working poc

app/build.gradle.kts

@@ -6,9 +6,7 @@ plugins {
 android {
     namespace = "sh.sar.callpipe"
     compileSdk {
-        version = release(36) {
-            minorApiLevel = 1
-        }
+        version = release(37)
     }
 
     defaultConfig {
@@ -48,6 +46,8 @@ dependencies {
     implementation(libs.androidx.compose.ui.tooling.preview)
     implementation(libs.androidx.core.ktx)
     implementation(libs.androidx.lifecycle.runtime.ktx)
+    implementation(libs.androidx.lifecycle.runtime.compose)
+    implementation(libs.nanohttpd.websocket)
     testImplementation(libs.junit)
     androidTestImplementation(platform(libs.androidx.compose.bom))
     androidTestImplementation(libs.androidx.compose.ui.test.junit4)

app/src/main/AndroidManifest.xml

@@ -2,6 +2,25 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools">
 
+    <!-- Control channel (WebSocket server on the phone; the Pi connects in) -->
+    <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
+    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
+    <uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
+
+    <!-- Telecom / call control -->
+    <uses-permission android:name="android.permission.READ_PHONE_STATE" />
+    <uses-permission android:name="android.permission.READ_PHONE_NUMBERS" />
+    <uses-permission android:name="android.permission.CALL_PHONE" />
+    <uses-permission android:name="android.permission.ANSWER_PHONE_CALLS" />
+    <uses-permission android:name="android.permission.MANAGE_OWN_CALLS" />
+
+    <!-- Foreground service keeps the control server + WiFi reachable 24/7 -->
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE_SPECIAL_USE" />
+    <uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
+    <uses-permission android:name="android.permission.WAKE_LOCK" />
+
     <application
         android:allowBackup="true"
         android:dataExtractionRules="@xml/data_extraction_rules"
@@ -10,18 +29,57 @@
         android:label="@string/app_name"
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
-        android:theme="@style/Theme.Callpipe">
+        android:theme="@style/Theme.Callpipe"
+        tools:targetApi="34">
+
         <activity
             android:name=".MainActivity"
             android:exported="true"
+            android:launchMode="singleTop"
             android:label="@string/app_name"
             android:theme="@style/Theme.Callpipe">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
-
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
+            <!-- Required to be eligible as the default phone app -->
+            <intent-filter>
+                <action android:name="android.intent.action.DIAL" />
+                <category android:name="android.intent.category.DEFAULT" />
+            </intent-filter>
+            <intent-filter>
+                <action android:name="android.intent.action.DIAL" />
+                <data android:scheme="tel" />
+                <category android:name="android.intent.category.DEFAULT" />
+            </intent-filter>
         </activity>
+
+        <!-- InCallService: intercepts and controls cellular calls -->
+        <service
+            android:name=".telecom.DialerCallService"
+            android:permission="android.permission.BIND_INCALL_SERVICE"
+            android:exported="true">
+            <meta-data
+                android:name="android.telecom.IN_CALL_SERVICE_UI"
+                android:value="true" />
+            <meta-data
+                android:name="android.telecom.IN_CALL_SERVICE_RINGING"
+                android:value="true" />
+            <intent-filter>
+                <action android:name="android.telecom.InCallService" />
+            </intent-filter>
+        </service>
+
+        <!-- Hub: relay TCP server (:9010) + agent HTTPS/WSS server (:8443) -->
+        <service
+            android:name=".hub.HubService"
+            android:foregroundServiceType="specialUse"
+            android:exported="false">
+            <property
+                android:name="android.app.PROPERTY_SPECIAL_USE_FGS_SUBTYPE"
+                android:value="callpipe cellular-call bridge: relays call audio between a paired Bluetooth device and browser agents on the LAN" />
+        </service>
+
     </application>
 
-</manifest>
+</manifest>

app/src/main/assets/web/app.js

@@ -0,0 +1,110 @@
+// CallPipe agent softphone.
+// Audio: 16 kHz mono PCM S16LE both ways over a binary WebSocket, matching the
+// relay/phone pipeline. One ScriptProcessor both captures the mic (-> uplink)
+// and plays received audio (<- downlink). Signaling is text JSON on the same WS.
+
+const RATE = 16000;
+const MAX_PLAY = RATE; // cap playback backlog at ~1s to bound latency
+
+let ws = null;
+let ac = null;
+let node = null;
+let micStream = null;
+let playBuf = [];        // queued Float32 samples to play
+let callActive = false;
+
+const $ = (id) => document.getElementById(id);
+function log(m) {
+  const el = $("log");
+  el.textContent = (new Date().toLocaleTimeString() + "  " + m + "\n" + el.textContent).slice(0, 2000);
+}
+
+function setDot(id, on) { $(id).classList.toggle("on", !!on); }
+function show(id, on) { $(id).classList.toggle("hide", !on); }
+
+// ---- WebSocket ----
+function connect() {
+  ws = new WebSocket(`wss://${location.host}/agent`);
+  ws.binaryType = "arraybuffer";
+  ws.onopen = () => { setDot("dotWs", true); $("wsText").textContent = "Connected"; log("ws open"); };
+  ws.onclose = () => {
+    setDot("dotWs", false); $("wsText").textContent = "Reconnecting…";
+    log("ws closed"); setTimeout(connect, 2000);
+  };
+  ws.onerror = () => log("ws error");
+  ws.onmessage = (e) => {
+    if (typeof e.data === "string") { onSignal(JSON.parse(e.data)); return; }
+    const i16 = new Int16Array(e.data);
+    for (let i = 0; i < i16.length; i++) playBuf.push(i16[i] / 32768);
+    if (playBuf.length > MAX_PLAY) playBuf.splice(0, playBuf.length - MAX_PLAY);
+  };
+}
+
+function send(obj) { if (ws && ws.readyState === 1) ws.send(JSON.stringify(obj)); }
+
+// ---- Signaling ----
+function onSignal(msg) {
+  if (msg.event === "state") {
+    const s = msg.state || "IDLE";
+    callActive = (s !== "IDLE" && s !== "DISCONNECTED");
+    $("stateText").textContent = prettyState(s);
+    $("numText").textContent = msg.number ? ((msg.direction || "") + " " + msg.number).trim() : "";
+    show("btnAnswer", s === "RINGING");
+    show("btnHangup", callActive);
+    show("btnDial", !callActive && ws && ws.readyState === 1);
+  } else if (msg.event === "relay") {
+    setDot("dotRelay", msg.connected);
+    $("relayText").textContent = msg.connected ? "Relay connected" : "Relay not connected";
+  } else if (msg.event === "error") {
+    log("error: " + msg.msg);
+  } else if (msg.event === "hello") {
+    log("hello from " + msg.app);
+  }
+}
+
+function prettyState(s) {
+  return { IDLE:"Idle", CONNECTING:"Connecting…", DIALING:"Ringing…",
+           RINGING:"Incoming call", ACTIVE:"Connected", HOLDING:"On hold",
+           DISCONNECTING:"Ending…", DISCONNECTED:"Call ended" }[s] || s;
+}
+
+// ---- Audio ----
+async function initAudio() {
+  ac = new AudioContext({ sampleRate: RATE });
+  micStream = await navigator.mediaDevices.getUserMedia({
+    audio: { channelCount: 1, echoCancellation: true, noiseSuppression: true, autoGainControl: true }
+  });
+  const src = ac.createMediaStreamSource(micStream);
+  node = ac.createScriptProcessor(2048, 1, 1);
+  node.onaudioprocess = (e) => {
+    // capture mic -> uplink
+    const inp = e.inputBuffer.getChannelData(0);
+    if (callActive && ws && ws.readyState === 1) {
+      const out = new Int16Array(inp.length);
+      for (let i = 0; i < inp.length; i++) {
+        let s = Math.max(-1, Math.min(1, inp[i]));
+        out[i] = s < 0 ? s * 32768 : s * 32767;
+      }
+      ws.send(out.buffer);
+    }
+    // playback downlink -> speakers
+    const o = e.outputBuffer.getChannelData(0);
+    for (let i = 0; i < o.length; i++) o[i] = playBuf.length ? playBuf.shift() : 0;
+  };
+  src.connect(node);
+  node.connect(ac.destination);
+  log("audio ready @ " + ac.sampleRate + "Hz");
+}
+
+// ---- Buttons ----
+$("btnStart").onclick = async () => {
+  $("btnStart").disabled = true;
+  try { await initAudio(); connect(); show("btnStart", false); }
+  catch (err) { log("mic failed: " + err); $("btnStart").disabled = false; }
+};
+$("btnAnswer").onclick = () => send({ cmd: "answer" });
+$("btnHangup").onclick = () => send({ cmd: "hangup" });
+$("btnDial").onclick = () => {
+  const n = prompt("Number to dial:");
+  if (n) send({ cmd: "dial", number: n });
+};

