Stabilize buyback flow and single-row buyback UI

- keep vendor buyback as one-item LIFO row in vendor window

- add robust pending buyback tracking with wire slot probing (74..85)

- recover from stale optimistic sell/buyback entries and refresh vendor list

- keep buy packet construction branch-compatible (direct packet build)

include/game/game_handler.hpp

@@ -1542,6 +1542,7 @@ private:
     std::deque<BuybackItem> buybackItems_;
     std::unordered_map<uint64_t, BuybackItem> pendingSellToBuyback_;
     int pendingBuybackSlot_ = -1;
+    uint32_t pendingBuybackWireSlot_ = 0;
     uint32_t pendingBuyItemId_ = 0;
     uint32_t pendingBuyItemSlot_ = 0;
 

src/game/game_handler.cpp

@@ -977,6 +977,7 @@ void GameHandler::handlePacket(network::Packet& packet) {
                     addSystemChatMessage(std::string(msg) + " (code " + std::to_string(resultCode) + ")");
                 }
                 pendingBuybackSlot_ = -1;
+                pendingBuybackWireSlot_ = 0;
 
                 // Refresh vendor list so UI state stays in sync after buyback result.
                 if (currentVendorItems.vendorGuid != 0 && socket && state == WorldState::IN_WORLD) {
@@ -1722,6 +1723,7 @@ void GameHandler::handlePacket(network::Packet& packet) {
                 if (result == 0) {
                     pendingSellToBuyback_.erase(itemGuid);
                 } else {
+                    bool removedPending = false;
                     auto it = pendingSellToBuyback_.find(itemGuid);
                     if (it != pendingSellToBuyback_.end()) {
                         for (auto bit = buybackItems_.begin(); bit != buybackItems_.end(); ++bit) {
@@ -1731,6 +1733,23 @@ void GameHandler::handlePacket(network::Packet& packet) {
                             }
                         }
                         pendingSellToBuyback_.erase(it);
+                        removedPending = true;
+                    }
+                    if (!removedPending) {
+                        // Some cores return a non-item GUID on sell failure; drop the newest
+                        // optimistic entry if it is still pending so stale rows don't block buyback.
+                        if (!buybackItems_.empty()) {
+                            uint64_t frontGuid = buybackItems_.front().itemGuid;
+                            if (pendingSellToBuyback_.erase(frontGuid) > 0) {
+                                buybackItems_.pop_front();
+                                removedPending = true;
+                            }
+                        }
+                    }
+                    if (!removedPending && !pendingSellToBuyback_.empty()) {
+                        // Last-resort desync recovery.
+                        pendingSellToBuyback_.clear();
+                        buybackItems_.clear();
                     }
                     static const char* sellErrors[] = {
                         "OK", "Can't find item", "Can't sell item",
@@ -1827,8 +1846,42 @@ void GameHandler::handlePacket(network::Packet& packet) {
                          " item/slot=", itemIdOrSlot,
                          " err=", static_cast<int>(errCode),
                          " pendingBuybackSlot=", pendingBuybackSlot_,
+                         " pendingBuybackWireSlot=", pendingBuybackWireSlot_,
                          " pendingBuyItemId=", pendingBuyItemId_,
                          " pendingBuyItemSlot=", pendingBuyItemSlot_);
+                if (pendingBuybackSlot_ >= 0) {
+                    // Some cores require probing absolute buyback slots until a live entry is found.
+                    if (errCode == 0) {
+                        constexpr uint16_t kWotlkCmsgBuybackItemOpcode = 0x290;
+                        constexpr uint32_t kBuybackSlotEnd = 85;
+                        if (pendingBuybackWireSlot_ >= 74 && pendingBuybackWireSlot_ < kBuybackSlotEnd &&
+                            socket && state == WorldState::IN_WORLD && currentVendorItems.vendorGuid != 0) {
+                            ++pendingBuybackWireSlot_;
+                            LOG_INFO("Buyback retry: vendorGuid=0x", std::hex, currentVendorItems.vendorGuid,
+                                     std::dec, " uiSlot=", pendingBuybackSlot_,
+                                     " wireSlot=", pendingBuybackWireSlot_);
+                            network::Packet retry(kWotlkCmsgBuybackItemOpcode);
+                            retry.writeUInt64(currentVendorItems.vendorGuid);
+                            retry.writeUInt32(pendingBuybackWireSlot_);
+                            socket->send(retry);
+                            break;
+                        }
+                        // Exhausted slot probe: drop stale local row and advance.
+                        if (pendingBuybackSlot_ < static_cast<int>(buybackItems_.size())) {
+                            buybackItems_.erase(buybackItems_.begin() + pendingBuybackSlot_);
+                        }
+                        pendingBuybackSlot_ = -1;
+                        pendingBuybackWireSlot_ = 0;
+                        if (currentVendorItems.vendorGuid != 0 && socket && state == WorldState::IN_WORLD) {
+                            auto pkt = ListInventoryPacket::build(currentVendorItems.vendorGuid);
+                            socket->send(pkt);
+                        }
+                        break;
+                    }
+                    pendingBuybackSlot_ = -1;
+                    pendingBuybackWireSlot_ = 0;
+                }
+
                 const char* msg = "Purchase failed.";
                 switch (errCode) {
                     case 0: msg = "Purchase failed: item not found."; break;
@@ -9078,6 +9131,7 @@ void GameHandler::closeVendor() {
     buybackItems_.clear();
     pendingSellToBuyback_.clear();
     pendingBuybackSlot_ = -1;
+    pendingBuybackWireSlot_ = 0;
     pendingBuyItemId_ = 0;
     pendingBuyItemSlot_ = 0;
 }
@@ -9089,7 +9143,14 @@ void GameHandler::buyItem(uint64_t vendorGuid, uint32_t itemId, uint32_t slot, u
              " wire=0x", std::hex, wireOpcode(Opcode::CMSG_BUY_ITEM), std::dec);
     pendingBuyItemId_ = itemId;
     pendingBuyItemSlot_ = slot;
-    auto packet = BuyItemPacket::build(vendorGuid, itemId, slot, count);
+    // Build directly to avoid helper-signature drift across branches (3-arg vs 4-arg helper).
+    network::Packet packet(wireOpcode(Opcode::CMSG_BUY_ITEM));
+    packet.writeUInt64(vendorGuid);
+    packet.writeUInt32(itemId); // item entry
+    packet.writeUInt32(slot);   // vendor slot index
+    packet.writeUInt32(count);
+    // WotLK/AzerothCore expects a trailing byte here.
+    packet.writeUInt8(0);
     socket->send(packet);
 }
 
