diff --git a/app/src/main/java/com/example/medilightv2android/services/BleDebugLogger.kt b/app/src/main/java/com/example/medilightv2android/services/BleDebugLogger.kt
index d081f16..1090778 100644
--- a/app/src/main/java/com/example/medilightv2android/services/BleDebugLogger.kt
+++ b/app/src/main/java/com/example/medilightv2android/services/BleDebugLogger.kt
@@ -81,6 +81,21 @@ class BleDebugLogger private constructor(private val context: Context) {
     private val dateFmt = SimpleDateFormat("yyyy-MM-dd_HHmmss", Locale.US)
     private val dayFmt = SimpleDateFormat("yyyy-MM-dd", Locale.US)
 
+    // 실시간 파일 기록 (화면 잠금/앱 종료에도 보존)
+    private var liveLogFile: File? = null
+    private fun ensureLiveLogFile(): File {
+        if (liveLogFile == null) {
+            val downloadsDir = android.os.Environment.getExternalStoragePublicDirectory(android.os.Environment.DIRECTORY_DOWNLOADS)
+            liveLogFile = File(downloadsDir, "VesiScan_BLE_${dateFmt.format(Date())}.log")
+        }
+        return liveLogFile!!
+    }
+    private fun appendToFile(line: String) {
+        try {
+            ensureLiveLogFile().appendText(line + "\n")
+        } catch (_: Exception) {}
+    }
+
     // ── Logging Methods ──
 
     fun tx(command: String, dataSize: Int = 0) {
@@ -106,6 +121,11 @@ class BleDebugLogger private constructor(private val context: Context) {
         sessionStart = System.currentTimeMillis()
         txCount = 0; rxCount = 0; errorCount = 0; packetTimeouts = 0; channelMissCount = 0
         rssiHistory.clear()
+        liveLogFile = null // 새 세션 → 새 파일
+        appendToFile("=== VesiScan BLE Debug Log ===")
+        appendToFile("Device: $name")
+        appendToFile("Session: ${dateFmt.format(Date())}")
+        appendToFile("============================================================")
         add(Entry(System.currentTimeMillis(), Level.CONN, "CONNECTED $name ($address)"))
     }
 
@@ -175,6 +195,7 @@ class BleDebugLogger private constructor(private val context: Context) {
         if (entries.size > MAX_MEMORY_ENTRIES) {
             entries.removeAt(0)
         }
+        appendToFile(entry.toLogLine())
     }
 
     fun getEntries(): List<Entry> = entries.toList()