android: fix startup crash (MediaStore rejects text/plain in DCIM); log sink fallback DCIM->Download->app-private, logging never throws

android/app/src/main/kotlin/com/mag160c/thermal/MainActivity.kt

@@ -10,8 +10,10 @@ import com.mag160c.thermal.ui.theme.Mag160cTheme
 class MainActivity : ComponentActivity() {
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
-        // field-debug crash hook + logcat/file logger (file opens on connect)
+        // field-debug crash hook + log file (opened at startup so even
+        // early crashes are captured; logging never throws)
         com.mag160c.thermal.media.DebugLog.init(applicationContext)
+        com.mag160c.thermal.media.DebugLog.startFile(applicationContext)
         enableEdgeToEdge()
         // immersive: hide the status bar (swipe to reveal)
         window.insetsController?.let { c ->

android/app/src/main/kotlin/com/mag160c/thermal/media/DebugLog.kt

@@ -16,13 +16,16 @@ import java.util.Locale
 
 /**
  * Field-debug logger: mirrors every line to logcat AND appends it to a
- * timestamped text file in the public DCIM/MAG160C album folder, so the user
+ * timestamped text file next to the photos (DCIM/MAG160C), so the user can
- * can hand over the file without adb (real-device bring-up, round 11).
+ * hand over the file without adb (real-device bring-up, round 11).
  *
- * Lines are flushed per write; the stream stays open for the session and is
+ * Logging must NEVER crash the app: every sink operation is guarded, and
- * closed by [closeFile] (or on process death — at most the very last line is
+ * writes are capped.  Sink fallback chain (scoped storage only allows media
- * lost).  A crash hook writes the stack trace before rethrowing to the
+ * under DCIM, text/plain may be rejected there):
- * previous handler.
+ *   1. MediaStore Files @ DCIM/MAG160C     (the album folder, preferred)
+ *   2. MediaStore Files @ Download/MAG160C (allowed for non-media files)
+ *   3. app-specific external dir (always writable; may need a PC to fetch)
+ * The header line records where the file actually ended up.
  */
 object DebugLog {
     private val fmt = SimpleDateFormat("HH:mm:ss.SSS", Locale.ENGLISH)
@@ -30,15 +33,13 @@ object DebugLog {
     private val lock = Any()
     private var stream: OutputStream? = null
     private var outUri: Uri? = null
-    private var appContext: Context? = null
     private var previousHandler: Thread.UncaughtExceptionHandler? = null
     private var bytesWritten = 0L
 
     /** Install once from MainActivity.onCreate: crash hook + app context. */
     fun init(context: Context) {
         synchronized(lock) {
-            if (appContext != null) return
+            if (previousHandler != null) return
-            appContext = context.applicationContext
             previousHandler = Thread.getDefaultUncaughtExceptionHandler()
             Thread.setDefaultUncaughtExceptionHandler { t, e ->
                 log("crash", "thread=$t ${Log.getStackTraceString(e)}")
@@ -48,20 +49,28 @@ object DebugLog {
         }
     }
 
-    /** Log one line (also to logcat as MAG160C/<tag>). */
+    /** Log one line (also to logcat as MAG160C/<tag>). Never throws. */
     fun log(tag: String, msg: String) {
-        Log.d("MAG160C/$tag", msg)
+        try {
+            Log.d("MAG160C/$tag", msg)
+        } catch (_: Exception) {
+        }
         val line = "${fmt.format(Date())} [$tag] $msg\n"
         synchronized(lock) {
-            val s = stream
+            val s = stream ?: return
-            if (s == null) {
-                Log.v("MAG160C/$tag", "(no file yet) $msg")
-                return
-            }
             try {
                 s.write(line.toByteArray(Charsets.UTF_8))
                 s.flush()
                 bytesWritten += line.length
+                if (bytesWritten > MAX_BYTES) {
+                    // cap the file: stop writing rather than grow unbounded
+                    try {
+                        s.close()
+                    } catch (_: Exception) {
+                    }
+                    stream = null
+                    Log.w("MAG160C/log", "log capped at $MAX_BYTES bytes, closed")
+                }
             } catch (e: Exception) {
                 Log.w("MAG160C/$tag", "log write failed", e)
             }
@@ -69,9 +78,9 @@ object DebugLog {
     }
 
