feat: relay ping with RTT, server TOFU, lock icons (Phase 2 backport)

Rust JNI:
- nativePingRelay: QUIC connect with 3s timeout, returns RTT + server
  certificate fingerprint as JSON. Static method, no engine needed.

Kotlin:
- WzpEngine.pingRelay() static wrapper
- SettingsRepository: TOFU fingerprint persistence (tofu_{address} keys)
- CallViewModel: pingAllServers() coroutine, lockStatus() helper,
  PingResult/LockStatus data types
- InCallScreen: server chips show lock icon + RTT color (green/yellow),
  "Ping All" button

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/build.yml

@@ -7,6 +7,8 @@ on:
       - 'feat/*'
     tags:
       - 'v*'
+    paths-ignore:
+      - '.gitea/**'
   workflow_dispatch:
 
 env:

android/app/src/main/java/com/wzp/audio/AudioPipeline.kt

@@ -60,6 +60,16 @@ class AudioPipeline(private val context: Context) {
     var debugRecording: Boolean = true
     private var captureThread: Thread? = null
     private var playoutThread: Thread? = null
+
+    // DirectByteBuffers for zero-copy JNI audio transfer.
+    // Allocated as class fields (NOT locals) because ART's JIT OSR
+    // can null local variables when it replaces the stack frame mid-loop.
+    // These survive OSR because they're on the heap.
+    private val captureDirectBuf: ByteBuffer =
+        ByteBuffer.allocateDirect(FRAME_SAMPLES * 2).order(ByteOrder.LITTLE_ENDIAN)
+    private val playoutDirectBuf: ByteBuffer =
+        ByteBuffer.allocateDirect(FRAME_SAMPLES * 2).order(ByteOrder.LITTLE_ENDIAN)
+
     /** Latch counted down by each audio thread after exiting its loop.
      *  stop() does NOT wait on this — teardown waits via awaitDrain(). */
     private var drainLatch: CountDownLatch? = null
@@ -205,8 +215,6 @@ class AudioPipeline(private val context: Context) {
         Log.i(TAG, "capture started: ${SAMPLE_RATE}Hz mono, buf=$bufSize, aec=${aec?.enabled}, ns=${ns?.enabled}")
 
         val pcm = ShortArray(FRAME_SAMPLES)
-        // DirectByteBuffer for zero-copy JNI (avoids ART GC SIGBUS on Android 16)
-        val directBuf = ByteBuffer.allocateDirect(FRAME_SAMPLES * 2).order(ByteOrder.LITTLE_ENDIAN)
         // Debug: PCM file + RMS CSV
         var pcmOut: BufferedOutputStream? = null
         var rmsCsv: OutputStreamWriter? = null
@@ -226,10 +234,10 @@ class AudioPipeline(private val context: Context) {
                 val read = recorder.read(pcm, 0, FRAME_SAMPLES)
                 if (read > 0) {
                     applyGain(pcm, read, captureGainDb)
-                    // Zero-copy write via DirectByteBuffer (no GC array interaction)
-                    directBuf.clear()
-                    directBuf.asShortBuffer().put(pcm, 0, read)
-                    engine.writeAudioDirect(directBuf, read)
+                    // Zero-copy write via DirectByteBuffer (class field, survives JIT OSR)
+                    captureDirectBuf.clear()
+                    captureDirectBuf.asShortBuffer().put(pcm, 0, read)
+                    engine.writeAudioDirect(captureDirectBuf, read)
 
