feat: Foreground Service + Detachment 개선 + Placement 가이드 모드

Foreground Service (BleForegroundService.kt):
- BLE 연결 시 자동 시작, 해제 시 자동 중단
- PARTIAL_WAKE_LOCK (최대 4시간)
- Notification: "VesiScan - BLE 기기 연결 중..."
- connectedDevice foregroundServiceType
- Doze 모드에서도 BLE 통신 유지
- keepScreenOn도 유지 (추가 안전장치)

Detachment 개선:
- THR_MEAN/STD 100→30 (완전 탈착만 감지, 거리 약화 무시)
- 6채널 모두 수신됐을 때만 체크 (BLE 거리 문제와 구분)
- Placement: if(false) 제거 → 활성화 + "센서가 부착되지 않았습니다"
- Monitoring: 정상 복귀 시 LED OFF

Placement 가이드 모드:
- Simple (기본): 3+채널 → 바로 좌우 (기존)
- Boundary: 올라갔다 내려오기 패턴 (경계 감지 → 최적점 복귀)
- 설정 톱니바퀴에 Simple/Boundary 스위치

BLE 로그:
- 역순 표시 (최신이 위) — 스크롤 위치 유지

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

app/src/main/AndroidManifest.xml

@@ -27,6 +27,11 @@
     <!-- Internet (AI 음성 fallback) -->
     <uses-permission android:name="android.permission.INTERNET" />
 
+    <!-- Foreground Service (BLE 연결 유지) -->
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE_CONNECTED_DEVICE" />
+    <uses-permission android:name="android.permission.WAKE_LOCK" />
+
     <!-- BLE feature -->
     <uses-feature android:name="android.hardware.bluetooth_le" android:required="true" />
 
@@ -56,6 +61,11 @@
         <receiver
             android:name=".services.ReminderReceiver"
             android:exported="false" />
+
+        <service
+            android:name=".services.BleForegroundService"
+            android:exported="false"
+            android:foregroundServiceType="connectedDevice" />
     </application>
 
 </manifest>

app/src/main/java/com/example/medilightv2android/MainActivity.kt

@@ -46,6 +46,7 @@ class MainActivity : ComponentActivity() {
         NotificationService.getInstance(this)
 
         enableEdgeToEdge()
+        window.addFlags(android.view.WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON)
         setContent {
             Medilightv2androidTheme {
                 Scaffold(modifier = Modifier.fillMaxSize()) { innerPadding ->

app/src/main/java/com/example/medilightv2android/ble/BleManager.kt

@@ -245,6 +245,7 @@ class BleManager private constructor(private val context: Context) {
         connectionTimer?.let { handler.removeCallbacks(it) }
         connectionTimer = null
         bluetoothGatt?.disconnect()
+        com.example.medilightv2android.services.BleForegroundService.stop(context)
     }
 
     fun disconnectAndUnbond() {
@@ -252,6 +253,7 @@ class BleManager private constructor(private val context: Context) {
         cancelAutoReconnect()
         stopWatchdog()
         stopBatteryPolling()
+        com.example.medilightv2android.services.BleForegroundService.stop(context)
         connectionTimer?.let { handler.removeCallbacks(it) }
         connectionTimer = null
 
@@ -790,6 +792,7 @@ class BleManager private constructor(private val context: Context) {
                         if (txCharacteristic != null && rxCharacteristic != null) {
                             isServiceReady.value = true
                             com.example.medilightv2android.services.AdcCsvLogger.newSession()
+                            com.example.medilightv2android.services.BleForegroundService.start(context)
                             startBatteryPolling()
                             startWatchdog()
                             sendDeviceInfoQuery()

app/src/main/java/com/example/medilightv2android/managers/DetachmentDetection.kt

@@ -17,8 +17,8 @@ object DetachmentDetection {
     const val WINDOW_END = 80
     const val BASELINE_WINDOW_START = 80
     const val BASELINE_WINDOW_END = 100
-    const val THR_MEAN = 100.0
+    const val THR_MEAN = 30.0
-    const val THR_STD = 100.0
+    const val THR_STD = 30.0
     const val N_CENTER_CH = 4
 
     data class DetachmentResult(

app/src/main/java/com/example/medilightv2android/managers/GreenZoneConstants.kt

@@ -13,10 +13,12 @@ package com.example.medilightv2android.managers
  * 각 상수의 의미와 영향 범위를 아래 주석 참고.
  */
 enum class DetectionMethod { METHOD_A, METHOD_B, METHOD_C }
+enum class PlacementGuideMode { SIMPLE, BOUNDARY }
 
 object GreenZoneConstants {
 
     var detectionMethod: DetectionMethod = DetectionMethod.METHOD_C
+    var placementGuideMode: PlacementGuideMode = PlacementGuideMode.SIMPLE
 