app/src/main/assets/web/index.html

@@ -0,0 +1,51 @@
+<!doctype html>
+<html lang="en">
+<head>
+<meta charset="utf-8">
+<meta name="viewport" content="width=device-width, initial-scale=1">
+<title>CallPipe Agent</title>
+<style>
+  :root { color-scheme: dark; }
+  * { box-sizing: border-box; }
+  body { margin:0; font-family: system-ui, sans-serif; background:#0b0f14; color:#e5e9ef;
+         display:flex; min-height:100vh; align-items:center; justify-content:center; }
+  .card { width:min(420px,92vw); background:#141a21; border-radius:16px; padding:24px;
+          box-shadow:0 10px 40px rgba(0,0,0,.4); }
+  h1 { margin:0 0 4px; font-size:22px; }
+  .sub { color:#8b98a8; font-size:13px; margin-bottom:16px; }
+  .row { display:flex; align-items:center; gap:8px; margin:8px 0; }
+  .dot { width:10px; height:10px; border-radius:50%; background:#64748b; }
+  .dot.on { background:#4ade80; }
+  .state { font-size:15px; font-weight:600; margin:14px 0 4px; }
+  .num { color:#8b98a8; font-family:ui-monospace,monospace; min-height:18px; }
+  button { border:0; border-radius:10px; padding:12px 16px; font-size:15px; font-weight:600;
+           cursor:pointer; width:100%; margin-top:10px; color:#04140a; background:#4ade80; }
+  button.secondary { background:#243040; color:#e5e9ef; }
+  button.danger { background:#dc2626; color:#fff; }
+  button:disabled { opacity:.4; cursor:default; }
+  .hide { display:none; }
+  #log { margin-top:14px; font-family:ui-monospace,monospace; font-size:11px; color:#64748b;
+         white-space:pre-wrap; max-height:120px; overflow:auto; }
+</style>
+</head>
+<body>
+  <div class="card">
+    <h1>CallPipe Agent</h1>
+    <div class="sub">browser softphone</div>
+
+    <div class="row"><span class="dot" id="dotWs"></span><span id="wsText">Not connected</span></div>
+    <div class="row"><span class="dot" id="dotRelay"></span><span id="relayText">Relay unknown</span></div>
+
+    <div class="state" id="stateText">Idle</div>
+    <div class="num" id="numText"></div>
+
+    <button id="btnStart">Connect &amp; enable mic</button>
+    <button id="btnAnswer" class="hide">Answer</button>
+    <button id="btnHangup" class="danger hide">Hang up</button>
+    <button id="btnDial" class="secondary hide">Dial…</button>
+
+    <div id="log"></div>
+  </div>
+  <script src="app.js"></script>
+</body>
+</html>

app/src/main/java/sh/sar/callpipe/MainActivity.kt

@@ -1,47 +1,191 @@
 package sh.sar.callpipe
 
+import android.Manifest
+import android.app.role.RoleManager
+import android.content.Context
+import android.content.Intent
+import android.content.pm.PackageManager
+import android.os.Build
 import android.os.Bundle
+import android.telecom.TelecomManager
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
+import androidx.activity.result.contract.ActivityResultContracts
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.shape.CircleShape
+import androidx.compose.material3.Button
+import androidx.compose.material3.ButtonDefaults
+import androidx.compose.material3.Card
+import androidx.compose.material3.CardDefaults
+import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Surface
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
-import androidx.compose.ui.tooling.preview.Preview
+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.unit.dp
+import androidx.compose.ui.unit.sp
+import androidx.core.content.ContextCompat
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import sh.sar.callpipe.hub.HubService
+import sh.sar.callpipe.hub.HubStatus
+import sh.sar.callpipe.telecom.CallController
 import sh.sar.callpipe.ui.theme.CallpipeTheme
+import java.net.Inet4Address
+import java.net.NetworkInterface
 
 class MainActivity : ComponentActivity() {
+
+    private val roleLauncher =
+        registerForActivityResult(ActivityResultContracts.StartActivityForResult()) { }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         enableEdgeToEdge()
+        requestNeededPermissions()
+        requestDialerRole()
+        HubService.start(this)
+
         setContent {
             CallpipeTheme {
-                Scaffold(modifier = Modifier.fillMaxSize()) { innerPadding ->
-                    Greeting(
-                        name = "Android",
-                        modifier = Modifier.padding(innerPadding)
+                Surface(modifier = Modifier.fillMaxSize()) {
+                    HubScreen(
+                        onAnswer = { CallController.answer(); CallController.routeBluetooth() },
+                        onHangup = { CallController.hangup() },
                     )
                 }
             }
         }
     }
-}
 
-@Composable
-fun Greeting(name: String, modifier: Modifier = Modifier) {
-    Text(
-        text = "Hello $name!",
-        modifier = modifier
-    )
-}
-
-@Preview(showBackground = true)
-@Composable
-fun GreetingPreview() {
-    CallpipeTheme {
-        Greeting("Android")
+    private fun requestNeededPermissions() {
+        val perms = mutableListOf(
+            Manifest.permission.READ_PHONE_STATE,
+            Manifest.permission.READ_PHONE_NUMBERS,
+            Manifest.permission.CALL_PHONE,
+            Manifest.permission.ANSWER_PHONE_CALLS,
+        )
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
+            perms.add(Manifest.permission.POST_NOTIFICATIONS)
+        }
+        val needed = perms.filter {
+            ContextCompat.checkSelfPermission(this, it) != PackageManager.PERMISSION_GRANTED
+        }
+        if (needed.isNotEmpty()) requestPermissions(needed.toTypedArray(), REQ_PERMS)
     }
-}
+
+    private fun requestDialerRole() {
+        val tm = getSystemService(Context.TELECOM_SERVICE) as TelecomManager
+        if (packageName == tm.defaultDialerPackage) return
+        val intent = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+            val rm = getSystemService(Context.ROLE_SERVICE) as RoleManager
+            if (!rm.isRoleAvailable(RoleManager.ROLE_DIALER) || rm.isRoleHeld(RoleManager.ROLE_DIALER)) return
+            rm.createRequestRoleIntent(RoleManager.ROLE_DIALER)
+        } else {
+            @Suppress("DEPRECATION")
+            Intent(TelecomManager.ACTION_CHANGE_DEFAULT_DIALER)
+                .putExtra(TelecomManager.EXTRA_CHANGE_DEFAULT_DIALER_PACKAGE_NAME, packageName)
+        }
+        roleLauncher.launch(intent)
+    }
+
+    companion object {
+        private const val REQ_PERMS = 100
+    }
+}
+
+@Composable
+private fun HubScreen(onAnswer: () -> Unit, onHangup: () -> Unit) {
+    val hub by HubStatus.info.collectAsStateWithLifecycle()
+    val call by CallController.state.collectAsStateWithLifecycle()
+    val ip = remembered()
+
+    Scaffold { pad ->
+        Column(
+            modifier = Modifier.fillMaxSize().padding(pad).padding(20.dp),
+            verticalArrangement = Arrangement.spacedBy(16.dp),
+        ) {
+            Text("callpipe hub", fontSize = 26.sp, fontWeight = FontWeight.Bold,
+                color = MaterialTheme.colorScheme.onBackground)
+            Text("phone = the bridge · agents ⇄ relay", fontSize = 13.sp,
+                color = MaterialTheme.colorScheme.onBackground.copy(alpha = 0.55f))
+
+            Card(colors = CardDefaults.cardColors(containerColor = MaterialTheme.colorScheme.surface)) {
+                Column(Modifier.padding(16.dp), verticalArrangement = Arrangement.spacedBy(8.dp)) {
+                    StatusRow(hub.webRunning, if (hub.webRunning) "Web server up" else "Web server down")
+                    hub.error?.let { Text("error: $it", color = Color(0xFFF87171), fontSize = 12.sp) }
+                    StatusRow(hub.relayConnected, if (hub.relayConnected) "Relay connected" else "Relay not connected")
+                    KeyVal("Agents connected", hub.agents.toString())
+                    KeyVal("Agents open", "https://test.shihaam.me:${hub.webPort}")
+                    KeyVal("(map that host to)", ip)
+                }
+            }
+
+            Card(colors = CardDefaults.cardColors(containerColor = MaterialTheme.colorScheme.surface)) {
+                Column(Modifier.padding(16.dp), verticalArrangement = Arrangement.spacedBy(8.dp)) {
+                    StatusRow(call.active, "Call: ${call.state}")
+                    Text(call.number?.let { "${call.direction ?: ""} $it".trim() } ?: "no call",
+                        color = MaterialTheme.colorScheme.onSurface.copy(alpha = 0.8f))
+                    if (call.state == CallController.STATE_RINGING) {
+                        Button(onClick = onAnswer, modifier = Modifier.fillMaxWidth()) { Text("Answer") }
+                    }
+                    if (call.active) {
+                        Button(onClick = onHangup, modifier = Modifier.fillMaxWidth(),
+                            colors = ButtonDefaults.buttonColors(
+                                containerColor = Color(0xFFDC2626), contentColor = Color.White)) {
+                            Text("Hang up")
+                        }
+                    }
+                }
+            }
+
+            Spacer(Modifier.height(4.dp))
+            Text("Answering happens from the agent browser; audio rides Bluetooth to the relay.",
+                fontSize = 12.sp, color = MaterialTheme.colorScheme.onBackground.copy(alpha = 0.45f))
+        }
+    }
+}
+
+@Composable
+private fun StatusRow(ok: Boolean, label: String) {
+    Row(verticalAlignment = Alignment.CenterVertically) {
+        Surface(modifier = Modifier.size(10.dp).clip(CircleShape),
+            color = if (ok) Color(0xFF4ADE80) else Color(0xFF64748B)) {}
+        Spacer(Modifier.size(8.dp))
+        Text(label, color = MaterialTheme.colorScheme.onSurface, fontWeight = FontWeight.Medium)
+    }
+}
+
+@Composable
+private fun KeyVal(key: String, value: String) {
+    Column {
+        Text(key, fontSize = 12.sp, color = MaterialTheme.colorScheme.onSurface.copy(alpha = 0.5f))
+        Text(value, fontFamily = FontFamily.Monospace, color = MaterialTheme.colorScheme.onSurface)
+    }
+}
+
+private fun remembered(): String = localIpv4() ?: "?.?.?.?"
+
+private fun localIpv4(): String? = try {
+    NetworkInterface.getNetworkInterfaces().toList()
+        .filter { it.isUp && !it.isLoopback }
+        .flatMap { it.inetAddresses.toList() }
+        .filterIsInstance<Inet4Address>()
+        .firstOrNull { it.isSiteLocalAddress }
+        ?.hostAddress
+} catch (_: Exception) { null }

