feat(oceanpark): add Ocean Park Hong Kong

README.md

@@ -125,6 +125,7 @@ Setup `index.js` with your new class, and edit `test.js` to test your destinatio
 * SixFlags
 * HansaPark
 * Knoebels
+* OceanParkHongKong
 <!-- END_DESTINATIONS -->
 
 ## Configuration

TODO.MD

@@ -27,8 +27,9 @@
 - Universal Studios Singapore (USS)
 - Lotte World
 - Chimelong: Guangzhou + Zhuhai (2 destinations)
+- Ocean Park Hong Kong: Auth token, coordinate affine transform, showtimes, park schedule
 
-**Totals: ~118 destinations, 1068 tests, 45 test files**
+**Totals: ~119 destinations, 1068 tests, 45 test files**
 
 ## Remaining Migrations
 

src/__tests__/datetime.test.ts

@@ -622,9 +622,11 @@ describe('DateTime Utilities', () => {
       expect(formatted1).toMatch(/^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}/);
       expect(formatted2).toMatch(/^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}/);
 
-      // Verify timezone offsets are included
-      expect(formatted1).toMatch(/(-5|GMT-5)/); // EST
-      expect(formatted2).toMatch(/(-4|GMT-4)/); // EDT
+      // Verify timezone offsets are included. formatInTimezone normalizes
+      // GMT-style offsets to the canonical RFC 3339 "-HH:MM" form; accept
+      // both shapes to keep the test resilient if the helper changes.
+      expect(formatted1).toMatch(/(-05:00|-5|GMT-5)/); // EST
+      expect(formatted2).toMatch(/(-04:00|-4|GMT-4)/); // EDT
     });
 
     test('should handle midnight correctly', () => {

src/datetime.ts

@@ -35,7 +35,22 @@ export function formatInTimezone(
     const hour = parts.find(p => p.type === 'hour')?.value;
     const minute = parts.find(p => p.type === 'minute')?.value;
     const second = parts.find(p => p.type === 'second')?.value;
-    const offset = parts.find(p => p.type === 'timeZoneName')?.value || 'Z';
+    const rawOffset = parts.find(p => p.type === 'timeZoneName')?.value || 'Z';
+
+    // Intl.DateTimeFormat's `shortOffset` value is locale-dependent: for some
+    // timezones (e.g. Asia/Hong_Kong, Europe/Paris in summer) it returns a
+    // GMT-prefixed form like "GMT+8" or "GMT+2" rather than the RFC 3339
+    // "+HH:MM" form. Normalize so callers always get a valid ISO 8601 string.
+    let offset = rawOffset;
+    if (rawOffset === 'GMT' || rawOffset === 'UTC' || rawOffset === 'Z') {
+      offset = '+00:00';
+    } else {
+      const gmtMatch = rawOffset.match(/^GMT([+-])(\d{1,2})(?::(\d{2}))?$/);
+      if (gmtMatch) {
+        const [, sign, h, m = '00'] = gmtMatch;
+        offset = `${sign}${h.padStart(2, '0')}:${m}`;
+      }
+    }
 
     return `${year}-${month}-${day}T${hour}:${minute}:${second}${offset}`;
   }