fix(polish): 订单购物车论坛粉边软化 + 论坛付费帖购链路

- 购物车/商品/论坛表面复用 #77 soft recipe（mix 边 + soft ring）
- 论坛 visibility=pay：订单 resource + 余额扣费闭环
- VIP 价/免费解锁 + 购买 CTA/AJAX，复用现有 Order/Credits

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

inc/classes/class-aksrt-credits.php

@@ -33,6 +33,13 @@ class AKSRT_Credits {
         return is_numeric($val) ? (int) $val : 0;
     }
 
+    /**
+     * Alias used by forum unlock/purchase paths.
+     */
+    public static function get_balance(int $user_id): int {
+        return self::balance($user_id);
+    }
+
     /**
      * 增加积分。
      *

inc/classes/class-aksrt-forum.php

@@ -144,6 +144,13 @@ class AKSRT_Forum {
         return ['enabled' => false];
     }
 
+    /**
+     * Alias kept for topic-service helpers that still call get_forum_config().
+     */
+    public function get_forum_config(): array {
+        return $this->get_config();
+    }
+
     public function get_boards(array $args = []): array {
         return $this->board_service()->get_boards($args);
     }
@@ -345,6 +352,7 @@ class AKSRT_Forum {
         add_action('wp_ajax_aksrt_forum_create_topic', [$this, 'ajax_create_topic']);
         add_action('wp_ajax_aksrt_forum_follow_plate', [$this, 'ajax_follow_plate']);
         add_action('wp_ajax_aksrt_forum_unlock_topic', [$this, 'ajax_unlock_topic']);
+        add_action('wp_ajax_aksrt_forum_purchase_topic', [$this, 'ajax_purchase_topic']);
 
         // §7.4 draft persistence
         add_action('wp_ajax_aksrt_forum_save_draft', [$this, 'ajax_save_draft']);
@@ -446,6 +454,26 @@ class AKSRT_Forum {
         $this->topic_service()->ajax_unlock_topic();
     }
 
+    public function ajax_purchase_topic(): void {
+        $this->topic_service()->ajax_purchase_topic();
+    }
+
+    /**
+     * Lightweight result helper for topic service actions.
+     *
+     * @return array{success:bool,message:string}
+     */
+    public function success(string $message = '', array $extra = []): array {
+        return array_merge(['success' => true, 'message' => $message], $extra);
+    }
+
+    /**
+     * @return array{success:bool,message:string}
+     */
+    public function error(string $message = '', array $extra = []): array {
+        return array_merge(['success' => false, 'message' => $message], $extra);
+    }
+
     public function apply_moderator(int $user_id, int $board_id, string $reason) {
         return $this->moderation_service()->apply_moderator($user_id, $board_id, $reason);
     }

inc/classes/forum/topic-service-traits/trait-aksrt-forum-topic-service-part-3.php

@@ -188,7 +188,7 @@ trait AKSRT_Forum_Topic_Service_Part_3 {
             if ($viewer_user_id <= 0) {
                 return false;
             }
-            return $this->has_user_unlocked_topic($viewer_user_id, (int) $post->ID);
+            return $this->has_user_paid_topic($viewer_user_id, (int) $post->ID);
         }
 
         if ($visibility === AKSRT_Forum::VISIBILITY_MODERATOR) {
@@ -324,16 +324,12 @@ trait AKSRT_Forum_Topic_Service_Part_3 {
             'topic_id' => $topic_id,
         ], sprintf(__('解锁帖子「%s」', 'aksrt'), get_the_title($topic_id)));
 
-        if (!$deducted) {
-            return $this->forum->error(__('积分扣除失败', 'aksrt'));
+        if (is_wp_error($deducted) || $deducted === false) {
+            $msg = is_wp_error($deducted) ? $deducted->get_error_message() : __('积分扣除失败', 'aksrt');
+            return $this->forum->error($msg ?: __('积分扣除失败', 'aksrt'));
         }
 
-        $unlocked = get_user_meta($user_id, 'aksrt_unlocked_topics', true);
-        if (!is_array($unlocked)) {
-            $unlocked = [];
-        }
-        $unlocked[] = $topic_id;
-        update_user_meta($user_id, 'aksrt_unlocked_topics', array_unique($unlocked));
+        $this->mark_topic_unlocked($user_id, $topic_id);
 
         $author_id = (int) $post->post_author;
         if ($author_id > 0 && $author_id !== $user_id) {
@@ -350,12 +346,211 @@ trait AKSRT_Forum_Topic_Service_Part_3 {
         return $this->forum->success(__('解锁成功', 'aksrt'));
     }
 
