{ secrets.SERVICE_ACCOUNT_JSON }}' > service_account.json
-          fastlane supply \
-            --aab "$AAB" \
-            --json_key service_account.json \
-            --package_name com.rtbishop.look4sat \
-            --track production \
-            --skip_upload_images true \
-            --skip_upload_screenshots true \
-          rm service_account.json
-
       - name: Create Release
+        env:
+          GH_TOKEN: ${{ github.token }}
         run: |
           gh release create $TAG_NAME --title=$TAG_NAME --generate-notes
           gh release upload $TAG_NAME app/build/outputs/apk/release/look4sat.apk

app/build.gradle.kts

@@ -1,3 +1,29 @@
+import java.util.Properties
+
 plugins {
     alias(libs.plugins.convention.applicationPlugin)
 }
+
+// Load signing config from keystore.properties (gitignored, never commit credentials)
+val keystoreProperties = Properties().apply {
+    val propsFile = rootProject.file("keystore.properties")
+    if (propsFile.exists()) propsFile.inputStream().use { load(it) }
+}
+
+android {
+    signingConfigs {
+        if (keystoreProperties["storeFile"] != null) {
+            create("release") {
+                storeFile = rootProject.file(keystoreProperties["storeFile"] as String)
+                storePassword = keystoreProperties["storePassword"] as String
+                keyAlias = keystoreProperties["keyAlias"] as String
+                keyPassword = keystoreProperties["keyPassword"] as String
+            }
+        }
+    }
+    buildTypes {
+        release {
+            signingConfig = signingConfigs.findByName("release")
+        }
+    }
+}

app/src/main/AndroidManifest.xml

@@ -43,7 +43,7 @@
 
         <meta-data
             android:name="android.telephony.PROPERTY_SATELLITE_DATA_OPTIMIZED"
-            android:value="com.rtbishop.look4sat" />
+            android:value="com.rtbishop.look4sat.bg7nta" />
 
     </application>
 </manifest>

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

@@ -72,6 +72,7 @@ import androidx.navigation3.runtime.rememberNavBackStack
 import androidx.navigation3.runtime.rememberSaveableStateHolderNavEntryDecorator
 import androidx.navigation3.ui.NavDisplay
 import com.rtbishop.look4sat.core.domain.repository.IContainerProvider
+import com.rtbishop.look4sat.core.domain.repository.MutualPassData
 import com.rtbishop.look4sat.core.presentation.DeeplinkResolver
 import com.rtbishop.look4sat.core.presentation.ElevationThresholds
 import com.rtbishop.look4sat.core.presentation.LocalElevationThresholds
@@ -84,6 +85,8 @@ import com.rtbishop.look4sat.feature.mutual.MutualScreen
 import com.rtbishop.look4sat.feature.mutual.MutualViewModel
 import com.rtbishop.look4sat.feature.passes.PassesDestination
 import com.rtbishop.look4sat.feature.radar.RadarDestination
+import com.rtbishop.look4sat.feature.roaming.RoamingScreen
+import com.rtbishop.look4sat.feature.roaming.RoamingViewModel
 import com.rtbishop.look4sat.feature.satellites.SatellitesDestination
 import com.rtbishop.look4sat.feature.settings.SettingsDestination
 
@@ -129,7 +132,7 @@ fun MainScreen(navigateToRadar: () -> Unit = {}) {
     val currentKey = backStack.lastOrNull()
     val navigateBack: () -> Unit = { backStack.removeLastOrNull() }
     val fadeTransition = fadeIn(animationSpec = tween(350)) togetherWith fadeOut(animationSpec = tween(350))
-    val navItems = listOf(Screen.Satellites, Screen.Passes, Screen.Radar, Screen.Mutual, Screen.Map, Screen.Settings)
+    val navItems = listOf(Screen.Satellites, Screen.Passes, Screen.Radar, Screen.Mutual, Screen.Roaming, Screen.Map, Screen.Settings)
 
     val context = LocalContext.current
     val container = (context.applicationContext as IContainerProvider).getMainContainer()
@@ -200,6 +203,7 @@ fun MainScreen(navigateToRadar: () -> Unit = {}) {
                         }
                         entry<Screen.Passes> {
                             PassesDestination { catNum, aosTime ->
+                                container.setMutualPassData(MutualPassData())
                                 container.satelliteRepo.selectPass(catNum, aosTime)
                                 backStack.add(Screen.Radar)
 //                            navigateToRadar()
@@ -216,12 +220,19 @@ fun MainScreen(navigateToRadar: () -> Unit = {}) {
                                 viewModel = mutualViewModel,
                                 navigateUp = navigateBack,
                                 navigateToRadar = { catNum, aosTime, pass ->
-                                    pass?.let { container.setMutualPassData(it) }
+                                    container.setMutualPassData(pass ?: MutualPassData())
                                     container.satelliteRepo.selectPass(catNum, aosTime)
                                     backStack.add(Screen.Radar)
                                 }
                             )
                         }
+                        entry<Screen.Roaming> {
+                            val roamingViewModel: RoamingViewModel = viewModel(
+                                viewModelStoreOwner = context as ViewModelStoreOwner,
+                                factory = RoamingViewModel.factory(container)
+                            )
+                            RoamingScreen(viewModel = roamingViewModel)
+                        }
                         entry<Screen.Settings> {
                             SettingsDestination()
                         }
@@ -245,6 +256,7 @@ fun MainScreen(navigateToRadar: () -> Unit = {}) {
                             .clickable {
                                 val pass = trackingState.currentPass
                                 if (pass != null) {
+                                    container.setMutualPassData(MutualPassData())
                                     container.satelliteRepo.selectPass(pass.catNum, pass.aosTime)
                                     backStack.add(Screen.Radar)
                                 }

build-logic/convention/src/main/java/com/rtbishop/look4sat/convention/ApplicationPlugin.kt

@@ -35,6 +35,7 @@ internal class ApplicationPlugin : Plugin<Project> {
             implementation(project(":feature:mutual"))
             implementation(project(":feature:passes"))
             implementation(project(":feature:radar"))
+            implementation(project(":feature:roaming"))
             implementation(project(":feature:satellites"))
             implementation(project(":feature:settings"))
             implementation(libs.androidx.core.splashscreen)

build-logic/convention/src/main/java/com/rtbishop/look4sat/convention/PluginSetupUtils.kt

@@ -57,7 +57,7 @@ internal fun Project.setupAndroidApp() {
         namespace = libs.versions.packageName.get()
         compileSdk = libs.versions.compileSdk.get().toInt()
         defaultConfig {
-            applicationId = libs.versions.packageName.get()
+            applicationId = libs.versions.applicationId.get()
             minSdk = libs.versions.minSdk.get().toInt()
             versionCode = libs.versions.appVersionCode.get().toInt()
             versionName = libs.versions.appVersionName.get()

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

@@ -95,14 +95,8 @@ class SatelliteRepo(
         }
     }
 
-    override suspend fun getRadios(
+    override suspend fun getRadios(satPos: OrbitalPos, radios: List<SatRadio>): List<SatRadio> {
-        sat: OrbitalObject,
-        pos: GeoPos,
-        radios: List<SatRadio>,
-        time: Long
-    ): List<SatRadio> {
         return withContext(dispatcher) {
-            val satPos = sat.getPosition(pos, time)
             radios.map { transmitter ->
                 transmitter.copy(
                     downlinkLow = transmitter.downlinkLow?.let { satPos.getDownlinkFreq(it) },
@@ -242,13 +236,16 @@ class SatelliteRepo(
             if (elevation > maxElevation) maxElevation = elevation
         } while (elevation < 0.0)
 
-        // refine AOS to ~500ms precision
+        // refine AOS to ~500ms precision via binary search.
-        calendarTimeMillis -= 60L * 1000L
+        // Elevation is monotonic across the horizon crossing, so binary search
-        do {
+        // finds the crossing in ~8 SGP4 calls instead of up to 120 linear steps.
-            calendarTimeMillis += 500L
+        var aosLo = calendarTimeMillis - 60L * 1000L // elevation < 0 (below horizon)
-            elevation = sat.getElevation(pos, calendarTimeMillis)
+        var aosHi = calendarTimeMillis // elevation >= 0 (above horizon)
-            if (elevation > maxElevation) maxElevation = elevation
+        while (aosHi - aosLo > 500L) {
-        } while (elevation < 0.0)
+            val mid = (aosLo + aosHi) / 2
+            if (sat.getElevation(pos, mid) < 0.0) aosLo = mid else aosHi = mid
+        }
+        calendarTimeMillis = aosHi
 