                     // Debug: write raw PCM + RMS
                     if (pcmOut != null) {
@@ -292,8 +300,6 @@ class AudioPipeline(private val context: Context) {
 
         val pcm = ShortArray(FRAME_SAMPLES)
         val silence = ShortArray(FRAME_SAMPLES)
-        // DirectByteBuffer for zero-copy JNI (avoids ART GC SIGBUS on Android 16)
-        val directBuf = ByteBuffer.allocateDirect(FRAME_SAMPLES * 2).order(ByteOrder.LITTLE_ENDIAN)
         // Debug: PCM file + RMS CSV for playout
         var pcmOut: BufferedOutputStream? = null
         var rmsCsv: OutputStreamWriter? = null
@@ -310,14 +316,12 @@ class AudioPipeline(private val context: Context) {
         }
         try {
             while (running) {
-                // Zero-copy read via DirectByteBuffer
-                directBuf.clear()
-                val read = engine.readAudioDirect(directBuf, FRAME_SAMPLES)
-                if (read > 0) {
-                    directBuf.rewind()
-                    directBuf.asShortBuffer().get(pcm, 0, read)
-                }
+                // Zero-copy read via DirectByteBuffer (class field, survives JIT OSR)
+                playoutDirectBuf.clear()
+                val read = engine.readAudioDirect(playoutDirectBuf, FRAME_SAMPLES)
                 if (read >= FRAME_SAMPLES) {
+                    playoutDirectBuf.rewind()
+                    playoutDirectBuf.asShortBuffer().get(pcm, 0, read)
                     applyGain(pcm, read, playoutGainDb)
                     track.write(pcm, 0, read)
 

android/app/src/main/java/com/wzp/data/SettingsRepository.kt

@@ -28,6 +28,8 @@ class SettingsRepository(context: Context) {
         private const val KEY_PREFER_IPV6 = "prefer_ipv6"
         private const val KEY_IDENTITY_SEED = "identity_seed_hex"
         private const val KEY_AEC_ENABLED = "aec_enabled"
+        private const val KEY_RECENT_ROOMS = "recent_rooms"
+        private const val TOFU_PREFIX = "tofu_"
     }
 
     // --- Servers ---
@@ -138,4 +140,43 @@ class SettingsRepository(context: Context) {
     fun saveSeedHex(hex: String) {
         prefs.edit().putString(KEY_IDENTITY_SEED, hex).apply()
     }
+
+    // --- Recent rooms ---
+
+    data class RecentRoom(val relay: String, val room: String)
+
+    fun addRecentRoom(relay: String, room: String) {
+        val rooms = loadRecentRooms().toMutableList()
+        rooms.removeAll { it.relay == relay && it.room == room }
+        rooms.add(0, RecentRoom(relay, room))
+        if (rooms.size > 5) rooms.subList(5, rooms.size).clear()
+        val arr = JSONArray()
+        rooms.forEach { arr.put(JSONObject().apply { put("relay", it.relay); put("room", it.room) }) }
+        prefs.edit().putString(KEY_RECENT_ROOMS, arr.toString()).apply()
+    }
+
+    fun loadRecentRooms(): List<RecentRoom> {
+        val json = prefs.getString(KEY_RECENT_ROOMS, null) ?: return emptyList()
+        return try {
+            val arr = JSONArray(json)
+            (0 until arr.length()).map { i ->
+                val o = arr.getJSONObject(i)
+                RecentRoom(o.getString("relay"), o.getString("room"))
+            }
+        } catch (_: Exception) { emptyList() }
+    }
+
+    fun clearRecentRooms() {
+        prefs.edit().remove(KEY_RECENT_ROOMS).apply()
+    }
+
+    // --- Server fingerprint TOFU ---
+
+    fun saveServerFingerprint(address: String, fingerprint: String) {
+        prefs.edit().putString("$TOFU_PREFIX$address", fingerprint).apply()
+    }
+
+    fun loadServerFingerprint(address: String): String? {
+        return prefs.getString("$TOFU_PREFIX$address", null)
+    }
 }

android/app/src/main/java/com/wzp/engine/WzpEngine.kt

@@ -158,6 +158,15 @@ class WzpEngine(private val callback: WzpCallback) {
         init {
             System.loadLibrary("wzp_android")
         }
+
+        /**
+         * Ping a relay server. Returns JSON `{"rtt_ms":N,"server_fingerprint":"hex"}`
+         * or null if unreachable. Does not require an engine instance.
+         */
+        fun pingRelay(address: String): String? = nativePingRelay(address)
+
+        @JvmStatic
+        private external fun nativePingRelay(relay: String): String?
     }
 }
 

