feat: 채널별 빔 각도 보정 (Python PR#20 동기화)

Method B:
- 채널별 otsu_ratio = OTSU_RATIO × cos(θ) 보정
- 큰 각도 채널은 threshold 완화 → 약한 후위벽 감지 개선
- detectLowEcho에 otsuRatioOverride 파라미터 추가
- analyzeMultiChannelWithTgc: initial + rerun 모두 각도 보정 적용

Method A:
- 채널별 min_wall_contrast_ratio = 1.2 × cos(θ) 보정
- detectMethodA에 contrastRatioOverride 파라미터 추가
- analyzeChannel에서 PiezoHW.degreeAll 기반 자동 계산

Monitoring:
- Detachment LED: 상태 변경 시에만 전송 (wasDetached 추적)

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

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

@@ -167,11 +167,18 @@ class PiezoEchoAnalyzer private constructor() {
         // TGC 전체 채널 통합 (Python preprocess_multichannel)
         val preprocessed = applyTgcMultichannel(denoised)
 
+        // 채널별 각도 보정 (Python _make_angle_kwargs_b)
+        val beamAngles = PiezoHW.degreeAll
+        fun channelOtsuRatio(chIdx: Int): Double {
+            if (chIdx >= beamAngles.size) return otsuRatio
+            return otsuRatio * kotlin.math.cos(beamAngles[chIdx] * Math.PI / 180.0)
+        }
+
         // 1) Initial detect + BR candidate
         val initialResults = mutableListOf<LowEchoResult?>()
         val brCandidates = mutableListOf<Int?>()
         for (i in channelData.indices) {
-            val r = detectLowEcho(raw = raws[i], denoised = preprocessed[i])
+            val r = detectLowEcho(raw = raws[i], denoised = preprocessed[i], otsuRatioOverride = channelOtsuRatio(channelData[i].channel))
             initialResults.add(r)
             brCandidates.add(if (r != null) BackReflection.buildCandidate(preprocessed[i], r.post, postMaxIdx) else null)
         }
@@ -201,7 +208,7 @@ class PiezoEchoAnalyzer private constructor() {
                 }
 
                 val cleaned = BackReflection.suppress(preprocessed[i], suppressIdx)
-                val r2 = detectLowEcho(raw = raws[i], denoised = cleaned, otsuSignal = preprocessed[i], dynamicPostMax = suppressIdx)
+                val r2 = detectLowEcho(raw = raws[i], denoised = cleaned, otsuSignal = preprocessed[i], dynamicPostMax = suppressIdx, otsuRatioOverride = channelOtsuRatio(ch.channel))
                 val chosen = BackReflection.chooseResult(r, r2, brIdx = BackReflection.selectIdx(preprocessed[i], r?.post ?: 0, postMaxIdx, antIdx = r?.ant, sharedIdx = sharedBrIdx, channelCandidate = brCandidates[i]), suppressIdx = suppressIdx, minGap = 8)
                 ChannelAnalysisResult(ch.channel, chosen, raws[i], cleaned)
             } catch (_: Exception) {
@@ -402,7 +409,7 @@ class PiezoEchoAnalyzer private constructor() {
     val minScore: Double = 3000.0
 
     /** 단일 1D 채널 → urine region 탐지 (Otsu-only, Python 동기화) */
-    fun detectLowEcho(raw: DoubleArray, denoised: DoubleArray, otsuSignal: DoubleArray? = null, dynamicPostMax: Int? = null, lowEchoAmpOverride: Double? = null): LowEchoResult? {
+    fun detectLowEcho(raw: DoubleArray, denoised: DoubleArray, otsuSignal: DoubleArray? = null, dynamicPostMax: Int? = null, lowEchoAmpOverride: Double? = null, otsuRatioOverride: Double? = null): LowEchoResult? {
         val sg = denoised
         if (sg.size < 10) return null
         val effectivePostMax = dynamicPostMax ?: postMaxIdx
@@ -417,10 +424,11 @@ class PiezoEchoAnalyzer private constructor() {
             return detectLowEchoCore(sg = sg, threshold = lowEchoAmpDefault, effectivePostMax = effectivePostMax)
         }
 
