diff --git a/data/build.gradle.kts b/data/build.gradle.kts
index d7aab12..ca92b3a 100644
--- a/data/build.gradle.kts
+++ b/data/build.gradle.kts
@@ -31,6 +31,7 @@ android {
         sourceCompatibility = JavaVersion.VERSION_17
         targetCompatibility = JavaVersion.VERSION_17
     }
+    compileSdkMinor = 0
 }
 
 kotlin {
diff --git a/domain/src/main/java/com/itlab/domain/usecase/CreateFolderUseCase.kt b/domain/src/main/java/com/itlab/domain/usecase/CreateFolderUseCase.kt
index b0d06dc..e4d68a7 100644
--- a/domain/src/main/java/com/itlab/domain/usecase/CreateFolderUseCase.kt
+++ b/domain/src/main/java/com/itlab/domain/usecase/CreateFolderUseCase.kt
@@ -3,13 +3,19 @@ package com.itlab.domain.usecase
 import com.itlab.domain.model.NoteFolder
 import com.itlab.domain.repository.NoteFolderRepository
 import kotlinx.datetime.Clock
+import java.util.UUID
 
 class CreateFolderUseCase(
     private val repo: NoteFolderRepository,
 ) {
     suspend operator fun invoke(folder: NoteFolder): String {
-        // discuss
-        val folder = folder.copy(createdAt = Clock.System.now())
+        val now = Clock.System.now()
+        val folder =
+            folder.copy(
+                id = UUID.randomUUID().toString(),
+                createdAt = now,
+                updatedAt = now,
+            )
         return repo.createFolder(folder)
     }
 }
diff --git a/domain/src/main/java/com/itlab/domain/usecase/CreateNoteUseCase.kt b/domain/src/main/java/com/itlab/domain/usecase/CreateNoteUseCase.kt
index fdc390a..ac3cc73 100644
--- a/domain/src/main/java/com/itlab/domain/usecase/CreateNoteUseCase.kt
+++ b/domain/src/main/java/com/itlab/domain/usecase/CreateNoteUseCase.kt
@@ -3,12 +3,20 @@ package com.itlab.domain.usecase
 import com.itlab.domain.model.Note
 import com.itlab.domain.repository.NotesRepository
 import kotlinx.datetime.Clock
+import java.util.UUID
 
 class CreateNoteUseCase(
     private val repo: NotesRepository,
 ) {
     suspend operator fun invoke(note: Note): String {
-        val note = note.copy(createdAt = Clock.System.now())
+        val now = Clock.System.now()
+
+        val note =
+            note.copy(
+                id = UUID.randomUUID().toString(),
+                createdAt = now,
+                updatedAt = now,
+            )
         return repo.createNote(note)
     }
 }
diff --git a/domain/src/test/java/com/itlab/domain/FolderUseCasesTest.kt b/domain/src/test/java/com/itlab/domain/FolderUseCasesTest.kt
index fbe465b..e66038c 100644
--- a/domain/src/test/java/com/itlab/domain/FolderUseCasesTest.kt
+++ b/domain/src/test/java/com/itlab/domain/FolderUseCasesTest.kt
@@ -58,11 +58,11 @@ class FolderUseCasesTest {
             val create = CreateFolderUseCase(repo)
             val get = GetFolderUseCase(repo)
 
-            val folder = NoteFolder(id = "1", name = "Test")
+            val folder = NoteFolder(name = "Test")
 
-            create(folder)
+            val id = create(folder)
 
-            val result = get("1")
+            val result = get(id)
 
             assertEquals("Test", result?.name)
         }
@@ -76,13 +76,16 @@ class FolderUseCasesTest {
             val update = UpdateFolderUseCase(repo)
             val get = GetFolderUseCase(repo)
 
-            val folder = NoteFolder(id = "1", name = "Old")
-            create(folder)
+            val folder = NoteFolder(name = "Old")
 
-            val updated = folder.copy(name = "New")
+            val id = create(folder)
+
+            val created = get(id)!!
+
+            val updated = created.copy(name = "New")
             update(updated)
 
-            val result = get("1")
+            val result = get(id)
 
             assertEquals("New", result?.name)
         }
@@ -96,12 +99,13 @@ class FolderUseCasesTest {
             val delete = DeleteFolderUseCase(repo)
             val get = GetFolderUseCase(repo)
 
-            val folder = NoteFolder(id = "1", name = "Test")
-            create(folder)
+            val folder = NoteFolder(name = "Test")
+
+            val id = create(folder)
 
-            delete("1")
+            delete(id)
 
-            val result = get("1")
+            val result = get(id)
 
             assertNull(result)
         }
@@ -113,7 +117,7 @@ class FolderUseCasesTest {
             val create = CreateFolderUseCase(repo)
             val observe = ObserveFoldersUseCase(repo)
 
-            create(NoteFolder(id = "1", name = "A"))
+            create(NoteFolder(name = "A"))
 
             val list = observe().first()
 
diff --git a/domain/src/test/java/com/itlab/domain/NoteUseCasesTest.kt b/domain/src/test/java/com/itlab/domain/NoteUseCasesTest.kt
index be3d572..5cc745a 100644
--- a/domain/src/test/java/com/itlab/domain/NoteUseCasesTest.kt
+++ b/domain/src/test/java/com/itlab/domain/NoteUseCasesTest.kt
@@ -77,19 +77,21 @@ class NoteUseCasesTest {
             val delete = DeleteNoteUseCase(repo)
             val get = GetNoteUseCase(repo)
 
-            val note = Note(id = "n1", title = "A")
+            val note = Note(title = "A")
 
-            create(note)
+            val id = create(note)
 
-            val updated = note.copy(title = "B")
+            val created = get(id)!!
+
+            val updated = created.copy(title = "B")
             update(updated)
 
-            val result = get("n1")
+            val result = get(id)
             assertEquals("B", result?.title)
 
-            delete("n1")
+            delete(id)
 
-            val result2 = get("n1")
+            val result2 = get(id)
             assertNull(result2)
         }
 
@@ -105,12 +107,13 @@ class NoteUseCasesTest {
             val folder = NoteFolder(id = "f1", name = "Folder")
             folderRepo.createFolder(folder)
 
-            val note = Note(id = "n1", title = "Note")
-            createNote(note)
+            val note = Note(title = "Note")
+
+            val noteId = createNote(note)
 
-            move("f1", "n1")
+            move("f1", noteId)
 
-            val updated = notesRepo.getNoteById("n1")
+            val updated = notesRepo.getNoteById(noteId)
 
             assertEquals("f1", updated?.folderId)
         }
@@ -122,8 +125,7 @@ class NoteUseCasesTest {
             val observe = ObserveNotesUseCase(repo)
             val create = CreateNoteUseCase(repo)
 
-            create(Note(id = "n1", title = "Test"))
-
+            create(Note(title = "Test"))
             val list = observe().first()
 
             assertEquals(1, list.size)