android/app/src/main/java/com/wzp/ui/call/CallViewModel.kt

@@ -12,6 +12,7 @@ import com.wzp.engine.CallStats
 import com.wzp.service.CallService
 import com.wzp.engine.WzpCallback
 import com.wzp.engine.WzpEngine
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.MutableStateFlow
@@ -19,6 +20,8 @@ import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.isActive
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+import org.json.JSONObject
 import java.io.File
 import java.net.Inet4Address
 import java.net.Inet6Address
@@ -26,6 +29,13 @@ import java.net.InetAddress
 
 data class ServerEntry(val address: String, val label: String)
 
+data class PingResult(
+    val rttMs: Int,
+    val serverFingerprint: String,
+)
+
+enum class LockStatus { UNKNOWN, OFFLINE, NEW, VERIFIED, CHANGED }
+
 class CallViewModel : ViewModel(), WzpCallback {
 
     private var engine: WzpEngine? = null
@@ -70,6 +80,16 @@ class CallViewModel : ViewModel(), WzpCallback {
     private val _preferIPv6 = MutableStateFlow(false)
     val preferIPv6: StateFlow<Boolean> = _preferIPv6.asStateFlow()
 
+    private val _recentRooms = MutableStateFlow<List<com.wzp.data.SettingsRepository.RecentRoom>>(emptyList())
+    val recentRooms: StateFlow<List<com.wzp.data.SettingsRepository.RecentRoom>> = _recentRooms.asStateFlow()
+
+    /** Ping results keyed by server address. */
+    private val _pingResults = MutableStateFlow<Map<String, PingResult>>(emptyMap())
+    val pingResults: StateFlow<Map<String, PingResult>> = _pingResults.asStateFlow()
+
+    /** Known server fingerprints (TOFU). */
+    private val _knownFingerprints = MutableStateFlow<Map<String, String>>(emptyMap())
+
     private val _playoutGainDb = MutableStateFlow(0f)
     val playoutGainDb: StateFlow<Float> = _playoutGainDb.asStateFlow()
 
@@ -139,6 +159,7 @@ class CallViewModel : ViewModel(), WzpCallback {
         _captureGainDb.value = s.loadCaptureGain()
         _seedHex.value = s.getOrCreateSeedHex()
         _aecEnabled.value = s.loadAecEnabled()
+        _recentRooms.value = s.loadRecentRooms()
     }
 
     fun selectServer(index: Int) {
@@ -182,6 +203,51 @@ class CallViewModel : ViewModel(), WzpCallback {
         settings?.saveSelectedServer(_selectedServer.value)
     }
 