-        // Otsu-only: 단일 시도, fallback 없음 (Python detect_low_echo_method_b 동일)
+        // Otsu-only: 단일 시도 (Python detect_low_echo_method_b 동일)
+        val effectiveRatio = otsuRatioOverride ?: otsuRatio
         val otsuInput = otsuSignal ?: sg
         val (thr, sep) = otsu1dWithSeparability(otsuInput, otsuInput.size)
-        lastOtsuThreshold = thr * otsuRatio
+        lastOtsuThreshold = thr * effectiveRatio
         lastOtsuSeparability = sep
         return detectLowEchoCore(sg = sg, threshold = lastOtsuThreshold, effectivePostMax = effectivePostMax)
     }

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

@@ -51,14 +51,18 @@ class PiezoEchoAnalyzerA private constructor() {
         }
         return try {
             val sg = PiezoEchoAnalyzer.shared.denoise(raw)
-            val result = detectMethodA(raw, sg)
+            // 각도 보정: min_wall_contrast_ratio × cos(θ)
+            val beamAngles = PiezoHW.degreeAll
+            val angleFactor = if (channel < beamAngles.size) kotlin.math.cos(beamAngles[channel] * Math.PI / 180.0) else 1.0
+            val result = detectMethodA(raw, sg, contrastRatioOverride = minWallContrastRatio * angleFactor)
             ChannelAnalysisResult(channel, result, raw, sg)
         } catch (_: Exception) {
             ChannelAnalysisResult(channel, null, raw, raw.copyOf())
         }
     }
 
-    fun detectMethodA(raw: DoubleArray, sg: DoubleArray): LowEchoResult? {
+    fun detectMethodA(raw: DoubleArray, sg: DoubleArray, contrastRatioOverride: Double? = null): LowEchoResult? {
+        val effectiveContrastRatio = contrastRatioOverride ?: minWallContrastRatio
         if (sg.size < 10) return null
 
         // 1) Composite signal y = sg + α|d1| + β|d2|
@@ -107,7 +111,7 @@ class PiezoEchoAnalyzerA private constructor() {
             for (i in leftLo..min(spanStart, sg.size - 1)) if (sg[i] > leftMax) leftMax = sg[i]
             var rightMax = 0.0
             for (i in spanEnd until rightHi) if (sg[i] > rightMax) rightMax = sg[i]
-            if (leftMax / platMean < minWallContrastRatio || rightMax / platMean < minWallContrastRatio) continue
+            if (leftMax / platMean < effectiveContrastRatio || rightMax / platMean < effectiveContrastRatio) continue
 
             // Find peaks
             val leftPks = findPeaksInRange(sg, leftLo, spanStart).filter { it < spanStart }

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

@@ -77,6 +77,7 @@ fun PiezoMonitoringView(appState: AppState) {
     var measureRetryCount by remember { mutableIntStateOf(0) }
     val maxMeasureRetries = 2
     var lastVolumeMl by remember { mutableStateOf(0.0) }
+    var wasDetached by remember { mutableStateOf(false) }
     var maxVolumeMl by remember { mutableStateOf(0.0) }
     var measureDoneSignal = remember { kotlinx.coroutines.CompletableDeferred<Unit>() }
     val lastMultiChannelResult = remember { mutableStateListOf<PiezoChannelData>() }
@@ -129,12 +130,17 @@ fun PiezoMonitoringView(appState: AppState) {
                     val sortedBuffers = channels.sortedBy { it.channel }.map { it.buffer }
                     val detachResult = com.example.medilightv2android.managers.DetachmentDetection.detect(sortedBuffers)
                     if (detachResult.isDetached) {
+                        if (!wasDetached) {
                             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) }
+                            wasDetached = true
+                        }
                     } else {
-                        // 정상 복귀 → LED OFF
+                        if (wasDetached) {
                             handler.post { bleManager.sendLedMode(0) }
+                            wasDetached = false
+                        }
                     }
                 }