     // ═══════════════════════════════════════════════════════════
     // 신호 범위

app/src/main/java/com/example/medilightv2android/services/BleForegroundService.kt

@@ -0,0 +1,136 @@
+package com.example.medilightv2android.services
+
+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.os.Build
+import android.os.IBinder
+import android.os.PowerManager
+import androidx.core.app.NotificationCompat
+import com.example.medilightv2android.MainActivity
+import com.example.medilightv2android.R
+
+/**
+ * BLE 연결 유지를 위한 Foreground Service.
+ *
+ * 화면이 꺼져도 Android Doze 모드에서 앱을 유지하여
+ * BLE 통신(TX/RX), watchdog, Auto 측정이 중단되지 않도록 한다.
+ */
+class BleForegroundService : Service() {
+
+    companion object {
+        const val CHANNEL_ID = "vesiscan_ble_channel"
+        const val NOTIFICATION_ID = 1001
+        const val ACTION_START = "com.example.medilightv2android.BLE_START"
+        const val ACTION_STOP = "com.example.medilightv2android.BLE_STOP"
+
+        fun start(context: Context) {
+            val intent = Intent(context, BleForegroundService::class.java).apply {
+                action = ACTION_START
+            }
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                context.startForegroundService(intent)
+            } else {
+                context.startService(intent)
+            }
+        }
+
+        fun stop(context: Context) {
+            val intent = Intent(context, BleForegroundService::class.java).apply {
+                action = ACTION_STOP
+            }
+            context.startService(intent)
+        }
+    }
+
+    private var wakeLock: PowerManager.WakeLock? = null
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    override fun onCreate() {
+        super.onCreate()
+        createNotificationChannel()
+    }
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        when (intent?.action) {
+            ACTION_STOP -> {
+                releaseWakeLock()
+                stopForeground(STOP_FOREGROUND_REMOVE)
+                stopSelf()
+                return START_NOT_STICKY
+            }
+            else -> {
+                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+                    startForeground(NOTIFICATION_ID, buildNotification(),
+                        android.content.pm.ServiceInfo.FOREGROUND_SERVICE_TYPE_CONNECTED_DEVICE)
+                } else {
+                    startForeground(NOTIFICATION_ID, buildNotification())
+                }
+                acquireWakeLock()
+            }
+        }
+        return START_STICKY
+    }
+
+    override fun onDestroy() {
+        releaseWakeLock()
+        super.onDestroy()
+    }
+
+    private fun createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            val channel = NotificationChannel(
+                CHANNEL_ID,
+                "VesiScan BLE Connection",
+                NotificationManager.IMPORTANCE_LOW
+            ).apply {
+                description = "BLE 기기 연결 유지"
+                setShowBadge(false)
+            }
+            val nm = getSystemService(NotificationManager::class.java)
+            nm.createNotificationChannel(channel)
+        }
+    }
+
+    private fun buildNotification(): Notification {
+        val pendingIntent = PendingIntent.getActivity(
+            this, 0,
+            Intent(this, MainActivity::class.java).apply {
+                flags = Intent.FLAG_ACTIVITY_SINGLE_TOP
+            },
+            PendingIntent.FLAG_IMMUTABLE or PendingIntent.FLAG_UPDATE_CURRENT
+        )
+
+        return NotificationCompat.Builder(this, CHANNEL_ID)
+            .setContentTitle("VesiScan")
+            .setContentText("BLE 기기 연결 중...")
+            .setSmallIcon(R.drawable.ic_launcher_foreground)
+            .setOngoing(true)
+            .setContentIntent(pendingIntent)
+            .build()
+    }
+
+    private fun acquireWakeLock() {
+        if (wakeLock == null) {
+            val pm = getSystemService(Context.POWER_SERVICE) as PowerManager
+            wakeLock = pm.newWakeLock(
+                PowerManager.PARTIAL_WAKE_LOCK,
+                "VesiScan::BleWakeLock"
+            ).apply {
+                acquire(4 * 60 * 60 * 1000L) // 최대 4시간
+            }
+        }
+    }
+
+    private fun releaseWakeLock() {
+        wakeLock?.let {
+            if (it.isHeld) it.release()
+        }
+        wakeLock = null
+    }
+}

app/src/main/java/com/example/medilightv2android/ui/views/monitoring/PiezoMonitoringView.kt