         // Get full position for AOS data (azimuth, altitude)
         val aosPos = sat.getFullPosition(pos, calendarTimeMillis)
@@ -262,13 +259,14 @@ class SatelliteRepo(
             if (elevation > maxElevation) maxElevation = elevation
         } while (elevation > 0.0)
 
-        // refine LOS to ~500ms precision
+        // refine LOS to ~500ms precision via binary search (same monotonic argument)
-        calendarTimeMillis -= 30L * 1000L
+        var losLo = calendarTimeMillis - 30L * 1000L // elevation > 0 (above horizon)
-        do {
+        var losHi = calendarTimeMillis // elevation <= 0 (below horizon)
-            calendarTimeMillis += 500L
+        while (losHi - losLo > 500L) {
-            elevation = sat.getElevation(pos, calendarTimeMillis)
+            val mid = (losLo + losHi) / 2
-            if (elevation > maxElevation) maxElevation = elevation
+            if (sat.getElevation(pos, mid) > 0.0) losLo = mid else losHi = mid
-        } while (elevation > 0.0)
+        }
+        calendarTimeMillis = losHi
 
         // Get full position for LOS data (azimuth, altitude)
         val losPos = sat.getFullPosition(pos, calendarTimeMillis)

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

@@ -213,8 +213,8 @@ class SettingsRepo(
     }
 
     private fun setStationPosition(latitude: Double, longitude: Double, altitude: Double, locator: String) {
-        val newLat = latitude.round(4)
+        val newLat = latitude.round(5)
-        val newLon = longitude.round(4)
+        val newLon = longitude.round(5)
         val newAlt = altitude.round(1)
         val timestamp = System.currentTimeMillis()
         println("Received new Position($newLat, $newLon, $newAlt) & Locator $locator")

core/domain/src/main/java/com/rtbishop/look4sat/core/domain/repository/ISatelliteRepo.kt

@@ -61,7 +61,7 @@ interface ISatelliteRepo {
     suspend fun getTrack(sat: OrbitalObject, pos: GeoPos, start: Long, end: Long): List<OrbitalPos>
 
     /** Get Doppler-shifted radio frequencies for a satellite at the given time. */
-    suspend fun getRadios(sat: OrbitalObject, pos: GeoPos, radios: List<SatRadio>, time: Long): List<SatRadio>
+    suspend fun getRadios(satPos: OrbitalPos, radios: List<SatRadio>): List<SatRadio>
 
     /** Fetch radio transceivers for a satellite by its catalog number. */
     suspend fun getRadiosWithId(id: Int): List<SatRadio>

core/domain/src/main/java/com/rtbishop/look4sat/core/domain/utility/QthConverter.kt

@@ -19,31 +19,78 @@ package com.rtbishop.look4sat.core.domain.utility
 
 import com.rtbishop.look4sat.core.domain.predict.GeoPos
 
+/**
+ * Converts a Maidenhead locator (QTH grid square) to a GeoPos.
+ * Supports 6-char (3 pair), 8-char (4 pair) and 10-char (5 pair) locators.
+ * The returned position is the center of the finest cell encoded by the locator:
+ *  - 6 char: 5' lon x 2.5' lat cell center
+ *  - 8 char: 30" lon x 15" lat cell center
+ *  - 10 char: 1.25" lon x 0.625" lat cell center
+ */
 fun qthToPosition(locator: String): GeoPos? {
-    val trimmedQth = locator.take(6)
+    val trimmedQth = locator.trim().uppercase()
     if (!isValidLocator(trimmedQth)) return null
-    val lonFirst = (trimmedQth[0].uppercaseChar().code - 65) * 20
+    val lonFirst = (trimmedQth[0].code - 65) * 20
-    val latFirst = (trimmedQth[1].uppercaseChar().code - 65) * 10
+    val latFirst = (trimmedQth[1].code - 65) * 10
     val lonSecond = trimmedQth[2].toString().toInt() * 2
     val latSecond = trimmedQth[3].toString().toInt()
-    val lonThird = (((trimmedQth[4].lowercaseChar().code - 97) / 12.0) + (1.0 / 24.0)) - 180
+    val lonThird = (trimmedQth[4].lowercaseChar().code - 97) / 12.0
-    val latThird = (((trimmedQth[5].lowercaseChar().code - 97) / 24.0) + (1.0 / 48.0)) - 90
+    val latThird = (trimmedQth[5].lowercaseChar().code - 97) / 24.0
-    val longitude = (lonFirst + lonSecond + lonThird).round(4)
+    var longitude = lonFirst + lonSecond + lonThird - 180
-    val latitude = (latFirst + latSecond + latThird).round(4)
+    var latitude = latFirst + latSecond + latThird - 90
-    return GeoPos(latitude, longitude)
+    // 8-char extension: 4th pair, digits, 30" lon x 15" lat cells
+    if (trimmedQth.length >= 8) {
+        longitude += trimmedQth[6].toString().toInt() / 120.0
+        latitude += trimmedQth[7].toString().toInt() / 240.0
+    }
+    // 10-char extension: 5th pair, letters, 1.25" lon x 0.625" lat cells
+    if (trimmedQth.length >= 10) {
+        longitude += (trimmedQth[8].lowercaseChar().code - 97) / 2880.0
+        latitude += (trimmedQth[9].lowercaseChar().code - 97) / 5760.0
+    }
+    // Offset to the center of the finest encoded cell
+    when (trimmedQth.length) {
+        8 -> {
+            longitude += 1.0 / 240.0
+            latitude += 1.0 / 480.0
+        }
+        10 -> {
+            longitude += 1.0 / 5760.0
+            latitude += 1.0 / 11520.0
+        }
+        else -> {
+            longitude += 1.0 / 24.0
+            latitude += 1.0 / 48.0
+        }
+    }
+    return GeoPos(latitude.round(6), longitude.round(6))
 }
 
-fun positionToQth(latitude: Double, longitude: Double): String? {
+/**
+ * Converts a GeoPos to a Maidenhead locator (QTH grid square).
+ * Default precision is 8 characters (4 pairs) giving 30" lon x 15" lat resolution,
+ * matching common 8-char grid square tools. Pass precision = 6 for the classic
+ * 5' x 2.5' resolution, or precision = 10 for the finest 1.25" x 0.625" resolution.
+ */
+fun positionToQth(latitude: Double, longitude: Double, precision: Int = 8): String? {
     if (!isValidPosition(latitude, longitude)) return null
-    val newLongitude = if (longitude > 180.0) longitude else longitude + 180
+    val newLongitude = longitude + 180
     val newLatitude = latitude + 90
-    val lonFirst = (65 + (newLongitude / 20)).toInt().toChar()
+    val lonFirst = (65 + (newLongitude / 20).toInt().coerceIn(0, 17)).toChar()
-    val latFirst = (65 + (newLatitude / 10)).toInt().toChar()
+    val latFirst = (65 + (newLatitude / 10).toInt().coerceIn(0, 17)).toChar()
-    val lonSecond = ((newLongitude / 2) % 10).toInt()
+    val lonSecond = ((newLongitude % 20) / 2).toInt()
     val latSecond = (newLatitude % 10).toInt()
     val lonThird = (65 + (newLongitude % 2) * 12).toInt().toChar().lowercaseChar()
     val latThird = (65 + (newLatitude % 1) * 24).toInt().toChar().lowercaseChar()
-    return "$lonFirst$latFirst$lonSecond$latSecond$lonThird$latThird"
+    val qth = "$lonFirst$latFirst$lonSecond$latSecond$lonThird$latThird"
+    if (precision < 8) return qth
+    val lonFourth = ((newLongitude % (1.0 / 12.0)) * 120).toInt()
+    val latFourth = ((newLatitude % (1.0 / 24.0)) * 240).toInt()
+    val qth8 = "$qth$lonFourth$latFourth"
+    if (precision < 10) return qth8
+    val lonFifth = (65 + (newLongitude % (1.0 / 120.0)) * 2880).toInt().toChar().lowercaseChar()
+    val latFifth = (65 + (newLatitude % (1.0 / 240.0)) * 5760).toInt().toChar().lowercaseChar()
+    return "$qth8$lonFifth$latFifth"
 }
 
 private fun isValidPosition(lat: Double, lon: Double): Boolean {
@@ -51,5 +98,49 @@ private fun isValidPosition(lat: Double, lon: Double): Boolean {
 }
 