app/src/main/java/sh/sar/callpipe/hub/Hub.kt

@@ -0,0 +1,135 @@
+package sh.sar.callpipe.hub
+
+import android.content.Context
+import android.util.Log
+import org.json.JSONObject
+import sh.sar.callpipe.relay.RelayServer
+import sh.sar.callpipe.telecom.CallController
+import java.util.Collections
+
+/**
+ * The hub. The phone is the center of the star: it holds the cellular call
+ * (Telecom), talks to the relay (Bluetooth audio, over TCP) and to the agents
+ * (browsers, over WSS). This object splices audio between the relay and the
+ * agents and translates agent commands / call state.
+ *
+ *   downlink: relay --onDownlinkAudio--> [Hub] --> all agents (binary)
+ *   uplink:   agent --onUplinkAudio-----> [Hub] --> relay.sendAudio
+ *   signaling: agent JSON <-> CallController; call state --> agents
+ */
+object Hub {
+
+    private const val TAG = "Hub"
+
+    /** An agent browser connection (implemented by the WSS socket). */
+    interface AgentChannel {
+        fun sendAudio(pcm: ByteArray)
+        fun sendEvent(json: String)
+    }
+
+    private lateinit var appContext: Context
+    private var relay: RelayServer? = null
+    private val agents = Collections.synchronizedSet(mutableSetOf<AgentChannel>())
+
+    @Volatile private var lastState: String = CallController.STATE_IDLE
+
+    fun init(context: Context, relay: RelayServer) {
+        this.appContext = context.applicationContext
+        this.relay = relay
+    }
+
+    // ── Relay side (RelayServer.Listener is wired in HubService) ──
+
+    fun onDownlinkAudio(pcm: ByteArray) {
+        val snapshot = synchronized(agents) { agents.toList() }
+        for (a in snapshot) a.sendAudio(pcm)
+    }
+
+    fun onRelayConnected() {
+        HubStatus.setRelay(true)
+        broadcastEvent(JSONObject().put("event", "relay").put("connected", true))
+    }
+
+    fun onRelayDisconnected() {
+        HubStatus.setRelay(false)
+        broadcastEvent(JSONObject().put("event", "relay").put("connected", false))
+    }
+
+    fun onRelayEvent(json: String) {
+        Log.i(TAG, "relay: $json")
+    }
+
+    // ── Agent side (called by the WSS socket) ──
+
+    fun addAgent(ch: AgentChannel) {
+        agents.add(ch)
+        HubStatus.setAgents(agents.size)
+        // greet + current relay + call state
+        ch.sendEvent(JSONObject().put("event", "hello").put("app", "callpipe").toString())
+        ch.sendEvent(JSONObject().put("event", "relay")
+            .put("connected", HubStatus.info.value.relayConnected).toString())
+        ch.sendEvent(stateEvent(CallController.state.value))
+    }
+
+    fun removeAgent(ch: AgentChannel) {
+        agents.remove(ch)
+        HubStatus.setAgents(agents.size)
+    }
+
+    fun onUplinkAudio(pcm: ByteArray) {
+        relay?.sendAudio(pcm)
+    }
+
+    fun onAgentCommand(json: String) {
+        val obj = try { JSONObject(json) } catch (_: Exception) { return }
+        when (obj.optString("cmd")) {
+            "answer" -> {
+                CallController.answer()
+                CallController.routeBluetooth()
+            }
+            "hangup" -> CallController.hangup()
+            "reject" -> CallController.reject()
+            "dial" -> {
+                val number = obj.optString("number")
+                val sim = if (obj.has("sim") && !obj.isNull("sim")) obj.optInt("sim") else null
+                val err = CallController.dial(appContext, number, sim)
+                if (err != null) broadcastEvent(JSONObject().put("event", "error").put("msg", err))
+                else CallController.routeBluetooth()
+            }
+        }
+    }
+
+    // ── Call state (fed from HubService's CallController.state collector) ──
+
+    fun onCallState(snap: CallController.Snapshot) {
+        broadcastEvent(JSONObject(stateEvent(snap)))
+        if (snap.state != lastState) {
+            when (snap.state) {
+                CallController.STATE_ACTIVE -> {
+                    CallController.routeBluetooth()
+                    relay?.sendStart()
+                }
+                CallController.STATE_IDLE, CallController.STATE_DISCONNECTED -> {
+                    relay?.sendStop()
+                }
+            }
+            lastState = snap.state
+        }
+    }
+
+    // ── helpers ──
+
+    private fun stateEvent(snap: CallController.Snapshot): String = JSONObject()
+        .put("event", "state")
+        .put("state", snap.state)
+        .put("number", snap.number ?: JSONObject.NULL)
+        .put("direction", snap.direction ?: JSONObject.NULL)
+        .toString()
+
+    private fun broadcastEvent(obj: JSONObject) = broadcastEvent(obj.toString())
+
+    private fun broadcastEvent(json: String) {
+        val snapshot = synchronized(agents) { agents.toList() }
+        for (a in snapshot) a.sendEvent(json)
+    }
+}

