diff --git a/backend/internal/web/handlers_etapes_test.go b/backend/internal/web/handlers_etapes_test.go
index 1280c4c..c714b28 100644
--- a/backend/internal/web/handlers_etapes_test.go
+++ b/backend/internal/web/handlers_etapes_test.go
@@ -27,6 +27,76 @@ func newEtapeTestRouter(q *sqlc.Queries, store *auth.Store) http.Handler {
 	return router
 }
 
+func TestEtapeSchemaIsOneLevelAndTaskAssignmentUnassignsOnDelete(t *testing.T) {
+	pool, cleanup := setupTestDB(t)
+	defer cleanup()
+
+	ctx := context.Background()
+
+	rows, err := pool.Query(ctx, `
+		SELECT column_name
+		FROM information_schema.columns
+		WHERE table_schema = current_schema()
+		  AND table_name = 'etapes'
+	`)
+	if err != nil {
+		t.Fatalf("query etapes columns: %v", err)
+	}
+	defer rows.Close()
+
+	etapeColumns := make(map[string]bool)
+	for rows.Next() {
+		var name string
+		if err := rows.Scan(&name); err != nil {
+			t.Fatalf("scan etapes column: %v", err)
+		}
+		etapeColumns[name] = true
+	}
+	if err := rows.Err(); err != nil {
+		t.Fatalf("iterate etapes columns: %v", err)
+	}
+	for _, forbidden := range []string{"parent_id", "parent_etape_id", "etape_id"} {
+		if etapeColumns[forbidden] {
+			t.Fatalf("etapes has nested-etape column %q; want one-level etapes only", forbidden)
+		}
+	}
+
+	var nullable string
+	if err := pool.QueryRow(ctx, `
+		SELECT is_nullable
+		FROM information_schema.columns
+		WHERE table_schema = current_schema()
+		  AND table_name = 'tasks'
+		  AND column_name = 'etape_id'
+	`).Scan(&nullable); err != nil {
+		t.Fatalf("query tasks.etape_id nullability: %v", err)
+	}
+	if nullable != "YES" {
+		t.Fatalf("tasks.etape_id is_nullable = %q; want YES", nullable)
+	}
+
+	var deleteRule string
+	if err := pool.QueryRow(ctx, `
+		SELECT rc.delete_rule
+		FROM information_schema.table_constraints AS tc
+		JOIN information_schema.key_column_usage AS kcu
+		  ON tc.constraint_schema = kcu.constraint_schema
+		 AND tc.constraint_name = kcu.constraint_name
+		JOIN information_schema.referential_constraints AS rc
+		  ON tc.constraint_schema = rc.constraint_schema
+		 AND tc.constraint_name = rc.constraint_name
+		WHERE tc.table_schema = current_schema()
+		  AND tc.table_name = 'tasks'
+		  AND tc.constraint_type = 'FOREIGN KEY'
+		  AND kcu.column_name = 'etape_id'
+	`).Scan(&deleteRule); err != nil {
+		t.Fatalf("query tasks.etape_id delete rule: %v", err)
+	}
+	if deleteRule != "SET NULL" {
+		t.Fatalf("tasks.etape_id delete rule = %q; want SET NULL", deleteRule)
+	}
+}
+
 func TestEtapeCreateRendersChipAndCount(t *testing.T) {
 	pool, cleanup := setupTestDB(t)
 	defer cleanup()