refactor: separate SignalManager from WzpEngine for direct calling

SignalManager (NEW):
- Dedicated Rust struct with its own QUIC connection to _signal
- Separate JNI handle (nativeSignalConnect/GetState/PlaceCall/etc)
- Kotlin wrapper polls state every 500ms via getState() JSON
- Lives independently of WzpEngine — survives across calls
- connect() blocks briefly on 8MB thread, then recv loop runs on dedicated thread

WzpEngine (CLEANED):
- Back to pure media-only role (audio, codec, FEC, jitter)
- Removed start_signaling/place_call/answer_call methods
- Removed signal_transport/signal_fingerprint from EngineState

CallViewModel:
- Two separate managers: signalManager (persistent) + engine (per-call)
- Two separate polling loops: signalPollJob + statsJob
- Auto-connect to media room when signal polling detects "setup" state
- hangupDirectCall() ends media but keeps signal alive

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

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

@@ -0,0 +1,97 @@
+package com.wzp.engine
+
+import org.json.JSONObject
+
+/**
+ * Persistent signal connection for direct 1:1 calls.
+ * Separate from WzpEngine — survives across calls.
+ *
+ * Lifecycle: connect() → [placeCall/answerCall] → destroy()
+ */
+class SignalManager {
+
+    private var handle: Long = 0L
+
+    val isConnected: Boolean get() = handle != 0L
+
+    /**
+     * Connect to relay and register for direct calls.
+     * MUST be called from a thread with sufficient stack (8MB).
+     * Blocks briefly during QUIC connect + register, then returns.
+     */
+    fun connect(relay: String, seedHex: String): Boolean {
+        if (handle != 0L) return true // already connected
+        handle = nativeSignalConnect(relay, seedHex)
+        return handle != 0L
+    }
+
+    /** Get current signal state as parsed object. Non-blocking. */
+    fun getState(): SignalState {
+        if (handle == 0L) return SignalState()
+        val json = nativeSignalGetState(handle) ?: return SignalState()
+        return try {
+            val obj = JSONObject(json)
+            SignalState(
+                status = obj.optString("status", "idle"),
+                fingerprint = obj.optString("fingerprint", ""),
+                incomingCallId = if (obj.isNull("incoming_call_id")) null else obj.optString("incoming_call_id"),
+                incomingCallerFp = if (obj.isNull("incoming_caller_fp")) null else obj.optString("incoming_caller_fp"),
+                incomingCallerAlias = if (obj.isNull("incoming_caller_alias")) null else obj.optString("incoming_caller_alias"),
+                callSetupRelay = if (obj.isNull("call_setup_relay")) null else obj.optString("call_setup_relay"),
+                callSetupRoom = if (obj.isNull("call_setup_room")) null else obj.optString("call_setup_room"),
+                callSetupId = if (obj.isNull("call_setup_id")) null else obj.optString("call_setup_id"),
+            )
+        } catch (e: Exception) {
+            SignalState()
+        }
+    }
+
+    /** Place a direct call to a target fingerprint. */
+    fun placeCall(targetFp: String): Int {
+        if (handle == 0L) return -1
+        return nativeSignalPlaceCall(handle, targetFp)
+    }
+
+    /** Answer an incoming call. mode: 0=Reject, 1=AcceptTrusted, 2=AcceptGeneric */
+    fun answerCall(callId: String, mode: Int = 2): Int {
+        if (handle == 0L) return -1
+        return nativeSignalAnswerCall(handle, callId, mode)
+    }
+
+    /** Send hangup signal. */
+    fun hangup() {
+        if (handle != 0L) nativeSignalHangup(handle)
+    }
+
+    /** Destroy the signal manager. */
+    fun destroy() {
+        if (handle != 0L) {
+            nativeSignalDestroy(handle)
+            handle = 0L
+        }
+    }
+
+    // JNI native methods
+    private external fun nativeSignalConnect(relay: String, seed: String): Long
+    private external fun nativeSignalGetState(handle: Long): String?
+    private external fun nativeSignalPlaceCall(handle: Long, targetFp: String): Int
+    private external fun nativeSignalAnswerCall(handle: Long, callId: String, mode: Int): Int
+    private external fun nativeSignalHangup(handle: Long)
+    private external fun nativeSignalDestroy(handle: Long)
+
+    companion object {
+        init { System.loadLibrary("wzp_android") }
+    }
+}
+
+/** Signal connection state. */
+data class SignalState(
+    val status: String = "idle",
+    val fingerprint: String = "",
+    val incomingCallId: String? = null,
+    val incomingCallerFp: String? = null,
+    val incomingCallerAlias: String? = null,
+    val callSetupRelay: String? = null,
+    val callSetupRoom: String? = null,
+    val callSetupId: String? = null,
+)

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

@@ -141,9 +141,9 @@ class CallViewModel : ViewModel(), WzpCallback {
     private val _targetFingerprint = MutableStateFlow("")
     val targetFingerprint: StateFlow<String> = _targetFingerprint.asStateFlow()
 
-    /** Signal connection state: 0=idle, 5=registered, 6=ringing, 7=incoming */
-    private val _signalState = MutableStateFlow(0)
-    val signalState: StateFlow<Int> = _signalState.asStateFlow()
+    /** Signal state string: "idle", "registered", "ringing", "incoming", "setup" */
+    private val _signalState = MutableStateFlow("idle")
+    val signalState: StateFlow<String> = _signalState.asStateFlow()
 
