diff --git a/src/components/NoteEditor.tsx b/src/components/NoteEditor.tsx
index e4e7db7..cf7bb7d 100644
--- a/src/components/NoteEditor.tsx
+++ b/src/components/NoteEditor.tsx
@@ -3,6 +3,7 @@ import type {
   NoteEditorProps,
   NoteFormProps,
 } from '../interfaces/note-editor'
+import { isTitleValid, normalizeTitle } from '../lib/noteValidation'
 import DeleteModal from './DeleteModal'
 
 const TITLE_REQUIRED_MESSAGE = 'Le titre est obligatoire.'
@@ -82,15 +83,15 @@ function NoteEditor(props: NoteEditorProps) {
 
   const handleTitleChange = (value: string) => {
     setTitle(value)
-    if (titleMissing && value.trim() !== '') setTitleMissing(false)
+    if (titleMissing && isTitleValid(value)) setTitleMissing(false)
   }
 
   const handleSubmit = () => {
-    if (title.trim() === '') {
+    if (!isTitleValid(title)) {
       setTitleMissing(true)
       return
     }
-    const safeTitle = title.trim()
+    const safeTitle = normalizeTitle(title)
     if (props.mode === 'create') {
       props.onCreate(safeTitle, content)
     } else {
diff --git a/src/lib/noteValidation.test.ts b/src/lib/noteValidation.test.ts
new file mode 100644
index 0000000..49f0a38
--- /dev/null
+++ b/src/lib/noteValidation.test.ts
@@ -0,0 +1,26 @@
+import { describe, expect, it } from 'vitest'
+import { isTitleValid, normalizeTitle } from './noteValidation'
+
+describe('isTitleValid', () => {
+  it('accepts a non-empty title', () => {
+    expect(isTitleValid('Courses')).toBe(true)
+  })
+
+  it('rejects an empty title', () => {
+    expect(isTitleValid('')).toBe(false)
+  })
+
+  it('rejects a whitespace-only title', () => {
+    expect(isTitleValid('   ')).toBe(false)
+  })
+})
+
+describe('normalizeTitle', () => {
+  it('trims surrounding whitespace', () => {
+    expect(normalizeTitle('  Courses  ')).toBe('Courses')
+  })
+
+  it('keeps an already trimmed title unchanged', () => {
+    expect(normalizeTitle('Courses')).toBe('Courses')
+  })
+})
\ No newline at end of file
diff --git a/src/lib/noteValidation.ts b/src/lib/noteValidation.ts
new file mode 100644
index 0000000..ff77495
--- /dev/null
+++ b/src/lib/noteValidation.ts
@@ -0,0 +1,7 @@
+export function isTitleValid(title: string): boolean {
+  return title.trim().length > 0
+}
+
+export function normalizeTitle(title: string): string {
+  return title.trim()
+}
\ No newline at end of file