feat: downloads tab + public Movies/yaris-obd/ folder

- Downloads now go to Movies/yaris-obd/ (visible in file managers)
- New Downloads tab: list downloaded files, tap to play (system player),
  delete button
- FileProvider added for video playback intent
- Downloaded files auto-refresh after each download

android/app/src/main/AndroidManifest.xml

@@ -36,6 +36,16 @@
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
+
+        <provider
+            android:name="androidx.core.content.FileProvider"
+            android:authorities="${applicationId}.fileprovider"
+            android:exported="false"
+            android:grantUriPermissions="true">
+            <meta-data
+                android:name="android.support.FILE_PROVIDER_PATHS"
+                android:resource="@xml/file_paths" />
+        </provider>
     </application>
 
 </manifest>

android/app/src/main/java/com/yarisobd/app/DashcamViewModel.kt

@@ -3,6 +3,7 @@ package com.yarisobd.app
 import android.app.Application
 import android.content.Context
 import android.os.Environment
+import android.webkit.MimeTypeMap
 import androidx.lifecycle.AndroidViewModel
 import androidx.lifecycle.viewModelScope
 import com.yarisobd.app.data.remote.PiApi
@@ -32,6 +33,12 @@ data class DownloadProgress(
     val totalBytes: Long,
 )
 
+data class DownloadedFile(
+    val name: String,
+    val size: Long,
+    val file: File,
+)
+
 class DashcamViewModel(application: Application) : AndroidViewModel(application) {
 
     private val baseUrl = "http://10.42.0.1"  // no trailing slash
@@ -66,8 +73,22 @@ class DashcamViewModel(application: Application) : AndroidViewModel(application)
     private val _downloadEvents = MutableSharedFlow<String>()
     val downloadEvents = _downloadEvents.asSharedFlow()
 
+    private val _downloadedFiles = MutableStateFlow<List<DownloadedFile>>(emptyList())
+    val downloadedFiles: StateFlow<List<DownloadedFile>> = _downloadedFiles.asStateFlow()
+
+    private fun getDownloadDir(): File {
+        // Public Movies/yaris-obd/ — visible in file managers
+        val dir = File(
+            Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MOVIES),
+            "yaris-obd"
+        )
+        dir.mkdirs()
+        return dir
+    }
+
     init {
         loadVideos()
+        scanDownloads()
     }
 
     fun loadVideos() {
@@ -134,6 +155,7 @@ class DashcamViewModel(application: Application) : AndroidViewModel(application)
                     "✓ Downloaded: ${localFile.name} (${downloaded} bytes)"
                 }
                 _downloadEvents.emit(result)
+                scanDownloads()
             } catch (e: Exception) {
                 _downloadProgress.value = _downloadProgress.value - video.path
                 _downloadEvents.emit("✗ Download failed: ${e.message}")
@@ -141,6 +163,25 @@ class DashcamViewModel(application: Application) : AndroidViewModel(application)
         }
     }
 
+    fun scanDownloads() {
+        val dir = getDownloadDir()
+        val files = dir.listFiles()?.filter { it.isFile }?.map { f ->
+            DownloadedFile(name = f.name, size = f.length(), file = f)
+        }?.sortedByDescending { it.file.lastModified() } ?: emptyList()
+        _downloadedFiles.value = files
+    }
+
+    fun deleteDownloaded(file: DownloadedFile) {
+        viewModelScope.launch {
+            if (file.file.delete()) {
+                _downloadEvents.emit("✓ Deleted: ${file.name}")
+                scanDownloads()
+            } else {
+                _downloadEvents.emit("✗ Could not delete: ${file.name}")
+            }
+        }
+    }
+
     fun deleteVideo(video: VideoFile) {
         viewModelScope.launch {
             try {