     /** Incoming call info */
     private val _incomingCallId = MutableStateFlow<String?>(null)
@@ -155,37 +155,65 @@ class CallViewModel : ViewModel(), WzpCallback {
     private val _incomingCallerAlias = MutableStateFlow<String?>(null)
     val incomingCallerAlias: StateFlow<String?> = _incomingCallerAlias.asStateFlow()
 
+    /** Separate signal manager (persistent, survives calls) */
+    private var signalManager: com.wzp.engine.SignalManager? = null
+    private var signalPollJob: Job? = null
+
     fun setCallMode(mode: Int) { _callMode.value = mode }
     fun setTargetFingerprint(fp: String) { _targetFingerprint.value = fp }
 
     /** Register on relay for direct calls */
     fun registerForCalls() {
-        if (engine == null) {
-            engine = WzpEngine(this).also { it.init() }
-        }
         val serverIdx = _selectedServer.value
         val serverList = _servers.value
         if (serverIdx >= serverList.size) return
 
         val relay = serverList[serverIdx].address
         val seed = _seedHex.value
-        val alias = _alias.value
-
-        // Start stats polling BEFORE blocking — startSignaling blocks the thread forever
-        startStatsPolling()
-
-        // Use a Java Thread with 8MB stack — blocks forever in signal recv loop
         val resolvedRelay = resolveToIp(relay) ?: relay
+
+        // Connect on a thread with 8MB stack (QUIC + TLS needs it)
         Thread(null, {
-            val result = engine?.startSignaling(resolvedRelay, seed, "", alias)
-            // Only reached if signaling disconnects
+            val mgr = com.wzp.engine.SignalManager()
+            val ok = mgr.connect(resolvedRelay, seed)
             viewModelScope.launch {
-                if (result != 0) {
-                    _errorMessage.value = "Signal connection lost"
+                if (ok) {
+                    signalManager = mgr
+                    startSignalPolling()
+                } else {
+                    _errorMessage.value = "Failed to register on relay"
                 }
-                _signalState.value = 0
             }
-        }, "wzp-register", 8 * 1024 * 1024).start()
+        }, "wzp-signal-connect", 8 * 1024 * 1024).start()
+    }
+
+    /** Poll signal manager state every 500ms */
+    private fun startSignalPolling() {
+        signalPollJob?.cancel()
+        signalPollJob = viewModelScope.launch {
+            while (isActive) {
+                val mgr = signalManager
+                if (mgr != null && mgr.isConnected) {
+                    val state = mgr.getState()
+                    _signalState.value = state.status
+                    _incomingCallId.value = state.incomingCallId
+                    _incomingCallerFp.value = state.incomingCallerFp
+                    _incomingCallerAlias.value = state.incomingCallerAlias
+
+                    // Auto-connect to media room when call is set up
+                    if (state.status == "setup" && state.callSetupRelay != null && state.callSetupRoom != null) {
+                        Log.i(TAG, "CallSetup: connecting to ${state.callSetupRelay} room ${state.callSetupRoom}")
+                        startCallInternal(state.callSetupRelay, state.callSetupRoom)
+                    }
+                }
+                delay(500L)
+            }
+        }
+    }
+
+    private fun stopSignalPolling() {
+        signalPollJob?.cancel()
+        signalPollJob = null
     }
 
     /** Place a direct call to the target fingerprint */
@@ -195,24 +223,28 @@ class CallViewModel : ViewModel(), WzpCallback {
             _errorMessage.value = "Enter a fingerprint to call"
             return
         }
-        engine?.placeCall(target)
-        _signalState.value = 6 // Ringing
+        signalManager?.placeCall(target)
     }
 
     /** Answer an incoming direct call */
     fun answerIncomingCall(mode: Int = 2) {
         val callId = _incomingCallId.value ?: return
-        engine?.answerCall(callId, mode)
+        signalManager?.answerCall(callId, mode)
     }
 
     /** Reject an incoming direct call */
     fun rejectIncomingCall() {
         val callId = _incomingCallId.value ?: return
-        engine?.answerCall(callId, 0) // 0 = Reject
-        _signalState.value = 5 // Back to registered
-        _incomingCallId.value = null
-        _incomingCallerFp.value = null
-        _incomingCallerAlias.value = null
+        signalManager?.answerCall(callId, 0)
+    }
+
+    /** Hang up direct call — media ends, signal stays alive */
+    fun hangupDirectCall() {
+        signalManager?.hangup()
+        engine?.stopCall()
+        engine?.destroy()
+        engine = null
+        engineInitialized = false
     }
 