app/src/main/java/sh/sar/callpipe/hub/HubService.kt

@@ -0,0 +1,145 @@
+package sh.sar.callpipe.hub
+
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.PendingIntent
+import android.app.Service
+import android.content.Context
+import android.content.Intent
+import android.content.pm.ServiceInfo
+import android.net.wifi.WifiManager
+import android.os.Build
+import android.os.IBinder
+import android.os.PowerManager
+import android.util.Log
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.SupervisorJob
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.launch
+import sh.sar.callpipe.MainActivity
+import sh.sar.callpipe.R
+import sh.sar.callpipe.relay.RelayServer
+import sh.sar.callpipe.telecom.CallController
+import sh.sar.callpipe.web.WebServer
+
+/**
+ * Foreground service hosting the hub: the relay TCP server (:9010) and the agent
+ * HTTPS/WSS server (:8443), kept reachable 24/7 with WiFi + wake locks. Relays
+ * call-state changes into [Hub].
+ */
+class HubService : Service() {
+
+    private val scope = CoroutineScope(SupervisorJob() + Dispatchers.Default)
+    private var relay: RelayServer? = null
+    private var web: WebServer? = null
+    private var wifiLock: WifiManager.WifiLock? = null
+    private var wakeLock: PowerManager.WakeLock? = null
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        startForegroundNotification()
+        acquireLocks()
+        startHub()
+        return START_STICKY
+    }
+
+    private fun startHub() {
+        if (relay != null) return
+        val relayServer = RelayServer(RelayServer.DEFAULT_PORT, relayListener)
+        relay = relayServer
+        Hub.init(applicationContext, relayServer)
+        relayServer.start()
+
+        try {
+            val server = WebServer(applicationContext, WebServer.DEFAULT_PORT)
+            server.start(0, false)
+            web = server
+            HubStatus.setWeb(true, WebServer.DEFAULT_PORT)
+            Log.i(TAG, "web server on :${WebServer.DEFAULT_PORT}, relay on :${RelayServer.DEFAULT_PORT}")
+        } catch (e: Exception) {
+            Log.e(TAG, "web server failed: ${e.message}")
+            HubStatus.setWeb(false, WebServer.DEFAULT_PORT, error = e.message ?: "web start failed")
+        }
+
+        // Feed call-state changes into the hub (ring agents, start/stop relay, etc.)
+        scope.launch {
+            CallController.state.collect { Hub.onCallState(it) }
+        }
+    }
+
+    private val relayListener = object : RelayServer.Listener {
+        override fun onRelayConnected() = Hub.onRelayConnected()
+        override fun onRelayDisconnected() = Hub.onRelayDisconnected()
+        override fun onDownlinkAudio(pcm: ByteArray) = Hub.onDownlinkAudio(pcm)
+        override fun onRelayEvent(json: String) = Hub.onRelayEvent(json)
+    }
+
+    private fun acquireLocks() {
+        try {
+            val wm = applicationContext.getSystemService(Context.WIFI_SERVICE) as WifiManager
+            @Suppress("DEPRECATION")
+            wifiLock = wm.createWifiLock(WifiManager.WIFI_MODE_FULL_HIGH_PERF, "callpipe:wifi").apply {
+                setReferenceCounted(false); acquire()
+            }
+        } catch (e: Exception) { Log.w(TAG, "wifi lock: ${e.message}") }
+        try {
+            val pm = applicationContext.getSystemService(Context.POWER_SERVICE) as PowerManager
+            wakeLock = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "callpipe:cpu").apply {
+                setReferenceCounted(false); acquire()
+            }
+        } catch (e: Exception) { Log.w(TAG, "wake lock: ${e.message}") }
+    }
+
+    private fun startForegroundNotification() {
+        val nm = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+        nm.createNotificationChannel(
+            NotificationChannel(CHANNEL, "Call bridge", NotificationManager.IMPORTANCE_LOW)
+                .apply { description = "callpipe hub (relay + agents)" }
+        )
+        val tap = PendingIntent.getActivity(
+            this, 0, Intent(this, MainActivity::class.java),
+            PendingIntent.FLAG_IMMUTABLE or PendingIntent.FLAG_UPDATE_CURRENT
+        )
+        val notif: Notification = Notification.Builder(this, CHANNEL)
+            .setContentTitle("callpipe hub")
+            .setContentText("relay :${RelayServer.DEFAULT_PORT} · agents :${WebServer.DEFAULT_PORT}")
+            .setSmallIcon(R.drawable.ic_stat_call)
+            .setOngoing(true)
+            .setContentIntent(tap)
+            .build()
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.UPSIDE_DOWN_CAKE) {
+            startForeground(NOTIF_ID, notif, ServiceInfo.FOREGROUND_SERVICE_TYPE_SPECIAL_USE)
+        } else {
+            startForeground(NOTIF_ID, notif)
+        }
+    }
+
+    override fun onDestroy() {
+        super.onDestroy()
+        scope.cancel()
+        try { web?.stop() } catch (_: Exception) {}
+        try { relay?.stop() } catch (_: Exception) {}
+        web = null; relay = null
+        try { wifiLock?.release() } catch (_: Exception) {}
+        try { wakeLock?.release() } catch (_: Exception) {}
+        HubStatus.setWeb(false, WebServer.DEFAULT_PORT)
+        Log.i(TAG, "hub stopped")
+    }
+
+    companion object {
+        private const val TAG = "HubService"
+        private const val CHANNEL = "callpipe_hub"
+        private const val NOTIF_ID = 1
+
+        fun start(context: Context) {
+            context.startForegroundService(Intent(context, HubService::class.java))
+        }
+
+        fun stop(context: Context) {
+            context.stopService(Intent(context, HubService::class.java))
+        }
+    }
+}

app/src/main/java/sh/sar/callpipe/hub/HubStatus.kt

@@ -0,0 +1,32 @@
+package sh.sar.callpipe.hub
+
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+
+/** Observable hub status for the UI. */
+object HubStatus {
+
+    data class Info(
+        val webRunning: Boolean = false,
+        val webPort: Int = 0,
+        val relayConnected: Boolean = false,
+        val agents: Int = 0,
+        val error: String? = null,
+    )
+
+    private val _info = MutableStateFlow(Info())
+    val info: StateFlow<Info> = _info.asStateFlow()
+
+    fun setWeb(running: Boolean, port: Int, error: String? = null) {
+        _info.value = _info.value.copy(webRunning = running, webPort = port, error = error)
+    }
+
+    fun setRelay(connected: Boolean) {
+        _info.value = _info.value.copy(relayConnected = connected)
+    }
+
+    fun setAgents(n: Int) {
+        _info.value = _info.value.copy(agents = n)
+    }
+}

app/src/main/java/sh/sar/callpipe/net/Frames.kt

@@ -0,0 +1,39 @@
+package sh.sar.callpipe.net
+
+import java.io.DataInputStream
+import java.io.DataOutputStream
+
+/**
+ * Wire framing for the relay TCP link (matches relay/callpipe-relay.py):
+ *   [4-byte big-endian length N][1-byte type][payload]   where N = 1 + payload.size
+ *   type 'A' (0x41) = PCM S16LE mono 16 kHz, 20 ms (640 B) frames
+ *   type 'C' (0x43) = control, payload is UTF-8 JSON
+ */
+object Frames {
+    const val TYPE_AUDIO = 0x41
+    const val TYPE_CTRL = 0x43
+
+    const val RATE = 16000
+    const val FRAME_MS = 20
+    const val FRAME_BYTES = RATE * 2 * FRAME_MS / 1000 // 640
+
+    /** Reads one frame; returns (type, payload) or null on EOF / malformed. */
+    fun read(input: DataInputStream): Pair<Int, ByteArray>? {
+        val len = try { input.readInt() } catch (_: Exception) { return null }
+        if (len <= 0 || len > 65536) return null
+        return try {
+            val type = input.readUnsignedByte()
+            val payload = ByteArray(len - 1)
+            input.readFully(payload)
+            type to payload
+        } catch (_: Exception) { null }
+    }
+
+    /** Writes one frame. Caller must serialize access to [output]. */
+    fun write(output: DataOutputStream, type: Int, payload: ByteArray) {
+        output.writeInt(payload.size + 1)
+        output.writeByte(type)
+        output.write(payload)
+        output.flush()
+    }
+}

app/src/main/java/sh/sar/callpipe/relay/RelayServer.kt

@@ -0,0 +1,119 @@
+package sh.sar.callpipe.relay
+
+import android.util.Log
+import sh.sar.callpipe.net.Frames
+import java.io.DataInputStream
+import java.io.DataOutputStream
+import java.net.InetSocketAddress
+import java.net.ServerSocket
+import java.net.Socket
+
+/**
+ * TCP server the CallPipe Relay (Pi) connects into. Carries call audio both ways
+ * plus start/stop control. Exactly one relay is expected; a new connection
+ * replaces any previous one.
+ *
+ * Downlink (customer voice) arrives as audio frames -> [Listener.onDownlinkAudio].
+ * Uplink (agent voice) is pushed out via [sendAudio]. [sendStart]/[sendStop] tell
+ * the relay when a call is up and routed to Bluetooth.
+ */
+class RelayServer(
+    private val port: Int,
+    private val listener: Listener,
+) {
+    interface Listener {
+        fun onRelayConnected()
+        fun onRelayDisconnected()
+        fun onDownlinkAudio(pcm: ByteArray)
+        fun onRelayEvent(json: String)
+    }
+
+    @Volatile private var serverSocket: ServerSocket? = null
+    @Volatile private var conn: Socket? = null
+    @Volatile private var out: DataOutputStream? = null
+    private val writeLock = Any()
+    @Volatile private var running = false
+
+    fun start() {
+        if (running) return
+        running = true
+        Thread({ acceptLoop() }, "relay-accept").start()
+    }
+
+    private fun acceptLoop() {
+        try {
+            val ss = ServerSocket()
+            ss.reuseAddress = true
+            ss.bind(InetSocketAddress(port))
+            serverSocket = ss
+            Log.i(TAG, "listening on :$port")
+            while (running) {
+                val c = ss.accept()
+                Log.i(TAG, "relay connected from ${c.inetAddress?.hostAddress}")
+                closeConn() // drop any previous relay
+                handle(c)
+            }
+        } catch (e: Exception) {
+            if (running) Log.e(TAG, "accept loop error: ${e.message}")
+        }
+    }
+
+    private fun handle(c: Socket) {
+        conn = c
+        try {
+            c.tcpNoDelay = true
+            val input = DataInputStream(c.getInputStream().buffered())
+            synchronized(writeLock) { out = DataOutputStream(c.getOutputStream().buffered()) }
+            listener.onRelayConnected()
+            while (running) {
+                val frame = Frames.read(input) ?: break
+                val (type, payload) = frame
+                when (type) {
+                    Frames.TYPE_AUDIO -> listener.onDownlinkAudio(payload)
+                    Frames.TYPE_CTRL -> listener.onRelayEvent(String(payload, Charsets.UTF_8))
+                }
+            }
+        } catch (e: Exception) {
+            Log.w(TAG, "relay conn error: ${e.message}")
+        } finally {
+            closeConn()
+            listener.onRelayDisconnected()
+        }
+    }
+
+    val isConnected: Boolean get() = conn?.isConnected == true && conn?.isClosed == false
+
+    fun sendAudio(pcm: ByteArray) = send(Frames.TYPE_AUDIO, pcm)
+    fun sendStart() = sendControl("""{"cmd":"start"}""")
+    fun sendStop() = sendControl("""{"cmd":"stop"}""")
+    fun sendControl(json: String) = send(Frames.TYPE_CTRL, json.toByteArray(Charsets.UTF_8))
+
+    private fun send(type: Int, payload: ByteArray) {
+        synchronized(writeLock) {
+            val o = out ?: return
+            try {
+                Frames.write(o, type, payload)
+            } catch (e: Exception) {
+                Log.w(TAG, "send failed: ${e.message}")
+            }
+        }
+    }
+
+    private fun closeConn() {
+        synchronized(writeLock) { out = null }
+        try { conn?.close() } catch (_: Exception) {}
+        conn = null
+    }
+
+    fun stop() {
+        running = false
+        closeConn()
+        try { serverSocket?.close() } catch (_: Exception) {}
+        serverSocket = null
+    }
+
+    companion object {
+        private const val TAG = "RelayServer"
+        const val DEFAULT_PORT = 9010
+    }
+}

