🐛 Fix PlatformFile child resolution for non-web

filekit-core/src/androidHostTest/kotlin/io/github/vinceglb/filekit/PlatformFileAndroidTest.kt

@@ -1,15 +1,30 @@
 package io.github.vinceglb.filekit
 
+import android.net.Uri
+import io.github.vinceglb.filekit.exceptions.FileKitException
+import io.github.vinceglb.filekit.exceptions.FileKitUriPathNotSupportedException
 import io.github.vinceglb.filekit.mimeType.MimeType
+import org.junit.Before
 import org.junit.runner.RunWith
 import org.robolectric.RobolectricTestRunner
+import org.robolectric.RuntimeEnvironment
 import org.robolectric.annotation.Config
 import kotlin.test.Test
 import kotlin.test.assertEquals
+import kotlin.test.assertFailsWith
+import kotlin.test.assertIs
+import kotlin.test.assertIsNot
+import kotlin.test.assertTrue
 
 @RunWith(RobolectricTestRunner::class)
 @Config(sdk = [36])
 class PlatformFileAndroidTest {
+    @Before
+    fun setup() {
+        // Initialize FileKit with Robolectric's application context
+        FileKit.manualFileKitCoreInitialization(RuntimeEnvironment.getApplication())
+    }
+
     private val resourceDirectory = FileKit.projectDir / "src/nonWebTest/resources"
     private val textFile = resourceDirectory / "hello.txt"
     private val imageFile = resourceDirectory / "compose-logo.png"
@@ -39,4 +54,41 @@ class PlatformFileAndroidTest {
             actual = resourceDirectory.mimeType(),
         )
     }
+
+    // Issue #415: Test `/` operator on FileWrapper (should work as before)
+    @Test
+    fun testDivOperatorOnFileWrapper() {
+        val base = PlatformFile("/tmp/test")
+        val child = base / "child.txt"
+
+        assertIs<AndroidFile.FileWrapper>(child.androidFile)
+        assertEquals("/tmp/test/child.txt", child.path)
+    }
+
+    // Issue #415: Test `/` operator on UriWrapper does NOT throw FileKitUriPathNotSupportedException
+    // Note: In Robolectric, DocumentFile.fromTreeUri() returns null (no real SAF support),
+    // so this test verifies that the ORIGINAL bug (FileKitUriPathNotSupportedException) is fixed.
+    // Full integration testing requires a real Android device with SAF support.
+    @Test
+    fun testDivOperatorOnUriWrapper_noLongerThrowsPathNotSupportedException() {
+        // Create a Uri-based PlatformFile (tree Uri format used by directory pickers)
+        val uri = Uri.parse("content://com.android.externalstorage.documents/tree/primary%3ADocuments")
+        val base = PlatformFile(uri)
+
+        // Before the fix, this would throw FileKitUriPathNotSupportedException
+        // because PlatformFile(base, child) called base.toKotlinxIoPath() which throws for UriWrapper.
+        // After the fix, it uses DocumentFile API instead, which fails in Robolectric
+        // with a generic FileKitException (not FileKitUriPathNotSupportedException).
+        val exception = assertFailsWith<FileKitException> {
+            base / "backup.zip"
+        }
+
+        // Verify it's NOT the old exception type (the bug we fixed)
+        assertIsNot<FileKitUriPathNotSupportedException>(exception)
+        // The error message should be about DocumentFile access, not Path conversion
+        assertTrue(
+            exception.message?.contains("Could not access Uri as directory") == true ||
+                exception.message?.contains("Could not create child file") == true,
+        )
+    }
 }

filekit-core/src/jvmAndNativeMain/kotlin/io/github/vinceglb/filekit/PlatformFile.jvmAndNative.kt

@@ -18,6 +18,9 @@ public actual val PlatformFile.path: String
 public actual fun PlatformFile(path: String): PlatformFile =
     PlatformFile(Path(path))
 
