fix: maa 이중 전송 방지 (BV_FAIL 근본 원인)

- isMeasuring=false를 handler.post로 메인 스레드 갱신
  (Thread 내 설정 → Compose state 지연 → 다음 measure() 통과 → maa 이중 전송)
- measure() 진입 시 isMeasuring 가드 추가 (중복 호출 방어)
- 채널 수신 로그 추가 (RECEIVED N channels)
- MTU 247 negotiation 추가 (reb: 208B 분할 전송 최소화)
- Spot 6ch 필터 추가 (allChannelsReceived)
- Auto Stop 시 값 유지 (재계산 안 함)

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

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

@@ -701,7 +701,11 @@ class BleManager private constructor(private val context: Context) {
                                 .apply()
                         } catch (_: Exception) {}
 
-                        gatt.discoverServices()
+                        // MTU 247 요청 (reb: 208B 패킷 드롭 방지)
+                        // onMtuChanged 콜백에서 discoverServices 호출
+                        if (!gatt.requestMtu(247)) {
+                            gatt.discoverServices() // MTU 요청 실패 시 바로 진행
+                        }
                         onConnectionStateChanged?.invoke(true)
                     }
                     BluetoothProfile.STATE_DISCONNECTED -> {
@@ -732,6 +736,12 @@ class BleManager private constructor(private val context: Context) {
             }
         }
 
+        override fun onMtuChanged(gatt: BluetoothGatt, mtu: Int, status: Int) {
+            logd { "MTU changed: $mtu (status=$status)" }
+            handler.post { debugLogger.info("MTU=$mtu") }
+            gatt.discoverServices()
+        }
+
         override fun onServicesDiscovered(gatt: BluetoothGatt, status: Int) {
             logd { "onServicesDiscovered: status=$status" }
             if (status != BluetoothGatt.GATT_SUCCESS) {

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

@@ -106,6 +106,10 @@ fun PiezoMonitoringView(appState: AppState) {
     }
 
     fun measure() {
+        if (isMeasuring) {
+            Log.w("PiezoMonitor", "measure() called while already measuring — SKIPPED")
+            return
+        }
         isMeasuring = true
         measureDoneSignal = kotlinx.coroutines.CompletableDeferred()
 
@@ -122,6 +126,7 @@ fun PiezoMonitoringView(appState: AppState) {
         Log.d("PiezoMonitor", "Sending measurement command...")
 
         bleManager.piezoCollector.onMultiChannelComplete = { channels ->
+            Log.d("PiezoMonitor", "RECEIVED ${channels.size} channels: ${channels.map { "CH${it.channel}(${it.buffer.size})" }}")
             // 분석을 백그라운드에서 수행 후 UI 업데이트만 메인으로
             Thread {
                 val analysisStart = System.currentTimeMillis()
@@ -311,7 +316,7 @@ fun PiezoMonitoringView(appState: AppState) {
                                 Log.d("PiezoMonitor", "AUTO trimmedMean=${"%.1f".format(displayVol)}ml from ${autoVolumeWindow.map { "%.0f".format(it) }}")
                             }
                         } else if (isSpotInProgress) {
-                            if (finalRawVol > 0) spotVolumes.add(finalRawVol)
+                            if (finalRawVol > 0 && allChannelsReceived) spotVolumes.add(finalRawVol)
                         } else {
                             lastVolumeMl = finalRawVol
                             maxVolumeMl = maxOf(maxVolumeMl, finalRawVol)
@@ -324,9 +329,11 @@ fun PiezoMonitoringView(appState: AppState) {
                         val level = (pct * BladderLevel.MAX_LEVEL).toInt().coerceIn(1, BladderLevel.MAX_LEVEL)
                         appState.bladderLevel = appState.bladderLevel.copy(currentLevel = level)
                     }
-                    isMeasuring = false
-                    measureRetryCount = 0
-                    try { measureDoneSignal.complete(Unit) } catch (_: Exception) {}
+                    handler.post {
+                        isMeasuring = false
+                        measureRetryCount = 0
+                        try { measureDoneSignal.complete(Unit) } catch (_: Exception) {}
+                    }
                 }
             }.start()
         }
@@ -379,17 +386,8 @@ fun PiezoMonitoringView(appState: AppState) {
     fun stopAutoMeasure() {
         isAutoMeasuring = false
         autoTickCount = 0
-        // 종료 시 최종 trimmed mean 반영
-        if (autoVolumeWindow.size >= 3) {
-            val finalVol = trimmedMean(autoVolumeWindow.toList())
-            lastVolumeMl = finalVol
-            maxVolumeMl = maxOf(maxVolumeMl, finalVol)
-            val maxVol = appState.piezoSettings.maxVolume.toDouble()
-            val pct = if (maxVol > 0) (finalVol / maxVol).coerceAtMost(1.0) else 0.0
-            val level = (pct * BladderLevel.MAX_LEVEL).toInt().coerceIn(1, BladderLevel.MAX_LEVEL)
-            appState.bladderLevel = appState.bladderLevel.copy(currentLevel = level)
-            Log.d("PiezoMonitor", "AUTO STOP finalTrimmedMean=${"%.1f".format(finalVol)}ml from ${autoVolumeWindow.size} samples")
-        }
+        // Stop 시 현재 표시값 유지 (재계산 안 함)
+        Log.d("PiezoMonitor", "AUTO STOP — keeping displayed vol=${"%.1f".format(lastVolumeMl)}ml")
         autoVolumeWindow.clear()
     }