**Implemented: Backend API Enhancement for Level 1 Compatibility**
Following IMPLEMENTATION_PLAN_META_COMPAT.md Phase 1
**OrdersController.php:**
✅ Added get_order_meta_data() - Expose meta in API responses
✅ Added update_order_meta_data() - Update meta from API
✅ Modified show() - Include meta in response
✅ Modified update() - Handle meta updates
✅ Added filter: woonoow/order_allowed_private_meta
✅ Added filter: woonoow/order_updatable_meta
✅ Added filter: woonoow/order_api_data
✅ Added action: woonoow/order_updated
**ProductsController.php:**
✅ Added get_product_meta_data() - Expose meta in API responses
✅ Added update_product_meta_data() - Update meta from API
✅ Modified format_product_full() - Include meta in response
✅ Modified update_product() - Handle meta updates
✅ Added filter: woonoow/product_allowed_private_meta
✅ Added filter: woonoow/product_updatable_meta
✅ Added filter: woonoow/product_api_data
✅ Added action: woonoow/product_updated
**Meta Filtering Logic:**
- Skip internal WooCommerce meta (_wc_*)
- Skip WooNooW internal meta (_woonoow_*)
- Public meta (no underscore) - always expose
- Private meta (starts with _) - check allowed list
- Plugins can add to allowed list via filters
**Default Allowed Meta (Orders):**
- _tracking_number
- _tracking_provider
- _tracking_url
- _shipment_tracking_items
- _wc_shipment_tracking_items
- _transaction_id
- _payment_method_title
**How It Works:**
1. Plugin stores: update_post_meta($order_id, '_tracking_number', '123')
2. WooNooW API exposes: GET /orders/123 returns meta._tracking_number
3. Frontend can read/write via API
4. Plugin works WITHOUT any extra effort
**Next Steps:**
- Phase 2: Frontend components (MetaFields, useMetaFields)
- Phase 3: PHP MetaFieldsRegistry system
- Testing with popular plugins
**Status:** Backend API ready for Level 1 compatibility! 🎉
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