app/src/main/java/sh/sar/callpipe/telecom/CallController.kt

@@ -0,0 +1,217 @@
+package sh.sar.callpipe.telecom
+
+import android.annotation.SuppressLint
+import android.content.Context
+import android.net.Uri
+import android.os.Build
+import android.os.Bundle
+import android.telecom.Call
+import android.telecom.CallAudioState
+import android.telecom.InCallService
+import android.telecom.TelecomManager
+import android.util.Log
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+
+/**
+ * Single source of truth for the phone's cellular call.
+ *
+ * In the BT-bridge architecture the phone does NO audio — audio rides Bluetooth
+ * HFP to the Raspberry Pi. This object only *controls* the call (place / answer /
+ * hang up) and publishes its state, so the control channel and the UI can both
+ * observe it. Commands arrive either from the local UI or from the Pi over the
+ * WebSocket control channel.
+ */
+object CallController {
+
+    private const val TAG = "CallController"
+
+    data class SimInfo(val index: Int, val label: String)
+
+    /** Immutable snapshot of the current call for observers. */
+    data class Snapshot(
+        val state: String = STATE_IDLE,
+        val number: String? = null,
+        /** "IN" | "OUT" | null */
+        val direction: String? = null,
+    ) {
+        val active: Boolean get() = state != STATE_IDLE && state != STATE_DISCONNECTED
+    }
+
+    private val _state = MutableStateFlow(Snapshot())
+    val state: StateFlow<Snapshot> = _state.asStateFlow()
+
+    @Volatile private var service: InCallService? = null
+    @Volatile private var activeCall: Call? = null
+
+    // ── InCallService plumbing ───────────────────────────
+
+    fun attachService(s: InCallService) { service = s }
+
+    fun onCallAdded(call: Call) {
+        activeCall = call
+        publish(call)
+    }
+
+    fun onCallRemoved(call: Call) {
+        if (activeCall == call) activeCall = null
+        // If no call remains, fall back to IDLE; otherwise reflect whatever's left.
+        val remaining = service?.calls?.firstOrNull { it != call }
+        if (remaining != null) {
+            activeCall = remaining
+            publish(remaining)
+        } else {
+            _state.value = Snapshot(STATE_IDLE)
+        }
+    }
+
+    fun onStateChanged(call: Call) {
+        if (activeCall == null) activeCall = call
+        publish(call)
+    }
+
+    private fun publish(call: Call) {
+        val details = call.details
+        val number = details?.handle?.schemeSpecificPart
+        _state.value = Snapshot(
+            state = stateName(call.state),
+            number = number,
+            direction = directionOf(call),
+        )
+    }
+
+    // ── Commands ─────────────────────────────────────────
+
+    /**
+     * Place an outgoing cellular call. [simIndex] selects the SIM (0-based, in the
+     * order returned by [listSims]); null uses the system default.
+     * Returns null on success, or an error message.
+     */
+    @SuppressLint("MissingPermission")
+    fun dial(context: Context, number: String, simIndex: Int? = null): String? {
+        val n = number.trim()
+        if (n.isEmpty()) return "empty number"
+        return try {
+            val tm = context.getSystemService(Context.TELECOM_SERVICE) as TelecomManager
+            val uri = Uri.fromParts("tel", n, null)
+            val extras = Bundle()
+            if (simIndex != null) {
+                val accounts = tm.callCapablePhoneAccounts
+                if (simIndex in accounts.indices) {
+                    extras.putParcelable(
+                        TelecomManager.EXTRA_PHONE_ACCOUNT_HANDLE, accounts[simIndex]
+                    )
+                } else {
+                    return "sim $simIndex out of range (${accounts.size} available)"
+                }
+            }
+            tm.placeCall(uri, extras)
+            Log.i(TAG, "dial $n sim=$simIndex")
+            null
+        } catch (e: SecurityException) {
+            Log.e(TAG, "dial denied: ${e.message}")
+            "permission denied (CALL_PHONE / default dialer?)"
+        } catch (e: Exception) {
+            Log.e(TAG, "dial failed: ${e.message}")
+            e.message ?: "dial failed"
+        }
+    }
+
+    fun answer(): Boolean {
+        val call = activeCall ?: return false
+        return try {
+            call.answer(call.details.videoState)
+            true
+        } catch (e: Exception) {
+            Log.e(TAG, "answer failed: ${e.message}"); false
+        }
+    }
+
+    fun hangup(): Boolean {
+        val call = activeCall ?: return false
+        return try {
+            when (call.state) {
+                Call.STATE_RINGING -> call.reject(false, "")
+                else -> call.disconnect()
+            }
+            true
+        } catch (e: Exception) {
+            Log.e(TAG, "hangup failed: ${e.message}"); false
+        }
+    }
+
+    fun reject(): Boolean {
+        val call = activeCall ?: return false
+        return try { call.reject(false, ""); true }
+        catch (e: Exception) { Log.e(TAG, "reject failed: ${e.message}"); false }
+    }
+
+    /**
+     * Route the active call's audio to the Bluetooth headset (the CallPipe Relay),
+     * so the modem's voice path goes out over HFP/SCO instead of the earpiece.
+     * This is what makes the relay able to see/inject the audio.
+     */
+    fun routeBluetooth(): Boolean = try {
+        service?.setAudioRoute(CallAudioState.ROUTE_BLUETOOTH); true
+    } catch (e: Exception) {
+        Log.w(TAG, "routeBluetooth failed: ${e.message}"); false
+    }
+
+    /** Is a Bluetooth device currently available as a call-audio route? */
+    val bluetoothAvailable: Boolean
+        get() = try {
+            (service?.callAudioState?.supportedRouteMask ?: 0) and CallAudioState.ROUTE_BLUETOOTH != 0
+        } catch (_: Exception) { false }
+
+    @SuppressLint("MissingPermission")
+    fun listSims(context: Context): List<SimInfo> = try {
+        val tm = context.getSystemService(Context.TELECOM_SERVICE) as TelecomManager
+        tm.callCapablePhoneAccounts.mapIndexed { i, handle ->
+            val label = try {
+                tm.getPhoneAccount(handle)?.label?.toString()
+            } catch (_: Exception) { null }
+            SimInfo(i, label?.ifBlank { null } ?: "SIM ${i + 1}")
+        }
+    } catch (e: Exception) {
+        Log.w(TAG, "listSims failed: ${e.message}"); emptyList()
+    }
+
+    // ── Helpers ──────────────────────────────────────────
+
+    private fun directionOf(call: Call): String? {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+            return when (call.details?.callDirection) {
+                Call.Details.DIRECTION_INCOMING -> "IN"
+                Call.Details.DIRECTION_OUTGOING -> "OUT"
+                else -> null
+            }
+        }
+        return when (call.state) {
+            Call.STATE_RINGING -> "IN"
+            Call.STATE_DIALING, Call.STATE_CONNECTING -> "OUT"
+            else -> null
+        }
+    }
+
+    private fun stateName(s: Int): String = when (s) {
+        Call.STATE_NEW, Call.STATE_CONNECTING -> STATE_CONNECTING
+        Call.STATE_DIALING -> STATE_DIALING
+        Call.STATE_RINGING -> STATE_RINGING
+        Call.STATE_ACTIVE -> STATE_ACTIVE
+        Call.STATE_HOLDING -> STATE_HOLDING
+        Call.STATE_DISCONNECTING -> STATE_DISCONNECTING
+        Call.STATE_DISCONNECTED -> STATE_DISCONNECTED
+        Call.STATE_SELECT_PHONE_ACCOUNT -> STATE_CONNECTING
+        else -> "UNKNOWN($s)"
+    }
+
+    const val STATE_IDLE = "IDLE"
+    const val STATE_CONNECTING = "CONNECTING"
+    const val STATE_DIALING = "DIALING"
+    const val STATE_RINGING = "RINGING"
+    const val STATE_ACTIVE = "ACTIVE"
+    const val STATE_HOLDING = "HOLDING"
+    const val STATE_DISCONNECTING = "DISCONNECTING"
+    const val STATE_DISCONNECTED = "DISCONNECTED"
+}

