fix: epoch-millis DB converter + biometric from onResume

Sync change detection:
- DbConverters was using epochSecond but comparisons used epochMilli —
  every file appeared modified on every scan, causing full re-sync each time
- DB migration 2→3 clears sync_file_states (all stored timestamps wrong)
- First sync after upgrade re-learns state; subsequent syncs skip unchanged files

Biometric:
- Move prompt trigger from LaunchedEffect to onResume() — guarantees
  the activity is in RESUMED state when authenticate() is called
- Add bestAuthenticators(): tries BIOMETRIC_STRONG|DEVICE_CREDENTIAL first,
  falls back to BIOMETRIC_WEAK|DEVICE_CREDENTIAL for side-sensor phones
- canAuthenticate() now accepts either strong or weak+credential
- onAuthenticationError always shows Unlock button (no infinite retry loop)
- isLocked/showRetry are Activity-level state, no need for Compose remember

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

app/src/main/kotlin/com/syncflow/MainActivity.kt

@@ -7,6 +7,7 @@ import androidx.activity.enableEdgeToEdge
 import androidx.appcompat.app.AppCompatActivity
 import androidx.biometric.BiometricManager
 import androidx.biometric.BiometricManager.Authenticators.BIOMETRIC_STRONG
+import androidx.biometric.BiometricManager.Authenticators.BIOMETRIC_WEAK
 import androidx.biometric.BiometricManager.Authenticators.DEVICE_CREDENTIAL
 import androidx.biometric.BiometricPrompt
 import androidx.compose.foundation.background
@@ -16,6 +17,7 @@ import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.size
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.Lock
 import androidx.compose.material3.Button
@@ -45,6 +47,7 @@ class MainActivity : AppCompatActivity() {
     @Inject lateinit var appPreferences: AppPreferences
 
     private var isLocked by mutableStateOf(false)
+    private var showRetry by mutableStateOf(false)
 
     override fun onCreate(savedInstanceState: Bundle?) {
         installSplashScreen()
@@ -56,81 +59,81 @@ class MainActivity : AppCompatActivity() {
                     SyncFlowNavGraph(rememberNavController())
                 }
                 if (isLocked) {
-                    var showRetry by remember { mutableStateOf(false) }
                     LockOverlay(
                         showRetry = showRetry,
-                        onRetry = {
+                        onRetry = { triggerBiometric() },
-                            showRetry = false
-                            showBiometricPrompt(
-                                onSuccess = { isLocked = false },
-                                onFailed = { showRetry = true },
-                            )
-                        },
                     )
-                    LaunchedEffect(Unit) {
-                        showBiometricPrompt(
-                            onSuccess = { isLocked = false },
-                            onFailed = { showRetry = true },
-                        )
-                    }
                 }
             }
         }
     }
 
+    override fun onResume() {
+        super.onResume()
+        if (isLocked) triggerBiometric()
+    }
+
     override fun onStop() {
         super.onStop()
         if (isChangingConfigurations) return
         lifecycleScope.launch {
             if (appPreferences.biometricLockEnabled.first() && canAuthenticate()) {
                 isLocked = true
+                showRetry = false
             }
         }
     }
 
-    private fun canAuthenticate(): Boolean {
+    private fun triggerBiometric() {
-        val authenticators = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R)
+        showRetry = false
-            BIOMETRIC_STRONG or DEVICE_CREDENTIAL
+        val authenticators = bestAuthenticators()
-        else
-            BIOMETRIC_STRONG
-        return BiometricManager.from(this).canAuthenticate(authenticators) ==
-            BiometricManager.BIOMETRIC_SUCCESS
-    }
-
-    private fun showBiometricPrompt(onSuccess: () -> Unit, onFailed: () -> Unit) {
         val executor = ContextCompat.getMainExecutor(this)
         val prompt = BiometricPrompt(this, executor, object : BiometricPrompt.AuthenticationCallback() {
             override fun onAuthenticationSucceeded(result: BiometricPrompt.AuthenticationResult) {
-                onSuccess()
+                isLocked = false
+                showRetry = false
             }
             override fun onAuthenticationError(errorCode: Int, errString: CharSequence) {
-                // User cancelled or lockout — re-show the prompt so they can retry
+                // Show the Unlock button so the user can tap to retry manually
-                if (errorCode != BiometricPrompt.ERROR_USER_CANCELED &&
+                showRetry = true
-                    errorCode != BiometricPrompt.ERROR_NEGATIVE_BUTTON) {
-                    showBiometricPrompt(onSuccess, onFailed)
-                } else {
-                    onFailed()
-                }
             }
             override fun onAuthenticationFailed() {
-                // Wrong finger/face — BiometricPrompt handles retries internally, no action needed
+                // Wrong biometric — BiometricPrompt retries automatically
             }
         })
         val promptInfo = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
             BiometricPrompt.PromptInfo.Builder()
                 .setTitle("Unlock SyncFlow")
-                .setSubtitle("Use fingerprint or device PIN")
+                .setSubtitle("Use fingerprint or PIN")
-                .setAllowedAuthenticators(BIOMETRIC_STRONG or DEVICE_CREDENTIAL)
+                .setAllowedAuthenticators(authenticators)
                 .build()
         } else {
             BiometricPrompt.PromptInfo.Builder()
                 .setTitle("Unlock SyncFlow")
-                .setSubtitle("Use fingerprint to continue")
+                .setSubtitle("Use fingerprint")
-                .setNegativeButtonText("Use PIN")
+                .setNegativeButtonText("Cancel")
                 .build()
         }
         prompt.authenticate(promptInfo)
     }
+
+    private fun bestAuthenticators(): Int {
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.R) return BIOMETRIC_STRONG
+        val bm = BiometricManager.from(this)
+        // Prefer strong+credential; fall back to weak+credential so side-sensor phones work
+        return if (bm.canAuthenticate(BIOMETRIC_STRONG or DEVICE_CREDENTIAL) == BiometricManager.BIOMETRIC_SUCCESS)
+            BIOMETRIC_STRONG or DEVICE_CREDENTIAL
+        else
+            BIOMETRIC_WEAK or DEVICE_CREDENTIAL
+    }
+
+    private fun canAuthenticate(): Boolean {
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.R)
+            return BiometricManager.from(this).canAuthenticate(BIOMETRIC_STRONG) == BiometricManager.BIOMETRIC_SUCCESS
+        val bm = BiometricManager.from(this)
+        return bm.canAuthenticate(BIOMETRIC_STRONG or DEVICE_CREDENTIAL) == BiometricManager.BIOMETRIC_SUCCESS ||
+            bm.canAuthenticate(BIOMETRIC_WEAK or DEVICE_CREDENTIAL) == BiometricManager.BIOMETRIC_SUCCESS
+    }
 }
 
