feat: disable outgoing video when phone is near ear during calls

Uses the proximity sensor to detect when the phone is held to the ear
and automatically pauses the camera/video track. Video resumes when the
phone is moved away, but only if the user had video enabled.

https://claude.ai/code/session_014espsysob7MrE8X8e75jFX

amethyst/src/main/java/com/vitorpamplona/amethyst/service/call/CallAudioManager.kt

@@ -24,6 +24,10 @@ import android.content.BroadcastReceiver
 import android.content.Context
 import android.content.Intent
 import android.content.IntentFilter
+import android.hardware.Sensor
+import android.hardware.SensorEvent
+import android.hardware.SensorEventListener
+import android.hardware.SensorManager
 import android.media.AudioAttributes
 import android.media.AudioDeviceInfo
 import android.media.AudioManager
@@ -62,6 +66,25 @@ class CallAudioManager(
     private val _isBluetoothAvailable = MutableStateFlow(false)
     val isBluetoothAvailable: StateFlow<Boolean> = _isBluetoothAvailable.asStateFlow()
 
+    // Proximity sensor — detects when the phone is held near the ear
+    private val sensorManager = context.getSystemService(Context.SENSOR_SERVICE) as? SensorManager
+    private val proximitySensor: Sensor? = sensorManager?.getDefaultSensor(Sensor.TYPE_PROXIMITY)
+    private val _isNearEar = MutableStateFlow(false)
+    val isNearEar: StateFlow<Boolean> = _isNearEar.asStateFlow()
+
+    private val proximityListener =
+        object : SensorEventListener {
+            override fun onSensorChanged(event: SensorEvent) {
+                val maxRange = event.sensor.maximumRange
+                _isNearEar.value = event.values[0] < maxRange
+            }
+
+            override fun onAccuracyChanged(
+                sensor: Sensor?,
+                accuracy: Int,
+            ) {}
+        }
+
     fun startRinging() {
         startRingtone()
         startVibration()
@@ -137,11 +160,24 @@ class CallAudioManager(
                 "amethyst:call_proximity",
             )
         proximityWakeLock?.acquire(60 * 60 * 1000L)
+        registerProximitySensor()
     }
 
     fun releaseProximityWakeLock() {
         proximityWakeLock?.let { if (it.isHeld) it.release() }
         proximityWakeLock = null
+        unregisterProximitySensor()
+    }
+
+    private fun registerProximitySensor() {
+        proximitySensor?.let {
+            sensorManager?.registerListener(proximityListener, it, SensorManager.SENSOR_DELAY_NORMAL)
+        }
+    }
+
+    private fun unregisterProximitySensor() {
+        sensorManager?.unregisterListener(proximityListener)
+        _isNearEar.value = false
     }
 
     fun release() {

amethyst/src/main/java/com/vitorpamplona/amethyst/service/call/CallController.kt

@@ -93,6 +93,9 @@ class CallController(
     val audioRoute: StateFlow<AudioRoute> = audioManager.audioRoute
     val isBluetoothAvailable: StateFlow<Boolean> = audioManager.isBluetoothAvailable
 
+    // Tracks whether video is paused because the phone is near the ear
+    private var videoPausedByProximity = false
+
     init {
         callManager.onRenegotiationOfferReceived = { event -> onRenegotiationOfferReceived(event) }
 
@@ -126,6 +129,22 @@ class CallController(
                 }
             }
         }
+
+        // Pause outgoing video when the phone is held near the ear
+        scope.launch {
+            audioManager.isNearEar.collect { nearEar ->
+                val session = webRtcSession ?: return@collect
+                if (nearEar && _isVideoEnabled.value && !videoPausedByProximity) {
+                    videoPausedByProximity = true
+                    session.setVideoEnabled(false)
+                    session.stopCamera()
+                } else if (!nearEar && videoPausedByProximity) {
+                    videoPausedByProximity = false
+                    session.setVideoEnabled(true)
+                    session.startCamera()
+                }
+            }
+        }
     }
 
     fun initiateCall(
@@ -323,6 +342,7 @@ class CallController(
         _isAudioMuted.value = false
         _isVideoEnabled.value = false
         _isRemoteVideoActive.value = false
+        videoPausedByProximity = false
         webRtcSession?.dispose()
         webRtcSession = null
         remoteDescriptionSet.set(false)