 private fun isValidLocator(locator: String): Boolean {
-    return locator.matches("[a-xA-X][a-xA-X]\\d\\d[a-xA-X][a-xA-X]".toRegex())
+    return locator.matches("[a-xA-X]{2}\\d{2}[a-xA-X]{2}(?:\\d{2}(?:[a-xA-X]{2})?)?".toRegex())
 }
+
+/**
+ * Returns the 4-char field+square part of a locator, e.g. "OL42ih45" -> "OL42".
+ * A 4-char input is returned as-is when valid.
+ */
+fun qthToSquare(locator: String): String {
+    val upper = locator.trim().uppercase()
+    return when {
+        upper.length >= 4 && isValidLocator(upper) -> upper.take(4)
+        upper.length == 4 && upper.matches("[a-xA-X]{2}\\d{2}".toRegex()) -> upper
+        else -> "----"
+    }
+}
+
+/**
+ * Builds the 3x3 grid of 4-char squares surrounding [square] (e.g. "OL42").
+ * Row 0 = north (lat +1), col 0 = west (lon -1). Handles field/square carry
+ * at boundaries (e.g. "AA00" wraps to "RR99" at the south-west corner).
+ * Mirrors the neighbor logic decompiled from the QTH定位器 app.
+ */
+fun qthNeighbors(square: String): List<String> {
+    if (square.length != 4) return emptyList()
+    val lonField = (square[0].uppercaseChar().code - 65).coerceIn(0, 17)
+    val latField = (square[1].uppercaseChar().code - 65).coerceIn(0, 17)
+    val lonSquare = square[2].digitToCharOrNull() ?: return emptyList()
+    val latSquare = square[3].digitToCharOrNull() ?: return emptyList()
+    val result = mutableListOf<String>()
+    for (dLat in 1 downTo -1) {          // north -> south
+        for (dLon in -1..1) {            // west -> east
+            var lf = lonField
+            var tf = latField
+            var ls = lonSquare + dLon
+            var ts = latSquare + dLat
+            if (ls < 0) { lf -= 1; ls = 9 } else if (ls > 9) { lf += 1; ls = 0 }
+            if (ts < 0) { tf -= 1; ts = 9 } else if (ts > 9) { tf += 1; ts = 0 }
+            lf = (lf + 18) % 18
+            tf = (tf + 18) % 18
+            result += "${('A' + lf).toChar()}${('A' + tf).toChar()}$ls$ts"
+        }
+    }
+    return result
+}
+
+private fun Char.digitToCharOrNull(): Int? = digitToIntOrNull()

core/domain/src/test/java/com/rtbishop/look4sat/core/domain/QthConverterTest.kt

@@ -18,7 +18,9 @@
 package com.rtbishop.look4sat.core.domain
 
 import com.rtbishop.look4sat.core.domain.utility.positionToQth
+import com.rtbishop.look4sat.core.domain.utility.qthNeighbors
 import com.rtbishop.look4sat.core.domain.utility.qthToPosition
+import com.rtbishop.look4sat.core.domain.utility.qthToSquare
 import org.junit.Test
 
 class QthConverterTest {
@@ -26,21 +28,36 @@ class QthConverterTest {
     @Test
     fun `Given valid QTH returns correct POS`() {
         var result = qthToPosition("io91VL39FX")
-        assert(result?.latitude == 51.4792 && result.longitude == -0.2083)
+        assert(result?.latitude == 51.499913 && result.longitude == -0.22309)
         result = qthToPosition("gf15vc")
-        assert(result?.latitude == -34.8958 && result.longitude == -56.2083)
+        assert(result?.latitude == -34.895833 && result.longitude == -56.208333)
+        // 8-char locators: finer 30" x 15" cell center
+        result = qthToPosition("io91vl47")
+        assert(result?.latitude == 51.489583 && result.longitude == -0.2125)
+        result = qthToPosition("jn58td25")
+        assert(result?.latitude == 48.147917 && result.longitude == 11.604167)
     }
 
     @Test
     fun `Given invalid QTH returns null`() {
         assert(qthToPosition("ZZ00zz") == null)
         assert(qthToPosition("JN58") == null)
+        assert(qthToPosition("io9") == null)
+        assert(qthToPosition("IO91VL7") == null)
+        assert(qthToPosition("IO91VL4X") == null)
     }
 
     @Test
     fun `Given valid POS returns correct QTH`() {
-        assert(positionToQth(51.4878, -0.2146) == "IO91vl")
+        // default precision is 8 chars
-        assert(positionToQth(48.1466, 11.6083) == "JN58td")
+        assert(positionToQth(51.4878, -0.2146) == "IO91vl47")
+        assert(positionToQth(48.1466, 11.6083) == "JN58td25")
+        // 6-char precision still available for backwards compatibility
+        assert(positionToQth(51.4878, -0.2146, 6) == "IO91vl")
+        assert(positionToQth(48.1466, 11.6083, 6) == "JN58td")
+        // 10-char precision
+        assert(positionToQth(51.4878, -0.2146, 10) == "IO91vl47fb")
+        assert(positionToQth(48.1466, 11.6083, 10) == "JN58td25xe")
     }
 
     @Test
@@ -48,4 +65,61 @@ class QthConverterTest {
         assert(positionToQth(91.0542, -170.1142) == null)
         assert(positionToQth(89.0542, -240.1142) == null)
     }
+
+    @Test
+    fun `Given boundary POS stays in valid grid`() {
+        // antipodal / edge cases must not overflow the A-R / 0-9 / a-x alphabet
+        assert(positionToQth(-90.0, -180.0, 8) == "AA00aa00")
+        assert(positionToQth(90.0, 180.0, 8) == "RR00aa00")
+        assert(positionToQth(0.0, 0.0, 8) == "JJ00aa00")
+        // roundtrip stability: 8-char roundtrip is stable across a sample of positions
+        val positions = listOf(
+            Pair(51.4878, -0.2146), Pair(48.1466, 11.6083), Pair(-33.8688, 151.2093),
+            Pair(39.9042, 116.4074), Pair(35.6895, 139.6917), Pair(41.714, -72.727)
+        )
+        positions.forEach { (lat, lon) ->
+            val qth = positionToQth(lat, lon, 8)
+            val pos = qthToPosition(qth!!)
+            val qth2 = positionToQth(pos!!.latitude, pos.longitude, 8)
+            assert(qth == qth2) { "Roundtrip failed for ($lat, $lon): $qth -> $qth2" }
+        }
+    }
+
+    @Test
+    fun `Given square returns correct 3x3 neighbors`() {
+        // Reference grid from the QTH定位器 screenshot: OL42
+        val neighbors = qthNeighbors("OL42")
+        assert(neighbors == listOf(
+            "OL33", "OL43", "OL53",
+            "OL32", "OL42", "OL52",
+            "OL31", "OL41", "OL51"
+        )) { "OL42 grid mismatch: $neighbors" }
+        // Center cell must be the input itself
+        assert(neighbors[4] == "OL42")
+        // 9 cells, all distinct
+        assert(neighbors.size == 9 && neighbors.toSet().size == 9)
+    }
+
+    @Test
+    fun `Given boundary square wraps fields correctly`() {
+        // South-west corner: AA00 neighbors wrap to RR99 / RA90 etc.
+        val sw = qthNeighbors("AA00")
+        assert(sw.size == 9 && sw.toSet().size == 9)
+        assert(sw[0] == "RA91" && sw[4] == "AA00" && sw[6] == "RR99" && sw[8] == "AR19")
+        // North-east corner: RR99 wraps to AA00
+        val ne = qthNeighbors("RR99")
+        assert(ne.size == 9 && ne.toSet().size == 9)
+        assert(ne[0] == "RA80" && ne[4] == "RR99" && ne[8] == "AR08")
+        // Field boundary: IO91's east neighbors cross into J field
+        val london = qthNeighbors("IO91")
+        assert(london[2] == "JO02" && london[5] == "JO01")
+    }
+
+    @Test
+    fun `Given full locator returns square part`() {
+        assert(qthToSquare("OL42ih45") == "OL42")
+        assert(qthToSquare("io91VL39FX") == "IO91")
+        assert(qthToSquare("JN58") == "JN58")
+        assert(qthToSquare("garbage!!") == "----")
+    }
 }

core/presentation/src/main/java/com/rtbishop/look4sat/core/presentation/Navigation.kt

@@ -36,7 +36,10 @@ sealed class Screen(val iconResId: Int, val titleResId: Int) : NavKey {
     data object Map : Screen(R.drawable.ic_map, R.string.nav_map)
 
     @Serializable
-    data object Mutual : Screen(R.drawable.ic_radar, R.string.nav_mutual)
+    data object Mutual : Screen(R.drawable.ic_match, R.string.nav_mutual)
+
+    @Serializable
+    data object Roaming : Screen(R.drawable.ic_roaming, R.string.nav_roaming)
 