     companion object {
@@ -690,30 +722,10 @@ class CallViewModel : ViewModel(), WzpCallback {
                         val s = CallStats.fromJson(json)
                         lastCallDuration = s.durationSecs
                         _stats.value = s
-                        // Track signal state changes for direct calling
-                        if (s.state in 5..7) {
-                            _signalState.value = s.state
-                            // Don't update callState for signal-only states
-                        } else if (s.state != 0) {
+                        // Only update callState from media engine stats (not signal)
+                        if (s.state != 0) {
                             _callState.value = s.state
                         }
-                        // Incoming call detection
-                        if (s.state == 7) { // IncomingCall
-                            _incomingCallId.value = s.incomingCallId
-                            _incomingCallerFp.value = s.incomingCallerFp
-                            _incomingCallerAlias.value = s.incomingCallerAlias
-                        }
-                        // CallSetup: auto-connect to media room
-                        if (s.state == 1 && s.incomingCallId != null && s.incomingCallId.contains("|")) {
-                            // Format: "relay_addr|room_name"
-                            val parts = s.incomingCallId.split("|", limit = 2)
-                            if (parts.size == 2) {
-                                val mediaRelay = parts[0]
-                                val mediaRoom = parts[1]
-                                Log.i(TAG, "CallSetup: connecting to $mediaRelay room $mediaRoom")
-                                startCallInternal(mediaRelay, mediaRoom)
-                            }
-                        }
                         if (s.state == 2 && !audioStarted) {
                             startAudio()
                         }

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

@@ -219,7 +219,7 @@ fun InCallScreen(
 
                 // Mode toggle: Room vs Direct Call
                 val callMode by viewModel.callMode.collectAsState()
-                val signalState by viewModel.signalState.collectAsState()
+                val signalState by viewModel.signalState.collectAsState()  // "idle"/"registered"/"ringing"/etc
                 val targetFp by viewModel.targetFingerprint.collectAsState()
                 val incomingCallId by viewModel.incomingCallId.collectAsState()
                 val incomingCallerFp by viewModel.incomingCallerFp.collectAsState()
@@ -309,7 +309,7 @@ fun InCallScreen(
                     }
                 } else {
                     // ── Direct call mode ──
-                    if (signalState < 5) {
+                    if (signalState == "idle") {
                         // Not registered yet
                         SectionLabel("ALIAS")
                         OutlinedTextField(
@@ -333,7 +333,7 @@ fun InCallScreen(
                                 color = Color.White
                             )
                         }
-                    } else if (signalState == 5) {
+                    } else if (signalState == "registered" || signalState == "incoming") {
                         // Registered — show dial pad
                         Text(
                             "\u2705 Registered — waiting for calls",
@@ -403,8 +403,7 @@ fun InCallScreen(
                                 color = Color.White
                             )
                         }
-                    } else if (signalState == 6) {
-                        // Ringing
+                    } else if (signalState == "ringing") {
                         Text(
                             "\uD83D\uDD14 Ringing...",
                             color = Yellow,
@@ -412,11 +411,10 @@ fun InCallScreen(
                             textAlign = TextAlign.Center,
                             modifier = Modifier.fillMaxWidth()
                         )
-                    } else if (signalState == 7) {
-                        // Incoming call (state 7 also handled above in registered view)
+                    } else if (signalState == "setup") {
                         Text(
-                            "\uD83D\uDCDE Incoming call...",
-                            color = Green,
+                            "Connecting to call...",
+                            color = Accent,
                             style = MaterialTheme.typography.titleMedium,
                             textAlign = TextAlign.Center,
                             modifier = Modifier.fillMaxWidth()

crates/wzp-android/src/engine.rs

@@ -97,10 +97,6 @@ pub(crate) struct EngineState {
     /// QUIC transport handle — stored so stop_call() can close it immediately,
     /// triggering relay-side leave + RoomUpdate broadcast.
     pub quic_transport: Mutex<Option<Arc<wzp_transport::QuinnTransport>>>,
-    /// Signal transport for direct calling — stored so place_call/answer_call can send.
-    pub signal_transport: Mutex<Option<Arc<wzp_transport::QuinnTransport>>>,
-    /// Our fingerprint (set during signaling registration).
-    pub signal_fingerprint: Mutex<Option<String>>,
 }
 
 pub struct WzpEngine {
@@ -122,8 +118,6 @@ impl WzpEngine {
             playout_ring: AudioRing::new(),
             audio_level_rms: AtomicU32::new(0),
             quic_transport: Mutex::new(None),
-            signal_transport: Mutex::new(None),
-            signal_fingerprint: Mutex::new(None),
         });
         Self {
             state,
@@ -250,203 +244,7 @@ impl WzpEngine {
     }
 