     /**
-     * Open a fresh debug_*.log in DCIM/MAG160C (API 29+, MediaStore, no
+     * Open a fresh debug_*.log.  Called once at app start (so even startup
-     * permission needed for own files) or the app-specific dir below Q.
+     * crashes are captured); never throws.  Returns the display path for
-     * Closes any previous file.  Returns the display path for logging.
+     * logging.  Closes any previous file.
      */
     fun startFile(context: Context): String {
         val name = "debug_${fileFmt.format(Date())}.log"
@@ -79,37 +88,66 @@ object DebugLog {
         synchronized(lock) {
             bytesWritten = 0
             val ctx = context.applicationContext
+            var where = "(log unavailable)"
             if (Build.VERSION.SDK_INT >= 29) {
-                val values = ContentValues().apply {
+                openSink(ctx, name, Environment.DIRECTORY_DCIM + "/MAG160C")
-                    put(MediaStore.MediaColumns.DISPLAY_NAME, name)
+                    ?.let { (uri, os) ->
-                    put(MediaStore.MediaColumns.MIME_TYPE, "text/plain")
+                        outUri = uri
-                    put(
+                        stream = os
-                        MediaStore.MediaColumns.RELATIVE_PATH,
+                        where = "DCIM/MAG160C/$name"
-                        Environment.DIRECTORY_DCIM + "/MAG160C",
+                    }
-                    )
+                if (stream == null) {
+                    openSink(ctx, name, Environment.DIRECTORY_DOWNLOADS + "/MAG160C")
+                        ?.let { (uri, os) ->
+                            outUri = uri
+                            stream = os
+                            where = "Download/MAG160C/$name (DCIM rejected for text/plain)"
+                        }
                 }
-                val uri = ctx.contentResolver.insert(
-                    MediaStore.Files.getContentUri("external"),
-                    values,
-                )
-                if (uri == null) {
-                    Log.w("MAG160C/log", "MediaStore insert failed")
-                    return "(insert failed)"
-                }
-                outUri = uri
-                stream = ctx.contentResolver.openOutputStream(uri)
-            } else {
-                val dir = File(ctx.getExternalFilesDir(null), "MAG160C").apply { mkdirs() }
-                val f = File(dir, name)
-                outUri = Uri.fromFile(f)
-                stream = FileOutputStream(f)
             }
-            val header = "MAG160C debug ${fileFmt.format(Date())} " +
+            if (stream == null) {
-                "sdk=${Build.VERSION.SDK_INT} dev=${Build.MANUFACTURER} ${Build.MODEL}\n"
+                try {
-            stream?.write(header.toByteArray(Charsets.UTF_8))
+                    val dir = File(ctx.getExternalFilesDir(null), "MAG160C").apply { mkdirs() }
-            stream?.flush()
+                    val f = File(dir, name)
+                    outUri = Uri.fromFile(f)
+                    stream = FileOutputStream(f)
+                    where = f.absolutePath + " (app-private; fetch via PC)"
+                } catch (e: Exception) {
+                    Log.w("MAG160C/log", "all log sinks failed", e)
+                    return where
+                }
+            }
+            try {
+                val header = "MAG160C debug ${fileFmt.format(Date())} " +
+                    "sdk=${Build.VERSION.SDK_INT} dev=${Build.MANUFACTURER} " +
+                    "${Build.MODEL} sink=$where\n"
+                stream?.write(header.toByteArray(Charsets.UTF_8))
+                stream?.flush()
+            } catch (e: Exception) {
+                Log.w("MAG160C/log", "header write failed", e)
+            }
+            return where
+        }
+    }
+
+    /** One MediaStore Files insert + output stream; null on any failure. */
+    private fun openSink(ctx: Context, name: String, relativePath: String): Pair<Uri, OutputStream>? {
+        return try {
+            val values = ContentValues().apply {
+                put(MediaStore.MediaColumns.DISPLAY_NAME, name)
+                put(MediaStore.MediaColumns.MIME_TYPE, "text/plain")
+                put(MediaStore.MediaColumns.RELATIVE_PATH, relativePath)
+            }
+            val uri = ctx.contentResolver.insert(
+                MediaStore.Files.getContentUri("external"),
+                values,
+            ) ?: return null
+            val os = ctx.contentResolver.openOutputStream(uri) ?: return null
+            uri to os
+        } catch (e: Exception) {
+            Log.w("MAG160C/log", "sink $relativePath failed: $e")
+            null
         }
-        return "DCIM/MAG160C/$name"
     }
 
     /** Flush + close the current file (kept visible in the gallery). */
@@ -124,4 +162,6 @@ object DebugLog {
             outUri = null
         }
     }
+
+    private const val MAX_BYTES = 4L * 1024 * 1024
 }

android/app/src/main/kotlin/com/mag160c/thermal/ui/live/LiveScreen.kt

@@ -295,6 +295,7 @@ private fun statusText(state: LiveViewModel.LiveState): String = when (state.sta
     "ddt_fail" -> "标定文件加载失败"
     "open_fail" -> "USB打开失败（查看调试日志）"
     "no_endpoints" -> "未找到数据端点（查看调试日志）"
+    "connect_fail" -> "连接流程异常（查看调试日志）"
     else -> {
         val prefix = if (state.status.startsWith("exception:")) {
             "异常：" + state.status.removePrefix("exception:")

android/app/src/main/kotlin/com/mag160c/thermal/ui/live/LiveViewModel.kt

@@ -103,32 +103,42 @@ class LiveViewModel(app: Application) : AndroidViewModel(app) {
 
