Add experimental AirPods heart-rate monitoring

android/app/build.gradle.kts

@@ -129,6 +129,7 @@ dependencies {
     implementation(libs.androidx.core.ktx)
     implementation(libs.androidx.lifecycle.process)
     implementation(libs.androidx.lifecycle.runtime.ktx)
+    implementation(libs.androidx.health.connect.client)
     implementation(libs.androidx.activity.compose)
     implementation(libs.androidx.ui)
     implementation(libs.androidx.ui.graphics)

android/app/src/main/AndroidManifest.xml

@@ -41,6 +41,11 @@
 <!--    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"-->
 <!--        android:maxSdkVersion="30" />-->
     <uses-permission android:name="com.android.vending.BILLING" />
+    <uses-permission android:name="android.permission.health.WRITE_HEART_RATE" />
+
+    <queries>
+        <package android:name="com.google.android.apps.healthdata" />
+    </queries>
 
     <application
         android:name=".LibrePodsApplication"
@@ -79,6 +84,26 @@
                 android:resource="@xml/battery_widget_info" />
         </receiver>
 
+        <activity
+            android:name=".HealthConnectPermissionsRationaleActivity"
+            android:exported="true"
+            android:theme="@style/Theme.LibrePods">
+            <intent-filter>
+                <action android:name="androidx.health.ACTION_SHOW_PERMISSIONS_RATIONALE" />
+            </intent-filter>
+        </activity>
+
+        <activity-alias
+            android:name="ViewPermissionUsageActivity"
+            android:exported="true"
+            android:permission="android.permission.START_VIEW_PERMISSION_USAGE"
+            android:targetActivity=".HealthConnectPermissionsRationaleActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.VIEW_PERMISSION_USAGE" />
+                <category android:name="android.intent.category.HEALTH_PERMISSIONS" />
+            </intent-filter>
+        </activity-alias>
+
         <activity
             android:name=".MainActivity"
             android:exported="true"

android/app/src/main/java/me/kavishdevar/librepods/HealthConnectPermissionsRationaleActivity.kt

@@ -0,0 +1,48 @@
+/*
+    LibrePods - AirPods liberated from Apple’s ecosystem
+    Copyright (C) 2025 LibrePods contributors
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    any later version.
+*/
+
+package me.kavishdevar.librepods
+
+import android.os.Bundle
+import androidx.activity.ComponentActivity
+import androidx.activity.compose.setContent
+import androidx.activity.enableEdgeToEdge
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.unit.dp
+import me.kavishdevar.librepods.presentation.screens.onboarding.PrivacyPolicyPage
+import me.kavishdevar.librepods.presentation.theme.LibrePodsTheme
+
+/** Privacy-policy entry point shown from Health Connect's permission UI. */
+class HealthConnectPermissionsRationaleActivity : ComponentActivity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        enableEdgeToEdge()
+        setContent {
+            LibrePodsTheme {
+                Box(
+                    modifier = Modifier
+                        .fillMaxSize()
+                        .background(MaterialTheme.colorScheme.surfaceContainer)
+                        .padding(16.dp)
+                ) {
+                    PrivacyPolicyPage(
+                        onForward = ::finish,
+                        actionLabel = "Close"
+                    )
+                }
+            }
+        }
+    }
+}

android/app/src/main/java/me/kavishdevar/librepods/MainActivity.kt

@@ -31,7 +31,6 @@ import android.content.Context
 import android.content.Context.MODE_PRIVATE
 import android.content.Intent
 import android.content.ServiceConnection
-import android.content.SharedPreferences
 import android.os.Bundle
 import android.os.IBinder
 import android.util.Log
@@ -40,8 +39,8 @@ import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.runtime.Composable
-import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.ui.platform.LocalContext
@@ -55,6 +54,7 @@ import me.kavishdevar.librepods.data.ControlCommandRepository
 import me.kavishdevar.librepods.presentation.navigation.NavigationRoot
 import me.kavishdevar.librepods.presentation.theme.LibrePodsTheme
 import me.kavishdevar.librepods.presentation.viewmodel.AirPodsViewModel
+import me.kavishdevar.librepods.presentation.viewmodel.AppSettingsViewModel
 import me.kavishdevar.librepods.services.AirPodsService
 import me.kavishdevar.librepods.utils.XposedState
 import kotlin.io.encoding.ExperimentalEncodingApi
@@ -80,23 +80,11 @@ class MainActivity : ComponentActivity() {
         enableEdgeToEdge()
 
         setContent {
-            val sharedPreferences = LocalContext.current.getSharedPreferences("settings", MODE_PRIVATE)
-            val m3eEnabled = remember { mutableStateOf(sharedPreferences.getBoolean("m3e_enabled", true)) }
+            val appSettingsViewModel: AppSettingsViewModel = viewModel()
+            val appSettingsState = appSettingsViewModel.uiState.collectAsState()
 