+    /**
+     * Cash/balance purchase for VISIBILITY_PAY topics.
+     *
+     * Reuses AKSRT_Order product_type=resource + balance credits conversion
+     * (1 CNY = 100 credits, same as AKSRT_Balance_Gateway).
+     *
+     * @return array{success:bool,message:string}
+     */
+    public function purchase_topic_with_balance(int $user_id, int $topic_id): array {
+        $post = get_post($topic_id);
+        if (!$post || $post->post_type !== 'aksrt_forum_topic') {
+            return $this->forum->error(__('主题不存在', 'aksrt'));
+        }
+
+        if ($user_id <= 0) {
+            return $this->forum->error(__('请先登录', 'aksrt'));
+        }
+
+        $visibility = (string) get_post_meta($topic_id, '_aksrt_visibility', true);
+        if ($visibility !== AKSRT_Forum::VISIBILITY_PAY) {
+            return $this->forum->error(__('该主题不是付费可见内容', 'aksrt'));
+        }
+
+        if ($this->has_user_paid_topic($user_id, $topic_id)) {
+            return $this->forum->success(__('已购买', 'aksrt'));
+        }
+
+        $price = $this->resolve_topic_pay_price($topic_id, $user_id);
+        if (!empty($price['is_free'])) {
+            $this->mark_topic_unlocked($user_id, $topic_id);
+            return $this->forum->success(__('VIP 免费解锁成功', 'aksrt'), [
+                'amount' => 0,
+                'free' => true,
+            ]);
+        }
+
+        $amount = (float) ($price['amount'] ?? 0);
+        if ($amount <= 0) {
+            return $this->forum->error(__('价格未设置', 'aksrt'));
+        }
+
+        if (!class_exists('AKSRT_Order') || !class_exists('AKSRT_Credits')) {
+            return $this->forum->error(__('支付系统不可用', 'aksrt'));
+        }
+
+        $product_type = class_exists('AKSRT_Domain_Model')
+            ? AKSRT_Domain_Model::ORDER_PRODUCT_RESOURCE
+            : 'resource';
+
+        $order_number = AKSRT_Order::get_instance()->create($user_id, $product_type, $topic_id, $amount, 'CNY');
+        if ($order_number === '') {
+            return $this->forum->error(__('创建订单失败', 'aksrt'));
+        }
+
+        // Align with AKSRT_Balance_Gateway: 1 CNY = 100 credits.
+        $credits_cost = (int) ceil($amount * 100);
+        $balance = AKSRT_Credits::get_balance($user_id);
+        if ($balance < $credits_cost) {
+            AKSRT_Order::get_instance()->update_status($order_number, AKSRT_Order::STATUS_CANCELLED, [
+                'note' => __('余额不足，自动取消', 'aksrt'),
+            ]);
+            return $this->forum->error(sprintf(
+                __('余额不足，需要 %d 积分（约 ¥%s），当前余额 %d', 'aksrt'),
+                $credits_cost,
+                number_format($amount, 2, '.', ''),
+                $balance
+            ));
+        }
+
+        $deducted = AKSRT_Credits::deduct(
+            $user_id,
+            $credits_cost,
+            'forum_topic_pay',
+            [
+                'topic_id' => $topic_id,
+                'order' => $order_number,
+            ],
+            sprintf(__('购买帖子「%s」', 'aksrt'), get_the_title($topic_id))
+        );
+
+        if (is_wp_error($deducted) || $deducted === false) {
+            AKSRT_Order::get_instance()->update_status($order_number, AKSRT_Order::STATUS_CANCELLED, [
+                'note' => __('扣款失败，自动取消', 'aksrt'),
+            ]);
+            $msg = is_wp_error($deducted) ? $deducted->get_error_message() : __('扣款失败', 'aksrt');
+            return $this->forum->error($msg ?: __('扣款失败', 'aksrt'));
+        }
+
+        $paid = AKSRT_Order::get_instance()->update_status($order_number, AKSRT_Order::STATUS_PAID, [
+            'payment_method' => 'balance',
+            'payment_transaction_id' => 'BAL_' . $order_number,
+            'note' => sprintf(__('论坛付费主题余额支付 %d 积分', 'aksrt'), $credits_cost),
+        ]);
+
+        if (!$paid) {
+            // Best-effort refund so user is not charged without access.
+            AKSRT_Credits::add(
+                $user_id,
+                $credits_cost,
+                'forum_topic_pay_refund',
+                ['topic_id' => $topic_id, 'order' => $order_number],
+                sprintf(__('购买失败退款：%s', 'aksrt'), get_the_title($topic_id))
+            );
+            return $this->forum->error(__('订单确认失败，已尝试退回积分', 'aksrt'));
+        }
+
+        $this->mark_topic_unlocked($user_id, $topic_id);
+
+        return $this->forum->success(__('购买成功', 'aksrt'), [
+            'order_number' => $order_number,
+            'amount' => $amount,
+            'credits_cost' => $credits_cost,
+        ]);
+    }
+
+    /**
+     * Resolve cash price for a pay-visibility topic.