     @Serializable
     data object Settings : Screen(R.drawable.ic_settings, R.string.nav_prefs)

core/presentation/src/main/res/drawable/ic_match.xml

@@ -0,0 +1,22 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="96"
+    android:viewportHeight="96">
+
+    <path
+        android:fillColor="@android:color/transparent"
+        android:strokeColor="@android:color/white"
+        android:strokeWidth="6"
+        android:strokeLineCap="round"
+        android:strokeLineJoin="round"
+        android:pathData="M 8 76 C 8 44, 21 24, 39 24 C 57 24, 70 44, 70 76" />
+
+    <path
+        android:fillColor="@android:color/transparent"
+        android:strokeColor="@android:color/white"
+        android:strokeWidth="6"
+        android:strokeLineCap="round"
+        android:strokeLineJoin="round"
+        android:pathData="M 30 76 C 30 54, 44 42, 62 42 C 80 42, 94 54, 94 76" />
+</vector>

core/presentation/src/main/res/drawable/ic_roaming.xml

@@ -0,0 +1,25 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="96"
+    android:viewportHeight="96">
+
+    <!-- Crosshair / grid-locator style icon: concentric rings + center dot -->
+    <path
+        android:fillColor="@android:color/transparent"
+        android:strokeColor="@android:color/white"
+        android:strokeWidth="6"
+        android:strokeLineCap="round"
+        android:strokeLineJoin="round"
+        android:pathData="M 48 12 L 48 84 M 12 48 L 84 48" />
+
+    <path
+        android:fillColor="@android:color/transparent"
+        android:strokeColor="@android:color/white"
+        android:strokeWidth="6"
+        android:pathData="M 48 26 A 22 22 0 1 0 48.1 26" />
+
+    <path
+        android:fillColor="@android:color/white"
+        android:pathData="M 44 44 L 52 44 L 52 52 L 44 52 Z" />
+</vector>

core/presentation/src/main/res/values-tr/strings.xml

@@ -192,14 +192,16 @@
     <string name="prefs_highlight_mid">Orta %1$d-%2$d°</string>
     <string name="prefs_highlight_high">Yüksek &gt; %1$d°</string>
 
-    <string name="prefs_outro_title">Teşekkürler</string>
+    <string name="prefs_outro_title">BG7NTA ve orijinal yazar teşekkür eder</string>
     <string name="prefs_outro_thanks" translatable="false">
         • Look4Sat users and contributors!
         \n• David A. B. Johnson (predict4java)
         \n• Dave Moten (predict4java)
         \n• Alexandru Csete (Gpredict)
         \n• Dr T.S. Kelso (Celestrak)
-        \n• Libre Space Foundation (SatNOGS)</string>
+        \n• Libre Space Foundation (SatNOGS)
+        \n• BA7OPF (pass matching feature)
+        \n• BG7NTA</string>
     <string name="prefs_outro_license">Bu uygulama herhangi bir garanti sunmaz</string>
 
 </resources>

core/presentation/src/main/res/values-zh/strings.xml

@@ -9,7 +9,7 @@
     <string name="nav_sat">卫星</string>
     <string name="nav_pass">过境</string>
     <string name="nav_radar">雷达</string>
-    <string name="nav_mutual">对台</string>
+    <string name="nav_mutual">匹配</string>
     <string name="nav_map">地图</string>
     <string name="nav_prefs">设置</string>
 
@@ -167,7 +167,7 @@
     <string name="prefs_highlight_mid">中 %1$d-%2$d°</string>
     <string name="prefs_highlight_high">高 &gt; %1$d°</string>
 
-    <string name="prefs_outro_title">我要感谢：</string>
+    <string name="prefs_outro_title">BG7NTA 与原作者感谢：</string>
     <string name="prefs_outro_thanks" translatable="false">
         • Look4Sat 所有用户及贡献者!
         \n• David A. B. Johnson (predict4java)
@@ -175,7 +175,9 @@
         \n• Alexandru Csete (Gpredict)
         \n• Dr T.S. Kelso (Celestrak)
         \n• Libre Space Foundation (SatNOGS)
-        \n• xdsopl 和 Robot36 贡献者!</string>
+        \n• xdsopl 和 Robot36 贡献者!
+        \n• BA7OPF(过境匹配功能)
+        \n• BG7NTA</string>
     <string name="prefs_outro_license">该应用程序不提供任何保修.</string>
 
 </resources>

core/presentation/src/main/res/values/strings.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
     <!-- Commmon -->
-    <string name="app_name" translatable="false">Look4Sat</string>
+    <string name="app_name" translatable="false">Look4Sat Pro</string>
     <string name="btn_accept">Accept</string>
     <string name="btn_cancel">Cancel</string>
     <string name="empty_list_message">No data to show</string>
@@ -10,7 +10,8 @@
     <string name="nav_sat">Satellites</string>
     <string name="nav_pass">Passes</string>
     <string name="nav_radar">Radar</string>
-    <string name="nav_mutual">Mutual</string>
+    <string name="nav_mutual">Match</string>
+    <string name="nav_roaming">Roaming</string>
     <string name="nav_map">Map</string>
     <string name="nav_prefs">Settings</string>
 
@@ -202,7 +203,7 @@
     <string name="prefs_highlight_mid">Mid %1$d–%2$d°</string>
     <string name="prefs_highlight_high">High &gt; %1$d°</string>
 
-    <string name="prefs_outro_title">I would like to say thanks to</string>
+    <string name="prefs_outro_title">BG7NTA &amp; the original author would like to thank</string>
     <string name="prefs_outro_thanks" translatable="false">
         * Look4Sat users and contributors!
         \n* David A. B. Johnson (predict4java)
@@ -211,6 +212,8 @@
         \n* Dr T.S. Kelso (Celestrak)
         \n* Libre Space Foundation (SatNOGS)
         \n* xdsopl and Robot36 contributors!
+        \n* BA7OPF (pass matching feature)
+        \n* BG7NTA
     </string>
     <string name="prefs_outro_license">The app comes with no warranty</string>
 

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

@@ -88,7 +88,7 @@ fun MutualScreen(
                 },
                 topInfo = {
                     Text(
-                        text = "对台过境",
+                        text = "过境匹配",
                         style = MaterialTheme.typography.titleMedium,
                         fontWeight = FontWeight.Bold
                     )
@@ -96,7 +96,7 @@ fun MutualScreen(
                 bottomInfo = {
                     if (state.mutualPasses.isNotEmpty()) {
                         Text(
-                            text = "找到 ${state.mutualPasses.size} 个过境",
+                            text = "找到 ${state.mutualPasses.size} 个匹配",
                             style = MaterialTheme.typography.bodySmall,
                             color = MaterialTheme.colorScheme.onSurfaceVariant
                         )
@@ -183,153 +183,91 @@ private fun MutualContent(
 
