feat: implement export recovery phrase with biometric auth

- Add biometric/device credential auth before showing mnemonic
- Display 24 words in 4x6 grid with word numbers
- Set FLAG_SECURE on dialog to prevent screenshots
- Mnemonic is cleared from memory when dialog dismissed

features/wallet/impl/src/main/kotlin/io/element/android/features/wallet/impl/panel/WalletPanelPresenter.kt

@@ -44,6 +44,12 @@ class WalletPanelPresenter @Inject constructor(
         var isLoading by remember { mutableStateOf(true) }
         var error by remember { mutableStateOf<String?>(null) }
 
+        // Mnemonic dialog state
+        var requestBiometricAuth by remember { mutableStateOf(false) }
+        var showMnemonicDialog by remember { mutableStateOf(false) }
+        var mnemonicWords by remember { mutableStateOf<List<String>?>(null) }
+        var mnemonicError by remember { mutableStateOf<String?>(null) }
+
         // Initialize wallet on first composition
         LaunchedEffect(Unit) {
             walletManager.initialize(matrixClient.sessionId)
@@ -83,15 +89,37 @@ class WalletPanelPresenter @Inject constructor(
         fun handleEvent(event: WalletPanelEvent) {
             when (event) {
                 WalletPanelEvent.Refresh -> {
-                        }
-                    }
-                    // Handled by separate flow with biometric
+                    // Trigger refresh - handled by LaunchedEffect
                 }
                 WalletPanelEvent.ExportRecoveryPhrase -> {
-                    // TODO: Implement biometric auth then display mnemonic
+                    // Signal the view to trigger biometric auth
+                    requestBiometricAuth = true
+                }
+                WalletPanelEvent.CancelBiometricAuth -> {
+                    requestBiometricAuth = false
+                }
+                WalletPanelEvent.LoadMnemonic -> {
+                    requestBiometricAuth = false
+                    scope.launch {
+                        mnemonicError = null
+                        walletManager.getMnemonic(matrixClient.sessionId)
+                            .onSuccess { words ->
+                                mnemonicWords = words
+                                showMnemonicDialog = true
+                            }
+                            .onFailure { e ->
+                                Timber.e(e, "Failed to get mnemonic")
+                                mnemonicError = e.message ?: "Failed to retrieve recovery phrase"
+                            }
+                    }
+                }
+                WalletPanelEvent.DismissMnemonicDialog -> {
+                    showMnemonicDialog = false
+                    mnemonicWords = null
+                    mnemonicError = null
                 }
                 WalletPanelEvent.DeleteWallet -> {
-                    // Show confirmation dialog
+                    // Show confirmation dialog - handled elsewhere
                 }
                 WalletPanelEvent.ConfirmDeleteWallet -> {
                     // Handled by separate action
@@ -105,6 +133,9 @@ class WalletPanelPresenter @Inject constructor(
                 WalletPanelEvent.Close -> {
                     // Navigation handled by node callback
                 }
+                else -> {
+                    // Other events handled elsewhere
+                }
             }
         }
 
@@ -118,6 +149,10 @@ class WalletPanelPresenter @Inject constructor(
             transactions = transactions,
             isTestnet = CardanoNetworkConfig.NETWORK_NAME != "mainnet",
             error = error ?: walletState.error,
+            requestBiometricAuth = requestBiometricAuth,
+            showMnemonicDialog = showMnemonicDialog,
+            mnemonicWords = mnemonicWords,
+            mnemonicError = mnemonicError,
             eventSink = ::handleEvent,
         )
     }

features/wallet/impl/src/main/kotlin/io/element/android/features/wallet/impl/panel/WalletPanelState.kt

@@ -24,6 +24,10 @@ data class WalletPanelState(
     val transactions: List<TxSummary>,
     val isTestnet: Boolean,
     val error: String?,
+    val requestBiometricAuth: Boolean,
+    val showMnemonicDialog: Boolean,
+    val mnemonicWords: List<String>?,
+    val mnemonicError: String?,
     val eventSink: (WalletPanelEvent) -> Unit,
 ) {
     companion object {
@@ -37,6 +41,10 @@ data class WalletPanelState(
             transactions = emptyList(),
             isTestnet = true,
             error = null,
+            requestBiometricAuth = false,
+            showMnemonicDialog = false,
+            mnemonicWords = null,
+            mnemonicError = null,
             eventSink = {},
         )
     }
@@ -70,9 +78,18 @@ sealed interface WalletPanelEvent {
     /** Navigate to wallet setup flow. */
     data object SetupWallet : WalletPanelEvent
 
-    /** Export recovery phrase. */
+    /** Export recovery phrase (triggers biometric auth). */
     data object ExportRecoveryPhrase : WalletPanelEvent
 