@@ -123,13 +123,19 @@ fun PiezoMonitoringView(appState: AppState) {
                 lastMultiChannelResult.clear()
                 lastMultiChannelResult.addAll(channels)
 
-                // Detachment 체크
+                // Detachment 체크 (6채널 모두 수신됐을 때만 — BLE 거리 문제와 구분)
+                val fullChannels = channels.filter { it.buffer.size >= 20 }
+                if (fullChannels.size >= 6) {
                     val sortedBuffers = channels.sortedBy { it.channel }.map { it.buffer }
                     val detachResult = com.example.medilightv2android.managers.DetachmentDetection.detect(sortedBuffers)
                     if (detachResult.isDetached) {
                         Log.w("PiezoMonitor", "DETACHED mean=${"%.1f".format(detachResult.meanAbs)} std=${"%.1f".format(detachResult.stdVal)}")
                         bleManager.debugLogger.warn("DETACHED mean=${"%.1f".format(detachResult.meanAbs)} std=${"%.1f".format(detachResult.stdVal)}")
                         handler.post { bleManager.sendLedMode(4) }
+                    } else {
+                        // 정상 복귀 → LED OFF
+                        handler.post { bleManager.sendLedMode(0) }
+                    }
                 }
 
                 var rawVolumeMl: Double? = null
@@ -1375,7 +1381,7 @@ private fun BleDebugPanel(bleManager: BleManager) {
         }
     }
 
-    val entries = remember(refreshTick) { logger.getRecentEntries(50) }
+    val entries = remember(refreshTick) { logger.getRecentEntries(50).reversed() }
     val stats = remember(refreshTick) { logger.getStats() }
 
     Card(
@@ -1439,12 +1445,13 @@ private fun BleDebugPanel(bleManager: BleManager) {
                 if (timeout > 0) Text("TOUT:$timeout", fontSize = 10.sp, color = Color(0xFFFF8A65))
             }
 
-            // Log entries
+            // Log entries (스크롤 위치 유지 — 자동 스크롤 안함)
+            val logScrollState = rememberScrollState()
             Column(
                 modifier = Modifier
                     .fillMaxWidth()
                     .heightIn(max = 200.dp)
-                    .verticalScroll(rememberScrollState())
+                    .verticalScroll(logScrollState)
             ) {
                 for (entry in entries) {
                     val color = when (entry.level) {

app/src/main/java/com/example/medilightv2android/ui/views/monitoring/PlacementGuideView.kt

@@ -77,6 +77,10 @@ fun PlacementGuideView(appState: AppState) {
 
     // 2단계 순차 탐색: VERTICAL → LATERAL → GREEN
     var placementPhase by remember { mutableStateOf(PlacementPhase.VERTICAL) }
+    // 상하 탐색: 상한 경계 감지 로직
+    var maxCenterSeen by remember { mutableIntStateOf(0) }
+    var stableAtMax by remember { mutableIntStateOf(0) }
+    var boundaryHit by remember { mutableStateOf(false) }
 
     // 화면 진입 시 상태 리셋
     LaunchedEffect(Unit) {
@@ -511,20 +515,25 @@ fun PlacementGuideView(appState: AppState) {
                     lastChannelData = channels
                     lastWallResults = allWalls.toList()
 
-                    // Detachment check (미부착 감지)
+                    // Detachment check (6채널 모두 수신됐을 때만)
+                    val fullCh = channels.filter { it.buffer.size >= 20 }
                     val buffers = channels.sortedBy { it.channel }.map { it.buffer }
-                    val detachResult = DetachmentDetection.detect(buffers)
+                    val detachResult = if (fullCh.size >= 6) DetachmentDetection.detect(buffers) else null
 
-                    if (false) { // detachment 비활성화
+                    if (detachResult != null && detachResult.isDetached) {
-                        directionHint = "Sensor detached — check contact"
+                        directionHint = "센서가 부착되지 않았습니다. 부착해주세요"
                         directionIcon = "exclamationmark.triangle"
                         placementScore = 0
-                        bleManager.sendLedMode(4) // DETACH_WARNING
+                        if (lastLedMode != 4) { bleManager.sendLedMode(4); lastLedMode = 4 }
                         bleManager.debugLogger.warn("DETACHED mean=${"%.1f".format(detachResult.meanAbs)} std=${"%.1f".format(detachResult.stdVal)}")
                         Log.w("PlacementGuide", "DETACHED mean=${
                             "%.1f".format(detachResult.meanAbs)} std=${"%.1f".format(detachResult.stdVal)}")
                     } else {
-                        val guideResult = computePlacementGuide(detected, urineLens, allWalls, scanCount, placementPhase)
+                        val vs = VerticalState(maxCenterSeen, stableAtMax, boundaryHit)
+                        val guideResult = computePlacementGuide(detected, urineLens, allWalls, scanCount, placementPhase, vs)
+                        maxCenterSeen = vs.maxCenterSeen
+                        stableAtMax = vs.stableAtMax
+                        boundaryHit = vs.boundaryHit
 