     /// Start persistent signaling connection for direct calls.
-    /// Spawns a background task that maintains the `_signal` connection.
-    /// Start persistent signaling for direct calls.
-    /// Blocks the calling thread (Kotlin provides a Thread with 8MB stack).
-    /// Same pattern as start_call: tokio block_on on the caller's thread.
-    pub fn start_signaling(
-        &mut self,
-        relay_addr: &str,
-        seed_hex: &str,
-        token: Option<&str>,
-        alias: Option<&str>,
-    ) -> Result<(), anyhow::Error> {
-        use wzp_proto::{MediaTransport, SignalMessage};
-
-
-        let addr: SocketAddr = relay_addr.parse()?;
-        let seed = if seed_hex.is_empty() {
-            wzp_crypto::Seed::generate()
-        } else {
-            wzp_crypto::Seed::from_hex(seed_hex).map_err(|e| anyhow::anyhow!(e))?
-        };
-        let identity = seed.derive_identity();
-        let pub_id = identity.public_identity();
-        let identity_pub = *pub_id.signing.as_bytes();
-        let fp = pub_id.fingerprint.to_string();
-        let token = token.map(|s| s.to_string());
-        let alias = alias.map(|s| s.to_string());
-        let state = self.state.clone();
-
-        info!(fingerprint = %fp, relay = %addr, "starting signaling");
-
-        self.state.running.store(true, Ordering::Release);
-
-        let rt = tokio::runtime::Builder::new_current_thread()
-            .enable_all()
-            .build()?;
-
-        let signal_state = state.clone();
-        rt.block_on(async move {
-            let bind: SocketAddr = "0.0.0.0:0".parse().unwrap();
-            let endpoint = match wzp_transport::create_endpoint(bind, None) {
-                Ok(e) => e,
-                Err(e) => { error!("signal endpoint: {e}"); return; }
-            };
-            let client_cfg = wzp_transport::client_config();
-            let conn = match wzp_transport::connect(&endpoint, addr, "_signal", client_cfg).await {
-                Ok(c) => c,
-                Err(e) => { error!("signal connect: {e}"); return; }
-            };
-            let transport = std::sync::Arc::new(wzp_transport::QuinnTransport::new(conn));
-
-            // Auth if token provided
-            if let Some(ref tok) = token {
-                let _ = transport.send_signal(&SignalMessage::AuthToken { token: tok.clone() }).await;
-            }
-
-            // Register presence
-            let _ = transport.send_signal(&SignalMessage::RegisterPresence {
-                identity_pub,
-                signature: vec![],
-                alias: alias.clone(),
-            }).await;
-
-            // Wait for ack
-            match transport.recv_signal().await {
-                Ok(Some(SignalMessage::RegisterPresenceAck { success: true, .. })) => {
-                    info!(fingerprint = %fp, "signal: registered");
-                    let mut stats = signal_state.stats.lock().unwrap();
-                    stats.state = crate::stats::CallState::Registered;
-                    drop(stats);
-                    // Store transport + fingerprint so place_call/answer_call can use them
-                    *signal_state.signal_transport.lock().unwrap() = Some(transport.clone());
-                    *signal_state.signal_fingerprint.lock().unwrap() = Some(fp.clone());
-                }
-                other => {
-                    error!("signal registration failed: {other:?}");
-                    return;
-                }
-            }
-
-            // Signal recv loop
-            loop {
-                if !signal_state.running.load(Ordering::Relaxed) {
-                    break;
-                }
-                match transport.recv_signal().await {
-                    Ok(Some(SignalMessage::CallRinging { call_id })) => {
-                        info!(call_id = %call_id, "signal: ringing");
-                        let mut stats = signal_state.stats.lock().unwrap();
-                        stats.state = crate::stats::CallState::Ringing;
-                    }
-                    Ok(Some(SignalMessage::DirectCallOffer { caller_fingerprint, caller_alias, call_id, .. })) => {
-                        info!(from = %caller_fingerprint, call_id = %call_id, "signal: incoming call");
-                        let mut stats = signal_state.stats.lock().unwrap();
-                        stats.state = crate::stats::CallState::IncomingCall;
-                        stats.incoming_call_id = Some(call_id);
-                        stats.incoming_caller_fp = Some(caller_fingerprint);
-                        stats.incoming_caller_alias = caller_alias;
-                    }
-                    Ok(Some(SignalMessage::DirectCallAnswer { call_id, accept_mode, .. })) => {
-                        info!(call_id = %call_id, mode = ?accept_mode, "signal: call answered");
-                    }
-                    Ok(Some(SignalMessage::CallSetup { call_id, room, relay_addr })) => {
-                        info!(call_id = %call_id, room = %room, relay = %relay_addr, "signal: call setup");
-                        // Connect to media room via the existing start_call mechanism
-                        // Store the room info so Kotlin can call startCall with it
-                        let mut stats = signal_state.stats.lock().unwrap();
-                        stats.state = crate::stats::CallState::Connecting;
-                        // Store call setup info for Kotlin to pick up
-                        stats.incoming_call_id = Some(format!("{relay_addr}|{room}"));
-                    }
-                    Ok(Some(SignalMessage::Hangup { reason })) => {
-                        info!(reason = ?reason, "signal: call ended by remote");
-                        let mut stats = signal_state.stats.lock().unwrap();
-                        stats.state = crate::stats::CallState::Closed;
-                        stats.incoming_call_id = None;
-                        stats.incoming_caller_fp = None;
-                        stats.incoming_caller_alias = None;
-                    }
-                    Ok(Some(_)) => {}
-                    Ok(None) => {
-                        info!("signal: connection closed");
-                        break;
-                    }
-                    Err(e) => {
-                        error!("signal recv error: {e}");
-                        break;
-                    }
-                }
-            }
-
-            let mut stats = signal_state.stats.lock().unwrap();
-            stats.state = crate::stats::CallState::Closed;
-        }); // block_on
-
-        Ok(())
-    }
-
-    /// Place a direct call to a target fingerprint via the signal transport.
-    pub fn place_call(&self, target_fingerprint: &str) -> Result<(), anyhow::Error> {
-        use wzp_proto::SignalMessage;
-
-        let transport = self.state.signal_transport.lock().unwrap().clone()
-            .ok_or_else(|| anyhow::anyhow!("not registered"))?;
-        let caller_fp = self.state.signal_fingerprint.lock().unwrap().clone()
-            .unwrap_or_default();
-        let target = target_fingerprint.to_string();
-        let call_id = format!("{:016x}", std::time::SystemTime::now()
-            .duration_since(std::time::UNIX_EPOCH).unwrap().as_nanos());
-
-        // Send on a separate thread since we can't block the UI thread
-        std::thread::spawn(move || {
-            let rt = tokio::runtime::Builder::new_current_thread()
-                .enable_all()
-                .build()
-                .expect("tokio runtime");
-            rt.block_on(async {
-                let _ = transport.send_signal(&SignalMessage::DirectCallOffer {
-                    caller_fingerprint: caller_fp,
-                    caller_alias: None,
-                    target_fingerprint: target,
-                    call_id,
-                    identity_pub: [0u8; 32],
-                    ephemeral_pub: [0u8; 32],
-                    signature: vec![],
-                    supported_profiles: vec![wzp_proto::QualityProfile::GOOD],
-                }).await;
-            });
-        });
-        Ok(())
-    }
-
-    /// Answer an incoming direct call via the signal transport.
-    pub fn answer_call(&self, call_id: &str, mode: wzp_proto::CallAcceptMode) -> Result<(), anyhow::Error> {
-        use wzp_proto::SignalMessage;
-
-        let transport = self.state.signal_transport.lock().unwrap().clone()
-            .ok_or_else(|| anyhow::anyhow!("not registered"))?;
-        let call_id = call_id.to_string();
-
-        std::thread::spawn(move || {
-            let rt = tokio::runtime::Builder::new_current_thread()
-                .enable_all()
-                .build()
-                .expect("tokio runtime");
-            rt.block_on(async {
-                let _ = transport.send_signal(&SignalMessage::DirectCallAnswer {
-                    call_id,
-                    accept_mode: mode,
-                    identity_pub: None,
-                    ephemeral_pub: None,
-                    signature: None,
-                    chosen_profile: Some(wzp_proto::QualityProfile::GOOD),
-                }).await;
-            });
-        });
-        Ok(())
-    }
+    // Signal methods (start_signaling, place_call, answer_call) moved to signal_mgr.rs
 