         // Input form
         item {
-            ElevatedCard(modifier = Modifier.fillMaxWidth()) {
+            Column(
-                Column(
+                modifier = Modifier.fillMaxWidth(),
-                    modifier = Modifier
+                verticalArrangement = Arrangement.spacedBy(6.dp)
-                        .fillMaxWidth()
+            ) {
-                        .padding(12.dp),
+                MatchIntroCard()
-                    verticalArrangement = Arrangement.spacedBy(8.dp)
+
-                ) {
+                if (isVertical) {
-                    Text(
+                    StationInputCard(
-                        text = "你的位置",
+                        title = "你的位置",
-                        style = MaterialTheme.typography.titleSmall,
+                        titleColor = MaterialTheme.colorScheme.primary,
-                        fontWeight = FontWeight.Medium
+                        lat = state.stationALat,
+                        lon = state.stationALon,
+                        grid = state.stationAGrid,
+                        minElev = state.stationAMinElev,
+                        latPlaceholder = "39.9042",
+                        lonPlaceholder = "116.4074",
+                        gridPlaceholder = "ON79uj",
+                        onLatChange = onStationALat,
+                        onLonChange = onStationALon,
+                        onGridChange = onStationAGrid,
+                        onMinElevChange = onStationAMinElev,
+                        currentPositionAction = onUseCurrentPosition
                     )
+                    StationInputCard(
+                        title = "友台位置",
+                        titleColor = MaterialTheme.colorScheme.tertiary,
+                        lat = state.stationBLat,
+                        lon = state.stationBLon,
+                        grid = state.stationBGrid,
+                        minElev = state.stationBMinElev,
+                        latPlaceholder = "34.0522",
+                        lonPlaceholder = "-118.2437",
+                        gridPlaceholder = "PM01tv",
+                        onLatChange = onStationBLat,
+                        onLonChange = onStationBLon,
+                        onGridChange = onStationBGrid,
+                        onMinElevChange = onStationBMinElev
+                    )
+                } else {
                     Row(
                         modifier = Modifier.fillMaxWidth(),
-                        horizontalArrangement = Arrangement.spacedBy(8.dp)
+                        horizontalArrangement = Arrangement.spacedBy(6.dp)
                     ) {
-                        OutlinedTextField(
+                        StationInputCard(
-                            value = state.stationALat,
+                            title = "你的位置",
-                            onValueChange = onStationALat,
+                            titleColor = MaterialTheme.colorScheme.primary,
-                            label = { Text("纬度") },
+                            lat = state.stationALat,
-                            placeholder = { Text("39.9042") },
+                            lon = state.stationALon,
-                            keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Decimal),
+                            grid = state.stationAGrid,
-                            singleLine = true,
+                            minElev = state.stationAMinElev,
+                            latPlaceholder = "39.9042",
+                            lonPlaceholder = "116.4074",
+                            gridPlaceholder = "ON79uj",
+                            onLatChange = onStationALat,
+                            onLonChange = onStationALon,
+                            onGridChange = onStationAGrid,
+                            onMinElevChange = onStationAMinElev,
+                            currentPositionAction = onUseCurrentPosition,
                             modifier = Modifier.weight(1f)
                         )
-                        OutlinedTextField(
+                        StationInputCard(
-                            value = state.stationALon,
+                            title = "友台位置",
-                            onValueChange = onStationALon,
+                            titleColor = MaterialTheme.colorScheme.tertiary,
-                            label = { Text("经度") },
+                            lat = state.stationBLat,
-                            placeholder = { Text("116.4074") },
+                            lon = state.stationBLon,
-                            keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Decimal),
+                            grid = state.stationBGrid,
-                            singleLine = true,
+                            minElev = state.stationBMinElev,
+                            latPlaceholder = "34.0522",
+                            lonPlaceholder = "-118.2437",
+                            gridPlaceholder = "PM01tv",
+                            onLatChange = onStationBLat,
+                            onLonChange = onStationBLon,
+                            onGridChange = onStationBGrid,
+                            onMinElevChange = onStationBMinElev,
                             modifier = Modifier.weight(1f)
                         )
                     }
-                    OutlinedTextField(
-                        value = state.stationAGrid,
-                        onValueChange = onStationAGrid,
-                        label = { Text("网格（4/6/8位，填此可省略经纬度）") },
-                        placeholder = { Text("ON79uj") },
-                        singleLine = true,
-                        modifier = Modifier.fillMaxWidth()
-                    )
-                    OutlinedButton(
-                        onClick = onUseCurrentPosition,
-                        modifier = Modifier.align(Alignment.End)
-                    ) {
-                        Text("当前精确位置", style = MaterialTheme.typography.bodySmall)
-                    }
-                    Text(
-                        text = "最小仰角：${state.stationAMinElev.toInt()}°",
-                        style = MaterialTheme.typography.bodySmall
-                    )
-                    Slider(
-                        value = state.stationAMinElev.toFloat(),
-                        onValueChange = { onStationAMinElev(it.toDouble()) },
-                        valueRange = 0f..90f,
-                        steps = 17
-                    )
-
-                    HorizontalDivider()
-
-                    Text(
-                        text = "友台位置",
-                        style = MaterialTheme.typography.titleSmall,
-                        fontWeight = FontWeight.Medium
-                    )
-                    Row(
-                        modifier = Modifier.fillMaxWidth(),
-                        horizontalArrangement = Arrangement.spacedBy(8.dp)
-                    ) {
-                        OutlinedTextField(
-                            value = state.stationBLat,
-                            onValueChange = onStationBLat,
-                            label = { Text("纬度") },
-                            placeholder = { Text("34.0522") },
-                            keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Decimal),
-                            singleLine = true,
-                            modifier = Modifier.weight(1f)
-                        )
-                        OutlinedTextField(
-                            value = state.stationBLon,
-                            onValueChange = onStationBLon,
-                            label = { Text("经度") },
-                            placeholder = { Text("-118.2437") },
-                            keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Decimal),
-                            singleLine = true,
-                            modifier = Modifier.weight(1f)
-                        )
-                    }
-                    OutlinedTextField(
-                        value = state.stationBGrid,
-                        onValueChange = onStationBGrid,
-                        label = { Text("网格（4/6/8位，填此可省略经纬度）") },
-                        placeholder = { Text("PM01tv") },
-                        singleLine = true,
-                        modifier = Modifier.fillMaxWidth()
-                    )
-                    Text(
-                        text = "最小仰角：${state.stationBMinElev.toInt()}°",
-                        style = MaterialTheme.typography.bodySmall
-                    )
-                    Slider(
-                        value = state.stationBMinElev.toFloat(),
-                        onValueChange = { onStationBMinElev(it.toDouble()) },
-                        valueRange = 0f..90f,
-                        steps = 17
-                    )
-
-                    HorizontalDivider()
-
-                    Text(
-                        text = "时间范围",
-                        style = MaterialTheme.typography.titleSmall,
-                        fontWeight = FontWeight.Medium
-                    )
-                    Row(
-                        modifier = Modifier.fillMaxWidth(),
-                        horizontalArrangement = Arrangement.spacedBy(8.dp)
-                    ) {
-                        listOf(6, 12, 24, 48, 72).forEach { hours ->
-                            FilterChip(
-                                selected = state.hoursAhead == hours,
-                                onClick = { onHoursAhead(hours) },
-                                label = { Text("${hours}h") }
-                            )
-                        }
-                    }
-
-                    Button(
-                        onClick = onQuery,
-                        enabled = !state.isCalculating,
-                        modifier = Modifier.fillMaxWidth()
-                    ) {
-                        if (state.isCalculating) {
-                            CircularProgressIndicator(
-                                modifier = Modifier
-                                    .height(18.dp)
-                                    .width(18.dp),
-                                strokeWidth = 2.dp,
-                                color = MaterialTheme.colorScheme.onPrimary
-                            )
-                            Spacer(Modifier.width(8.dp))
-                        }
-                        Text(if (state.isCalculating) "计算中..." else "查询过境")
-                    }
                 }
+
+                MatchSearchCard(
+                    hoursAhead = state.hoursAhead,
+                    isCalculating = state.isCalculating,
+                    onHoursAhead = onHoursAhead,
+                    onQuery = onQuery
+                )
             }
         }
 