+    /** Ping all servers in background, update results. */
+    fun pingAllServers() {
+        viewModelScope.launch {
+            val results = mutableMapOf<String, PingResult>()
+            val known = mutableMapOf<String, String>()
+            _servers.value.forEach { server ->
+                val pr = withContext(Dispatchers.IO) {
+                    try {
+                        val json = WzpEngine.pingRelay(server.address) ?: return@withContext null
+                        val obj = JSONObject(json)
+                        PingResult(
+                            rttMs = obj.getInt("rtt_ms"),
+                            serverFingerprint = obj.optString("server_fingerprint", ""),
+                        )
+                    } catch (e: Exception) {
+                        Log.w(TAG, "ping ${server.address} failed: ${e.message}")
+                        null
+                    }
+                }
+                if (pr != null) {
+                    results[server.address] = pr
+                    // TOFU: save fingerprint on first contact
+                    if (pr.serverFingerprint.isNotEmpty()) {
+                        val saved = settings?.loadServerFingerprint(server.address)
+                        if (saved == null) {
+                            settings?.saveServerFingerprint(server.address, pr.serverFingerprint)
+                        }
+                        known[server.address] = saved ?: pr.serverFingerprint
+                    }
+                }
+            }
+            _pingResults.value = results
+            _knownFingerprints.value = known
+        }
+    }
+
+    /** Get lock status for a server. */
+    fun lockStatus(address: String): LockStatus {
+        val pr = _pingResults.value[address] ?: return LockStatus.UNKNOWN
+        val known = _knownFingerprints.value[address]
+        if (pr.serverFingerprint.isEmpty()) return LockStatus.NEW
+        if (known == null) return LockStatus.NEW
+        return if (pr.serverFingerprint == known) LockStatus.VERIFIED else LockStatus.CHANGED
+    }
+
     fun setRoomName(name: String) {
         _roomName.value = name
         settings?.saveRoom(name)
@@ -287,6 +353,8 @@ class CallViewModel : ViewModel(), WzpCallback {
         _debugReportAvailable.value = false
         _debugReportStatus.value = null
         lastCallServer = serverEntry.address
+        settings?.addRecentRoom(serverEntry.address, room)
+        _recentRooms.value = settings?.loadRecentRooms() ?: emptyList()
         debugReporter?.prepareForCall()
         try {
             // Teardown previous call but don't stop the service (we're about to restart it)

android/app/src/main/java/com/wzp/ui/call/InCallScreen.kt

@@ -42,11 +42,13 @@ 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 com.wzp.engine.CallStats
+import com.wzp.ui.call.LockStatus
 import kotlin.math.roundToInt
 
 @OptIn(ExperimentalLayoutApi::class)
@@ -117,18 +119,31 @@ fun InCallScreen(
                     color = MaterialTheme.colorScheme.onSurfaceVariant
                 )
                 Spacer(modifier = Modifier.height(4.dp))
+                val pingResults by viewModel.pingResults.collectAsState()
+
                 FlowRow(
                     modifier = Modifier.fillMaxWidth(),
                     horizontalArrangement = Arrangement.Center
                 ) {
                     servers.forEachIndexed { idx, entry ->
                         val isSelected = selectedServer == idx
+                        val ping = pingResults[entry.address]
+                        val lockStatus = viewModel.lockStatus(entry.address)
+                        val lockIcon = when (lockStatus) {
+                            LockStatus.VERIFIED -> "\uD83D\uDD12" // 🔒
+                            LockStatus.NEW -> "\uD83D\uDD13"      // 🔓
+                            LockStatus.CHANGED -> "⚠\uFE0F"       // ⚠️
+                            LockStatus.OFFLINE -> "\uD83D\uDD34"   // 🔴
+                            LockStatus.UNKNOWN -> ""
+                        }
+                        val rttText = ping?.let { "${it.rttMs}ms" } ?: ""
+
                         FilledTonalIconButton(
                             onClick = { viewModel.selectServer(idx) },
                             modifier = Modifier
                                 .padding(2.dp)
-                                .height(36.dp)
-                                .width(140.dp),
+                                .height(40.dp)
+                                .width(160.dp),
                             shape = RoundedCornerShape(8.dp),
                             colors = if (isSelected) {
                                 IconButtonDefaults.filledTonalIconButtonColors(
@@ -139,11 +154,28 @@ fun InCallScreen(
                                 IconButtonDefaults.filledTonalIconButtonColors()
                             }
                         ) {
-                            Text(
-                                text = entry.label,
-                                style = MaterialTheme.typography.labelSmall,
-                                maxLines = 1
-                            )
+                            Row(verticalAlignment = Alignment.CenterVertically) {
+                                if (lockIcon.isNotEmpty()) {
+                                    Text(text = lockIcon, fontSize = 12.sp)
+                                    Spacer(modifier = Modifier.width(4.dp))
+                                }
+                                Text(
+                                    text = entry.label,
+                                    style = MaterialTheme.typography.labelSmall,
+                                    maxLines = 1
+                                )
+                                if (rttText.isNotEmpty()) {
+                                    Spacer(modifier = Modifier.width(4.dp))
+                                    Text(
+                                        text = rttText,
+                                        style = MaterialTheme.typography.labelSmall.copy(fontSize = 9.sp),
+                                        color = when {
+                                            (ping?.rttMs ?: 0) > 200 -> Color(0xFFFACC15) // yellow
+                                            else -> Color(0xFF4ADE80) // green
+                                        }
+                                    )
+                                }
+                            }
                         }
                     }
                     // + Add button
@@ -151,13 +183,18 @@ fun InCallScreen(
                         onClick = { showAddServerDialog = true },
                         modifier = Modifier
                             .padding(2.dp)
-                            .height(36.dp),
+                            .height(40.dp),
                         shape = RoundedCornerShape(8.dp)
                     ) {
                         Text("+", style = MaterialTheme.typography.labelMedium)
                     }
                 }
 