                         // 디바운스: 같은 phase 2회 연속 + 최소 3초 유지
                         if (guideResult.nextPhase == lastGuidePhase) {
@@ -675,6 +684,24 @@ fun PlacementGuideView(appState: AppState) {
 
                     HorizontalDivider()
 
+                    // Guide mode
+                    var useBoundary by remember { mutableStateOf(com.example.medilightv2android.managers.GreenZoneConstants.placementGuideMode == com.example.medilightv2android.managers.PlacementGuideMode.BOUNDARY) }
+                    Row(modifier = Modifier.fillMaxWidth(), verticalAlignment = Alignment.CenterVertically) {
+                        Text("Guide", fontSize = 14.sp, fontWeight = FontWeight.SemiBold)
+                        Spacer(modifier = Modifier.width(8.dp))
+                        Text(if (useBoundary) "Boundary" else "Simple", fontSize = 13.sp, fontWeight = FontWeight.Bold,
+                            color = if (useBoundary) Color(0xFFFF5722) else MlPrimary)
+                        Spacer(modifier = Modifier.weight(1f))
+                        Switch(checked = useBoundary, onCheckedChange = {
+                            useBoundary = it
+                            com.example.medilightv2android.managers.GreenZoneConstants.placementGuideMode =
+                                if (it) com.example.medilightv2android.managers.PlacementGuideMode.BOUNDARY
+                                else com.example.medilightv2android.managers.PlacementGuideMode.SIMPLE
+                        }, colors = SwitchDefaults.colors(checkedTrackColor = Color(0xFFFF5722)))
+                    }
+
+                    HorizontalDivider()
+
                     // Otsu toggle
                     var otsuEnabled by remember { mutableStateOf(analyzer.useAdaptiveThreshold) }
                     Row(modifier = Modifier.fillMaxWidth(), verticalAlignment = Alignment.CenterVertically) {
@@ -898,12 +925,19 @@ private const val DEFAULT_LR_DEV_THR = 0.25
  * [3단계] 최종 Green: CV 확인
  *   - CV ≤ threshold → Green (LED 6)
  */
+data class VerticalState(
+    var maxCenterSeen: Int = 0,
+    var stableAtMax: Int = 0,
+    var boundaryHit: Boolean = false
+)
+
 private fun computePlacementGuide(
     detected: List<Boolean>,
     urineLens: List<Int>,
     walls: List<Pair<Int, Int>?> = emptyList(),
     repeatCount: Int = 0,
-    currentPhase: PlacementPhase = PlacementPhase.VERTICAL
+    currentPhase: PlacementPhase = PlacementPhase.VERTICAL,
+    verticalState: VerticalState? = null
 ): PlacementGuideResult {
     val detectedCount = detected.count { it }
 
@@ -912,7 +946,6 @@ private fun computePlacementGuide(
             phase = PlacementPhase.VERTICAL, nextPhase = PlacementPhase.VERTICAL)
     }
 
-    // Center 채널 정보
     val centerLens = (0..3).map { urineLens.getOrElse(it) { 0 } }
     val centerDetected = (0..3).count { detected.getOrElse(it) { false } }
     val ch0 = detected.getOrElse(0) { false }
@@ -922,39 +955,60 @@ private fun computePlacementGuide(
     val len0 = centerLens[0]; val len1 = centerLens[1]
     val len2 = centerLens[2]; val len3 = centerLens[3]
 
