test heavy workload spreading

backend/tests/Feature/Schedule/ScheduleEndpointTest.php

@@ -253,14 +253,14 @@ class ScheduleEndpointTest extends TestCase
         ]);
     }
 
-    public function test_it_rejects_spread_placement_for_a_dense_schedule(): void
+    public function test_it_spreads_heavier_days_across_the_full_range(): void
     {
         $user = $this->createUser('reader@example.com');
         $set = $this->createSet($user, 'Course');
         $lessonLevel = $this->createLevel($set, 'lesson');
         $repository = app(ElementRepository::class);
 
-        foreach (range(1, 5) as $number) {
+        foreach (range(1, 13) as $number) {
             $repository->create(new CreateElementDto(
                 name: "Lesson {$number}",
                 level: $lessonLevel,
@@ -269,15 +269,22 @@ class ScheduleEndpointTest extends TestCase
         }
         $this->createSession($user, 'valid-token');
 
-        $this->credentialedPost('/api/schedules', [
+        $response = $this->credentialedPost('/api/schedules', [
             'setId' => $set->getId(),
             'levelId' => $lessonLevel->getId(),
             'startDate' => '2026-08-10',
-            'targetDate' => '2026-08-13',
+            'targetDate' => '2026-08-14',
             'workloadPlacement' => 'spread',
-        ])->assertBadRequest()->assertExactJson([
+        ])->assertCreated();
-            'error' => 'spread placement requires fewer assignments than days',
+
-        ]);
+        $days = $response->json('schedule.days');
+        $this->assertIsArray($days);
+        $this->assertSame(
+            [3, 2, 3, 2, 3],
+            array_map(function (array $day): int {
+                return count($day['assignments']);
+            }, $days),
+        );
     }
 
     public function test_it_lists_only_the_users_schedules_newest_first(): void

backend/tests/Unit/Schedule/EvenDistributionSchedulerTest.php

@@ -60,6 +60,27 @@ class EvenDistributionSchedulerTest extends TestCase
         }
     }
 
+    public function test_it_spreads_heavier_days_across_the_full_range(): void
+    {
+        $scheduler = new EvenDistributionScheduler;
+        $expectedCounts = [
+            11 => [2, 2, 3, 2, 2],
+            12 => [3, 2, 2, 2, 3],
+            13 => [3, 2, 3, 2, 3],
+        ];
+
+        foreach ($expectedCounts as $assignmentCount => $dailyCounts) {
+            $dates = $scheduler->scheduledDates(
+                assignmentCount: $assignmentCount,
+                startDate: $this->utc('2026-08-10'),
+                targetDate: $this->utc('2026-08-14'),
+                workloadPlacement: WorkloadPlacement::Spread,
+            );
+
+            $this->assertSame($dailyCounts, $this->dailyCounts($dates));
+        }
+    }
+
     public function test_it_places_sparse_assignments_at_the_requested_position(): void
     {
         $scheduler = new EvenDistributionScheduler;