     pub fn set_mute(&self, muted: bool) {
         self.state.muted.store(muted, Ordering::Relaxed);

crates/wzp-android/src/jni_bridge.rs

@@ -390,87 +390,132 @@ pub unsafe extern "system" fn Java_com_wzp_engine_WzpEngine_nativeGetFingerprint
 
 // ── Direct calling JNI functions ──
 
-/// Start persistent signaling connection to relay for direct calls.
-/// Returns 0 immediately — the actual work happens on a dedicated thread.
-/// The JNI function MUST be minimal because Android's DefaultDispatch thread
-/// has a tiny stack that overflows with any Rust crypto/network code.
+// ── SignalManager JNI functions ──
+
+/// Opaque handle for SignalManager (separate from EngineHandle).
+struct SignalHandle {
+    mgr: crate::signal_mgr::SignalManager,
+}
+
+unsafe fn signal_ref(handle: jlong) -> &'static SignalHandle {
+    unsafe { &*(handle as *const SignalHandle) }
+}
+
+/// Connect to relay for signaling. Returns handle (jlong) or 0 on error.
+/// MUST be called from a thread with sufficient stack (8MB).
 #[unsafe(no_mangle)]
-pub unsafe extern "system" fn Java_com_wzp_engine_WzpEngine_nativeStartSignaling<'a>(
+pub unsafe extern "system" fn Java_com_wzp_engine_SignalManager_nativeSignalConnect<'a>(
+    mut env: JNIEnv<'a>,
+    _class: JClass,
+    relay_j: JString,
+    seed_j: JString,
+) -> jlong {
+    let relay: String = env.get_string(&relay_j).map(|s| s.into()).unwrap_or_default();
+    let seed: String = env.get_string(&seed_j).map(|s| s.into()).unwrap_or_default();
+
+    match crate::signal_mgr::SignalManager::connect(&relay, &seed) {
+        Ok(mgr) => {
+            // Spawn recv loop on a dedicated thread
+            let mgr_ref = &mgr as *const crate::signal_mgr::SignalManager;
+            let handle = Box::new(SignalHandle { mgr });
+            let raw = Box::into_raw(handle);
+
+            // Get a reference for the recv thread
+            let recv_ref = unsafe { &(*raw).mgr };
+            std::thread::Builder::new()
+                .name("wzp-signal-recv".into())
+                .stack_size(4 * 1024 * 1024)
+                .spawn(move || {
+                    recv_ref.run_recv_loop();
+                })
+                .ok();
+
+            raw as jlong
+        }
+        Err(e) => {
+            error!("signal connect failed: {e}");
+            0
+        }
+    }
+}
+
+/// Get signal state as JSON string.
+#[unsafe(no_mangle)]
+pub unsafe extern "system" fn Java_com_wzp_engine_SignalManager_nativeSignalGetState<'a>(
     mut env: JNIEnv<'a>,
     _class: JClass,
     handle: jlong,
-    relay_addr_j: JString,
-    seed_hex_j: JString,
-    token_j: JString,
-    alias_j: JString,
+) -> jstring {
+    if handle == 0 { return JObject::null().into_raw(); }
+    let h = signal_ref(handle);
+    let json = h.mgr.get_state_json();
+    env.new_string(&json)
+        .map(|s| s.into_raw())
+        .unwrap_or(JObject::null().into_raw())
+}
+
+/// Place a direct call.
+#[unsafe(no_mangle)]
+pub unsafe extern "system" fn Java_com_wzp_engine_SignalManager_nativeSignalPlaceCall<'a>(
+    mut env: JNIEnv<'a>,
+    _class: JClass,
+    handle: jlong,
+    target_j: JString,
 ) -> jint {
-    // Extract JNI strings — this is all we do on the caller's thread
-    let relay_addr: String = env.get_string(&relay_addr_j).map(|s| s.into()).unwrap_or_default();
-    let seed_hex: String = env.get_string(&seed_hex_j).map(|s| s.into()).unwrap_or_default();
-    let token: String = env.get_string(&token_j).map(|s| s.into()).unwrap_or_default();
-    let alias: String = env.get_string(&alias_j).map(|s| s.into()).unwrap_or_default();
-
-    // Use the existing start_call pattern — create engine, call start_signaling
-    // which spawns a thread internally. This is the same pattern that works for room calls.
-    let h = unsafe { handle_ref(handle) };
-
-    match h.engine.start_signaling(
-        &relay_addr,
-        &seed_hex,
-        if token.is_empty() { None } else { Some(&token) },
-        if alias.is_empty() { None } else { Some(&alias) },
-    ) {
+    if handle == 0 { return -1; }
+    let h = signal_ref(handle);
+    let target: String = env.get_string(&target_j).map(|s| s.into()).unwrap_or_default();
+    match h.mgr.place_call(&target) {
         Ok(()) => 0,
-        Err(e) => { error!("start_signaling failed: {e}"); -1 }
+        Err(e) => { error!("place_call: {e}"); -1 }
     }
 }
 
