feat(data): persist ndot and protect manually imported transceivers

- DB v2 migration: entries.ndot column so hasDecayed() actually works after
  reload (parsed ndot was dropped on write, making the decay detection dead
  code); radios.isCustom column to mark manually imported transceivers.
- updateTransceiversFromFile marks imported radios isCustom=true; remote
  updates now deleteManagedRadios() then insert the fresh snapshot, keeping
  manual imports (no source can refresh them, so nothing would bring them back).
- Wire MIGRATION_1_2 into MainContainer (fallbackToDestructiveMigration=false
  would otherwise crash on upgrade).

core/data/src/main/java/com/rtbishop/look4sat/core/data/database/Look4SatDao.kt

@@ -60,4 +60,7 @@ interface Look4SatDao {
 
     @Query("DELETE FROM radios")
     suspend fun deleteRadios()
+
+    @Query("DELETE FROM radios WHERE isCustom = 0")
+    suspend fun deleteManagedRadios()
 }

core/data/src/main/java/com/rtbishop/look4sat/core/data/database/Look4SatDb.kt

@@ -19,19 +19,21 @@ package com.rtbishop.look4sat.core.data.database
 
 import androidx.room.Database
 import androidx.room.RoomDatabase
+import androidx.room.migration.Migration
+import androidx.sqlite.db.SupportSQLiteDatabase
 import com.rtbishop.look4sat.core.data.database.entity.SatEntry
 import com.rtbishop.look4sat.core.data.database.entity.SatRadio
 
-@Database(entities = [SatEntry::class, SatRadio::class], version = 1, exportSchema = false)
+@Database(entities = [SatEntry::class, SatRadio::class], version = 2, exportSchema = false)
 abstract class Look4SatDb : RoomDatabase() {
     abstract fun look4SatDao(): Look4SatDao
 }
 
-//val MIGRATION_1_2 = object : Migration(1, 2) {
-//    override fun migrate(database: SupportSQLiteDatabase) {
-//        database.execSQL("CREATE TABLE entries_backup (name TEXT NOT NULL, epoch REAL NOT NULL, meanmo REAL NOT NULL, eccn REAL NOT NULL, incl REAL NOT NULL, raan REAL NOT NULL, argper REAL NOT NULL, meanan REAL NOT NULL, catnum INTEGER NOT NULL, bstar REAL NOT NULL, xincl REAL NOT NULL, xnodeo REAL NOT NULL, omegao REAL NOT NULL, xmo REAL NOT NULL, xno REAL NOT NULL, orbitalPeriod REAL NOT NULL, isDeepSpace INTEGER NOT NULL, comment TEXT, PRIMARY KEY(catnum))")
-//        database.execSQL("INSERT INTO entries_backup (name, epoch, meanmo, eccn, incl, raan, argper, meanan, catnum, bstar, xincl, xnodeo, omegao, xmo, xno, orbitalPeriod, isDeepSpace, comment) SELECT name, epoch, meanmo, eccn, incl, raan, argper, meanan, catnum, bstar, xincl, xnodeo, omegao, xmo, xno, 1440 / meanmo, 1440 / meanmo >= 225.0, comment FROM entries")
-//        database.execSQL("DROP TABLE entries")
-//        database.execSQL("ALTER TABLE entries_backup RENAME TO entries")
-//    }
-//}
+/** Adds the mean motion derivative, needed to tell decayed satellites apart, and marks the
+ * transceivers that were imported from a file, so that remote updates leave them alone. */
+val MIGRATION_1_2 = object : Migration(1, 2) {
+    override fun migrate(db: SupportSQLiteDatabase) {
+        db.execSQL("ALTER TABLE entries ADD COLUMN ndot REAL NOT NULL DEFAULT 0.0")
+        db.execSQL("ALTER TABLE radios ADD COLUMN isCustom INTEGER NOT NULL DEFAULT 0")
+    }
+}

core/data/src/main/java/com/rtbishop/look4sat/core/data/database/entity/SatEntry.kt

@@ -30,5 +30,6 @@ data class SatEntry(
     val argper: Double,
     val meanan: Double,
     val catnum: Int,
-    val bstar: Double
+    val bstar: Double,
+    val ndot: Double = 0.0
 )

core/data/src/main/java/com/rtbishop/look4sat/core/data/database/entity/SatRadio.kt

@@ -32,5 +32,7 @@ data class SatRadio(
     val uplinkHigh: Long?,
     val uplinkMode: String?,
     val isInverted: Boolean,
-    val catnum: Int?
+    val catnum: Int?,
+    /** Set for manually imported transceivers, which remote updates must not replace. */
+    val isCustom: Boolean = false
 )

core/data/src/main/java/com/rtbishop/look4sat/core/data/injection/MainContainer.kt

@@ -24,6 +24,7 @@ import android.hardware.display.DisplayManager
 import android.location.LocationManager
 import androidx.room.Room
 import com.rtbishop.look4sat.core.data.database.Look4SatDb
+import com.rtbishop.look4sat.core.data.database.MIGRATION_1_2
 import com.rtbishop.look4sat.core.data.framework.BluetoothReporter
 import com.rtbishop.look4sat.core.data.framework.Ft817Controller
 import com.rtbishop.look4sat.core.data.framework.Ic705Controller
@@ -167,7 +168,10 @@ class MainContainer(private val context: Context) : IMainContainer {
 
     private fun provideLocalSource(): ILocalSource {
         val builder = Room.databaseBuilder(context, Look4SatDb::class.java, "Look4SatDBv400")
-        val database = builder.fallbackToDestructiveMigration(false).build()
+        val database = builder
+            .addMigrations(MIGRATION_1_2)
+            .fallbackToDestructiveMigration(false)
+            .build()
         return LocalSource(database.look4SatDao())
     }
 