+public actual fun PlatformFile(base: PlatformFile, child: String): PlatformFile =
+    PlatformFile(base.toKotlinxIoPath() / child)
+
 public actual fun PlatformFile.isRegularFile(): Boolean = withScopedAccess {
     SystemFileSystem.metadataOrNull(toKotlinxIoPath())?.isRegularFile ?: false
 }

filekit-core/src/nonWebMain/kotlin/io/github/vinceglb/filekit/PlatformFile.nonWeb.kt

@@ -1,6 +1,5 @@
 package io.github.vinceglb.filekit
 
-import io.github.vinceglb.filekit.utils.div
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.IO
 import kotlinx.coroutines.withContext
@@ -38,8 +37,7 @@ public expect fun PlatformFile(path: String): PlatformFile
  * @param child The child path string.
  * @return A [PlatformFile] instance representing the combined path.
  */
-public fun PlatformFile(base: PlatformFile, child: String): PlatformFile =
-    PlatformFile(base.toKotlinxIoPath() / child)
+public expect fun PlatformFile(base: PlatformFile, child: String): PlatformFile
 
 /**
  * Converts this [PlatformFile] to a [Path].

sample/shared/src/commonMain/kotlin/io/github/vinceglb/filekit/sample/shared/ui/screens/debug/DebugScreen.kt

@@ -10,6 +10,7 @@ import androidx.compose.runtime.Composable
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
@@ -23,9 +24,11 @@ import io.github.vinceglb.filekit.sample.shared.ui.components.AppScreenHeader
 import io.github.vinceglb.filekit.sample.shared.ui.components.AppScreenHeaderButtonState
 import io.github.vinceglb.filekit.sample.shared.ui.icons.LucideIcons
 import io.github.vinceglb.filekit.sample.shared.ui.icons.MessageCircleCode
+import io.github.vinceglb.filekit.sample.shared.ui.screens.directorypicker.rememberDirectoryPickerLauncher
 import io.github.vinceglb.filekit.sample.shared.ui.theme.AppMaxWidth
 import io.github.vinceglb.filekit.sample.shared.ui.theme.AppTheme
 import io.github.vinceglb.filekit.sample.shared.util.plus
+import kotlinx.coroutines.launch
 
 @Composable
 internal fun DebugRoute(
@@ -51,6 +54,15 @@ private fun DebugScreen(
         files = file?.let(::listOf) ?: emptyList()
     }
 
+    val scope = rememberCoroutineScope()
+    val folderPicker = rememberDirectoryPickerLauncher(directory = null) { folder ->
+        scope.launch {
+            folder?.let {
+                debugPlatformTest(folder)
+            }
+        }
+    }
+
     Scaffold(
         topBar = {
             AppPickerTopBar(
@@ -75,7 +87,8 @@ private fun DebugScreen(
                     primaryButtonState = buttonState,
                     onPrimaryButtonClick = {
                         buttonState = AppScreenHeaderButtonState.Loading
-                        picker.launch()
+                        // picker.launch()
+                        folderPicker.launch()
                     },
                     modifier = Modifier.sizeIn(maxWidth = AppMaxWidth),
                 )
@@ -94,6 +107,8 @@ private fun DebugScreen(
     }
 }
 
+internal expect suspend fun debugPlatformTest(folder: PlatformFile)
+
 @Preview
 @Composable
 private fun DebugScreenPreview() {

sample/shared/src/nonWebMain/kotlin/io/github/vinceglb/filekit/sample/shared/ui/screens/debug/DebugScreen.nonWeb.kt

@@ -1,2 +1,10 @@
-package io.github.vinceglb.filekit.sample.shared.ui.screens.debug 
+package io.github.vinceglb.filekit.sample.shared.ui.screens.debug
 
+import io.github.vinceglb.filekit.PlatformFile
+import io.github.vinceglb.filekit.div
+import io.github.vinceglb.filekit.writeString
+
+internal actual suspend fun debugPlatformTest(folder: PlatformFile) {
+    val file = folder / "debug-test-file.txt"
+    file.writeString("Vince")
+}