fix(recordings): open folder with android picker

android/app/src/main/kotlin/es/freetimelab/pluriwave/MainActivity.kt

@@ -1,12 +1,16 @@
 package es.freetimelab.pluriwave
 
 import android.Manifest
+import android.app.ActivityNotFoundException
 import android.content.Intent
 import android.content.pm.PackageManager
+import android.net.Uri
 import android.media.audiofx.Visualizer
 import android.os.Build
+import android.os.Environment
 import android.os.Handler
 import android.os.Looper
+import android.provider.DocumentsContract
 import androidx.core.app.NotificationManagerCompat
 import com.ryanheise.audioservice.AudioServiceActivity
 import io.flutter.embedding.engine.FlutterEngine
@@ -16,6 +20,7 @@ import io.flutter.plugin.common.MethodChannel
 class MainActivity : AudioServiceActivity() {
     private val visualizerChannel = "pluriwave/audio_visualizer"
     private val alarmChannel = "pluriwave/alarm_scheduler"
+    private val fileActionsChannel = "pluriwave/file_actions"
     private val permissionRequestCode = 4821
     private var visualizer: Visualizer? = null
     private var pendingSink: EventChannel.EventSink? = null
@@ -96,6 +101,23 @@ class MainActivity : AudioServiceActivity() {
                 else -> result.notImplemented()
             }
         }
+
+        MethodChannel(
+            flutterEngine.dartExecutor.binaryMessenger,
+            fileActionsChannel
+        ).setMethodCallHandler { call, result ->
+            when (call.method) {
+                "openDirectory" -> {
+                    val path = call.argument<String>("path")
+                    if (path.isNullOrBlank()) {
+                        result.success(false)
+                    } else {
+                        result.success(openDirectory(path))
+                    }
+                }
+                else -> result.notImplemented()
+            }
+        }
     }
 
     override fun onNewIntent(intent: Intent) {
@@ -122,6 +144,38 @@ class MainActivity : AudioServiceActivity() {
         )
     }
 
+    private fun openDirectory(path: String): Boolean {
+        val intent = Intent(Intent.ACTION_OPEN_DOCUMENT_TREE).apply {
+            addFlags(
+                Intent.FLAG_GRANT_READ_URI_PERMISSION or
+                    Intent.FLAG_GRANT_WRITE_URI_PERMISSION or
+                    Intent.FLAG_GRANT_PERSISTABLE_URI_PERMISSION or
+                    Intent.FLAG_GRANT_PREFIX_URI_PERMISSION
+            )
+            directoryTreeUri(path)?.let { putExtra(DocumentsContract.EXTRA_INITIAL_URI, it) }
+        }
+        return try {
+            startActivity(intent)
+            true
+        } catch (_: ActivityNotFoundException) {
+            false
+        } catch (_: Throwable) {
+            false
+        }
+    }
+
+    private fun directoryTreeUri(path: String): Uri? {
+        val external = Environment.getExternalStorageDirectory()?.absolutePath ?: return null
+        if (!path.startsWith(external)) return null
+
+        val relative = path.removePrefix(external).trimStart('/')
+        val documentId = if (relative.isBlank()) "primary:" else "primary:$relative"
+        return DocumentsContract.buildTreeDocumentUri(
+            "com.android.externalstorage.documents",
+            documentId
+        )
+    }
+
     private fun startVisualizerWhenAllowed() {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M &&
             checkSelfPermission(Manifest.permission.RECORD_AUDIO)