+     *
+     * @return array{amount:float,is_vip_price:bool,is_free:bool,label:string,base:float,vip_set:bool}
+     */
+    public function resolve_topic_pay_price(int $topic_id, int $user_id = 0): array {
+        $base_raw = get_post_meta($topic_id, '_aksrt_pay_price', true);
+        $base = is_numeric($base_raw) ? (float) $base_raw : 0.0;
+
+        $vip_raw = get_post_meta($topic_id, '_aksrt_pay_vip_price', true);
+        $vip_set = ($vip_raw !== '' && $vip_raw !== null && $vip_raw !== false);
+        $vip_price = $vip_set && is_numeric($vip_raw) ? (float) $vip_raw : 0.0;
+
+        $is_vip = $user_id > 0 && function_exists('aksrt_is_vip') && aksrt_is_vip($user_id);
+        if (!$is_vip && $user_id > 0 && function_exists('aksrt_is_vip_exempt') && aksrt_is_vip_exempt($user_id)) {
+            $is_vip = true;
+        }
+
+        if ($is_vip && $vip_set) {
+            return [
+                'amount' => max(0.0, $vip_price),
+                'is_vip_price' => true,
+                'is_free' => $vip_price <= 0,
+                'label' => $vip_price <= 0
+                    ? __('VIP 免费', 'aksrt')
+                    : sprintf(__('VIP ¥%s', 'aksrt'), number_format($vip_price, 2, '.', '')),
+                'base' => $base,
+                'vip_set' => true,
+            ];
+        }
+
+        return [
+            'amount' => max(0.0, $base),
+            'is_vip_price' => false,
+            'is_free' => false,
+            'label' => $base > 0
+                ? sprintf(__('¥%s', 'aksrt'), number_format($base, 2, '.', ''))
+                : __('价格未设置', 'aksrt'),
+            'base' => $base,
+            'vip_set' => $vip_set,
+        ];
+    }
+
+    public function mark_topic_unlocked(int $user_id, int $topic_id): void {
+        if ($user_id <= 0 || $topic_id <= 0) {
+            return;
+        }
+        $unlocked = get_user_meta($user_id, 'aksrt_unlocked_topics', true);
+        if (!is_array($unlocked)) {
+            $unlocked = [];
+        }
+        $unlocked[] = $topic_id;
+        update_user_meta($user_id, 'aksrt_unlocked_topics', array_values(array_unique(array_map('intval', $unlocked))));
+    }
+
     public function has_user_unlocked_topic(int $user_id, int $post_id): bool {
         $unlocked = get_user_meta($user_id, 'aksrt_unlocked_topics', true);
         if (!is_array($unlocked)) {
             return false;
         }
-        return in_array($post_id, $unlocked, true);
+        return in_array($post_id, array_map('intval', $unlocked), true);
+    }
+
+    /**
+     * Paid access for VISIBILITY_PAY: unlock list OR paid resource order OR VIP free.
+     */
+    public function has_user_paid_topic(int $user_id, int $topic_id): bool {
+        if ($user_id <= 0 || $topic_id <= 0) {
+            return false;
+        }
+
+        if ($this->has_user_unlocked_topic($user_id, $topic_id)) {
+            return true;
+        }
+
+        if (class_exists('AKSRT_Order')) {
+            $product_type = class_exists('AKSRT_Domain_Model')
+                ? AKSRT_Domain_Model::ORDER_PRODUCT_RESOURCE
+                : 'resource';
+            if (AKSRT_Order::get_instance()->has_paid_access($user_id, $product_type, $topic_id)) {
+                return true;
+            }
+        }
+
+        $price = $this->resolve_topic_pay_price($topic_id, $user_id);
+        if (!empty($price['is_free'])) {
+            return true;
+        }
+
+        return false;
     }
 
     public function has_user_commented_on(int $user_id, int $post_id): bool {

inc/classes/forum/topic-service-traits/trait-aksrt-forum-topic-service-part-4.php

@@ -263,4 +263,25 @@ trait AKSRT_Forum_Topic_Service_Part_4 {
             wp_send_json_error(['message' => $result['message'] ?? __('解锁失败', 'aksrt')]);
         }
     }
+
+    public function ajax_purchase_topic(): void {
+        check_ajax_referer('aksrt_forum_action', '_nonce');
+
+        $user_id = get_current_user_id();
+        if ($user_id <= 0) {
+            wp_send_json_error(['message' => __('请先登录', 'aksrt')]);
+        }
+
+        $topic_id = (int) ($_POST['topic_id'] ?? 0);
+        if ($topic_id <= 0) {
+            wp_send_json_error(['message' => __('主题不存在', 'aksrt')]);
+        }
+
+        $result = $this->purchase_topic_with_balance($user_id, $topic_id);
+        if (!empty($result['success'])) {
+            wp_send_json_success($result);
+        } else {
+            wp_send_json_error(['message' => $result['message'] ?? __('购买失败', 'aksrt')]);
+        }
+    }
 }