app/src/main/java/sh/sar/callpipe/telecom/DialerCallService.kt

@@ -0,0 +1,39 @@
+package sh.sar.callpipe.telecom
+
+import android.telecom.Call
+import android.telecom.InCallService
+import android.util.Log
+
+/**
+ * InCallService — Android routes every cellular call through this once the app is
+ * the default phone app. We forward all events to [CallController], which owns the
+ * call state and command surface.
+ */
+class DialerCallService : InCallService() {
+
+    private val callback = object : Call.Callback() {
+        override fun onStateChanged(call: Call, state: Int) {
+            Log.i(TAG, "state -> $state")
+            CallController.onStateChanged(call)
+        }
+    }
+
+    override fun onCallAdded(call: Call) {
+        super.onCallAdded(call)
+        Log.i(TAG, "call added: ${call.details?.handle?.schemeSpecificPart}")
+        CallController.attachService(this)
+        call.registerCallback(callback)
+        CallController.onCallAdded(call)
+    }
+
+    override fun onCallRemoved(call: Call) {
+        super.onCallRemoved(call)
+        Log.i(TAG, "call removed")
+        call.unregisterCallback(callback)
+        CallController.onCallRemoved(call)
+    }
+
+    companion object {
+        private const val TAG = "DialerCallService"
+    }
+}

app/src/main/java/sh/sar/callpipe/ui/theme/Theme.kt

@@ -1,58 +1,26 @@
 package sh.sar.callpipe.ui.theme
 
-import android.app.Activity
-import android.os.Build
-import androidx.compose.foundation.isSystemInDarkTheme
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.darkColorScheme
-import androidx.compose.material3.dynamicDarkColorScheme
-import androidx.compose.material3.dynamicLightColorScheme
-import androidx.compose.material3.lightColorScheme
 import androidx.compose.runtime.Composable
-import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.graphics.Color
 
-private val DarkColorScheme = darkColorScheme(
-    primary = Purple80,
-    secondary = PurpleGrey80,
-    tertiary = Pink80
-)
-
-private val LightColorScheme = lightColorScheme(
-    primary = Purple40,
-    secondary = PurpleGrey40,
-    tertiary = Pink40
-
-    /* Other default colors to override
-    background = Color(0xFFFFFBFE),
-    surface = Color(0xFFFFFBFE),
-    onPrimary = Color.White,
-    onSecondary = Color.White,
-    onTertiary = Color.White,
-    onBackground = Color(0xFF1C1B1F),
-    onSurface = Color(0xFF1C1B1F),
-    */
+private val CallpipeColors = darkColorScheme(
+    primary = Color(0xFF4ADE80),      // green — "connected / active"
+    secondary = Color(0xFF38BDF8),
+    background = Color(0xFF0B0F14),
+    surface = Color(0xFF141A21),
+    onPrimary = Color(0xFF04140A),
+    onBackground = Color(0xFFE5E9EF),
+    onSurface = Color(0xFFE5E9EF),
 )
 
+/** App is a headless-ish control client — always dark, no dynamic color. */
 @Composable
-fun CallpipeTheme(
-    darkTheme: Boolean = isSystemInDarkTheme(),
-    // Dynamic color is available on Android 12+
-    dynamicColor: Boolean = true,
-    content: @Composable () -> Unit
-) {
-    val colorScheme = when {
-        dynamicColor && Build.VERSION.SDK_INT >= Build.VERSION_CODES.S -> {
-            val context = LocalContext.current
-            if (darkTheme) dynamicDarkColorScheme(context) else dynamicLightColorScheme(context)
-        }
-
-        darkTheme -> DarkColorScheme
-        else -> LightColorScheme
-    }
-
+fun CallpipeTheme(content: @Composable () -> Unit) {
     MaterialTheme(
-        colorScheme = colorScheme,
+        colorScheme = CallpipeColors,
         typography = Typography,
-        content = content
+        content = content,
     )
-}
+}

app/src/main/java/sh/sar/callpipe/web/WebServer.kt

@@ -0,0 +1,114 @@
+package sh.sar.callpipe.web
+
+import android.content.Context
+import android.util.Log
+import fi.iki.elonen.NanoHTTPD
+import fi.iki.elonen.NanoHTTPD.IHTTPSession
+import fi.iki.elonen.NanoHTTPD.Response
+import fi.iki.elonen.NanoWSD
+import fi.iki.elonen.NanoWSD.WebSocket
+import fi.iki.elonen.NanoWSD.WebSocketFrame
+import sh.sar.callpipe.hub.Hub
+import java.io.IOException
+import java.security.KeyStore
+import javax.net.ssl.KeyManagerFactory
+import javax.net.ssl.SSLContext
+
+/**
+ * Agent-facing server: HTTPS (so the browser gets a secure context for
+ * getUserMedia) serving the softphone page, and a WSS endpoint at /agent that
+ * carries the agent's mic/speaker PCM (binary frames) plus signaling (text JSON).
+ *
+ * TLS uses the bundled PKCS12 (assets/certs/callpipe.p12, CN=test.shihaam.me) —
+ * agents reach the phone at https://test.shihaam.me:8443 with a hosts entry
+ * mapping test.shihaam.me -> phone IP.
+ */
+class WebServer(
+    private val context: Context,
+    port: Int,
+) : NanoWSD(port) {
+
+    init {
+        makeSecure(buildSslFactory(context), null)
+    }
+
+    override fun serveHttp(session: IHTTPSession): Response {
+        val uri = session.uri
+        return when (uri) {
+            "/", "/index.html" -> asset("web/index.html", "text/html")
+            "/app.js" -> asset("web/app.js", "application/javascript")
+            else -> NanoHTTPD.newFixedLengthResponse(Response.Status.NOT_FOUND, "text/plain", "not found")
+        }
+    }
+
+    private fun asset(path: String, mime: String): Response = try {
+        val bytes = context.assets.open(path).use { it.readBytes() }
+        NanoHTTPD.newFixedLengthResponse(Response.Status.OK, mime, bytes.inputStream(), bytes.size.toLong())
+    } catch (e: IOException) {
+        NanoHTTPD.newFixedLengthResponse(Response.Status.NOT_FOUND, "text/plain", "missing: $path")
+    }
+
+    override fun openWebSocket(handshake: IHTTPSession): WebSocket =
+        if (handshake.uri == "/agent") AgentSocket(handshake)
+        else object : WebSocket(handshake) {
+            override fun onOpen() { try { close(WebSocketFrame.CloseCode.PolicyViolation, "bad path", false) } catch (_: Exception) {} }
+            override fun onClose(c: WebSocketFrame.CloseCode?, r: String?, b: Boolean) {}
+            override fun onMessage(m: WebSocketFrame) {}
+            override fun onPong(p: WebSocketFrame) {}
+            override fun onException(e: IOException) {}
+        }
+
+    /** One agent (browser) connection. */
+    inner class AgentSocket(handshake: IHTTPSession) : WebSocket(handshake), Hub.AgentChannel {
+        private val sendLock = Any()
+
+        override fun onOpen() {
+            Log.i(TAG, "agent connected")
+            Hub.addAgent(this)
+        }
+
+        override fun onClose(code: WebSocketFrame.CloseCode?, reason: String?, remote: Boolean) {
+            Log.i(TAG, "agent disconnected")
+            Hub.removeAgent(this)
+        }
+
+        override fun onMessage(message: WebSocketFrame) {
+            if (message.opCode == WebSocketFrame.OpCode.Binary) {
+                Hub.onUplinkAudio(message.binaryPayload)
+            } else {
+                Hub.onAgentCommand(message.textPayload ?: return)
+            }
+        }
+
+        override fun onPong(pong: WebSocketFrame) {}
+        override fun onException(exception: IOException) {
+            Log.w(TAG, "agent socket error: ${exception.message}")
+        }
+
+        // Hub.AgentChannel
+        override fun sendAudio(pcm: ByteArray) = safeSend { send(pcm) }
+        override fun sendEvent(json: String) = safeSend { send(json) }
+
+        private inline fun safeSend(block: () -> Unit) {
+            synchronized(sendLock) {
+                try { block() } catch (e: IOException) { /* dropped */ }
+            }
+        }
+    }
+
+    companion object {
+        private const val TAG = "WebServer"
+        const val DEFAULT_PORT = 8443
+
+        private fun buildSslFactory(context: Context): javax.net.ssl.SSLServerSocketFactory {
+            val pass = "callpipe".toCharArray()
+            val ks = KeyStore.getInstance("PKCS12")
+            context.assets.open("certs/callpipe.p12").use { ks.load(it, pass) }
+            val kmf = KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm())
+            kmf.init(ks, pass)
+            val ssl = SSLContext.getInstance("TLS")
+            ssl.init(kmf.keyManagers, null, null)
+            return ssl.serverSocketFactory
+        }
+    }
+}

