Add mail item attachment support for sending

- CMSG_SEND_MAIL now includes item GUIDs (up to 12 per WotLK)
- Right-click items in bags to attach when mail compose is open
- Compose window shows 12-slot attachment grid with item icons
- Click attached items to remove them
- Classic/Vanilla falls back to single item GUID format

src/game/game_handler.cpp

@@ -12851,10 +12851,114 @@ void GameHandler::sendMail(const std::string& recipient, const std::string& subj
         LOG_WARNING("sendMail: mailboxGuid_ is 0 (mailbox closed?)");
         return;
     }
-    auto packet = packetParsers_->buildSendMail(mailboxGuid_, recipient, subject, body, money, cod);
+    // Collect attached item GUIDs
+    std::vector<uint64_t> itemGuids;
+    for (const auto& att : mailAttachments_) {
+        if (att.occupied()) {
+            itemGuids.push_back(att.itemGuid);
+        }
+    }
+    auto packet = packetParsers_->buildSendMail(mailboxGuid_, recipient, subject, body, money, cod, itemGuids);
     LOG_INFO("sendMail: to='", recipient, "' subject='", subject, "' money=", money,
-             " mailboxGuid=", mailboxGuid_);
+             " attachments=", itemGuids.size(), " mailboxGuid=", mailboxGuid_);
     socket->send(packet);
+    clearMailAttachments();
+}
+
+bool GameHandler::attachItemFromBackpack(int backpackIndex) {
+    if (backpackIndex < 0 || backpackIndex >= inventory.getBackpackSize()) return false;
+    const auto& slot = inventory.getBackpackSlot(backpackIndex);
+    if (slot.empty()) return false;
+
+    uint64_t itemGuid = backpackSlotGuids_[backpackIndex];
+    if (itemGuid == 0) {
+        itemGuid = resolveOnlineItemGuid(slot.item.itemId);
+    }
+    if (itemGuid == 0) {
+        addSystemChatMessage("Cannot attach: item not found.");
+        return false;
+    }
+
+    // Check not already attached
+    for (const auto& att : mailAttachments_) {
+        if (att.occupied() && att.itemGuid == itemGuid) return false;
+    }
+
+    // Find free attachment slot
+    for (int i = 0; i < MAIL_MAX_ATTACHMENTS; ++i) {
+        if (!mailAttachments_[i].occupied()) {
+            mailAttachments_[i].itemGuid = itemGuid;
+            mailAttachments_[i].item = slot.item;
+            mailAttachments_[i].srcBag = 0xFF;
+            mailAttachments_[i].srcSlot = static_cast<uint8_t>(23 + backpackIndex);
+            LOG_INFO("Mail attach: slot=", i, " item='", slot.item.name, "' guid=0x",
+                     std::hex, itemGuid, std::dec, " from backpack[", backpackIndex, "]");
+            return true;
+        }
+    }
+    addSystemChatMessage("Cannot attach: all attachment slots full.");
+    return false;
+}
+
+bool GameHandler::attachItemFromBag(int bagIndex, int slotIndex) {
+    if (bagIndex < 0 || bagIndex >= inventory.NUM_BAG_SLOTS) return false;
+    if (slotIndex < 0 || slotIndex >= inventory.getBagSize(bagIndex)) return false;
+    const auto& slot = inventory.getBagSlot(bagIndex, slotIndex);
+    if (slot.empty()) return false;
+
+    uint64_t itemGuid = 0;
+    uint64_t bagGuid = equipSlotGuids_[19 + bagIndex];
+    if (bagGuid != 0) {
+        auto it = containerContents_.find(bagGuid);
+        if (it != containerContents_.end() && slotIndex < static_cast<int>(it->second.numSlots)) {
+            itemGuid = it->second.slotGuids[slotIndex];
+        }
+    }
+    if (itemGuid == 0) {
+        itemGuid = resolveOnlineItemGuid(slot.item.itemId);
+    }
+    if (itemGuid == 0) {
+        addSystemChatMessage("Cannot attach: item not found.");
+        return false;
+    }
+
+    for (const auto& att : mailAttachments_) {
+        if (att.occupied() && att.itemGuid == itemGuid) return false;
+    }
+
+    for (int i = 0; i < MAIL_MAX_ATTACHMENTS; ++i) {
+        if (!mailAttachments_[i].occupied()) {
+            mailAttachments_[i].itemGuid = itemGuid;
+            mailAttachments_[i].item = slot.item;
+            mailAttachments_[i].srcBag = static_cast<uint8_t>(19 + bagIndex);
+            mailAttachments_[i].srcSlot = static_cast<uint8_t>(slotIndex);
+            LOG_INFO("Mail attach: slot=", i, " item='", slot.item.name, "' guid=0x",
+                     std::hex, itemGuid, std::dec, " from bag[", bagIndex, "][", slotIndex, "]");
+            return true;
+        }
+    }
+    addSystemChatMessage("Cannot attach: all attachment slots full.");
+    return false;
+}
+
+bool GameHandler::detachMailAttachment(int attachIndex) {
+    if (attachIndex < 0 || attachIndex >= MAIL_MAX_ATTACHMENTS) return false;
+    if (!mailAttachments_[attachIndex].occupied()) return false;
+    LOG_INFO("Mail detach: slot=", attachIndex, " item='", mailAttachments_[attachIndex].item.name, "'");
+    mailAttachments_[attachIndex] = MailAttachSlot{};
+    return true;
+}
+
+void GameHandler::clearMailAttachments() {
+    for (auto& att : mailAttachments_) att = MailAttachSlot{};
+}
+
+int GameHandler::getMailAttachmentCount() const {
+    int count = 0;
+    for (const auto& att : mailAttachments_) {
+        if (att.occupied()) ++count;
+    }
+    return count;
 }
 