-/// Place a direct call to a target fingerprint.
-/// Returns 0 on success, -1 on error.
+/// Answer an incoming call.
 #[unsafe(no_mangle)]
-pub unsafe extern "system" fn Java_com_wzp_engine_WzpEngine_nativePlaceCall<'a>(
-    mut env: JNIEnv<'a>,
-    _class: JClass,
-    handle: jlong,
-    target_fp_j: JString,
-) -> jint {
-    let result = panic::catch_unwind(panic::AssertUnwindSafe(|| {
-        let h = unsafe { handle_ref(handle) };
-        let target: String = env.get_string(&target_fp_j).map(|s| s.into()).unwrap_or_default();
-        h.engine.place_call(&target)
-    }));
-
-    match result {
-        Ok(Ok(())) => 0,
-        Ok(Err(e)) => { error!("place_call failed: {e}"); -1 }
-        Err(_) => { error!("place_call panicked"); -1 }
-    }
-}
-
-/// Answer an incoming direct call.
-/// mode: 0=Reject, 1=AcceptTrusted, 2=AcceptGeneric
-#[unsafe(no_mangle)]
-pub unsafe extern "system" fn Java_com_wzp_engine_WzpEngine_nativeAnswerCall<'a>(
+pub unsafe extern "system" fn Java_com_wzp_engine_SignalManager_nativeSignalAnswerCall<'a>(
     mut env: JNIEnv<'a>,
     _class: JClass,
     handle: jlong,
     call_id_j: JString,
     mode: jint,
 ) -> jint {
-    let result = panic::catch_unwind(panic::AssertUnwindSafe(|| {
-        let h = unsafe { handle_ref(handle) };
-        let call_id: String = env.get_string(&call_id_j).map(|s| s.into()).unwrap_or_default();
-        let accept_mode = match mode {
-            0 => wzp_proto::CallAcceptMode::Reject,
-            1 => wzp_proto::CallAcceptMode::AcceptTrusted,
-            _ => wzp_proto::CallAcceptMode::AcceptGeneric,
-        };
-        h.engine.answer_call(&call_id, accept_mode)
-    }));
-
-    match result {
-        Ok(Ok(())) => 0,
-        Ok(Err(e)) => { error!("answer_call failed: {e}"); -1 }
-        Err(_) => { error!("answer_call panicked"); -1 }
+    if handle == 0 { return -1; }
+    let h = signal_ref(handle);
+    let call_id: String = env.get_string(&call_id_j).map(|s| s.into()).unwrap_or_default();
+    let accept_mode = match mode {
+        0 => wzp_proto::CallAcceptMode::Reject,
+        1 => wzp_proto::CallAcceptMode::AcceptTrusted,
+        _ => wzp_proto::CallAcceptMode::AcceptGeneric,
+    };
+    match h.mgr.answer_call(&call_id, accept_mode) {
+        Ok(()) => 0,
+        Err(e) => { error!("answer_call: {e}"); -1 }
     }
 }
+
+/// Send hangup signal.
+#[unsafe(no_mangle)]
+pub unsafe extern "system" fn Java_com_wzp_engine_SignalManager_nativeSignalHangup(
+    _env: JNIEnv,
+    _class: JClass,
+    handle: jlong,
+) {
+    if handle == 0 { return; }
+    let h = signal_ref(handle);
+    h.mgr.hangup();
+}
+
+/// Destroy the signal manager and free resources.
+#[unsafe(no_mangle)]
+pub unsafe extern "system" fn Java_com_wzp_engine_SignalManager_nativeSignalDestroy(
+    _env: JNIEnv,
+    _class: JClass,
+    handle: jlong,
+) {
+    if handle == 0 { return; }
+    let h = signal_ref(handle);
+    h.mgr.stop();
+    // Reclaim the Box
+    let _ = unsafe { Box::from_raw(handle as *mut SignalHandle) };
+}