+                // Ping button
+                TextButton(onClick = { viewModel.pingAllServers() }) {
+                    Text("Ping All", style = MaterialTheme.typography.labelSmall)
+                }
+
                 // IPv4/IPv6 preference
                 Spacer(modifier = Modifier.height(8.dp))
                 Row(
@@ -200,6 +237,36 @@ fun InCallScreen(
                     modifier = Modifier.fillMaxWidth(0.6f)
                 )
 
+                // Recent rooms
+                val recentRooms by viewModel.recentRooms.collectAsState()
+                if (recentRooms.isNotEmpty()) {
+                    Spacer(modifier = Modifier.height(8.dp))
+                    FlowRow(
+                        modifier = Modifier.fillMaxWidth(),
+                        horizontalArrangement = Arrangement.Center
+                    ) {
+                        recentRooms.forEach { recent ->
+                            Surface(
+                                onClick = {
+                                    viewModel.setRoomName(recent.room)
+                                    // Select matching server
+                                    val idx = servers.indexOfFirst { it.address == recent.relay }
+                                    if (idx >= 0) viewModel.selectServer(idx)
+                                },
+                                shape = RoundedCornerShape(16.dp),
+                                color = MaterialTheme.colorScheme.surfaceVariant,
+                                modifier = Modifier.padding(2.dp)
+                            ) {
+                                Text(
+                                    text = recent.room,
+                                    style = MaterialTheme.typography.labelSmall,
+                                    modifier = Modifier.padding(horizontal = 12.dp, vertical = 4.dp)
+                                )
+                            }
+                        }
+                    }
+                }
+
                 Spacer(modifier = Modifier.height(24.dp))
 
                 Button(
@@ -262,11 +329,33 @@ fun InCallScreen(
                         color = MaterialTheme.colorScheme.onSurfaceVariant
                     )
                     unique.forEach { member ->
-                        Text(
-                            text = member.displayName,
-                            style = MaterialTheme.typography.labelSmall,
-                            color = MaterialTheme.colorScheme.onSurfaceVariant
-                        )
+                        Row(
+                            verticalAlignment = Alignment.CenterVertically,
+                            modifier = Modifier.padding(vertical = 2.dp)
+                        ) {
+                            com.wzp.ui.components.Identicon(
+                                fingerprint = member.fingerprint.ifEmpty { member.displayName },
+                                size = 28.dp,
+                            )
+                            Spacer(modifier = Modifier.width(8.dp))
+                            Column {
+                                Text(
+                                    text = member.displayName,
+                                    style = MaterialTheme.typography.labelSmall,
+                                    color = MaterialTheme.colorScheme.onSurfaceVariant
+                                )
+                                if (member.fingerprint.isNotEmpty()) {
+                                    com.wzp.ui.components.CopyableFingerprint(
+                                        fingerprint = member.fingerprint.take(16),
+                                        style = MaterialTheme.typography.labelSmall.copy(
+                                            fontSize = 9.sp,
+                                            fontFamily = FontFamily.Monospace,
+                                        ),
+                                        color = MaterialTheme.colorScheme.onSurfaceVariant.copy(alpha = 0.6f),
+                                    )
+                                }
+                            }
+                        }
                     }
                 }
 