 void GameHandler::mailTakeMoney(uint32_t mailId) {

src/game/packet_parsers_classic.cpp

@@ -728,7 +728,8 @@ network::Packet ClassicPacketParsers::buildSendMail(uint64_t mailboxGuid,
                                                      const std::string& recipient,
                                                      const std::string& subject,
                                                      const std::string& body,
-                                                     uint32_t money, uint32_t cod) {
+                                                     uint32_t money, uint32_t cod,
+                                                     const std::vector<uint64_t>& itemGuids) {
     network::Packet packet(wireOpcode(Opcode::CMSG_SEND_MAIL));
     packet.writeUInt64(mailboxGuid);
     packet.writeString(recipient);
@@ -736,7 +737,9 @@ network::Packet ClassicPacketParsers::buildSendMail(uint64_t mailboxGuid,
     packet.writeString(body);
     packet.writeUInt32(0);       // stationery
     packet.writeUInt32(0);       // unknown
-    packet.writeUInt64(0);       // item GUID (0 = no attachment, single item only in Vanilla)
+    // Vanilla supports only one item attachment (single uint64 GUID)
+    uint64_t singleItemGuid = itemGuids.empty() ? 0 : itemGuids[0];
+    packet.writeUInt64(singleItemGuid);
     packet.writeUInt32(money);
     packet.writeUInt32(cod);
     packet.writeUInt64(0);       // unk3 (clients > 1.9.4)

src/game/world_packets.cpp

@@ -3939,7 +3939,8 @@ network::Packet GetMailListPacket::build(uint64_t mailboxGuid) {
 
 network::Packet SendMailPacket::build(uint64_t mailboxGuid, const std::string& recipient,
                                       const std::string& subject, const std::string& body,
-                                      uint32_t money, uint32_t cod) {
+                                      uint32_t money, uint32_t cod,
+                                      const std::vector<uint64_t>& itemGuids) {
     // WotLK 3.3.5a format
     network::Packet packet(wireOpcode(Opcode::CMSG_SEND_MAIL));
     packet.writeUInt64(mailboxGuid);
@@ -3948,7 +3949,12 @@ network::Packet SendMailPacket::build(uint64_t mailboxGuid, const std::string& r
     packet.writeString(body);
     packet.writeUInt32(0);       // stationery
     packet.writeUInt32(0);       // unknown
-    packet.writeUInt8(0);        // attachment count (0 = no attachments)
+    uint8_t attachCount = static_cast<uint8_t>(itemGuids.size());
+    packet.writeUInt8(attachCount);
+    for (uint8_t i = 0; i < attachCount; ++i) {
+        packet.writeUInt8(i);            // attachment slot index
+        packet.writeUInt64(itemGuids[i]);
+    }
     packet.writeUInt32(money);
     packet.writeUInt32(cod);
     return packet;

src/ui/game_screen.cpp

@@ -7384,8 +7384,8 @@ void GameScreen::renderMailComposeWindow(game::GameHandler& gameHandler) {
     float screenW = window ? static_cast<float>(window->getWidth()) : 1280.0f;
     float screenH = window ? static_cast<float>(window->getHeight()) : 720.0f;
 
-    ImGui::SetNextWindowPos(ImVec2(screenW / 2 - 175, screenH / 2 - 200), ImGuiCond_Appearing);
-    ImGui::SetNextWindowSize(ImVec2(380, 400), ImGuiCond_Appearing);
+    ImGui::SetNextWindowPos(ImVec2(screenW / 2 - 190, screenH / 2 - 250), ImGuiCond_Appearing);
+    ImGui::SetNextWindowSize(ImVec2(400, 500), ImGuiCond_Appearing);
 
     bool open = true;
     if (ImGui::Begin("Send Mail", &open)) {
@@ -7401,8 +7401,56 @@ void GameScreen::renderMailComposeWindow(game::GameHandler& gameHandler) {
 
         ImGui::Text("Body:");
         ImGui::InputTextMultiline("##MailBody", mailBodyBuffer_, sizeof(mailBodyBuffer_),
-                                   ImVec2(-1, 150));
+                                   ImVec2(-1, 120));
 
