docs: update Rajaongkir snippet and add generic shipping bridge pattern

RAJAONGKIR_INTEGRATION.md:
- Hide country/state/city when Indonesia is the only allowed country
- Make destination_id required for Indonesia-only stores
- Force country to ID in session bridge
- Added billing_destination_id fallback

SHIPPING_BRIDGE_PATTERN.md:
- New generic template for shipping provider integrations
- Documents architecture, hooks, and field types
- Provides copy-paste template for new providers
- Includes checklist for new integrations

RAJAONGKIR_INTEGRATION.md

@@ -88,8 +88,8 @@ function woonoow_rajaongkir_search_destinations($request) {
 }
 
 // ============================================================
-// 2. Add destination field to checkout fields (both billing and shipping)
+// 2. Add destination field and hide redundant fields for Indonesia
-//    Always add for Indonesia zone (no premature country check)
+//    The destination_id from Rajaongkir contains province/city/subdistrict
 // ============================================================
 add_filter('woocommerce_checkout_fields', function($fields) {
     // Check if Rajaongkir is active
@@ -103,11 +103,47 @@ add_filter('woocommerce_checkout_fields', function($fields) {
         return $fields;
     }
     
+    // Check if Indonesia is the ONLY allowed country
+    $indonesia_only = count($allowed) === 1 && isset($allowed['ID']);
+    
+    // If Indonesia only, hide country/state/city fields (Rajaongkir destination has all this)
+    if ($indonesia_only) {
+        // Hide billing fields
+        if (isset($fields['billing']['billing_country'])) {
+            $fields['billing']['billing_country']['type'] = 'hidden';
+            $fields['billing']['billing_country']['default'] = 'ID';
+            $fields['billing']['billing_country']['required'] = false;
+        }
+        if (isset($fields['billing']['billing_state'])) {
+            $fields['billing']['billing_state']['type'] = 'hidden';
+            $fields['billing']['billing_state']['required'] = false;
+        }
+        if (isset($fields['billing']['billing_city'])) {
+            $fields['billing']['billing_city']['type'] = 'hidden';
+            $fields['billing']['billing_city']['required'] = false;
+        }
+        
+        // Hide shipping fields
+        if (isset($fields['shipping']['shipping_country'])) {
+            $fields['shipping']['shipping_country']['type'] = 'hidden';
+            $fields['shipping']['shipping_country']['default'] = 'ID';
+            $fields['shipping']['shipping_country']['required'] = false;
+        }
+        if (isset($fields['shipping']['shipping_state'])) {
+            $fields['shipping']['shipping_state']['type'] = 'hidden';
+            $fields['shipping']['shipping_state']['required'] = false;
+        }
+        if (isset($fields['shipping']['shipping_city'])) {
+            $fields['shipping']['shipping_city']['type'] = 'hidden';
+            $fields['shipping']['shipping_city']['required'] = false;
+        }
+    }
+    
     // Destination field definition (reused for billing and shipping)
     $destination_field = [
         'type'            => 'searchable_select',
         'label'           => __('Destination (Province, City, Subdistrict)', 'woonoow'),
-        'required'        => false, // Frontend will manage this based on country
+        'required'        => $indonesia_only, // Required if Indonesia only
         'priority'        => 85,
         'class'           => ['form-row-wide'],
         'placeholder'     => __('Search destination...', 'woonoow'),
@@ -133,15 +169,27 @@ add_filter('woocommerce_checkout_fields', function($fields) {
 
 // ============================================================
 // 3. Bridge WooNooW shipping data to Rajaongkir session
+//    Sets destination_id in WC session for Rajaongkir to use
 // ============================================================
 add_action('woonoow/shipping/before_calculate', function($shipping, $items) {
-    // Set country in WC customer
+    // Check if Rajaongkir is active
-    if (!empty($shipping['country'])) {
+    if (!class_exists('Cekongkir_API')) {
+        return;
+    }
+    
+    // For Indonesia-only stores, always set country to ID
+    $allowed = WC()->countries->get_allowed_countries();
+    $indonesia_only = count($allowed) === 1 && isset($allowed['ID']);
+    
+    if ($indonesia_only) {
+        WC()->customer->set_shipping_country('ID');
+        WC()->customer->set_billing_country('ID');
+    } elseif (!empty($shipping['country'])) {
         WC()->customer->set_shipping_country($shipping['country']);
         WC()->customer->set_billing_country($shipping['country']);
     }
     
