fix: keep the start number of an ordered list

src/Rules/OrderedListRule.php

@@ -39,7 +39,7 @@ public function shouldParse(Parser $parser): bool
 
     public function parse(Parser $parser): ?Token
     {
-        $parser->consumeWhile('0123456789');
+        $number = $parser->consumeWhile('0123456789');
         $parser->consumeIncluding('.');
         $content = trim($parser->consumeUntil(Parser::NEW_LINE));
         $parser->consumeWhile(Parser::NEW_LINE);
@@ -68,6 +68,6 @@ public function parse(Parser $parser): ?Token
             return null;
         }
 
-        return new OrderedListToken([$item]);
+        return new OrderedListToken([$item], (int) $number);
     }
 }

src/Tokens/OrderedListToken.php

@@ -18,6 +18,9 @@ final class OrderedListToken implements Token
     public function __construct(
         /** @var \Tempest\Markdown\Tokens\ListItem[] */
         public array $items = [],
+
+        /** The number the list starts at, as written in the first item's marker. */
+        public int $start = 1,
     ) {}
 
     public function parse(Parser $parser): string
@@ -33,7 +36,9 @@ public function parse(Parser $parser): string
             new TextRule(),
         ]);
 
-        $list = '<ol>';
+        $list = $this->start === 1
+            ? '<ol>'
+            : '<ol start="' . $this->start . '">';
 
         foreach ($this->items as $item) {
             $content = $parser->parse($item->content);

tests/Rules/OrderedListRuleTest.php

@@ -40,7 +40,10 @@ public function test_lex_multi_digit_numbers(): void
                 "10. ten\n11. eleven\n",
             );
 
-        $this->assertSame('<ol><li>ten</li><li>eleven</li></ol>', $html);
+        $this->assertSame(
+            '<ol start="10"><li>ten</li><li>eleven</li></ol>',
+            $html,
+        );
     }
 
     #[Test]
@@ -117,4 +120,29 @@ public function test_only_numbers_are_allowed(): void
 
         $this->assertSame('', $html);
     }
+
+    #[Test]
+    public function lex_keeps_the_start_number(): void
+    {
+        $html =
+            (string) new Parser(highlighter: null, rules: [new OrderedListRule()])->parse(
+                "2. two\n3. three\n",
+            );
+
+        $this->assertSame(
+            '<ol start="2"><li>two</li><li>three</li></ol>',
+            $html,
+        );
+    }
+
+    #[Test]
+    public function lex_omits_the_start_attribute_when_the_list_starts_at_one(): void
+    {
+        $html =
+            (string) new Parser(highlighter: null, rules: [new OrderedListRule()])->parse(
+                "1. one\n5. five\n",
+            );
+
+        $this->assertSame('<ol><li>one</li><li>five</li></ol>', $html);
+    }
 }