+        // Attachments section
+        int attachCount = gameHandler.getMailAttachmentCount();
+        ImGui::Text("Attachments (%d/12):", attachCount);
+        ImGui::SameLine();
+        ImGui::TextColored(ImVec4(0.6f, 0.6f, 0.6f, 1.0f), "Right-click items in bags to attach");
+
+        const auto& attachments = gameHandler.getMailAttachments();
+        // Show attachment slots in a grid (6 per row)
+        for (int i = 0; i < game::GameHandler::MAIL_MAX_ATTACHMENTS; ++i) {
+            if (i % 6 != 0) ImGui::SameLine();
+            ImGui::PushID(i + 5000);
+            const auto& att = attachments[i];
+            if (att.occupied()) {
+                // Show item with quality color border
+                ImVec4 qualColor = ui::InventoryScreen::getQualityColor(att.item.quality);
+                ImGui::PushStyleColor(ImGuiCol_Button, ImVec4(qualColor.x * 0.3f, qualColor.y * 0.3f, qualColor.z * 0.3f, 0.8f));
+                ImGui::PushStyleColor(ImGuiCol_ButtonHovered, ImVec4(qualColor.x * 0.5f, qualColor.y * 0.5f, qualColor.z * 0.5f, 0.9f));
+
+                // Try to show icon
+                VkDescriptorSet icon = inventoryScreen.getItemIcon(att.item.displayInfoId);
+                bool clicked = false;
+                if (icon) {
+                    clicked = ImGui::ImageButton("##att", (ImTextureID)icon, ImVec2(30, 30));
+                } else {
+                    // Truncate name to fit
+                    std::string label = att.item.name.substr(0, 4);
+                    clicked = ImGui::Button(label.c_str(), ImVec2(36, 36));
+                }
+                ImGui::PopStyleColor(2);
+
+                if (clicked) {
+                    gameHandler.detachMailAttachment(i);
+                }
+                if (ImGui::IsItemHovered()) {
+                    ImGui::BeginTooltip();
+                    ImGui::TextColored(qualColor, "%s", att.item.name.c_str());
+                    ImGui::TextColored(ImVec4(0.7f, 0.7f, 0.7f, 1.0f), "Click to remove");
+                    ImGui::EndTooltip();
+                }
+            } else {
+                ImGui::PushStyleColor(ImGuiCol_Button, ImVec4(0.15f, 0.15f, 0.15f, 0.5f));
+                ImGui::Button("##empty", ImVec2(36, 36));
+                ImGui::PopStyleColor();
+            }
+            ImGui::PopID();
+        }
+
+        ImGui::Spacing();
         ImGui::Text("Money:");
         ImGui::SameLine(60);
         ImGui::SetNextItemWidth(60);
@@ -7429,7 +7477,8 @@ void GameScreen::renderMailComposeWindow(game::GameHandler& gameHandler) {
                               static_cast<uint32_t>(mailComposeMoney_[1]) * 100 +
                               static_cast<uint32_t>(mailComposeMoney_[2]);
 
-        ImGui::TextColored(ImVec4(0.6f, 0.6f, 0.6f, 1.0f), "Sending cost: 30c");
+        uint32_t sendCost = attachCount > 0 ? static_cast<uint32_t>(30 * attachCount) : 30u;
+        ImGui::TextColored(ImVec4(0.6f, 0.6f, 0.6f, 1.0f), "Sending cost: %uc", sendCost);
 
         ImGui::Spacing();
         bool canSend = (strlen(mailRecipientBuffer_) > 0);

src/ui/inventory_screen.cpp

@@ -1428,7 +1428,11 @@ void InventoryScreen::renderItemSlot(game::Inventory& inventory, const game::Ite
                      " bagIndex=", bagIndex, " bagSlotIndex=", bagSlotIndex,
                      " vendorMode=", vendorMode_,
                      " bankOpen=", gameHandler_->isBankOpen());
-            if (gameHandler_->isBankOpen() && kind == SlotKind::BACKPACK && backpackIndex >= 0) {
+            if (gameHandler_->isMailComposeOpen() && kind == SlotKind::BACKPACK && backpackIndex >= 0) {
+                gameHandler_->attachItemFromBackpack(backpackIndex);
+            } else if (gameHandler_->isMailComposeOpen() && kind == SlotKind::BACKPACK && isBagSlot) {
+                gameHandler_->attachItemFromBag(bagIndex, bagSlotIndex);
+            } else if (gameHandler_->isBankOpen() && kind == SlotKind::BACKPACK && backpackIndex >= 0) {
                 gameHandler_->depositItem(0xFF, static_cast<uint8_t>(23 + backpackIndex));
             } else if (gameHandler_->isBankOpen() && kind == SlotKind::BACKPACK && isBagSlot) {
                 gameHandler_->depositItem(static_cast<uint8_t>(19 + bagIndex), static_cast<uint8_t>(bagSlotIndex));