-    // ═══ 1단계: 상하 탐색 (치골→위로→CH0 안잡히면 아래로) ═══
+    // ═══ 1단계: 상하 탐색 ═══
     if (currentPhase == PlacementPhase.VERTICAL) {
-        if (centerDetected < 3) {
+        val guideMode = com.example.medilightv2android.managers.GreenZoneConstants.placementGuideMode
-            val hint: String
+        val vs = verticalState ?: VerticalState()
-            val icon: String
+
+        // ── BOUNDARY 모드: 올라갔다 내려오기 ──
+        if (guideMode == com.example.medilightv2android.managers.PlacementGuideMode.BOUNDARY) {
+            if (centerDetected < 2) {
+                vs.stableAtMax = 0
+                val hint: String; val icon: String
                 when {
-                // 위쪽만 잡힘 → 아래로 내리세요
+                    (ch3 || ch2) && !ch0 && !ch1 -> { hint = "센서를 아래로 천천히 내리세요 ↓"; icon = "arrow.down" }
-                (ch3 || ch2) && !ch0 && !ch1 -> {
+                    else -> { hint = "센서를 위로 천천히 올리세요 ↑"; icon = "arrow.up" }
-                    hint = "센서를 아래로 천천히 내리세요 ↓"
-                    icon = "arrow.down"
-                }
-                // 아래쪽만 잡힘 → 위로 올리세요
-                (ch0 || ch1) && !ch3 && !ch2 -> {
-                    hint = "센서를 위로 천천히 올리세요 ↑"
-                    icon = "arrow.up"
-                }
-                // 아무것도 또는 1개만 → 위로 올리세요 (치골에서 시작 기준)
-                else -> {
-                    hint = "센서를 위로 천천히 올리세요 ↑"
-                    icon = "arrow.up"
-                }
                 }
                 return PlacementGuideResult(hint, icon, centerDetected * 10,
                     phase = PlacementPhase.VERTICAL, nextPhase = PlacementPhase.VERTICAL)
             }
+            if (centerDetected >= vs.maxCenterSeen) { vs.maxCenterSeen = centerDetected; vs.stableAtMax++ }
+            if (!vs.boundaryHit && vs.stableAtMax >= 2 && centerDetected < vs.maxCenterSeen) {
+                vs.boundaryHit = true
+                return PlacementGuideResult("너무 올라갔습니다. 아래로 내리세요 ↓", "arrow.down", 30,
+                    phase = PlacementPhase.VERTICAL, nextPhase = PlacementPhase.VERTICAL)
+            }
+            if (vs.boundaryHit) {
+                if (centerDetected < vs.maxCenterSeen) {
+                    return PlacementGuideResult("조금 더 아래로 ↓", "arrow.down", 35,
+                        phase = PlacementPhase.VERTICAL, nextPhase = PlacementPhase.VERTICAL)
+                }
+                vs.boundaryHit = false; vs.stableAtMax = 0
+                val l4 = urineLens.getOrElse(4) { 0 }; val l5 = urineLens.getOrElse(5) { 0 }
+                val lrHint = when { l4 > 0 && l5 > 0 && l4 > l5 -> "최적 위치! 오른쪽으로 →"; l4 > 0 && l5 > 0 && l5 > l4 -> "최적 위치! 왼쪽으로 ←"; else -> "최적 위치! 좌우 조절하세요 ↔" }
+                val lrIcon = when { l4 > 0 && l5 > 0 && l4 > l5 -> "arrow.right"; l4 > 0 && l5 > 0 && l5 > l4 -> "arrow.left"; else -> "arrow.left.arrow.right" }
+                return PlacementGuideResult(lrHint, lrIcon, 40, phase = PlacementPhase.VERTICAL, nextPhase = PlacementPhase.LATERAL)
+            }
+            return PlacementGuideResult("센서를 위로 천천히 올리세요 ↑", "arrow.up", centerDetected * 10,
+                phase = PlacementPhase.VERTICAL, nextPhase = PlacementPhase.VERTICAL)
+        }
 
-        // 3개 이상 검출 — CH0 유무 확인
+        // ── SIMPLE 모드: 3+채널 안정 → 바로 좌우 ──
+        if (centerDetected < 3) {
+            val hint: String; val icon: String
+            when {
+                (ch3 || ch2) && !ch0 && !ch1 -> { hint = "센서를 아래로 천천히 내리세요 ↓"; icon = "arrow.down" }
+                (ch0 || ch1) && !ch3 && !ch2 -> { hint = "센서를 위로 천천히 올리세요 ↑"; icon = "arrow.up" }
+                else -> { hint = "센서를 위로 천천히 올리세요 ↑"; icon = "arrow.up" }
+            }
+            return PlacementGuideResult(hint, icon, centerDetected * 10,
+                phase = PlacementPhase.VERTICAL, nextPhase = PlacementPhase.VERTICAL)
+        }
         if (!ch0 && ch3) {
             return PlacementGuideResult("CH0이 약합니다. 센서를 아래로 조금 내리세요 ↓", "arrow.down", 25,
                 phase = PlacementPhase.VERTICAL, nextPhase = PlacementPhase.VERTICAL)
         }
 
-        // 크기 패턴 확인
         val validLens = (0..3).filter { detected.getOrElse(it) { false } }.map { centerLens[it] }
         val maxLen = validLens.maxOrNull() ?: 0
         val minLen = validLens.minOrNull() ?: 0