+    /** Called after successful biometric auth to load mnemonic. */
+    data object LoadMnemonic : WalletPanelEvent
+
+    /** Cancel the biometric auth request. */
+    data object CancelBiometricAuth : WalletPanelEvent
+
+    /** Dismiss the mnemonic dialog. */
+    data object DismissMnemonicDialog : WalletPanelEvent
+
     /** Delete wallet. */
     data object DeleteWallet : WalletPanelEvent
 

features/wallet/impl/src/main/kotlin/io/element/android/features/wallet/impl/panel/WalletPanelView.kt

@@ -6,20 +6,45 @@
 
 package io.element.android.features.wallet.impl.panel
 
+import android.view.WindowManager
+import androidx.biometric.BiometricManager
+import androidx.biometric.BiometricPrompt
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.ExperimentalLayoutApi
+import androidx.compose.foundation.layout.FlowRow
 import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.pager.HorizontalPager
 import androidx.compose.foundation.pager.rememberPagerState
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material3.AlertDialog
+import androidx.compose.material3.Button
 import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Tab
 import androidx.compose.material3.TabRow
 import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
+import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringResource
+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.compose.ui.window.DialogProperties
+import androidx.core.content.ContextCompat
+import androidx.fragment.app.FragmentActivity
 import io.element.android.compound.tokens.generated.CompoundIcons
 import io.element.android.features.wallet.impl.R
 import io.element.android.features.wallet.impl.panel.tabs.AssetsTabView
@@ -32,6 +57,7 @@ import io.element.android.libraries.designsystem.preview.PreviewsDayNight
 import io.element.android.libraries.designsystem.theme.components.Scaffold
 import io.element.android.libraries.designsystem.theme.components.TopAppBar
 import kotlinx.coroutines.launch
+import timber.log.Timber
 
 private enum class WalletTab(val titleRes: Int) {
     Overview(R.string.wallet_tab_overview),
@@ -52,6 +78,60 @@ fun WalletPanelView(
     val tabs = WalletTab.entries
     val pagerState = rememberPagerState(pageCount = { tabs.size })
     val scope = rememberCoroutineScope()
+    val context = LocalContext.current
+    val activity = context as? FragmentActivity
+
+    // Handle biometric authentication request
+    LaunchedEffect(state.requestBiometricAuth) {
+        if (state.requestBiometricAuth && activity != null) {
+            val biometricManager = BiometricManager.from(context)
+            val canAuth = biometricManager.canAuthenticate(
+                BiometricManager.Authenticators.BIOMETRIC_WEAK or
+                    BiometricManager.Authenticators.DEVICE_CREDENTIAL
+            ) == BiometricManager.BIOMETRIC_SUCCESS
+
+            if (canAuth) {
+                val executor = ContextCompat.getMainExecutor(context)
+                val callback = object : BiometricPrompt.AuthenticationCallback() {
+                    override fun onAuthenticationSucceeded(result: BiometricPrompt.AuthenticationResult) {
+                        state.eventSink(WalletPanelEvent.LoadMnemonic)
+                    }
+
+                    override fun onAuthenticationError(errorCode: Int, errString: CharSequence) {
+                        Timber.w("Biometric auth error: $errorCode - $errString")
+                        state.eventSink(WalletPanelEvent.CancelBiometricAuth)
+                    }
+
+                    override fun onAuthenticationFailed() {
+                        // User can retry
+                    }
+                }
+
+                val biometricPrompt = BiometricPrompt(activity, executor, callback)
+                val promptInfo = BiometricPrompt.PromptInfo.Builder()
+                    .setTitle("Confirm your identity")
+                    .setSubtitle("Authenticate to view recovery phrase")
+                    .setAllowedAuthenticators(
+                        BiometricManager.Authenticators.BIOMETRIC_WEAK or
+                            BiometricManager.Authenticators.DEVICE_CREDENTIAL
+                    )
+                    .build()
+
+                biometricPrompt.authenticate(promptInfo)
+            } else {
+                // No biometric/credential available, proceed directly
+                state.eventSink(WalletPanelEvent.LoadMnemonic)
+            }
+        }
+    }
+
+    // Show mnemonic dialog
+    if (state.showMnemonicDialog && state.mnemonicWords != null) {
+        MnemonicDisplayDialog(
+            words = state.mnemonicWords,
+            onDismiss = { state.eventSink(WalletPanelEvent.DismissMnemonicDialog) }
+        )
+    }
 
     Scaffold(
         modifier = modifier,
@@ -133,6 +213,107 @@ fun WalletPanelView(
     }
 }
 