android/app/src/main/java/com/wzp/ui/components/Identicon.kt

@@ -0,0 +1,141 @@
+package com.wzp.ui.components
+
+import android.widget.Toast
+import androidx.compose.foundation.Canvas
+import androidx.compose.foundation.clickable
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.geometry.Size
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.platform.LocalClipboardManager
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.text.AnnotatedString
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.dp
+import kotlin.math.min
+
+/**
+ * Deterministic identicon — generates a unique 5x5 symmetric pattern
+ * from a hex fingerprint string. Identical algorithm to the desktop
+ * TypeScript implementation in identicon.ts.
+ */
+@Composable
+fun Identicon(
+    fingerprint: String,
+    size: Dp = 36.dp,
+    clickToCopy: Boolean = true,
+    modifier: Modifier = Modifier,
+) {
+    val clipboard = LocalClipboardManager.current
+    val context = LocalContext.current
+    val bytes = hashBytes(fingerprint)
+    val (bg, fg) = deriveColors(bytes)
+    val grid = buildGrid(bytes)
+
+    Canvas(
+        modifier = modifier
+            .size(size)
+            .clip(RoundedCornerShape(size * 0.12f))
+            .then(
+                if (clickToCopy && fingerprint.isNotEmpty()) {
+                    Modifier.clickable {
+                        clipboard.setText(AnnotatedString(fingerprint))
+                        Toast.makeText(context, "Copied", Toast.LENGTH_SHORT).show()
+                    }
+                } else Modifier
+            )
+    ) {
+        val cellW = this.size.width / 5f
+        val cellH = this.size.height / 5f
+
+        // Background
+        drawRect(color = bg, size = this.size)
+
+        // Foreground cells
+        for (y in 0 until 5) {
+            for (x in 0 until 5) {
+                if (grid[y][x]) {
+                    drawRect(
+                        color = fg,
+                        topLeft = Offset(x * cellW, y * cellH),
+                        size = Size(cellW, cellH),
+                    )
+                }
+            }
+        }
+    }
+}
+
+/**
+ * Fingerprint text that copies to clipboard on tap.
+ */
+@Composable
+fun CopyableFingerprint(
+    fingerprint: String,
+    modifier: Modifier = Modifier,
+    style: androidx.compose.ui.text.TextStyle = androidx.compose.material3.MaterialTheme.typography.bodySmall,
+    color: Color = Color.Unspecified,
+) {
+    val clipboard = LocalClipboardManager.current
+    val context = LocalContext.current
+
+    androidx.compose.material3.Text(
+        text = fingerprint,
+        style = style,
+        color = color,
+        modifier = modifier.clickable {
+            if (fingerprint.isNotEmpty()) {
+                clipboard.setText(AnnotatedString(fingerprint))
+                Toast.makeText(context, "Fingerprint copied", Toast.LENGTH_SHORT).show()
+            }
+        }
+    )
+}
+
+// --- Internal helpers (matching desktop identicon.ts) ---
+
+private fun hashBytes(hex: String): List<Int> {
+    val clean = hex.filter { it.isLetterOrDigit() }
+    val bytes = mutableListOf<Int>()
+    var i = 0
+    while (i + 1 < clean.length) {
+        val b = clean.substring(i, i + 2).toIntOrNull(16) ?: 0
+        bytes.add(b)
+        i += 2
+    }
+    // Pad to at least 16 bytes
+    while (bytes.size < 16) bytes.add(0)
+    return bytes
+}
+
+private fun deriveColors(bytes: List<Int>): Pair<Color, Color> {
+    val hue1 = bytes[0] * 360f / 256f
+    val hue2 = (bytes[1] * 360f / 256f + 120f) % 360f
+    val bg = hslToColor(hue1, 0.65f, 0.35f)
+    val fg = hslToColor(hue2, 0.70f, 0.55f)
+    return bg to fg
+}
+
+private fun buildGrid(bytes: List<Int>): List<List<Boolean>> {
+    return (0 until 5).map { y ->
+        val left = (0 until 3).map { x ->
+            val idx = 2 + y * 3 + x
+            bytes[idx % bytes.size] > 128
+        }
+        // Mirror: col3 = col1, col4 = col0
+        listOf(left[0], left[1], left[2], left[1], left[0])
+    }
+}
+
+private fun hslToColor(h: Float, s: Float, l: Float): Color {
+    val k = { n: Float -> (n + h / 30f) % 12f }
+    val a = s * min(l, 1f - l)
+    val f = { n: Float ->
+        l - a * maxOf(-1f, minOf(k(n) - 3f, minOf(9f - k(n), 1f)))
+    }
+    return Color(f(0f), f(8f), f(4f))
+}

