Fix timezone conversion for stepped cron expressions

src/Illuminate/Console/Scheduling/CronExpressionTimezoneConverter.php

@@ -125,13 +125,19 @@ protected static function expressionsForHourCarry(array $segments, array $parts,
      */
     protected static function shiftAndGroup($field, $offset, $mod, $min = 0)
     {
-        if ($offset === 0 || ! preg_match('/^[\d,]+$/', $field)) {
+        if ($offset === 0) {
+            return [0 => $field];
+        }
+
+        $values = static::expandField($field, $mod, $min);
+
+        if ($values === null) {
             return [0 => $field];
         }
 
         $groups = [];
 
-        foreach (explode(',', $field) as $value) {
+        foreach ($values as $value) {
             $new = (int) $value + $offset;
             $carry = 0;
 
@@ -153,6 +159,35 @@ protected static function shiftAndGroup($field, $offset, $mod, $min = 0)
         })->all();
     }
 
+    /**
+     * Expand a cron field containing stepped values.
+     *
+     * @param  string  $field
+     * @param  int  $mod
+     * @param  int  $min
+     * @return array<int>|null
+     */
+    protected static function expandField($field, $mod, $min = 0)
+    {
+        if (preg_match('/^[\d,]+$/', $field)) {
+            return array_map('intval', explode(',', $field));
+        }
+
+        if (! preg_match('/^(?<start>\*|\d+)(?:-(?<end>\d+))?\/(?<step>\d+)$/', $field, $matches)) {
+            return null;
+        }
+
+        $start = $matches['start'] === '*' ? $min : (int) $matches['start'];
+        $end = $matches['end'] !== '' ? (int) $matches['end'] : $mod + $min - 1;
+        $step = (int) $matches['step'];
+
+        if ($step === 0 || $start < $min || $end >= $mod + $min || $start > $end) {
+            return null;
+        }
+
+        return range($start, $end, $step);
+    }
+
     /**
      * Shift a cron field by the given offset.
      *

tests/Integration/Console/Scheduling/ScheduleListCommandTest.php

@@ -256,14 +256,16 @@ public static function expressionTimezoneConversionProvider()
             // No conversion needed — same timezone
             'same timezone' => ['0 8 * * *', 'UTC', null, ['0 8 * * *']],
 
-            // Wildcards/steps — pass through unchanged
+            // Wildcards and unsupported ranges — pass through unchanged
             'every minute' => ['* * * * *', 'America/New_York', null, ['* * * * *']],
             'every five minutes' => ['*/5 * * * *', 'Asia/Tokyo', null, ['*/5 * * * *']],
-            'every two hours' => ['0 */2 * * *', 'Asia/Tokyo', null, ['0 */2 * * *']],
-            'every odd hour' => ['0 1-23/2 * * *', 'Asia/Tokyo', null, ['0 1-23/2 * * *']],
             'quarterly step month' => ['0 0 1 1-12/3 *', 'Asia/Tokyo', null, ['0 15 31 1-12/3 *']],
             'weekdays range' => ['0 8 * * 1-5', 'Asia/Tokyo', null, ['0 23 * * 1-5']],
 
+            // Stepped hours
+            'every two hours' => ['0 */2 * * *', 'Asia/Tokyo', null, ['0 15,17,19,21,23 * * *', '0 1,3,5,7,9,11,13 * * *']],
+            'every odd hour' => ['0 1-23/2 * * *', 'Asia/Tokyo', null, ['0 16,18,20,22 * * *', '0 0,2,4,6,8,10,12,14 * * *']],
+
             // Simple hour shift (no day boundary)
             'daily LA to UTC' => ['0 8 * * *', 'America/Los_Angeles', null, ['0 16 * * *']],
             'daily Tokyo to UTC' => ['0 14 * * *', 'Asia/Tokyo', null, ['0 5 * * *']],
@@ -343,6 +345,25 @@ public function testExpressionTimezoneConversion($expression, $eventTimezone, $d
         }
     }
 
+    public function testExpressionTimezoneConversionHandlesSteppedHours()
+    {
+        Carbon::setTestNow('2023-07-01');
+
+        $this->schedule->command('inspire')->everyFourHours()->timezone('Europe/London');
+
+        $this->withoutMockingConsoleOutput()->artisan(ScheduleListCommand::class, [
+            '--timezone' => 'UTC',
+            '--json' => true,
+        ]);
+
+        $data = json_decode(Artisan::output(), true);
+
+        $this->assertSame([
+            '0 23 * * *',
+            '0 3,7,11,15,19 * * *',
+        ], array_column($data, 'expression'));
+    }
+
     public function testDisplayScheduleCliSplitsExpressionWhenMixedCarry()
     {
         // 13+8=21 (no carry), 17+8=1 (carry +1) — splits into two CLI rows