-            val sharedPreferenceChangeListener = SharedPreferences.OnSharedPreferenceChangeListener { sharedPreferences, key ->
-                when (key) {
-                    "m3e_enabled" -> m3eEnabled.value = sharedPreferences.getBoolean(key, true)
-                }
-            }
-
-            DisposableEffect(Unit) {
-                sharedPreferences.registerOnSharedPreferenceChangeListener(sharedPreferenceChangeListener)
-                onDispose {
-                    sharedPreferences.unregisterOnSharedPreferenceChangeListener(sharedPreferenceChangeListener)
-                }
-            }
             LibrePodsTheme(
-                m3eEnabled = m3eEnabled.value
+                m3eEnabled = appSettingsState.value.m3eEnabled
             ) {
 //                For demo screenshots
 //                val windowInsetsController = WindowCompat.getInsetsController(window, window.decorView)

android/app/src/main/java/me/kavishdevar/librepods/bluetooth/AACPManager.kt

@@ -34,6 +34,7 @@ import kotlin.io.encoding.ExperimentalEncodingApi
  */
 class AACPManager {
     private val TAG = "AACPManager[${System.identityHashCode(this)}]"
+    private val writerLock = Any()
     companion object {
         @Suppress("unused")
         object Opcodes {
@@ -62,6 +63,34 @@ class AACPManager {
 
         private val HEADER_BYTES = byteArrayOf(0x04, 0x00, 0x04, 0x00)
 
+        // Exact AACP 1.3 initialization used by the validated RTBuddy probe before HR streaming.
+        private val HEART_RATE_CONNECT_SERVICE_0 = byteArrayOf(
+            0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x03, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+        )
+        private val HEART_RATE_CAPABILITIES_SERVICE_0 =
+            byteArrayOf(0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00)
+        private val HEART_RATE_CONNECT_SERVICE_4 = byteArrayOf(
+            0x00, 0x00, 0x04, 0x00, 0x01, 0x00, 0x03, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+        )
+        private val HEART_RATE_CAPABILITIES_SERVICE_4 =
+            byteArrayOf(0x04, 0x00, 0x04, 0x00, 0x01, 0x00, 0x00)
+
+        // Verified RTBuddy SensorDataWX HEARTRATE(19) service-setting frames from the legacy probe.
+        // These arrays intentionally omit HEADER_BYTES because sendDataPacket() adds it.
+        private val HEART_RATE_START_1S = byteArrayOf(
+            0x17, 0x00, 0x00, 0x00, 0x10, 0x00, 0x10, 0x00,
+            0x08, 0xE3.toByte(), 0x46, 0x42, 0x0B, 0x08, 0x13, 0x10,
+            0x02, 0x1A, 0x05, 0x01, 0x40, 0x42, 0x0F, 0x00
+        )
+
+        private val HEART_RATE_STOP = byteArrayOf(
+            0x17, 0x00, 0x00, 0x00, 0x10, 0x00, 0x10, 0x00,
+            0x08, 0xED.toByte(), 0x46, 0x42, 0x0B, 0x08, 0x13, 0x10,
+            0x02, 0x1A, 0x05, 0x01, 0x00, 0x00, 0x00, 0x00
+        )
+
         data class ControlCommandStatus(
             val identifier: ControlCommandIdentifiers, val value: ByteArray
         ) {
@@ -235,6 +264,7 @@ class AACPManager {
         fun onControlCommandReceived(controlCommand: ByteArray)
         fun onDeviceInformationReceived(deviceInformation: AirPodsInformation)
         fun onHeadTrackingReceived(headTracking: ByteArray)
+        fun onHeartRateReceived(sample: HeartRateSample)
         fun onUnknownPacketReceived(packet: ByteArray)
         fun onProximityKeysReceived(proximityKeys: ByteArray)
         fun onStemPressReceived(stemPress: ByteArray)
@@ -280,6 +310,7 @@ class AACPManager {
     }
 
     private var callback: PacketCallback? = null
+    private val heartRateDecoder = RtBuddyHeartRateDecoder()
 
     fun setPacketCallback(callback: PacketCallback) {
         this.callback = callback
@@ -306,6 +337,18 @@ class AACPManager {
         return sendPacket(createDataPacket(data))
     }
 