android/app/src/main/java/com/wzp/ui/settings/SettingsScreen.kt

@@ -158,20 +158,30 @@ fun SettingsScreen(
 
             Spacer(modifier = Modifier.height(16.dp))
 
-            // Fingerprint display
+            // Fingerprint display with identicon
             val fingerprint = if (draftSeedHex.length >= 16) draftSeedHex.take(16).uppercase() else "Not generated"
             Text(
                 text = "Fingerprint",
                 style = MaterialTheme.typography.labelSmall,
                 color = MaterialTheme.colorScheme.onSurfaceVariant
             )
-            Text(
-                text = fingerprint.chunked(4).joinToString(" "),
-                style = MaterialTheme.typography.bodyMedium.copy(
-                    fontFamily = FontFamily.Monospace
-                ),
-                color = MaterialTheme.colorScheme.onSurface
-            )
+            Row(
+                verticalAlignment = Alignment.CenterVertically,
+                modifier = Modifier.padding(vertical = 4.dp)
+            ) {
+                com.wzp.ui.components.Identicon(
+                    fingerprint = draftSeedHex,
+                    size = 40.dp,
+                )
+                Spacer(modifier = Modifier.width(12.dp))
+                com.wzp.ui.components.CopyableFingerprint(
+                    fingerprint = fingerprint.chunked(4).joinToString(" "),
+                    style = MaterialTheme.typography.bodyMedium.copy(
+                        fontFamily = FontFamily.Monospace
+                    ),
+                    color = MaterialTheme.colorScheme.onSurface,
+                )
+            }
 
             Spacer(modifier = Modifier.height(12.dp))
 

crates/wzp-android/Cargo.toml

@@ -17,7 +17,7 @@ wzp-crypto = { workspace = true }
 wzp-transport = { workspace = true }
 tokio = { workspace = true }
 tracing = { workspace = true }
-tracing-subscriber = { workspace = true }
+tracing-subscriber = { workspace = true, features = ["env-filter"] }
 bytes = { workspace = true }
 serde = { workspace = true }
 serde_json = "1"