crates/wzp-android/src/lib.rs

@@ -14,5 +14,6 @@ pub mod audio_ring;
 pub mod commands;
 pub mod engine;
 pub mod pipeline;
+pub mod signal_mgr;
 pub mod stats;
 pub mod jni_bridge;

crates/wzp-android/src/signal_mgr.rs

@@ -0,0 +1,265 @@
+//! Persistent signal connection manager for direct 1:1 calls.
+//!
+//! Separate from the media engine — survives across calls.
+//! Connects to relay via `_signal` SNI, registers presence,
+//! and handles call signaling (offer/answer/setup/hangup).
+
+use std::net::SocketAddr;
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::{Arc, Mutex};
+
+use tracing::{error, info, warn};
+use wzp_proto::{MediaTransport, SignalMessage};
+
+/// Signal connection status.
+#[derive(Clone, Debug, Default, serde::Serialize)]
+pub struct SignalState {
+    pub status: String, // "idle", "registered", "ringing", "incoming", "setup"
+    pub fingerprint: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub incoming_call_id: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub incoming_caller_fp: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub incoming_caller_alias: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub call_setup_relay: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub call_setup_room: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub call_setup_id: Option<String>,
+}
+
+/// Manages a persistent `_signal` QUIC connection to a relay.
+pub struct SignalManager {
+    transport: Arc<wzp_transport::QuinnTransport>,
+    state: Arc<Mutex<SignalState>>,
+    running: Arc<AtomicBool>,
+}
+
+impl SignalManager {
+    /// Connect to relay, register presence, return immediately.
+    /// Call `run_recv_loop()` on a separate thread after this.
+    pub fn connect(relay_addr: &str, seed_hex: &str) -> Result<Self, anyhow::Error> {
+        let addr: SocketAddr = relay_addr.parse()?;
+        let seed = if seed_hex.is_empty() {
+            wzp_crypto::Seed::generate()
+        } else {
+            wzp_crypto::Seed::from_hex(seed_hex).map_err(|e| anyhow::anyhow!(e))?
+        };
+        let identity = seed.derive_identity();
+        let pub_id = identity.public_identity();
+        let identity_pub = *pub_id.signing.as_bytes();
+        let fp = pub_id.fingerprint.to_string();
+
+        info!(fingerprint = %fp, relay = %addr, "signal: connecting");
+
+        // Synchronous QUIC connect + register (runs on caller's thread)
+        let rt = tokio::runtime::Builder::new_current_thread()
+            .enable_all()
+            .build()?;
+
+        let transport = rt.block_on(async {
+            let bind: SocketAddr = "0.0.0.0:0".parse().unwrap();
+            let endpoint = wzp_transport::create_endpoint(bind, None)?;
+            let client_cfg = wzp_transport::client_config();
+            let conn = wzp_transport::connect(&endpoint, addr, "_signal", client_cfg).await?;
+            let transport = Arc::new(wzp_transport::QuinnTransport::new(conn));
+
+            // Register presence
+            transport.send_signal(&SignalMessage::RegisterPresence {
+                identity_pub,
+                signature: vec![],
+                alias: None,
+            }).await?;
+
+            match transport.recv_signal().await? {
+                Some(SignalMessage::RegisterPresenceAck { success: true, .. }) => {
+                    info!(fingerprint = %fp, "signal: registered");
+                }
+                other => {
+                    return Err(anyhow::anyhow!("registration failed: {other:?}"));
+                }
+            }
+
+            Ok::<_, anyhow::Error>(transport)
+        })?;
+
+        // Don't drop the runtime — we need it for the recv loop
+        // Store it... actually, we'll create a new one in run_recv_loop
+        drop(rt);
+
+        let state = Arc::new(Mutex::new(SignalState {
+            status: "registered".into(),
+            fingerprint: fp,
+            ..Default::default()
+        }));
+
+        Ok(Self {
+            transport,
+            state,
+            running: Arc::new(AtomicBool::new(true)),
+        })
+    }
+
+    /// Blocking signal recv loop. Run on a dedicated thread.
+    pub fn run_recv_loop(&self) {
+        let rt = tokio::runtime::Builder::new_current_thread()
+            .enable_all()
+            .build()
+            .expect("tokio runtime for signal recv");
+
+        let transport = self.transport.clone();
+        let state = self.state.clone();
+        let running = self.running.clone();
+
+        rt.block_on(async move {
+            loop {
+                if !running.load(Ordering::Relaxed) { break; }
+
+                match transport.recv_signal().await {
+                    Ok(Some(SignalMessage::CallRinging { call_id })) => {
+                        info!(call_id = %call_id, "signal: ringing");
+                        let mut s = state.lock().unwrap();
+                        s.status = "ringing".into();
+                    }
+                    Ok(Some(SignalMessage::DirectCallOffer { caller_fingerprint, caller_alias, call_id, .. })) => {
+                        info!(from = %caller_fingerprint, call_id = %call_id, "signal: incoming call");
+                        let mut s = state.lock().unwrap();
+                        s.status = "incoming".into();
+                        s.incoming_call_id = Some(call_id);
+                        s.incoming_caller_fp = Some(caller_fingerprint);
+                        s.incoming_caller_alias = caller_alias;