@@ -365,6 +303,169 @@ private fun MutualContent(
     }
 }
 
+@Composable
+private fun MatchIntroCard(modifier: Modifier = Modifier) {
+    ElevatedCard(modifier = modifier.fillMaxWidth()) {
+        Column(
+            modifier = Modifier.padding(12.dp),
+            verticalArrangement = Arrangement.spacedBy(4.dp)
+        ) {
+            Text(
+                text = "位置匹配",
+                style = MaterialTheme.typography.titleSmall,
+                fontWeight = FontWeight.Medium,
+                color = MaterialTheme.colorScheme.primary
+            )
+            Text(
+                text = "输入双方位置，查找共同可见的卫星过境窗口",
+                style = MaterialTheme.typography.bodySmall,
+                color = MaterialTheme.colorScheme.onSurfaceVariant
+            )
+        }
+    }
+}
+
+@Composable
+private fun StationInputCard(
+    title: String,
+    titleColor: androidx.compose.ui.graphics.Color,
+    lat: String,
+    lon: String,
+    grid: String,
+    minElev: Double,
+    latPlaceholder: String,
+    lonPlaceholder: String,
+    gridPlaceholder: String,
+    onLatChange: (String) -> Unit,
+    onLonChange: (String) -> Unit,
+    onGridChange: (String) -> Unit,
+    onMinElevChange: (Double) -> Unit,
+    modifier: Modifier = Modifier,
+    currentPositionAction: (() -> Unit)? = null
+) {
+    ElevatedCard(modifier = modifier.fillMaxWidth()) {
+        Column(
+            modifier = Modifier.padding(12.dp),
+            verticalArrangement = Arrangement.spacedBy(8.dp)
+        ) {
+            Row(
+                modifier = Modifier.fillMaxWidth(),
+                horizontalArrangement = Arrangement.SpaceBetween,
+                verticalAlignment = Alignment.CenterVertically
+            ) {
+                Text(
+                    text = title,
+                    style = MaterialTheme.typography.titleSmall,
+                    fontWeight = FontWeight.Medium,
+                    color = titleColor
+                )
+                if (currentPositionAction != null) {
+                    OutlinedButton(onClick = currentPositionAction) {
+                        Text("填入当前位置", style = MaterialTheme.typography.bodySmall)
+                    }
+                }
+            }
+
+            Row(
+                modifier = Modifier.fillMaxWidth(),
+                horizontalArrangement = Arrangement.spacedBy(8.dp)
+            ) {
+                OutlinedTextField(
+                    value = lat,
+                    onValueChange = onLatChange,
+                    label = { Text("纬度") },
+                    placeholder = { Text(latPlaceholder) },
+                    keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Decimal),
+                    singleLine = true,
+                    modifier = Modifier.weight(1f)
+                )
+                OutlinedTextField(
+                    value = lon,
+                    onValueChange = onLonChange,
+                    label = { Text("经度") },
+                    placeholder = { Text(lonPlaceholder) },
+                    keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Decimal),
+                    singleLine = true,
+                    modifier = Modifier.weight(1f)
+                )
+            }
+
+            OutlinedTextField(
+                value = grid,
+                onValueChange = onGridChange,
+                label = { Text("网格") },
+                placeholder = { Text(gridPlaceholder) },
+                supportingText = { Text("支持 4/6/8 位 Maidenhead 网格；也可直接输入经纬度") },
+                singleLine = true,
+                modifier = Modifier.fillMaxWidth()
+            )
+
+            Text(
+                text = "最小仰角：${minElev.toInt()}°",
+                style = MaterialTheme.typography.bodySmall,
+                color = MaterialTheme.colorScheme.onSurfaceVariant
+            )
+            Slider(
+                value = minElev.toFloat(),
+                onValueChange = { onMinElevChange(it.toDouble()) },
+                valueRange = 0f..90f,
+                steps = 17
+            )
+        }
+    }
+}
+
+@Composable
+private fun MatchSearchCard(
+    hoursAhead: Int,
+    isCalculating: Boolean,
+    onHoursAhead: (Int) -> Unit,
+    onQuery: () -> Unit,
+    modifier: Modifier = Modifier
+) {
+    ElevatedCard(modifier = modifier.fillMaxWidth()) {
+        Column(
+            modifier = Modifier.padding(12.dp),
+            verticalArrangement = Arrangement.spacedBy(10.dp)
+        ) {
+            Text(
+                text = "时间范围",
+                style = MaterialTheme.typography.titleSmall,
+                fontWeight = FontWeight.Medium
+            )
+            Row(
+                modifier = Modifier.fillMaxWidth(),
+                horizontalArrangement = Arrangement.spacedBy(8.dp)
+            ) {
+                listOf(6, 12, 24, 48, 72).forEach { hours ->
+                    FilterChip(
+                        selected = hoursAhead == hours,
+                        onClick = { onHoursAhead(hours) },
+                        label = { Text("${hours}h") }
+                    )
+                }
+            }
+            Button(
+                onClick = onQuery,
+                enabled = !isCalculating,
+                modifier = Modifier.fillMaxWidth()
+            ) {
+                if (isCalculating) {
+                    CircularProgressIndicator(
+                        modifier = Modifier
+                            .height(18.dp)
+                            .width(18.dp),
+                        strokeWidth = 2.dp,
+                        color = MaterialTheme.colorScheme.onPrimary
+                    )
+                    Spacer(Modifier.width(8.dp))
+                }
+                Text(if (isCalculating) "计算中..." else "查询匹配")
+            }
+        }
+    }
+}
+
 @Composable
 private fun MutualPassCard(
     pass: MutualPass,
@@ -380,7 +481,6 @@ private fun MutualPassCard(
     var dragProgress by remember(pass) { mutableFloatStateOf(0.5f) }
 
     // Filter to only show the portion where both stations are above their minElev
-    // (satlover.de style — only the usable common window)
     val visibleSamples = remember(pass, minElevA, minElevB) {
         pass.elevationSamples.filter { (_, elev) ->
             elev.first >= minElevA && elev.second >= minElevB
@@ -447,7 +547,7 @@ private fun MutualPassCard(
                     // Dual-station radar track (polar plot)
                     if (visibleTracks.isNotEmpty()) {
                         Text(
-                            text = "双方轨迹（雷达图）",
+                            text = "双方轨迹",
                             style = MaterialTheme.typography.titleSmall,
                             fontWeight = FontWeight.Medium,
                             color = MaterialTheme.colorScheme.onSurfaceVariant

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

@@ -352,20 +352,23 @@ class MutualViewModel(
                 tSample += sampleInterval
             }
 
-            // The pass list already filters by maxElev > minElevation, so we trust
+            // Search uses the 0° horizon as the pass boundary, but the user sliders are
-            // the pass is valid. The mutual pass just needs both stations' curves.
+            // a final visibility filter. Both stations must exceed their own threshold;
-            results.add(
+            // otherwise the result would expand to an empty filtered chart.
-                MutualPass(
+            if (maxElevA > minElevADeg && maxElevB > minElevBDeg) {
-                    catNum = pass.catNum,
+                results.add(
-                    name = pass.orbitalObject.data.name,
+                    MutualPass(
-                    startTime = refinedAos,
+                        catNum = pass.catNum,
-                    endTime = refinedLos,
+                        name = pass.orbitalObject.data.name,
-                    maxElevationA = (maxElevA * 10).roundToInt() / 10.0,
+                        startTime = refinedAos,
-                    maxElevationB = (maxElevB * 10).roundToInt() / 10.0,
+                        endTime = refinedLos,
-                    elevationSamples = samples,
+                        maxElevationA = (maxElevA * 10).roundToInt() / 10.0,
-                    trackSamples = tracks
+                        maxElevationB = (maxElevB * 10).roundToInt() / 10.0,
+                        elevationSamples = samples,
+                        trackSamples = tracks
+                    )
                 )
-            )
+            }
         }
         return results
     }
@@ -413,10 +416,12 @@ class MutualViewModel(
 
         var tSample = refinedAos
         while (tSample <= refinedLos) {
+            // Use getElevation for elevation, matching the main pass predictor; use
+            // getFullPosition only for azimuth needed by the radar plot.
+            val elevA = elevationDeg(sat, posA, tSample)
+            val elevB = elevationDeg(sat, posB, tSample)
             val fullA = sat.getFullPosition(posA, tSample)
             val fullB = sat.getFullPosition(posB, tSample)
-            val elevA = fullA.elevation * 180.0 / PI
-            val elevB = fullB.elevation * 180.0 / PI
             if (elevA > maxElevA) maxElevA = elevA
             if (elevB > maxElevB) maxElevB = elevB
             samples.add(tSample to (elevA to elevB))

feature/radar/src/main/java/com/rtbishop/look4sat/feature/radar/RadarScreen.kt

@@ -73,6 +73,7 @@ import com.rtbishop.look4sat.core.presentation.getDefaultPass
 import com.rtbishop.look4sat.core.presentation.isVerticalLayout
 import com.rtbishop.look4sat.core.presentation.layoutPadding
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.delay
 import kotlin.math.PI
 
 private enum class RadarPage(val title: String) {
@@ -87,6 +88,23 @@ fun RadarDestination(navigateUp: () -> Unit) {
     val viewModel: RadarViewModel = viewModel(factory = RadarViewModel.factory(container))
     val uiState by viewModel.uiState.collectAsStateWithLifecycle()
     val mutualData by container.mutualPassData.collectAsStateWithLifecycle()
+    val navigateUpAndClearMutual = {
+        if (container.mutualPassData.value.endTime > 0L) {
+            container.setMutualPassData(MutualPassData())
+        }
+        navigateUp()
+    }
+    LaunchedEffect(mutualData.endTime) {
+        if (mutualData.endTime <= 0L) return@LaunchedEffect
+        while (true) {
+            val remainingMs = mutualData.endTime - System.currentTimeMillis()
+            if (remainingMs <= 0L) {
+                navigateUpAndClearMutual()
+                return@LaunchedEffect
+            }
+            delay(remainingMs.coerceAtMost(1000L))
+        }
+    }
     // Sync actual permission state on every recomposition so it survives screen re-entry
     val hasPermission = ContextCompat.checkSelfPermission(
         context, Manifest.permission.RECORD_AUDIO
@@ -101,7 +119,7 @@ fun RadarDestination(navigateUp: () -> Unit) {
         viewModel.onAction(RadarAction.SstvPermissionResult(granted))
         viewModel.onAction(RadarAction.CwPermissionResult(granted))
     }
-    RadarScreen(uiState, viewModel::onAction, navigateUp, mutualData, requestMicPermission = {
+    RadarScreen(uiState, viewModel::onAction, navigateUpAndClearMutual, mutualData, requestMicPermission = {
         permissionLauncher.launch(Manifest.permission.RECORD_AUDIO)
     })
 }