app/src/main/res/drawable/ic_stat_call.xml

@@ -0,0 +1,10 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24"
+    android:tint="#FFFFFFFF">
+    <path
+        android:fillColor="@android:color/white"
+        android:pathData="M6.62,10.79c1.44,2.83 3.76,5.14 6.59,6.59l2.2,-2.2c0.27,-0.27 0.67,-0.36 1.02,-0.24 1.12,0.37 2.33,0.57 3.57,0.57 0.55,0 1,0.45 1,1V20c0,0.55 -0.45,1 -1,1 -9.39,0 -17,-7.61 -17,-17 0,-0.55 0.45,-1 1,-1h3.5c0.55,0 1,0.45 1,1 0,1.24 0.2,2.45 0.57,3.57 0.11,0.35 0.03,0.74 -0.25,1.02l-2.2,2.2z" />
+</vector>

app/src/main/res/values/themes.xml

@@ -1,5 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
 
-    <style name="Theme.Callpipe" parent="android:Theme.Material.Light.NoActionBar" />
+    <style name="Theme.Callpipe" parent="android:Theme.Material.NoActionBar">
+        <item name="android:windowBackground">@color/black</item>
+    </style>
 </resources>

docs/control-protocol.md

@@ -0,0 +1,48 @@
+# callpipe control protocol (Pi ⇄ phone)
+
+The phone app hosts a **WebSocket server** on the LAN (default port **8090**). The Pi
+(or any client, e.g. `wscat`) connects in and drives the cellular call. **No audio**
+crosses this channel — audio is Bluetooth HFP between the phone and the Pi. This is
+purely call *control* + *state*.
+
+Endpoint: `ws://<phone-ip>:8090/`  (any path is accepted)
+
+## Commands  (client → phone)
+
+| JSON | Action |
+|------|--------|
+| `{"cmd":"dial","number":"+9607…","sim":0}` | Place outgoing call. `sim` optional (0-based index from the `sims` event); omit for default SIM. |
+| `{"cmd":"answer"}` | Answer the ringing call. |
+| `{"cmd":"hangup"}` | End the active call (or reject if still ringing). |
+| `{"cmd":"reject"}`  | Reject the ringing call. |
+| `{"cmd":"state"}`   | Ask for the current call snapshot. |
+| `{"cmd":"sims"}`    | Ask for the SIM list. |
+| `{"cmd":"ping"}`    | Liveness check → `pong`. |
+
+## Events  (phone → client)
+
+| JSON | Meaning |
+|------|---------|
+| `{"event":"hello","app":"callpipe","proto":1}` | Sent on connect. |
+| `{"event":"sims","sims":[{"index":0,"label":"Ooredoo"},{"index":1,"label":"Dhiraagu"}]}` | SIM list (sent on connect + on request). |
+| `{"event":"state","state":"ACTIVE","number":"+9607…","direction":"OUT"}` | Call state. Pushed on every change + on connect. |
+| `{"event":"ack","cmd":"dial"}` | Command accepted. |
+| `{"event":"error","cmd":"dial","msg":"…"}` | Command failed. |
+| `{"event":"pong"}` | Reply to `ping`. |
+
+`state` values: `IDLE`, `CONNECTING`, `DIALING`, `RINGING`, `ACTIVE`, `HOLDING`,
+`DISCONNECTING`, `DISCONNECTED`. `direction`: `IN`, `OUT`, or `null`.
+
+## Quick test (before the Pi is ready)
+
+```sh
+# phone IP is 10.0.1.239 (adb wireless). Install app, open it once so the
+# foreground service + default-dialer role are granted.
+npm i -g wscat        # or: nix-shell -p nodePackages.wscat
+wscat -c ws://10.0.1.239:8090/
+> {"cmd":"sims"}
+> {"cmd":"dial","number":"+9607xxxxxx"}
+> {"cmd":"hangup"}
+```
+
+You should see `hello`, `sims`, and live `state` events stream back.

gradle/libs.versions.toml

@@ -8,6 +8,8 @@ lifecycleRuntimeKtx = "2.11.0"
 activityCompose = "1.13.0"
 kotlin = "2.2.10"
 composeBom = "2026.02.01"
+nanohttpd = "2.3.1"
+lifecycleRuntimeCompose = "2.11.0"
 
 [libraries]
 androidx-core-ktx = { group = "androidx.core", name = "core-ktx", version.ref = "coreKtx" }
@@ -24,6 +26,8 @@ androidx-compose-ui-tooling-preview = { group = "androidx.compose.ui", name = "u
 androidx-compose-ui-test-manifest = { group = "androidx.compose.ui", name = "ui-test-manifest" }
 androidx-compose-ui-test-junit4 = { group = "androidx.compose.ui", name = "ui-test-junit4" }
 androidx-compose-material3 = { group = "androidx.compose.material3", name = "material3" }
+androidx-lifecycle-runtime-compose = { group = "androidx.lifecycle", name = "lifecycle-runtime-compose", version.ref = "lifecycleRuntimeCompose" }
+nanohttpd-websocket = { group = "org.nanohttpd", name = "nanohttpd-websocket", version.ref = "nanohttpd" }
 
 [plugins]
 android-application = { id = "com.android.application", version.ref = "agp" }

relay/README.md

@@ -0,0 +1,42 @@
+# CallPipe Relay (Raspberry Pi)
+
+The Pi pairs to the phone as a **Bluetooth HFP hands-free unit**. During a call the
+phone routes call audio to it over SCO; `bluez-alsa` exposes that as ALSA PCMs.
+`callpipe-relay.py` is a dumb audio pipe: Bluetooth SCO (via `arecord`/`aplay`) ⇄
+the phone's audio TCP server over WiFi. Call control lives on the phone.
+
+See `../docs/relay-setup.md` for the one-time Bluetooth stack setup.
+
+## Install
+
+```sh
+# on the Pi (root):
+apt-get install -y bluez bluez-firmware bluez-alsa-utils alsa-utils python3 python-is-python3
+install -D callpipe-relay.py /opt/callpipe/callpipe-relay.py
+install -D callpipe-relay.service /etc/systemd/system/callpipe-relay.service
+# set the phone IP:
+systemctl edit callpipe-relay        # or edit Environment=CALLPIPE_PHONE=... in the unit
+systemctl enable --now callpipe-relay
+```
+
+## Config (env)
+
+| var | default | meaning |
+|-----|---------|---------|
+| `CALLPIPE_PHONE` | `10.0.1.239` | phone (hub) IP |
+| `CALLPIPE_PORT`  | `9010`       | phone audio TCP port |
+| `CALLPIPE_BT`    | auto         | HFP device MAC (auto-detected from bluez-alsa) |
+
+## Wire protocol (TCP, both directions)
+
+`[4B big-endian len N][1B type][payload]`  where `N = 1 + len(payload)`
+- `A` (0x41): PCM S16LE mono 16 kHz, 20 ms (640 B) frames
+- `C` (0x43): control JSON — phone sends `{"cmd":"start"|"stop"}`; relay sends
+  `{"event":"hello|started|stopped|error", ...}`
+
+## Manual test
+
+```sh
+CALLPIPE_PHONE=<dev-ip> python /opt/callpipe/callpipe-relay.py
+# with tools/phone_stub.py running on <dev-ip>, place a call routed to BT
+```

