diff --git a/commons/src/jvmTest/kotlin/com/vitorpamplona/amethyst/commons/util/FileDeletionTest.kt b/commons/src/jvmTest/kotlin/com/vitorpamplona/amethyst/commons/util/FileDeletionTest.kt
new file mode 100644
index 0000000000..b9f2ed652d
--- /dev/null
+++ b/commons/src/jvmTest/kotlin/com/vitorpamplona/amethyst/commons/util/FileDeletionTest.kt
@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.commons.util
+
+import java.io.File
+import java.nio.file.Files
+import kotlin.test.AfterTest
+import kotlin.test.Test
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+
+class FileDeletionTest {
+    private val createdFiles = mutableListOf<File>()
+
+    @AfterTest
+    fun cleanup() {
+        createdFiles.asReversed().forEach { it.delete() }
+        createdFiles.clear()
+    }
+
+    private fun tempFile(): File =
+        File.createTempFile("file-deletion-test", ".tmp").also {
+            createdFiles.add(it)
+        }
+
+    @Test
+    fun deletesExistingFileAndReturnsTrue() {
+        val file = tempFile()
+        assertTrue(file.exists())
+
+        assertTrue(file.deleteOrWarn("FileDeletionTest", "temp file"))
+        assertFalse(file.exists())
+    }
+
+    @Test
+    fun alreadyGoneFileIsSuccess() {
+        val file = tempFile()
+        assertTrue(file.delete())
+
+        // Simulates a concurrent eviction: the file vanished before our delete.
+        assertTrue(file.deleteOrWarn("FileDeletionTest", "temp file"))
+    }
+
+    @Test
+    fun undeletableFileReturnsFalseAndKeepsFile() {
+        // A non-empty directory cannot be deleted, and still exists afterwards —
+        // the genuine-failure branch.
+        val dir = Files.createTempDirectory("file-deletion-test").toFile()
+        val child = File(dir, "child.txt").apply { writeText("keeps dir non-empty") }
+        createdFiles.add(dir)
+        createdFiles.add(child)
+
+        assertFalse(dir.deleteOrWarn("FileDeletionTest", "non-empty dir"))
+        assertTrue(dir.exists())
+    }
+}
diff --git a/commons/src/jvmTest/kotlin/com/vitorpamplona/amethyst/commons/util/FilePermissionsTest.kt b/commons/src/jvmTest/kotlin/com/vitorpamplona/amethyst/commons/util/FilePermissionsTest.kt
new file mode 100644
index 0000000000..6640ffa76f
--- /dev/null
+++ b/commons/src/jvmTest/kotlin/com/vitorpamplona/amethyst/commons/util/FilePermissionsTest.kt
@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.commons.util
+
+import java.io.File
+import java.nio.file.FileSystems
+import java.nio.file.Files
+import java.nio.file.attribute.PosixFilePermission
+import kotlin.test.AfterTest
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class FilePermissionsTest {
+    private val createdFiles = mutableListOf<File>()
+
+    @AfterTest
+    fun cleanup() {
+        createdFiles.asReversed().forEach { it.delete() }
+        createdFiles.clear()
+    }
+
+    private fun isPosix() = FileSystems.getDefault().supportedFileAttributeViews().contains("posix")
+
+    @Test
+    fun restrictsFileToOwnerReadWrite() {
+        if (!isPosix()) return // Windows: restrictToOwner is documented as a silent no-op
+
+        val file = File.createTempFile("file-permissions-test", ".tmp")
+        createdFiles.add(file)
+
+        file.restrictToOwner("FilePermissionsTest")
+
+        assertEquals(
+            setOf(PosixFilePermission.OWNER_READ, PosixFilePermission.OWNER_WRITE),
+            Files.getPosixFilePermissions(file.toPath()),
+        )
+    }
+
+    @Test
+    fun restrictsDirectoryToOwnerReadWriteExecute() {
+        if (!isPosix()) return
+
+        val dir = Files.createTempDirectory("file-permissions-test").toFile()
+        createdFiles.add(dir)
+
+        dir.restrictToOwner("FilePermissionsTest")
+
+        assertEquals(
+            setOf(
+                PosixFilePermission.OWNER_READ,
+                PosixFilePermission.OWNER_WRITE,
+                PosixFilePermission.OWNER_EXECUTE,
+            ),
+            Files.getPosixFilePermissions(dir.toPath()),
+        )
+    }
+
+    @Test
+    fun missingFileDoesNotThrow() {
+        val ghost = File(System.getProperty("java.io.tmpdir"), "file-permissions-test-missing-${System.nanoTime()}")
+
+        // Best-effort contract: failures are logged, never thrown.
+        ghost.restrictToOwner("FilePermissionsTest")
+    }
+}