 @Composable
@@ -143,18 +146,18 @@ private fun LockOverlay(showRetry: Boolean, onRetry: () -> Unit) {
     ) {
         Column(
             horizontalAlignment = Alignment.CenterHorizontally,
-            verticalArrangement = Arrangement.Center,
+            verticalArrangement = Arrangement.spacedBy(12.dp),
         ) {
-            Icon(Icons.Default.Lock, null, modifier = Modifier.height(48.dp), tint = MaterialTheme.colorScheme.primary)
+            Icon(Icons.Default.Lock, null, modifier = Modifier.size(56.dp), tint = MaterialTheme.colorScheme.primary)
-            Spacer(Modifier.height(16.dp))
             Text("SyncFlow is locked", style = MaterialTheme.typography.titleMedium)
-            Spacer(Modifier.height(8.dp))
             if (showRetry) {
-                Spacer(Modifier.height(8.dp))
                 Button(onClick = onRetry) { Text("Unlock") }
             } else {
-                Text("Use fingerprint or PIN to unlock", style = MaterialTheme.typography.bodySmall,
+                Text(
-                    color = MaterialTheme.colorScheme.onSurfaceVariant)
+                    "Use fingerprint or PIN to unlock",
+                    style = MaterialTheme.typography.bodySmall,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                )
             }
         }
     }

app/src/main/kotlin/com/syncflow/data/db/DbConverters.kt

@@ -4,6 +4,6 @@ import androidx.room.TypeConverter
 import java.time.Instant
 
 class DbConverters {
-    @TypeConverter fun fromInstant(v: Instant?): Long? = v?.epochSecond
+    @TypeConverter fun fromInstant(v: Instant?): Long? = v?.toEpochMilli()
-    @TypeConverter fun toInstant(v: Long?): Instant? = v?.let { Instant.ofEpochSecond(it) }
+    @TypeConverter fun toInstant(v: Long?): Instant? = v?.let { Instant.ofEpochMilli(it) }
 }

app/src/main/kotlin/com/syncflow/data/db/SyncDatabase.kt

@@ -3,6 +3,8 @@ package com.syncflow.data.db
 import androidx.room.Database
 import androidx.room.RoomDatabase
 import androidx.room.TypeConverters
+import androidx.room.migration.Migration
+import androidx.sqlite.db.SupportSQLiteDatabase
 import com.syncflow.data.db.entities.*
 
 @Database(
@@ -13,11 +15,21 @@ import com.syncflow.data.db.entities.*
         SyncConflictEntity::class,
         SyncEventEntity::class,
     ],
-    version = 2,
+    version = 3,
     exportSchema = true,
 )
 @TypeConverters(DbConverters::class)
 abstract class SyncDatabase : RoomDatabase() {
+
+    companion object {
+        // Wipe file states: timestamps were stored as epoch-seconds, now epoch-millis.
+        // All previously saved states are wrong so we drop and re-learn on next sync.
+        val MIGRATION_2_3 = object : Migration(2, 3) {
+            override fun migrate(db: SupportSQLiteDatabase) {
+                db.execSQL("DELETE FROM sync_file_states")
+            }
+        }
+    }
     abstract fun cloudAccountDao(): CloudAccountDao
     abstract fun syncPairDao(): SyncPairDao
     abstract fun syncFileStateDao(): SyncFileStateDao

app/src/main/kotlin/com/syncflow/di/AppModule.kt

@@ -21,9 +21,8 @@ object AppModule {
     @Provides @Singleton
     fun provideDatabase(@ApplicationContext ctx: Context): SyncDatabase =
         Room.databaseBuilder(ctx, SyncDatabase::class.java, "syncflow.db")
-            // Only fall back to destructive migration for very old dev builds (v1).
-            // All future version bumps must include a proper Migration object.
             .fallbackToDestructiveMigrationFrom(1)
+            .addMigrations(SyncDatabase.MIGRATION_2_3)
             .build()
 
     @Provides fun provideCloudAccountDao(db: SyncDatabase): CloudAccountDao = db.cloudAccountDao()

version.properties

@@ -1,2 +1,2 @@
-VERSION_NAME=1.0.4
+VERSION_NAME=1.0.5
-VERSION_CODE=5
+VERSION_CODE=6