feature/radar/src/main/java/com/rtbishop/look4sat/feature/radar/RadarView.kt

@@ -94,14 +94,21 @@ fun RadarViewCompose(
         animationSpec = infiniteRepeatable(tween(1000)),
         label = "animScale"
     )
-    // Drive the sweep from the animation framework to eliminate state mutation inside the draw block
+    // Drive the sweep from the animation framework to eliminate state mutation inside the draw block.
-    val sweepTransition = rememberInfiniteTransition(label = "sweep")
+    // Only create the infinite transition when the sweep is enabled — otherwise the canvas would
-    val sweepDegrees by sweepTransition.animateFloat(
+    // be invalidated every frame for an effect that isn't visible, wasting GPU and battery.
-        initialValue = 0f,
+    val sweepDegrees = if (shouldShowSweep) {
-        targetValue = 360f,
+        val sweepTransition = rememberInfiniteTransition(label = "sweep")
-        animationSpec = infiniteRepeatable(tween(SWEEP_DURATION_MS, easing = LinearEasing)),
+        val animatedSweep by sweepTransition.animateFloat(
-        label = "sweepDegrees"
+            initialValue = 0f,
-    )
+            targetValue = 360f,
+            animationSpec = infiniteRepeatable(tween(SWEEP_DURATION_MS, easing = LinearEasing)),
+            label = "sweepDegrees"
+        )
+        animatedSweep
+    } else {
+        0f
+    }
     val measurer = rememberTextMeasurer()
     val sunPainter = painterResource(R.drawable.ic_sun)
     val moonPainter = painterResource(R.drawable.ic_moon)
@@ -112,9 +119,10 @@ fun RadarViewCompose(
     var cachedSweepColor by remember { mutableStateOf(Color.Unspecified) }
     var trackPath by remember { mutableStateOf(Path()) }
     var trackEffect by remember { mutableStateOf(PathEffect.cornerPathEffect(0f)) }
-    // Station-B overlay track (dashed)
+    // Station-B overlay track (dashed, with the same directional arrow stamp as station A)
     var cachedTrackBRef by remember { mutableStateOf<List<OrbitalPos>?>(null) }
     var trackBPath by remember { mutableStateOf(Path()) }
+    var trackBEffect by remember { mutableStateOf(PathEffect.cornerPathEffect(0f)) }
     // ShaderBrush is cached to avoid allocating a new GPU shader object every frame
     var cachedSweepBrush by remember { mutableStateOf<ShaderBrush?>(null) }
 
@@ -124,7 +132,10 @@ fun RadarViewCompose(
         if (radius != cachedRadius || items !== cachedItemsRef || trackB !== cachedTrackBRef) {
             trackPath = createTrackPath(items, radius)
             trackEffect = createTrackEffect(trackPath)
-            trackBPath = trackB?.let { createTrackPath(it, radius) } ?: Path()
+            val newTrackBPath = trackB?.let { createTrackPath(it, radius) } ?: Path()
+            trackBPath = newTrackBPath
+            trackBEffect = if (!newTrackBPath.isEmpty) createTrackEffect(newTrackBPath)
+            else PathEffect.cornerPathEffect(0f)
             cachedSweepBrush = makeSweepBrush(center, primaryColor)
             cachedRadius = radius
             cachedItemsRef = items
@@ -141,13 +152,14 @@ fun RadarViewCompose(
             drawElevationLabels(radius, primaryColor, measurer)
             translate(center.x, center.y) {
                 drawTrack(trackPath, trackEffect, aimColor, primaryColor)
-                // Station-B overlay: full dashed track + live position dot
+                // Station-B overlay: full dashed track + directional arrows + live position dot
-                // (same display mode as the local station: track line + pulsing dot)
+                // (same display mode as the local station: track line/arrow + pulsing dot)
                 if (trackB != null && trackB.isNotEmpty() && !trackBPath.isEmpty) {
                     drawPath(
                         trackBPath, trackBColor,
                         style = Stroke(STROKE_WIDTH, pathEffect = PathEffect.dashPathEffect(floatArrayOf(18f, 12f)))
                     )
+                    drawPath(trackBPath, trackBColor, style = Stroke(pathEffect = trackBEffect))
                 }
                 trackBPosition?.let { posB ->
                     if (posB.elevation > 0) {

feature/radar/src/main/java/com/rtbishop/look4sat/feature/radar/RadarViewModel.kt

@@ -139,6 +139,8 @@ class RadarViewModel(
         val passes = satelliteRepo.passes.value
         val (catNum, aosTime) = satelliteRepo.selectedPass.value
         return passes.find { it.catNum == catNum && it.aosTime == aosTime }
+            ?: passes.find { it.catNum == catNum && aosTime in it.aosTime..it.losTime }
+            ?: passes.find { it.catNum == catNum }
             ?: passes.firstOrNull()
     }
 
@@ -179,7 +181,7 @@ class RadarViewModel(
                 orbitalPos = pos, sunPosition = cachedSunPos, moonPosition = cachedMoonPos
             )
         }
-        processRadios(allRadios, pass.orbitalObject, timeNow)
+        processRadios(allRadios, pos)
         sendPassData(pos)
     }
 
@@ -340,8 +342,8 @@ class RadarViewModel(
         }
     }
 
-    private suspend fun processRadios(radios: List<SatRadio>, orbitalObject: OrbitalObject, time: Long) {
+    private suspend fun processRadios(radios: List<SatRadio>, satPos: OrbitalPos) {
-        val transmitters = satelliteRepo.getRadios(orbitalObject, stationPos, radios, time)
+        val transmitters = satelliteRepo.getRadios(satPos, radios)
         _uiState.update { state ->
             val freq = if (state.transceivers.selectedUuid != null) {
                 val selectedRadio = transmitters.firstOrNull { it.uuid == state.transceivers.selectedUuid }

feature/roaming/build.gradle.kts

@@ -0,0 +1,11 @@
+plugins {
+    alias(libs.plugins.convention.featurePlugin)
+}
+
+android {
+    namespace = "com.rtbishop.look4sat.feature.roaming"
+}
+
+dependencies {
+    implementation(project(":core:data"))
+}

feature/roaming/src/main/java/com/rtbishop/look4sat/feature/roaming/RoamingScreen.kt