android/app/src/main/java/com/yarisobd/app/DownloadsScreen.kt

@@ -0,0 +1,150 @@
+package com.yarisobd.app
+
+import android.content.Intent
+import androidx.compose.foundation.clickable
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.lazy.items
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material3.Button
+import androidx.compose.material3.ButtonDefaults
+import androidx.compose.material3.Card
+import androidx.compose.material3.CardDefaults
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.unit.dp
+import androidx.core.content.FileProvider
+
+@Composable
+fun DownloadsScreen(
+    files: List<DownloadedFile>,
+    onDelete: (DownloadedFile) -> Unit,
+    onRefresh: () -> Unit,
+) {
+    val context = LocalContext.current
+
+    Column(modifier = Modifier.fillMaxSize()) {
+        Card(
+            modifier = Modifier
+                .fillMaxWidth()
+                .padding(16.dp),
+            colors = CardDefaults.cardColors(
+                containerColor = MaterialTheme.colorScheme.surfaceContainerHigh
+            )
+        ) {
+            Column(modifier = Modifier.padding(16.dp)) {
+                Text(
+                    text = "Downloads",
+                    style = MaterialTheme.typography.titleLarge,
+                    color = MaterialTheme.colorScheme.primary
+                )
+                Spacer(modifier = Modifier.height(4.dp))
+                Text(
+                    text = "${files.size} files in Movies/yaris-obd/",
+                    style = MaterialTheme.typography.bodyMedium,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant
+                )
+            }
+        }
+
+        if (files.isEmpty()) {
+            Box(
+                modifier = Modifier.fillMaxSize(),
+                contentAlignment = Alignment.Center
+            ) {
+                Text(
+                    text = "No downloaded files yet.\nDownload a video from the Dashcam tab.",
+                    style = MaterialTheme.typography.bodyLarge,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant
+                )
+            }
+        } else {
+            LazyColumn(
+                contentPadding = androidx.compose.foundation.layout.PaddingValues(
+                    start = 16.dp, end = 16.dp, bottom = 16.dp
+                ),
+                verticalArrangement = Arrangement.spacedBy(8.dp)
+            ) {
+                items(files, key = { it.name }) { file ->
+                    Card(
+                        modifier = Modifier
+                            .fillMaxWidth()
+                            .clickable {
+                                // Open with system video player
+                                val uri = FileProvider.getUriForFile(
+                                    context,
+                                    "${context.packageName}.fileprovider",
+                                    file.file
+                                )
+                                val intent = Intent(Intent.ACTION_VIEW).apply {
+                                    setDataAndType(uri, "video/*")
+                                    addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
+                                }
+                                context.startActivity(intent)
+                            },
+                        colors = CardDefaults.cardColors(
+                            containerColor = MaterialTheme.colorScheme.surfaceContainerHigh
+                        )
+                    ) {
+                        Row(
+                            modifier = Modifier
+                                .fillMaxWidth()
+                                .padding(12.dp),
+                            verticalAlignment = Alignment.CenterVertically
+                        ) {
+                            Column(modifier = Modifier.weight(1f)) {
+                                Text(
+                                    text = file.name,
+                                    style = MaterialTheme.typography.bodyMedium,
+                                    fontWeight = FontWeight.Medium,
+                                    maxLines = 1,
+                                    overflow = TextOverflow.Ellipsis,
+                                    color = MaterialTheme.colorScheme.onSurface
+                                )
+                                Text(
+                                    text = formatBytes(file.size),
+                                    style = MaterialTheme.typography.bodySmall,
+                                    color = MaterialTheme.colorScheme.onSurfaceVariant
+                                )
+                            }
+                            Button(
+                                onClick = { onDelete(file) },
+                                colors = ButtonDefaults.buttonColors(
+                                    containerColor = MaterialTheme.colorScheme.error
+                                ),
+                                modifier = Modifier.height(36.dp)
+                            ) {
+                                Text("✕", style = MaterialTheme.typography.bodySmall)
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
+private fun formatBytes(bytes: Long): String {
+    return when {
+        bytes >= 1_000_000_000 -> "%.1f GB".format(bytes / 1_000_000_000.0)
+        bytes >= 1_000_000 -> "%.1f MB".format(bytes / 1_000_000.0)
+        bytes >= 1_000 -> "%.1f KB".format(bytes / 1_000.0)
+        else -> "$bytes B"
+    }
+}

android/app/src/main/java/com/yarisobd/app/MainActivity.kt

@@ -53,6 +53,7 @@ fun YarisMainScreen(client: OkHttpClient) {
     val isLoading by dashcamVm.isLoading.collectAsState()
     val error by dashcamVm.error.collectAsState()
     val downloadProgress by dashcamVm.downloadProgress.collectAsState()
+    val downloadedFiles by dashcamVm.downloadedFiles.collectAsState()
 
     val snackbarHostState = remember { SnackbarHostState() }
     var selectedTab by remember { mutableIntStateOf(0) }
@@ -77,7 +78,13 @@ fun YarisMainScreen(client: OkHttpClient) {
                 NavigationBarItem(
                     selected = selectedTab == 1,
                     onClick = { selectedTab = 1 },
-                    icon = { Text("🔌") },
+                    icon = { Text("�") },
+                    label = { Text("Downloads") }
+                )
+                NavigationBarItem(
+                    selected = selectedTab == 2,
+                    onClick = { selectedTab = 2 },
+                    icon = { Text("�🔌") },
                     label = { Text("Test") }
                 )
             }
@@ -96,7 +103,12 @@ fun YarisMainScreen(client: OkHttpClient) {
                     onDownload = { dashcamVm.downloadVideo(it) },
                     onDelete = { dashcamVm.deleteVideo(it) },
                 )
-                1 -> DualNetworkTestScreen(
+                1 -> DownloadsScreen(
+                    files = downloadedFiles,
+                    onDelete = { dashcamVm.deleteDownloaded(it) },
+                    onRefresh = { dashcamVm.scanDownloads() },
+                )
+                2 -> DualNetworkTestScreen(
                     piClient = client,
                     serverClient = client,
                 )

android/app/src/main/res/xml/file_paths.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<paths>
+    <external-path name="movies" path="Movies/yaris-obd/" />
+</paths>