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

@@ -58,7 +58,7 @@ class DatabaseRepo(
         var importedCount = 0
         remoteSource.getFileStream(uri)?.let { stream ->
             val transceivers = dataParser.parseJSONStream(unwrapIfZipped(uri, stream))
-            localSource.insertRadios(transceivers)
+            localSource.insertRadios(transceivers, isCustom = true)
             importedCount = transceivers.size
         }
         setUpdateSuccessful(System.currentTimeMillis())
@@ -105,9 +105,16 @@ class DatabaseRepo(
             val normUrl = normalizeUrl(rawUrl)
             result.stream?.let { dataParser.parseJSONStream(unwrapIfZipped(normUrl, it)) }.orEmpty()
         }.filter { it.uuid.isNotBlank() }.distinctBy { it.uuid }
-        // insert parsed data into the database
-        localSource.insertEntries(importedEntries)
-        localSource.insertRadios(importedRadios)
+        // insert parsed data into the database.
+        // Transceivers are a full snapshot: sources publish active entries only, so a retired
+        // transceiver simply disappears from the feed and has to be dropped locally as well.
+        // Manually imported ones (isCustom) are kept: no source can refresh them, so nothing
+        // would bring them back if they were replaced here.
+        if (importedRadios.isNotEmpty()) {
+            localSource.deleteManagedRadios()
+            localSource.insertRadios(importedRadios)
+        }
+        if (importedEntries.isNotEmpty()) localSource.insertEntries(importedEntries)
         setUpdateSuccessful(System.currentTimeMillis())
     }
 

core/data/src/main/java/com/rtbishop/look4sat/core/data/source/LocalSource.kt

@@ -51,12 +51,12 @@ class LocalSource(private val look4SatDao: Look4SatDao) : ILocalSource {
 
     private fun FrameworkEntry.toDomain() = OrbitalData(
         this.name, this.epoch, this.meanmo, this.eccn, this.incl,
-        this.raan, this.argper, this.meanan, this.catnum, this.bstar
+        this.raan, this.argper, this.meanan, this.catnum, this.bstar, this.ndot
     )
 
     private fun OrbitalData.toEntity() = FrameworkEntry(
         this.name, this.epoch, this.meanmo, this.eccn, this.incl,
-        this.raan, this.argper, this.meanan, this.catnum, this.bstar
+        this.raan, this.argper, this.meanan, this.catnum, this.bstar, this.ndot
     )
 
     private fun List<OrbitalData>.toEntity() = this.map { item -> item.toEntity() }
@@ -73,20 +73,22 @@ class LocalSource(private val look4SatDao: Look4SatDao) : ILocalSource {
         return look4SatDao.getRadiosWithId(id).toDomainRadios()
     }
 
-    override suspend fun insertRadios(radios: List<SatRadio>) {
-        look4SatDao.insertRadios(radios.toFrameworkRadios())
+    override suspend fun insertRadios(radios: List<SatRadio>, isCustom: Boolean) {
+        look4SatDao.insertRadios(radios.map { it.copy(isCustom = isCustom) }.toFrameworkRadios())
     }
 
+    override suspend fun deleteManagedRadios() = look4SatDao.deleteManagedRadios()
+
     override suspend fun deleteRadios() = look4SatDao.deleteRadios()
 
     private fun DomainRadio.toFramework() = FrameworkRadio(
         this.uuid, this.info, this.isAlive, this.downlinkLow, this.downlinkHigh, this.downlinkMode,
-        this.uplinkLow, this.uplinkHigh, this.uplinkMode, this.isInverted, this.catnum
+        this.uplinkLow, this.uplinkHigh, this.uplinkMode, this.isInverted, this.catnum, this.isCustom
     )
 
     private fun FrameworkRadio.toDomain() = DomainRadio(
         this.uuid, this.info, this.isAlive, this.downlinkLow, this.downlinkHigh, this.downlinkMode,
-        this.uplinkLow, this.uplinkHigh, this.uplinkMode, this.isInverted, this.catnum
+        this.uplinkLow, this.uplinkHigh, this.uplinkMode, this.isInverted, this.catnum, this.isCustom
     )
 
     private fun List<DomainRadio>.toFrameworkRadios() = this.map { radio -> radio.toFramework() }

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

@@ -185,8 +185,12 @@ private class FakeLocalSource : ILocalSource {
 
     override suspend fun getRadiosWithId(id: Int): List<SatRadio> = emptyList()
 
-    override suspend fun insertRadios(radios: List<SatRadio>) {
-        insertedRadios += radios
+    override suspend fun insertRadios(radios: List<SatRadio>, isCustom: Boolean) {
+        insertedRadios += radios.map { it.copy(isCustom = isCustom) }
+    }
+
+    override suspend fun deleteManagedRadios() {
+        insertedRadios.removeAll { !it.isCustom }
     }
 
     override suspend fun deleteRadios() {