relay/callpipe-relay.py

@@ -0,0 +1,238 @@
+#!/usr/bin/env python3
+"""
+callpipe relay daemon — runs on the Raspberry Pi ("CallPipe Relay").
+
+The Pi is paired to the phone as a Bluetooth HFP hands-free unit, so during a
+call the phone routes call audio to it over SCO. This daemon is a DUMB AUDIO
+PIPE between that Bluetooth SCO PCM (via bluez-alsa / arecord+aplay) and the
+phone's audio TCP server over WiFi:
+
+    customer <-cellular-> phone <-BT/SCO-> [arecord] -> TCP -> phone -> agent
+    agent -> phone -> TCP -> [aplay] -> BT/SCO -> phone <-cellular-> customer
+
+It does no call control — the phone (the hub) tells it when to start/stop via a
+control frame, because SCO only exists while a call is up and routed to BT.
+
+Wire framing on the TCP socket, both directions:
+    [4-byte big-endian length N][1-byte type][payload...]     (N = 1 + len(payload))
+    type 'A' (0x41) = PCM S16LE mono 16 kHz (20 ms = 640 bytes/frame)
+    type 'C' (0x43) = control, payload is UTF-8 JSON
+
+Control (phone -> relay):
+    {"cmd":"start"[,"mac":"AA:BB:.."]}   begin bridging (mac optional; auto-detected)
+    {"cmd":"stop"}                        stop bridging
+Control (relay -> phone):
+    {"event":"hello","mac":"..","rate":16000}
+    {"event":"started"} / {"event":"stopped"} / {"event":"error","msg":".."}
+
+Env / config:
+    CALLPIPE_PHONE   phone IP           (default 10.0.1.239)
+    CALLPIPE_PORT    phone audio port   (default 9010)
+    CALLPIPE_BT      BT MAC override    (default: auto-detect from bluealsa)
+"""
+
+import os
+import re
+import socket
+import struct
+import subprocess
+import sys
+import threading
+import time
+
+PHONE_HOST = os.environ.get("CALLPIPE_PHONE", "10.0.1.239")
+PHONE_PORT = int(os.environ.get("CALLPIPE_PORT", "9010"))
+BT_OVERRIDE = os.environ.get("CALLPIPE_BT")
+
+RATE = 16000
+FRAME_MS = 20
+FRAME_BYTES = RATE * 2 * FRAME_MS // 1000  # 640
+
+TYPE_AUDIO = 0x41  # 'A'
+TYPE_CTRL = 0x43   # 'C'
+
+import json
+
+
+def log(*a):
+    print("[relay]", *a, file=sys.stderr, flush=True)
+
+
+def detect_mac():
+    if BT_OVERRIDE:
+        return BT_OVERRIDE
+    try:
+        out = subprocess.check_output(["bluealsa-cli", "list-pcms"], text=True, timeout=5)
+    except Exception as e:
+        log("list-pcms failed:", e)
+        return None
+    for line in out.splitlines():
+        m = re.search(r"dev_([0-9A-Fa-f_]+)/hfphf", line)
+        if m:
+            return m.group(1).replace("_", ":")
+    return None
+
+
+def alsa_dev(mac):
+    return f"bluealsa:DEV={mac},PROFILE=sco"
+
+
+class Bridge:
+    """Bridges one accepted/connected phone socket <-> Bluetooth SCO PCM."""
+
+    def __init__(self, sock):
+        self.sock = sock
+        self.send_lock = threading.Lock()
+        self.arec = None
+        self.aplay = None
+        self.active = False
+        self.mac = None
+        self.cap_thread = None
+
+    # ---- framing ----
+    def send(self, ftype, payload=b""):
+        body = bytes([ftype]) + payload
+        with self.send_lock:
+            self.sock.sendall(struct.pack(">I", len(body)) + body)
+
+    def send_ctrl(self, obj):
+        try:
+            self.send(TYPE_CTRL, json.dumps(obj).encode())
+        except OSError:
+            pass
+
+    def _recv_exact(self, n):
+        buf = bytearray()
+        while len(buf) < n:
+            chunk = self.sock.recv(n - len(buf))
+            if not chunk:
+                return None
+            buf += chunk
+        return bytes(buf)
+
+    # ---- audio ----
+    def start_audio(self, mac):
+        if self.active:
+            return
+        self.mac = mac or detect_mac()
+        if not self.mac:
+            self.send_ctrl({"event": "error", "msg": "no HFP device connected"})
+            return
+        dev = alsa_dev(self.mac)
+        log("start audio on", dev)
+        try:
+            self.aplay = subprocess.Popen(
+                ["aplay", "-q", "-D", dev, "-f", "S16_LE", "-c", "1", "-r", str(RATE), "-t", "raw"],
+                stdin=subprocess.PIPE,
+            )
+            self.arec = subprocess.Popen(
+                ["arecord", "-q", "-D", dev, "-f", "S16_LE", "-c", "1", "-r", str(RATE), "-t", "raw"],
+                stdout=subprocess.PIPE,
+            )
+        except Exception as e:
+            self.send_ctrl({"event": "error", "msg": f"spawn failed: {e}"})
+            self.stop_audio()
+            return
+        self.active = True
+        self.cap_thread = threading.Thread(target=self._capture_loop, daemon=True)
+        self.cap_thread.start()
+        self.send_ctrl({"event": "started"})
+
+    def _capture_loop(self):
+        # Reads downlink (customer) PCM from arecord and ships it to the phone.
+        arec = self.arec
+        try:
+            while self.active and arec and arec.poll() is None:
+                data = arec.stdout.read(FRAME_BYTES)
+                if not data:
+                    break
+                try:
+                    self.send(TYPE_AUDIO, data)
+                except OSError:
+                    break
+        except Exception as e:
+            log("capture loop error:", e)
+        log("capture loop ended")
+
+    def feed_playback(self, pcm):
+        # Writes uplink (agent) PCM to aplay -> Bluetooth mic -> customer.
+        if self.active and self.aplay and self.aplay.stdin:
+            try:
+                self.aplay.stdin.write(pcm)
+            except (BrokenPipeError, OSError):
+                pass
+
+    def stop_audio(self):
+        self.active = False
+        for p in (self.arec, self.aplay):
+            if p and p.poll() is None:
+                try:
+                    p.terminate()
+                except Exception:
+                    pass
+        self.arec = None
+        self.aplay = None
+
+    # ---- main receive loop ----
+    def run(self):
+        self.send_ctrl({"event": "hello", "mac": detect_mac(), "rate": RATE})
+        while True:
+            hdr = self._recv_exact(4)
+            if not hdr:
+                break
+            (n,) = struct.unpack(">I", hdr)
+            if n == 0 or n > 65536:
+                log("bad frame len", n)
+                break
+            body = self._recv_exact(n)
+            if body is None:
+                break
+            ftype = body[0]
+            payload = body[1:]
+            if ftype == TYPE_AUDIO:
+                self.feed_playback(payload)
+            elif ftype == TYPE_CTRL:
+                self._on_ctrl(payload)
+        self.stop_audio()
+
+    def _on_ctrl(self, payload):
+        try:
+            msg = json.loads(payload.decode())
+        except Exception:
+            return
+        cmd = msg.get("cmd")
+        if cmd == "start":
+            self.start_audio(msg.get("mac"))
+        elif cmd == "stop":
+            self.stop_audio()
+            self.send_ctrl({"event": "stopped"})
+
+
+def main():
+    log(f"connecting to phone {PHONE_HOST}:{PHONE_PORT}; frame={FRAME_BYTES}B @ {RATE}Hz")
+    backoff = 1
+    while True:
+        try:
+            sock = socket.create_connection((PHONE_HOST, PHONE_PORT), timeout=10)
+            sock.settimeout(None)
+            sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
+            log("connected to phone")
+            backoff = 1
+            Bridge(sock).run()
+            log("phone disconnected")
+        except (ConnectionRefusedError, OSError) as e:
+            log("connect failed:", e)
+        finally:
+            try:
+                sock.close()
+            except Exception:
+                pass
+        time.sleep(backoff)
+        backoff = min(backoff * 2, 15)
+
+
+if __name__ == "__main__":
+    try:
+        main()
+    except KeyboardInterrupt:
+        pass

relay/callpipe-relay.service

@@ -0,0 +1,16 @@
+[Unit]
+Description=CallPipe relay (Bluetooth HFP SCO <-> phone audio TCP bridge)
+After=bluetooth.service bluealsa.service network-online.target
+Wants=network-online.target
+
+[Service]
+Type=simple
+# Point at the phone (the hub). Override with: systemctl edit callpipe-relay
+Environment=CALLPIPE_PHONE=10.0.1.239
+Environment=CALLPIPE_PORT=9010
+ExecStart=/usr/bin/python /opt/callpipe/callpipe-relay.py
+Restart=always
+RestartSec=2
+
+[Install]
+WantedBy=multi-user.target