+                    }
+                    Ok(Some(SignalMessage::DirectCallAnswer { call_id, accept_mode, .. })) => {
+                        info!(call_id = %call_id, mode = ?accept_mode, "signal: call answered");
+                    }
+                    Ok(Some(SignalMessage::CallSetup { call_id, room, relay_addr })) => {
+                        info!(call_id = %call_id, room = %room, relay = %relay_addr, "signal: call setup");
+                        let mut s = state.lock().unwrap();
+                        s.status = "setup".into();
+                        s.call_setup_relay = Some(relay_addr);
+                        s.call_setup_room = Some(room);
+                        s.call_setup_id = Some(call_id);
+                    }
+                    Ok(Some(SignalMessage::Hangup { reason })) => {
+                        info!(reason = ?reason, "signal: hangup");
+                        let mut s = state.lock().unwrap();
+                        s.status = "registered".into();
+                        s.incoming_call_id = None;
+                        s.incoming_caller_fp = None;
+                        s.incoming_caller_alias = None;
+                        s.call_setup_relay = None;
+                        s.call_setup_room = None;
+                        s.call_setup_id = None;
+                    }
+                    Ok(Some(_)) => {}
+                    Ok(None) => {
+                        info!("signal: connection closed");
+                        break;
+                    }
+                    Err(e) => {
+                        error!("signal recv error: {e}");
+                        break;
+                    }
+                }
+            }
+
+            let mut s = state.lock().unwrap();
+            s.status = "idle".into();
+        });
+    }
+
+    /// Get current state (non-blocking).
+    pub fn get_state(&self) -> SignalState {
+        self.state.lock().unwrap().clone()
+    }
+
+    /// Get state as JSON string.
+    pub fn get_state_json(&self) -> String {
+        serde_json::to_string(&self.get_state()).unwrap_or_else(|_| "{}".into())
+    }
+
+    /// Place a direct call.
+    pub fn place_call(&self, target_fp: &str) -> Result<(), anyhow::Error> {
+        let fp = self.state.lock().unwrap().fingerprint.clone();
+        let target = target_fp.to_string();
+        let call_id = format!("{:016x}", std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH).unwrap().as_nanos());
+        let transport = self.transport.clone();
+
+        // Send on a small thread (async send needs a runtime)
+        std::thread::Builder::new()
+            .name("wzp-call-send".into())
+            .spawn(move || {
+                let rt = tokio::runtime::Builder::new_current_thread()
+                    .enable_all().build().expect("rt");
+                rt.block_on(async {
+                    let _ = transport.send_signal(&SignalMessage::DirectCallOffer {
+                        caller_fingerprint: fp,
+                        caller_alias: None,
+                        target_fingerprint: target,
+                        call_id,
+                        identity_pub: [0u8; 32],
+                        ephemeral_pub: [0u8; 32],
+                        signature: vec![],
+                        supported_profiles: vec![wzp_proto::QualityProfile::GOOD],
+                    }).await;
+                });
+            })?;
+        Ok(())
+    }
+
+    /// Answer an incoming call.
+    pub fn answer_call(&self, call_id: &str, mode: wzp_proto::CallAcceptMode) -> Result<(), anyhow::Error> {
+        let call_id = call_id.to_string();
+        let transport = self.transport.clone();
+
+        std::thread::Builder::new()
+            .name("wzp-answer-send".into())
+            .spawn(move || {
+                let rt = tokio::runtime::Builder::new_current_thread()
+                    .enable_all().build().expect("rt");
+                rt.block_on(async {
+                    let _ = transport.send_signal(&SignalMessage::DirectCallAnswer {
+                        call_id,
+                        accept_mode: mode,
+                        identity_pub: None,
+                        ephemeral_pub: None,
+                        signature: None,
+                        chosen_profile: Some(wzp_proto::QualityProfile::GOOD),
+                    }).await;
+                });
+            })?;
+        Ok(())
+    }
+
+    /// Send hangup.
+    pub fn hangup(&self) {
+        let transport = self.transport.clone();
+        let state = self.state.clone();
+        std::thread::spawn(move || {
+            let rt = tokio::runtime::Builder::new_current_thread()
+                .enable_all().build().expect("rt");
+            rt.block_on(async {
+                let _ = transport.send_signal(&SignalMessage::Hangup {
+                    reason: wzp_proto::HangupReason::Normal,
+                }).await;
+            });
+            let mut s = state.lock().unwrap();
+            s.status = "registered".into();
+            s.incoming_call_id = None;
+            s.incoming_caller_fp = None;
+            s.incoming_caller_alias = None;
+            s.call_setup_relay = None;
+            s.call_setup_room = None;
+            s.call_setup_id = None;
+        });
+    }
+
+    /// Stop the signal connection.
+    pub fn stop(&self) {
+        self.running.store(false, Ordering::Release);
+        self.transport.connection().close(0u32.into(), b"shutdown");
+    }
+}