+    fun sendHeartRateStartFrame(): Boolean = sendDataPacket(HEART_RATE_START_1S)
+
+    fun sendHeartRateStopFrame(): Boolean = sendDataPacket(HEART_RATE_STOP)
+
+    fun sendHeartRateConnectService0(): Boolean = sendPacket(HEART_RATE_CONNECT_SERVICE_0)
+
+    fun sendHeartRateCapabilitiesService0(): Boolean = sendPacket(HEART_RATE_CAPABILITIES_SERVICE_0)
+
+    fun sendHeartRateConnectService4(): Boolean = sendPacket(HEART_RATE_CONNECT_SERVICE_4)
+
+    fun sendHeartRateCapabilitiesService4(): Boolean = sendPacket(HEART_RATE_CAPABILITIES_SERVICE_4)
+
     fun sendControlCommand(identifier: Byte, value: ByteArray): Boolean {
         val controlPacket = createControlCommandPacket(identifier, value)
         setControlCommandStatusValue(
@@ -397,8 +440,23 @@ class AACPManager {
         return opcode + data
     }
 
+    fun receivePacket(packet: ByteArray): Boolean {
+        val heartRateResult = heartRateDecoder.feed(packet)
+        if (heartRateResult.relatedFrameCount > 0) {
+            Log.d(
+                TAG,
+                "Received RTBuddy heart-rate frames=${heartRateResult.relatedFrameCount}, " +
+                    "rejected=${heartRateResult.rejectedFrameCount}, " +
+                    "samples=${heartRateResult.samples.size}"
+            )
+        }
+        heartRateResult.samples.forEach { callback?.onHeartRateReceived(it) }
+        heartRateResult.passthroughPackets.forEach(::receiveStandardPacket)
+        return heartRateResult.suppressRawLogging
+    }
+
     @OptIn(ExperimentalStdlibApi::class)
-    fun receivePacket(packet: ByteArray) {
+    private fun receiveStandardPacket(packet: ByteArray) {
         if (!packet.toHexString().startsWith("04000400")) {
             Log.w(
                 TAG, "Received packet does not start with expected header: ${
@@ -1139,7 +1197,11 @@ class AACPManager {
     @OptIn(ExperimentalStdlibApi::class)
     fun sendPacket(packet: ByteArray): Boolean {
         try {
-            Log.d(TAG, "Sending packet: ${packet.joinToString(" ") { "%02X".format(it) }}")
+            if (isHeartRateRtBuddyPacket(packet)) {
+                Log.d(TAG, "Sending RTBuddy heart-rate stream control packet")
+            } else {
+                Log.d(TAG, "Sending packet: ${packet.joinToString(" ") { "%02X".format(it) }}")
+            }
 
             if (packet[4] == Opcodes.CONTROL_COMMAND) {
                 val controlCommand = try {
@@ -1159,15 +1221,16 @@ class AACPManager {
                 )
             }
 
-            val socket = BluetoothConnectionManager.aacpSocket ?: return false
-
-            if (socket.isConnected) {
-                socket.outputStream?.write(packet)
-                socket.outputStream?.flush()
-                return true
-            } else {
-                Log.d(TAG, "Can't send packet: Socket not initialized or connected")
-                return false
+            return synchronized(writerLock) {
+                val socket = BluetoothConnectionManager.aacpSocket
+                if (socket?.isConnected == true) {
+                    socket.outputStream.write(packet)
+                    socket.outputStream.flush()
+                    true
+                } else {
+                    Log.d(TAG, "Can't send packet: Socket not initialized or connected")
+                    false
+                }
             }
         } catch (e: Exception) {
             Log.e(TAG, "Error sending packet: ${e.message}")
@@ -1269,8 +1332,14 @@ class AACPManager {
         )
     }
 
+    private fun isHeartRateRtBuddyPacket(packet: ByteArray): Boolean {
+        return packet.contentEquals(HEADER_BYTES + HEART_RATE_START_1S) ||
+            packet.contentEquals(HEADER_BYTES + HEART_RATE_STOP)
+    }
+
     fun disconnected() {
         Log.d(TAG, "Disconnected, clearing state")
+        heartRateDecoder.reset()
         controlCommandStatusList.clear()
         controlCommandListeners.clear()
         owns = false