diff --git a/server/src/auth.ts b/server/src/auth.ts
index a84a092..7cdbfd5 100644
--- a/server/src/auth.ts
+++ b/server/src/auth.ts
@@ -61,19 +61,40 @@ export function createClass(name: string, level: string | null, nickname: string
 
 export function joinClass(code: string, nickname: string): NewSession | null {
   const row = db
-    .prepare<[string], { id: number; name: string; level: string | null }>(
-      'SELECT id, name, level FROM classes WHERE code = ?',
+    .prepare<[string], { id: number; name: string; level: string | null; flash_message: string | null }>(
+      'SELECT id, name, level, flash_message FROM classes WHERE code = ?',
     )
     .get(code)
   if (!row) return null
+
+  // Si un membre porte déjà ce pseudo dans la classe, on lui rouvre une
+  // session (nouveau jeton) au lieu de créer un doublon. L'admin peut ainsi
+  // se reconnecter avec son pseudo pour retrouver ses droits.
+  const existing = db
+    .prepare<[number, string], { id: number; role: Role; is_creator: number }>(
+      'SELECT id, role, is_creator FROM members WHERE class_id = ? AND nickname = ?',
+    )
+    .get(row.id, nickname)
+
+  const klass: ClassInfo = { id: row.id, name: row.name, level: row.level, flashMessage: row.flash_message }
   const token = newToken()
+
+  if (existing) {
+    db.prepare('UPDATE members SET token = ? WHERE id = ?').run(token, existing.id)
+    return {
+      token,
+      member: { id: existing.id, classId: row.id, nickname, role: existing.role, isCreator: existing.is_creator === 1 },
+      klass,
+    }
+  }
+
   const memberId = db
-    .prepare('INSERT INTO members (class_id, nickname, role, token, created_at) VALUES (?, ?, ?, ?, ?)')
-    .run(row.id, nickname, 'student', token, nowIso()).lastInsertRowid as number
+    .prepare('INSERT INTO members (class_id, nickname, role, is_creator, token, created_at) VALUES (?, ?, ?, ?, ?, ?)')
+    .run(row.id, nickname, 'student', 0, token, nowIso()).lastInsertRowid as number
   return {
     token,
     member: { id: memberId, classId: row.id, nickname, role: 'student', isCreator: false },
-    klass: { id: row.id, name: row.name, level: row.level, flashMessage: null },
+    klass,
   }
 }