diff --git a/apps/api/app/Http/Controllers/ReportController.php b/apps/api/app/Http/Controllers/ReportController.php
index 81e46a2..9326d7d 100644
--- a/apps/api/app/Http/Controllers/ReportController.php
+++ b/apps/api/app/Http/Controllers/ReportController.php
@@ -55,6 +55,11 @@ public function store(Request $request): JsonResponse
             'layout.fields.*.order' => 'sometimes|integer',
             'layout.group_order' => 'nullable|array',
             'layout.group_order.*' => 'string',
+            // Declared explicitly: validate() only returns keys that carry a rule, so
+            // anything omitted here is dropped before the report is persisted.
+            'layout.view_id' => 'nullable|uuid|exists:views,id',
+            'layout.show_headers_only' => 'nullable|boolean',
+            'layout.per_page' => 'nullable|integer|min:1|max:100',
         ]);
 
         $report = Report::create($validated);
@@ -84,6 +89,11 @@ public function update(Request $request, Report $report): JsonResponse
             'layout.fields.*.order' => 'sometimes|integer',
             'layout.group_order' => 'nullable|array',
             'layout.group_order.*' => 'string',
+            // Declared explicitly: validate() only returns keys that carry a rule, so
+            // anything omitted here is dropped before the report is persisted.
+            'layout.view_id' => 'nullable|uuid|exists:views,id',
+            'layout.show_headers_only' => 'nullable|boolean',
+            'layout.per_page' => 'nullable|integer|min:1|max:100',
         ]);
 
         $report->update($validated);
@@ -243,11 +253,13 @@ private function generateCsvResponse(array $columns, array $groups, ?string $gro
 
             $csvHeaders = [];
             $showHeadersOnly = ($layout['show_headers_only'] ?? false) === true;
+            // The group field is commonly also a selected column; emit it once.
+            $groupIsSelectedColumn = $groupBy !== null && in_array($groupBy, $columns, true);
             if ($showHeadersOnly) {
                 $csvHeaders[] = $groupBy ?? 'Groupe';
                 $csvHeaders[] = 'Nombre de fiches';
             } else {
-                if ($groupBy) {
+                if ($groupBy && ! $groupIsSelectedColumn) {
                     $csvHeaders[] = $groupBy;
                 }
                 foreach ($columns as $col) {
@@ -264,7 +276,7 @@ private function generateCsvResponse(array $columns, array $groups, ?string $gro
                 } else {
                     foreach ($group['records'] as $rec) {
                         $row = [];
-                        if ($groupBy) {
+                        if ($groupBy && ! $groupIsSelectedColumn) {
                             $row[] = $groupKey;
                         }
                         foreach ($columns as $col) {
diff --git a/apps/api/tests/Feature/ReportFeatureTest.php b/apps/api/tests/Feature/ReportFeatureTest.php
index 9edd274..17ad79b 100644
--- a/apps/api/tests/Feature/ReportFeatureTest.php
+++ b/apps/api/tests/Feature/ReportFeatureTest.php
@@ -6,6 +6,7 @@
 use App\Models\Report;
 use App\Models\Table;
 use App\Models\User;
+use App\Models\View;
 use App\Models\Workspace;
 use App\Models\WorkspaceMember;
 use Illuminate\Foundation\Testing\RefreshDatabase;
@@ -359,3 +360,75 @@ function createAuthenticatedUser()
     expect($previewCsvResponse->headers->get('Content-Type'))->toContain('text/csv');
     expect(str_contains($previewCsvResponse->streamedContent(), 'title'))->toBeTrue();
 });
+
+test('layout view_id, show_headers_only and per_page survive save and reload', function () {
+    $setup = createAuthenticatedUser();
+    $user = $setup['user'];
+    $table = $setup['table'];
+    $view = View::factory()->create(['table_id' => $table->id]);
+
+    $payload = [
+        'table_id' => $table->id,
+        'name' => 'Rapport avec vue',
+        'query' => ['select' => ['Nom'], 'group_by' => 'Ville'],
+        'layout' => [
+            'fields' => [['name' => 'Nom', 'visible' => true, 'order' => 1]],
+            'view_id' => $view->id,
+            'show_headers_only' => true,
+            'per_page' => 25,
+        ],
+    ];
+
+    $created = $this->actingAs($user)->postJson('/api/v1/reports', $payload);
+    $created->assertStatus(201);
+
+    $report = Report::find($created->json('id'));
+    expect($report->layout['view_id'])->toBe($view->id);
+    expect($report->layout['show_headers_only'])->toBeTrue();
+    expect($report->layout['per_page'])->toBe(25);
+
+    // The same keys must also survive an update.
+    $otherView = View::factory()->create(['table_id' => $table->id]);
+    $payload['layout']['view_id'] = $otherView->id;
+    $payload['layout']['per_page'] = 50;
+
+    $this->actingAs($user)
+        ->putJson("/api/v1/reports/{$report->id}", $payload)
+        ->assertStatus(200);
+
+    $report->refresh();
+    expect($report->layout['view_id'])->toBe($otherView->id);
+    expect($report->layout['per_page'])->toBe(50);
+});
+
+test('csv export emits the group field once when it is also a selected column', function () {
+    $setup = createAuthenticatedUser();
+    $user = $setup['user'];
+    $table = $setup['table'];
+
+    Field::factory()->create(['table_id' => $table->id, 'name' => 'Ville', 'type' => 'text']);
+    Field::factory()->create(['table_id' => $table->id, 'name' => 'Nom', 'type' => 'text']);
+
+    Record::create([
+        'table_id' => $table->id,
+        'data' => ['Ville' => 'Québec', 'Nom' => 'Tremblay'],
+        'version' => 1,
+    ]);
+
+    $response = $this->actingAs($user)->postJson('/api/v1/reports/preview/csv', [
+        'table_id' => $table->id,
+        'query' => ['select' => ['Ville', 'Nom'], 'group_by' => 'Ville'],
+        'layout' => ['fields' => [
+            ['name' => 'Ville', 'visible' => true, 'order' => 1],
+            ['name' => 'Nom', 'visible' => true, 'order' => 2],
+        ]],
+    ]);
+
+    $response->assertStatus(200);
+    $csv = $response->streamedContent();
+    $headerLine = str_getcsv(explode("\n", trim($csv))[0]);
+    $headerLine[0] = preg_replace('/^\x{FEFF}/u', '', $headerLine[0]);
+
+    expect($headerLine)->toBe(['Ville', 'Nom']);
+    expect(array_count_values($headerLine)['Ville'])->toBe(1);
+});