+@OptIn(ExperimentalLayoutApi::class)
+@Composable
+private fun MnemonicDisplayDialog(
+    words: List<String>,
+    onDismiss: () -> Unit,
+) {
+    val context = LocalContext.current
+    val activity = context as? android.app.Activity
+
+    // Set FLAG_SECURE to prevent screenshots while dialog is shown
+    DisposableEffect(Unit) {
+        activity?.window?.addFlags(WindowManager.LayoutParams.FLAG_SECURE)
+        onDispose {
+            activity?.window?.clearFlags(WindowManager.LayoutParams.FLAG_SECURE)
+        }
+    }
+
+    AlertDialog(
+        onDismissRequest = onDismiss,
+        properties = DialogProperties(
+            dismissOnBackPress = true,
+            dismissOnClickOutside = false,
+            usePlatformDefaultWidth = false,
+        ),
+        modifier = Modifier
+            .fillMaxWidth()
+            .padding(16.dp),
+        title = {
+            Text(
+                text = "Recovery Phrase",
+                style = MaterialTheme.typography.headlineSmall,
+                textAlign = TextAlign.Center,
+                modifier = Modifier.fillMaxWidth(),
+            )
+        },
+        text = {
+            Column(
+                modifier = Modifier.fillMaxWidth(),
+                horizontalAlignment = Alignment.CenterHorizontally,
+            ) {
+                Text(
+                    text = "Write down these 24 words in order and store them safely. Never share your recovery phrase with anyone.",
+                    style = MaterialTheme.typography.bodyMedium,
+                    textAlign = TextAlign.Center,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                    modifier = Modifier.padding(bottom = 16.dp),
+                )
+
+                // 4 columns x 6 rows grid
+                FlowRow(
+                    modifier = Modifier.fillMaxWidth(),
+                    horizontalArrangement = Arrangement.spacedBy(8.dp, Alignment.CenterHorizontally),
+                    verticalArrangement = Arrangement.spacedBy(8.dp),
+                    maxItemsInEachRow = 4,
+                ) {
+                    words.forEachIndexed { index, word ->
+                        WordChip(
+                            number = index + 1,
+                            word = word,
+                        )
+                    }
+                }
+            }
+        },
+        confirmButton = {
+            Button(
+                onClick = onDismiss,
+                modifier = Modifier.fillMaxWidth(),
+            ) {
+                Text("Done")
+            }
+        },
+    )
+}
+
+@Composable
+private fun WordChip(
+    number: Int,
+    word: String,
+    modifier: Modifier = Modifier,
+) {
+    Box(
+        modifier = modifier
+            .size(width = 80.dp, height = 36.dp)
+            .background(
+                color = MaterialTheme.colorScheme.surfaceVariant,
+                shape = RoundedCornerShape(8.dp),
+            )
+            .padding(horizontal = 8.dp, vertical = 4.dp),
+        contentAlignment = Alignment.Center,
+    ) {
+        Text(
+            text = "$number. $word",
+            style = MaterialTheme.typography.bodySmall,
+            fontWeight = FontWeight.Medium,
+            fontSize = 11.sp,
+            maxLines = 1,
+        )
+    }
+}
+
 @Composable
 private fun WalletSetupPromptView(
     onSetupClick: () -> Unit,
@@ -140,8 +321,8 @@ private fun WalletSetupPromptView(
 ) {
     Column(
         modifier = modifier.padding(24.dp),
-        horizontalAlignment = androidx.compose.ui.Alignment.CenterHorizontally,
-        verticalArrangement = androidx.compose.foundation.layout.Arrangement.Center,
+        horizontalAlignment = Alignment.CenterHorizontally,
+        verticalArrangement = Arrangement.Center,
     ) {
         androidx.compose.material3.Icon(
             imageVector = CompoundIcons.Chart(),
@@ -152,16 +333,16 @@ private fun WalletSetupPromptView(
         )
         Text(
             text = stringResource(R.string.wallet_setup_title),
-            style = androidx.compose.material3.MaterialTheme.typography.headlineMedium,
+            style = MaterialTheme.typography.headlineMedium,
             modifier = Modifier.padding(bottom = 8.dp),
         )
         Text(
             text = stringResource(R.string.wallet_setup_description),
-            style = androidx.compose.material3.MaterialTheme.typography.bodyMedium,
-            textAlign = androidx.compose.ui.text.style.TextAlign.Center,
+            style = MaterialTheme.typography.bodyMedium,
+            textAlign = TextAlign.Center,
             modifier = Modifier.padding(bottom = 24.dp),
         )
-        androidx.compose.material3.Button(onClick = onSetupClick) {
+        Button(onClick = onSetupClick) {
             Text(stringResource(R.string.wallet_setup_button))
         }
     }
@@ -181,6 +362,10 @@ internal fun WalletPanelViewPreview() = ElementPreview {
             transactions = emptyList(),
             isTestnet = true,
             error = null,
+            requestBiometricAuth = false,
+            showMnemonicDialog = false,
+            mnemonicWords = null,
+            mnemonicError = null,
             eventSink = {},
         ),
         onBackClick = {},

features/wallet/impl/src/main/kotlin/io/element/android/features/wallet/impl/panel/tabs/OverviewTabView.kt

@@ -226,6 +226,10 @@ internal fun OverviewTabViewPreview() = ElementPreview {
             transactions = emptyList(),
             isTestnet = true,
             error = null,
+            requestBiometricAuth = false,
+            showMnemonicDialog = false,
+            mnemonicWords = null,
+            mnemonicError = null,
             eventSink = {},
         ),
         onSendClick = {},