-    // Only process for Indonesia
+    // Only process Rajaongkir for Indonesia
     $country = $shipping['country'] ?? WC()->customer->get_shipping_country();
     if ($country !== 'ID') {
         // Clear destination for non-Indonesia
@@ -153,6 +201,7 @@ add_action('woonoow/shipping/before_calculate', function($shipping, $items) {
     // Get destination_id from shipping data (various possible keys)
     $destination_id = $shipping['destination_id'] 
                    ?? $shipping['shipping_destination_id']
+                   ?? $shipping['billing_destination_id']
                    ?? null;
     
     if (empty($destination_id)) {
@@ -165,6 +214,7 @@ add_action('woonoow/shipping/before_calculate', function($shipping, $items) {
     // Also set label if provided
     $label = $shipping['destination_label'] 
           ?? $shipping['shipping_destination_id_label']
+          ?? $shipping['billing_destination_id_label']
           ?? '';
     if ($label) {
         WC()->session->set('selected_destination_label', sanitize_text_field($label));

SHIPPING_BRIDGE_PATTERN.md

@@ -0,0 +1,219 @@
+# WooNooW Shipping Bridge Pattern
+
+This document describes a generic pattern for integrating any external shipping API with WooNooW's SPA checkout.
+
+---
+
+## Overview
+
+WooNooW provides hooks and endpoints that allow any shipping plugin to:
+1. **Register custom checkout fields** (searchable selects, dropdowns, etc.)
+2. **Bridge data to the plugin's session/API** before shipping calculation
+3. **Display live rates** from external APIs
+
+This pattern is NOT specific to Rajaongkir - it can be used for any shipping provider.
+
+---
+
+## Architecture
+
+```
+┌─────────────────────────────────────────────────────────────────┐
+│                     WooNooW Customer SPA                        │
+├─────────────────────────────────────────────────────────────────┤
+│  1. Checkout loads → calls /checkout/fields                     │
+│  2. Renders custom fields (e.g., searchable destination)        │
+│  3. User fills form → calls /checkout/shipping-rates            │
+│  4. Hook triggers → shipping plugin calculates rates            │
+│  5. Rates displayed → user selects → order submitted            │
+└─────────────────────────────────────────────────────────────────┘
+                              │
+                              ▼
+┌─────────────────────────────────────────────────────────────────┐
+│                   Your Bridge Snippet                            │
+├─────────────────────────────────────────────────────────────────┤
+│  • woocommerce_checkout_fields → Add custom fields               │
+│  • register_rest_route → API endpoint for field data             │
+│  • woonoow/shipping/before_calculate → Set session/data          │
+└─────────────────────────────────────────────────────────────────┘
+                              │
+                              ▼
+┌─────────────────────────────────────────────────────────────────┐
+│                   Shipping Plugin (Any)                          │
+├─────────────────────────────────────────────────────────────────┤
+│  • Reads from WC session or customer data                        │
+│  • Calls external API (Rajaongkir, Sicepat, JNE, etc.)           │
+│  • Returns rates via get_rates_for_package()                     │
+└─────────────────────────────────────────────────────────────────┘
+```
+
+---
+
+## Generic Bridge Template
+
+```php
+<?php
+/**
+ * [PROVIDER_NAME] Bridge for WooNooW SPA Checkout
+ * 
+ * Replace [PROVIDER_NAME], [PROVIDER_CLASS], and [PROVIDER_SESSION_KEY] 
+ * with your shipping plugin's specifics.
+ */
+
+// ============================================================
+// 1. REST API Endpoint: Search/fetch data from provider
+// ============================================================
+add_action('rest_api_init', function() {
+    register_rest_route('woonoow/v1', '/[provider]/search', [
+        'methods'             => 'GET',
+        'callback'            => 'woonoow_[provider]_search',
+        'permission_callback' => '__return_true', // Public for customer use
+        'args'                => [
+            'search' => ['type' => 'string', 'required' => false],
+        ],
+    ]);
+});
+
+function woonoow_[provider]_search($request) {
+    $search = sanitize_text_field($request->get_param('search') ?? '');
+    