crates/wzp-android/src/jni_bridge.rs

@@ -41,8 +41,17 @@ fn init_logging() {
         let _ = std::panic::catch_unwind(|| {
             use tracing_subscriber::layer::SubscriberExt;
             use tracing_subscriber::util::SubscriberInitExt;
+            use tracing_subscriber::EnvFilter;
             if let Ok(layer) = tracing_android::layer("wzp_android") {
-                let _ = tracing_subscriber::registry().with(layer).try_init();
+                // Filter: INFO for our crates, WARN for everything else.
+                // The jni crate emits VERBOSE logs for every method lookup
+                // (~10 lines per JNI call, 100+ calls/sec) which floods logcat
+                // and causes the system to kill the app.
+                let filter = EnvFilter::new("warn,wzp_android=info,wzp_proto=info,wzp_transport=info,wzp_codec=info,wzp_fec=info,wzp_crypto=info");
+                let _ = tracing_subscriber::registry()
+                    .with(layer)
+                    .with(filter)
+                    .try_init();
             }
         });
     });
@@ -308,3 +317,79 @@ pub unsafe extern "system" fn Java_com_wzp_engine_WzpEngine_nativeDestroy(
         drop(h);
     }));
 }
+
+/// Ping a relay server — returns JSON `{"rtt_ms":N,"server_fingerprint":"hex"}` or null on failure.
+/// Does NOT require an engine handle — creates a temporary QUIC connection.
+#[unsafe(no_mangle)]
+pub unsafe extern "system" fn Java_com_wzp_engine_WzpEngine_nativePingRelay<'a>(
+    mut env: JNIEnv<'a>,
+    _class: JClass,
+    relay_j: JString,
+) -> jstring {
+    let result = panic::catch_unwind(panic::AssertUnwindSafe(|| {
+        let relay: String = env.get_string(&relay_j).map(|s| s.into()).unwrap_or_default();
+        let addr: std::net::SocketAddr = match relay.parse() {
+            Ok(a) => a,
+            Err(_) => return None,
+        };
+
+        let _ = rustls::crypto::ring::default_provider().install_default();
+
+        let rt = match tokio::runtime::Builder::new_current_thread()
+            .enable_all()
+            .build()
+        {
+            Ok(rt) => rt,
+            Err(_) => return None,
+        };
+
+        rt.block_on(async {
+            let bind: std::net::SocketAddr = "0.0.0.0:0".parse().unwrap();
+            let endpoint = match wzp_transport::create_endpoint(bind, None) {
+                Ok(e) => e,
+                Err(_) => return None,
+            };
+            let client_cfg = wzp_transport::client_config();
+            let start = std::time::Instant::now();
+
+            match tokio::time::timeout(
+                std::time::Duration::from_secs(3),
+                wzp_transport::connect(&endpoint, addr, "ping", client_cfg),
+            )
+            .await
+            {
+                Ok(Ok(conn)) => {
+                    let rtt_ms = start.elapsed().as_millis() as u64;
+                    let server_fp = conn
+                        .peer_identity()
+                        .and_then(|id| {
+                            id.downcast::<Vec<rustls::pki_types::CertificateDer>>().ok()
+                        })
+                        .and_then(|certs| {
+                            certs.first().map(|c| {
+                                use std::hash::{Hash, Hasher};
+                                let mut h = std::collections::hash_map::DefaultHasher::new();
+                                c.as_ref().hash(&mut h);
+                                format!("{:016x}", h.finish())
+                            })
+                        })
+                        .unwrap_or_default();
+                    conn.close(0u32.into(), b"ping");
+                    Some(format!(
+                        r#"{{"rtt_ms":{},"server_fingerprint":"{}"}}"#,
+                        rtt_ms, server_fp
+                    ))
+                }
+                _ => None,
+            }
+        })
+    }));
+
+    let json = match result {
+        Ok(Some(s)) => s,
+        _ => return JObject::null().into_raw(),
+    };
+    env.new_string(&json)
+        .map(|s| s.into_raw())
+        .unwrap_or(JObject::null().into_raw())
+}

scripts/build-android-cloud.sh

@@ -196,6 +196,12 @@ do_upload() {
 do_build() {
   log "Building Rust native library (arm64-v8a, release)..."
 
+  # Clean Rust release target to force full rebuild.
+  # cargo-ndk only copies libc++_shared.so when it actually links — a partial
+  # clean that skips relinking leaves libc++_shared.so missing from jniLibs.
+  ssh_cmd "rm -rf /root/wzp-build/target/aarch64-linux-android/release \
+    /root/wzp-build/android/app/src/main/jniLibs/arm64-v8a"
+
   # ANDROID_NDK must be set (not just ANDROID_NDK_HOME) — cmake checks it
   ssh_cmd "source \$HOME/.cargo/env && \
     export ANDROID_HOME=\$HOME/android-sdk && \