@@ -0,0 +1,216 @@
+/*
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.rtbishop.look4sat.feature.roaming
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.border
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.aspectRatio
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.shape.CircleShape
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.text.font.FontFamily
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextAlign
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.unit.sp
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import com.rtbishop.look4sat.core.presentation.CardButton
+
+private val InfoCyan = Color(0xFF0CCFE2)
+private val GridBlue = Color(0xFF12ACE0)
+private val LabelBlue = Color(0xFF135678)
+private val PositionRed = Color(0xFFFF0000)
+private val DividerWhite = Color(0xFFF7F7F7)
+
+@Composable
+fun RoamingScreen(viewModel: RoamingViewModel) {
+    val state by viewModel.uiState.collectAsStateWithLifecycle()
+    Column(modifier = Modifier.fillMaxSize()) {
+        InfoHeader(state = state, onGpsClick = viewModel::onGpsClick)
+        GridPanel(state = state)
+    }
+}
+
+@Composable
+private fun InfoHeader(state: RoamingState, onGpsClick: () -> Unit) {
+    Column(
+        modifier = Modifier
+            .fillMaxWidth()
+            .background(InfoCyan)
+            .padding(horizontal = 16.dp, vertical = 10.dp)
+    ) {
+        // Top row: GPS status + big locator
+        Row(verticalAlignment = Alignment.CenterVertically) {
+            Text(
+                text = "GPS",
+                fontSize = 20.sp,
+                fontWeight = FontWeight.Medium,
+                color = Color.Black
+            )
+            Spacer(modifier = Modifier.width(8.dp))
+            Box(
+                modifier = Modifier
+                    .size(12.dp)
+                    .clip(CircleShape)
+                    .background(if (state.qthLocator != "----") Color(0xFF3BAF52) else Color.Gray)
+            )
+            Spacer(modifier = Modifier.weight(1f))
+            Text(
+                text = state.qthLocator,
+                fontSize = 30.sp,
+                fontWeight = FontWeight.Bold,
+                fontFamily = FontFamily.Monospace,
+                color = Color.Black
+            )
+        }
+        Spacer(modifier = Modifier.height(10.dp))
+        // Lat / Lon rows with DMS + decimal
+        CoordinateRow(label = "Lat", value = state.latitude, isLat = true)
+        Spacer(modifier = Modifier.height(4.dp))
+        CoordinateRow(label = "Lon", value = state.longitude, isLat = false)
+        Spacer(modifier = Modifier.height(10.dp))
+        CardButton(
+            onClick = onGpsClick,
+            text = "GPS 定位",
+            modifier = Modifier.fillMaxWidth()
+        )
+    }
+}
+
+@Composable
+private fun CoordinateRow(label: String, value: Double, isLat: Boolean) {
+    Row(
+        verticalAlignment = Alignment.CenterVertically,
+        modifier = Modifier.fillMaxWidth()
+    ) {
+        Text(
+            text = label,
+            fontSize = 16.sp,
+            fontWeight = FontWeight.Medium,
+            color = Color.Black,
+            modifier = Modifier.width(44.dp)
+        )
+        Text(
+            text = formatDms(value, isLat),
+            fontSize = 15.sp,
+            color = Color.Black
+        )
+        Spacer(modifier = Modifier.weight(1f))
+        Text(
+            text = "${formatDecimal(value)}°",
+            fontSize = 14.sp,
+            color = LabelBlue
+        )
+    }
+}
+
+@Composable
+private fun GridPanel(state: RoamingState) {
+    Column(
+        modifier = Modifier
+            .fillMaxSize()
+            .background(GridBlue)
+            .padding(4.dp)
+    ) {
+        // 3x3 grid: row 0 = north
+        for (row in 0..2) {
+            Row(
+                modifier = Modifier
+                    .fillMaxWidth()
+                    .weight(1f),
+                horizontalArrangement = Arrangement.spacedBy(4.dp)
+            ) {
+                for (col in 0..2) {
+                    val index = row * 3 + col
+                    val isCenter = index == 4
+                    GridCell(
+                        label = state.gridSquares.getOrElse(index) { "----" },
+                        isCenter = isCenter,
+                        showMarker = isCenter && state.qthLocator != "----",
+                        modifier = Modifier.weight(1f)
+                    )
+                }
+            }
+            if (row < 2) Spacer(modifier = Modifier.height(4.dp))
+        }
+    }
+}
+
+@Composable
+private fun GridCell(
+    label: String,
+    isCenter: Boolean,
+    showMarker: Boolean,
+    modifier: Modifier = Modifier
+) {
+    Box(
+        contentAlignment = Alignment.Center,
+        modifier = modifier
+            .aspectRatio(1f)
+            .background(if (isCenter) InfoCyan else GridBlue)
+            .border(1.dp, DividerWhite)
+    ) {
+        Column(horizontalAlignment = Alignment.CenterHorizontally) {
+            Text(
+                text = label,
+                fontSize = if (isCenter) 26.sp else 16.sp,
+                fontWeight = if (isCenter) FontWeight.Bold else FontWeight.Normal,
+                color = LabelBlue,
+                textAlign = TextAlign.Center
+            )
+            if (showMarker) {
+                Spacer(modifier = Modifier.height(4.dp))
+                Box(
+                    modifier = Modifier
+                        .size(12.dp)
+                        .background(PositionRed)
+                        .border(2.dp, DividerWhite)
+                )
+            }
+        }
+    }
+}
+
+private fun formatDms(value: Double, isLat: Boolean): String {
+    val abs = kotlin.math.abs(value)
+    val deg = abs.toInt()
+    val minFull = (abs - deg) * 60
+    val min = minFull.toInt()
+    val sec = ((minFull - min) * 60).toInt()
+    val hemi = if (value >= 0) (if (isLat) "N" else "E") else (if (isLat) "S" else "W")
+    return "$deg° $min' $sec\" $hemi"
+}
+
+private fun formatDecimal(value: Double): String = String.format("%.5f", value)

feature/roaming/src/main/java/com/rtbishop/look4sat/feature/roaming/RoamingViewModel.kt

@@ -0,0 +1,83 @@
+/*
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.rtbishop.look4sat.feature.roaming
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import androidx.lifecycle.viewmodel.initializer
+import androidx.lifecycle.viewmodel.viewModelFactory
+import com.rtbishop.look4sat.core.domain.predict.GeoPos
+import com.rtbishop.look4sat.core.domain.repository.IMainContainer
+import com.rtbishop.look4sat.core.domain.repository.ISettingsRepo
+import com.rtbishop.look4sat.core.domain.utility.positionToQth
+import com.rtbishop.look4sat.core.domain.utility.qthNeighbors
+import com.rtbishop.look4sat.core.domain.utility.qthToSquare
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.update
+import kotlinx.coroutines.launch
+
+data class RoamingState(
+    val latitude: Double = 0.0,
+    val longitude: Double = 0.0,
+    val altitude: Double = 0.0,
+    val qthLocator: String = "----",
+    val gridSquares: List<String> = List(9) { "----" },
+    val isUpdating: Boolean = false,
+    val messageResId: Int = 0
+)
+
+class RoamingViewModel(private val settingsRepo: ISettingsRepo) : ViewModel() {
+
+    private val _uiState = MutableStateFlow(RoamingState())
+    val uiState: StateFlow<RoamingState> = _uiState
+
+    init {
+        viewModelScope.launch {
+            settingsRepo.stationPosition.collect { geoPos ->
+                _uiState.update { it.copy(isUpdating = false, messageResId = 0).withPosition(geoPos) }
+            }
+        }
+    }
+
+    fun onGpsClick() {
+        val success = settingsRepo.setStationPosition()
+        if (success) {
+            _uiState.update { it.copy(isUpdating = true) }
+        }
+    }
+
+    private fun RoamingState.withPosition(pos: GeoPos): RoamingState {
+        val locator = positionToQth(pos.latitude, pos.longitude) ?: return copy(qthLocator = "----")
+        val square = qthToSquare(locator)
+        val squares = if (square != "----") qthNeighbors(square) else List(9) { "----" }
+        return copy(
+            latitude = pos.latitude,
+            longitude = pos.longitude,
+            altitude = pos.altitude,
+            qthLocator = locator,
+            gridSquares = squares
+        )
+    }
+
+    companion object {
+        fun factory(container: IMainContainer) = viewModelFactory {
+            initializer { RoamingViewModel(container.settingsRepo) }
+        }
+    }
+}

feature/settings/src/main/java/com/rtbishop/look4sat/feature/settings/SettingsScreen.kt

@@ -339,6 +339,8 @@ private fun LocationCard(
             Row(horizontalArrangement = Arrangement.SpaceBetween, modifier = Modifier.fillMaxWidth()) {
                 Text(text = "Lat: ${settings.stationPos.latitude}°")
                 Text(text = "Lon: ${settings.stationPos.longitude}°")
+            }
+            Row(horizontalArrangement = Arrangement.SpaceBetween, modifier = Modifier.fillMaxWidth()) {
                 Text(text = "Qth: ${settings.stationPos.qthLocator}")
             }
             Spacer(modifier = Modifier.height(1.dp))

gradle.properties

@@ -1,5 +1,6 @@
 # Configure your build environment: http://www.gradle.org/docs/current/userguide/build_environment.html
 org.gradle.caching=true
-org.gradle.jvmargs=-Xmx6g -XX:MaxMetaspaceSize=1g -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF-8
+# NOTE: lowered from -Xmx6g for the 2GB build server; heavy release builds run on GitHub Actions
-org.gradle.parallel=true
+org.gradle.jvmargs=-Xmx768m -XX:MaxMetaspaceSize=256m -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF-8
-org.gradle.workers.max=4
+org.gradle.parallel=false
+org.gradle.workers.max=1

gradle/libs.versions.toml

@@ -1,8 +1,8 @@
 [versions]
 #noinspection UnusedVersionCatalogEntry
-appVersionCode = "443"
+appVersionCode = "446"
 #noinspection UnusedVersionCatalogEntry
-appVersionName = "4.4.3"
+appVersionName = "4.4.6"
 #noinspection UnusedVersionCatalogEntry
 compileSdk = "37"
 #noinspection UnusedVersionCatalogEntry
@@ -11,6 +11,11 @@ minSdk = "24"
 jdkVersion = "21"
 #noinspection UnusedVersionCatalogEntry
 packageName = "com.rtbishop.look4sat"
+# Fork application ID: official app uses com.rtbishop.look4sat with a different
+# signing cert. Installing a fork with the same applicationId would conflict
+# with the official build (signature mismatch / cannot overwrite), so the fork
+# ships under its own applicationId suffix.
+applicationId = "com.rtbishop.look4sat.bg7nta"
 
 android-gradle-plugin = "9.3.1"
 

settings.gradle.kts

@@ -25,6 +25,7 @@ include(
     ":feature:mutual",
     ":feature:passes",
     ":feature:radar",
+    ":feature:roaming",
     ":feature:satellites",
     ":feature:settings"
 )