perf(query): 优化后台手机号精确查询

backend/internal/modules/chat/support.go

@@ -307,10 +307,22 @@ func (r *Repository) adminConversationBase(ctx context.Context, principal Princi
 		Joins("LEFT JOIN rental_listings AS l ON l.id = COALESCE(explicit_lo.listing_id, c.listing_id)")
 	if keyword != "" {
 		upper := strings.ToUpper(keyword)
-		if len(keyword) == 11 && keyword[0] == '1' && isAllDigits(keyword) {
-			db = db.Joins("LEFT JOIN users AS renter ON renter.id = explicit_lo.renter_id").
-				Joins("LEFT JOIN users AS owner ON owner.id = COALESCE(explicit_lo.owner_id, l.owner_id)").
-				Where("(renter.phone = ? OR owner.phone = ?)", keyword, keyword)
+		if isPhoneKeyword(keyword) {
+			// 先由 users(phone) 唯一索引解析用户，再分别从订单群和发布群定位会话。
+			// 保持原有语义：订单群匹配订单号主/租客，发布群仅匹配商品号主。
+			db = db.Joins(`JOIN (
+				SELECT c2.id AS conversation_id
+				FROM chat_conversations AS c2
+				JOIN rental_orders AS o2 ON o2.id = c2.order_id
+				WHERE o2.owner_id = (SELECT id FROM users WHERE phone = ?)
+				   OR o2.renter_id = (SELECT id FROM users WHERE phone = ?)
+				UNION ALL
+				SELECT c2.id AS conversation_id
+				FROM chat_conversations AS c2
+				JOIN rental_listings AS l2 ON l2.id = c2.listing_id
+				WHERE c2.order_id IS NULL
+				  AND l2.owner_id = (SELECT id FROM users WHERE phone = ?)
+			) AS matched_phone ON matched_phone.conversation_id = c.id`, keyword, keyword, keyword)
 		} else if strings.HasPrefix(upper, "RO") || strings.HasPrefix(upper, "ORD") {
 			db = db.Where("(explicit_lo.order_no = ? OR c.latest_order_no = ?)", keyword, keyword)
 		} else if strings.HasPrefix(upper, "L") || (len(keyword) >= 12 && isAllDigits(keyword)) {
@@ -492,3 +504,7 @@ func isAllDigits(s string) bool {
 	}
 	return true
 }
+
+func isPhoneKeyword(s string) bool {
+	return len(s) == 11 && s[0] == '1' && isAllDigits(s)
+}