     /** Begin USB permission flow, then start streaming. No device -> idle notice. */
     fun connect() {
-        val context = getApplication<Application>()
+        try {
-        com.mag160c.thermal.media.DebugLog.startFile(context)
+            com.mag160c.thermal.media.DebugLog.log("vm", "connect()")
-        com.mag160c.thermal.media.DebugLog.log("vm", "connect()")
+            val context = getApplication<Application>()
-        val transport = com.mag160c.thermal.usb.UsbTransport(context)
+            val transport = com.mag160c.thermal.usb.UsbTransport(context)
-        val dev = transport.findDevice()
+            val dev = transport.findDevice()
-        if (dev == null) {
+            if (dev == null) {
-            com.mag160c.thermal.media.DebugLog.log("vm", "no_device")
+                com.mag160c.thermal.media.DebugLog.log("vm", "no_device")
-            _state.value = _state.value.copy(
+                _state.value = _state.value.copy(
-                connected = false,
+                    connected = false,
-                streaming = false,
+                    streaming = false,
-                status = "no_device",
+                    status = "no_device",
-            )
-            return
-        }
-        transport.requestPermission { ok ->
-            if (ok) {
-                val ddt = runCatching { context.assets.open("mag160c.ddt").readBytes() }
-                    .getOrDefault(ByteArray(0))
-                com.mag160c.thermal.media.DebugLog.log(
-                    "vm", "permission ok, ddt ${ddt.size} bytes, starting session",
                 )
-                session.start(ddt)
+                return
-            } else {
-                com.mag160c.thermal.media.DebugLog.log("vm", "permission denied")
-                _state.value = _state.value.copy(connected = false, status = "no_permission")
             }
+            transport.requestPermission { ok ->
+                try {
+                    if (ok) {
+                        val ddt = runCatching { context.assets.open("mag160c.ddt").readBytes() }
+                            .getOrDefault(ByteArray(0))
+                        com.mag160c.thermal.media.DebugLog.log(
+                            "vm", "permission ok, ddt ${ddt.size} bytes, starting session",
+                        )
+                        session.start(ddt)
+                    } else {
+                        com.mag160c.thermal.media.DebugLog.log("vm", "permission denied")
+                        _state.value = _state.value.copy(connected = false, status = "no_permission")
+                    }
+                } catch (e: Exception) {
+                    com.mag160c.thermal.media.DebugLog.log("vm", "permission flow failed: $e")
+                    _state.value = _state.value.copy(connected = false, status = "connect_fail")
+                }
+            }
+        } catch (e: Exception) {
+            // logging/USB must never kill the UI (round-12 crash fix)
+            com.mag160c.thermal.media.DebugLog.log("vm", "connect failed: $e")
+            _state.value = _state.value.copy(connected = false, status = "connect_fail")
         }
     }
 

docs/android_app/session_state.md

@@ -233,6 +233,22 @@
 - 注：调试日志文件由 MediaStore Files（非 Images）写入，部分相册 app 不显示
   text/plain，可用系统"文件"应用或 PC 复制 DCIM/MAG160C/debug_*.log。
 
+## 用户反馈修复 第十二轮（2026-09-10，打开即闪退：日志落点修复）
+
+- [x] **用户反馈**：第 11 轮 APK 装好后直接打开就闪退。
+- [x] **根因**：`DebugLog.startFile` 用 `MediaStore.Files` 往 DCIM/MAG160C 插
+      text/plain 文件；scoped storage 规定 DCIM 只收图片/视频，非媒体文件被拒，
+      `insert()` 抛 IllegalArgumentException，而该调用在 `LaunchedEffect →
+      connect()` 协程里无 try/catch → 启动即崩。
+- [x] **修复**：DebugLog 全链路 try/catch 永不抛异常；落点三级回退
+      DCIM/MAG160C → Download/MAG160C（非媒体允许目录）→ 应用私有外部目录；
+      文件头写实际落点 `sink=`；日志 4MB 封顶。`startFile` 提前到
+      MainActivity.onCreate（启动崩溃也有记录）；`connect()`/权限回调整体
+      try/catch，失败置 `connect_fail`（statusText 显示"连接流程异常"）。
+- [x] 构建+单测全过，dex 抽查通过；APK 已更新（11.87MB）。
+- 注：取日志时 DCIM/MAG160C 和 Download/MAG160C 都看一眼（文件头 sink= 注明
+  实际位置）；若在前者失败会自动落后者。
+
 ## 待办
 
 - 真机USB实测（温度绝对值标定、FFC/录像/MDT保存端到端）——当前进行中：