+    if (strlen($search) < 3) {
+        return [];
+    }
+    
+    // Check if plugin is active
+    if (!class_exists('[PROVIDER_CLASS]')) {
+        return new WP_Error('[provider]_missing', 'Plugin not active', ['status' => 400]);
+    }
+    
+    // Call provider's API
+    // $results = [PROVIDER_CLASS]::search($search);
+    
+    // Format for WooNooW's SearchableSelect
+    $formatted = [];
+    foreach ($results as $r) {
+        $formatted[] = [
+            'value' => (string) $r['id'],
+            'label' => $r['name'],
+        ];
+    }
+    
+    return array_slice($formatted, 0, 50);
+}
+
+// ============================================================
+// 2. Add custom field(s) to checkout
+// ============================================================
+add_filter('woocommerce_checkout_fields', function($fields) {
+    if (!class_exists('[PROVIDER_CLASS]')) {
+        return $fields;
+    }
+    
+    $custom_field = [
+        'type'            => 'searchable_select', // or 'select', 'text'
+        'label'           => __('[Field Label]', 'woonoow'),
+        'required'        => true,
+        'priority'        => 85,
+        'class'           => ['form-row-wide'],
+        'placeholder'     => __('Search...', 'woonoow'),
+        'search_endpoint' => '/[provider]/search', // Relative to /wp-json/woonoow/v1
+        'search_param'    => 'search',
+        'min_chars'       => 3,
+    ];
+    
+    $fields['billing']['billing_[provider]_field'] = $custom_field;
+    $fields['shipping']['shipping_[provider]_field'] = $custom_field;
+    
+    return $fields;
+}, 20);
+
+// ============================================================
+// 3. Bridge data to provider before shipping calculation
+// ============================================================
+add_action('woonoow/shipping/before_calculate', function($shipping, $items) {
+    if (!class_exists('[PROVIDER_CLASS]')) {
+        return;
+    }
+    
+    // Get custom field value from shipping data
+    $field_value = $shipping['[provider]_field'] 
+                ?? $shipping['shipping_[provider]_field']
+                ?? $shipping['billing_[provider]_field']
+                ?? null;
+    
+    if (empty($field_value)) {
+        return;
+    }
+    
+    // Set in WC session for the shipping plugin to use
+    WC()->session->set('[PROVIDER_SESSION_KEY]', $field_value);
+    
+    // Clear shipping cache to force recalculation
+    WC()->session->set('shipping_for_package_0', false);
+    
+}, 10, 2);
+```
+
+---
+
+## Supported Field Types
+
+| Type | Description | Use Case |
+|------|-------------|----------|
+| `searchable_select` | Dropdown with API search | Destinations, locations, service points |
+| `select` | Static dropdown | Service types, delivery options |
+| `text` | Free text input | Reference numbers, notes |
+| `hidden` | Hidden field | Default values, auto-set data |
+
+---
+
+## WooNooW Hooks Reference
+
+| Hook | Type | Description |
+|------|------|-------------|
+| `woonoow/shipping/before_calculate` | Action | Called before shipping rates are calculated |
+| `woocommerce_checkout_fields` | Filter | Standard WC filter for checkout fields |
+
+---
+
+## Examples
+
+### Example 1: Sicepat Integration
+```php
+// Endpoint
+register_rest_route('woonoow/v1', '/sicepat/destinations', ...);
+
+// Session key
+WC()->session->set('sicepat_destination_code', $code);
+```
+
+### Example 2: JNE Direct API
+```php
+// Endpoint for origin selection
+register_rest_route('woonoow/v1', '/jne/origins', ...);
+register_rest_route('woonoow/v1', '/jne/destinations', ...);
+
+// Multiple session keys
+WC()->session->set('jne_origin', $origin);
+WC()->session->set('jne_destination', $destination);
+```
+
+---
+
+## Checklist for New Integration
+
+- [ ] Identify the shipping plugin's class name
+- [ ] Find what session/data it reads for API calls
+- [ ] Create REST endpoint for searchable data
+- [ ] Add checkout field(s) via filter
+- [ ] Bridge data via `woonoow/shipping/before_calculate`
+- [ ] Test shipping rate calculation
+- [ ] Document in dedicated `[PROVIDER]_INTEGRATION.md`
+
+---
+
+## Related Documentation
+
+- [RAJAONGKIR_INTEGRATION.md](RAJAONGKIR_INTEGRATION.md) - Rajaongkir-specific implementation
+- [SHIPPING_INTEGRATION.md](SHIPPING_INTEGRATION.md) - General shipping patterns
+- [HOOKS_REGISTRY.md](HOOKS_REGISTRY.md) - All WooNooW hooks