@@ -9102,13 +9163,18 @@ void GameHandler::buyBackItem(uint32_t buybackSlot) {
     // This request is independent from normal buy path; avoid stale pending buy context in logs.
     pendingBuyItemId_ = 0;
     pendingBuyItemSlot_ = 0;
+    // Build directly so this compiles even when Opcode::CMSG_BUYBACK_ITEM / BuybackItemPacket
+    // are not available in some branches.
+    constexpr uint16_t kWotlkCmsgBuybackItemOpcode = 0x290;
     LOG_INFO("Buyback request: vendorGuid=0x", std::hex, currentVendorItems.vendorGuid,
              std::dec, " uiSlot=", buybackSlot, " wireSlot=", wireSlot,
              " source=absolute-buyback-slot",
-             " wire=0x", std::hex,
+             " wire=0x", std::hex, kWotlkCmsgBuybackItemOpcode, std::dec);
-             wireOpcode(Opcode::CMSG_BUYBACK_ITEM), std::dec);
     pendingBuybackSlot_ = static_cast<int>(buybackSlot);
-    auto packet = BuybackItemPacket::build(currentVendorItems.vendorGuid, wireSlot);
+    pendingBuybackWireSlot_ = wireSlot;
+    network::Packet packet(kWotlkCmsgBuybackItemOpcode);
+    packet.writeUInt64(currentVendorItems.vendorGuid);
+    packet.writeUInt32(wireSlot);
     socket->send(packet);
 }
 

src/ui/game_screen.cpp

@@ -361,8 +361,18 @@ void GameScreen::render(game::GameHandler& gameHandler) {
     inventoryScreen.setVendorMode(gameHandler.isVendorWindowOpen(), &gameHandler);
 
     // Auto-open bags when vendor window opens
-    if (gameHandler.isVendorWindowOpen() && !inventoryScreen.isOpen()) {
+    if (gameHandler.isVendorWindowOpen()) {
-        inventoryScreen.setOpen(true);
+        if (inventoryScreen.isSeparateBags()) {
+            if (!inventoryScreen.isBackpackOpen() &&
+                !inventoryScreen.isBagOpen(0) &&
+                !inventoryScreen.isBagOpen(1) &&
+                !inventoryScreen.isBagOpen(2) &&
+                !inventoryScreen.isBagOpen(3)) {
+                inventoryScreen.openAllBags();
+            }
+        } else if (!inventoryScreen.isOpen()) {
+            inventoryScreen.setOpen(true);
+        }
     }
 
     // Bags (B key toggle handled inside)
@@ -800,7 +810,7 @@ void GameScreen::renderChatWindow(game::GameHandler& gameHandler) {
         if (!bonusLine.empty()) {
             ImGui::TextColored(green, "%s", bonusLine.c_str());
         }
-        if (!isWeapon && info->armor > 0) {
+        if (info->armor > 0) {
             ImGui::Text("%d Armor", info->armor);
         }
         if (info->sellPrice > 0) {
@@ -826,7 +836,7 @@ void GameScreen::renderChatWindow(game::GameHandler& gameHandler) {
                     float dps = ((eq->item.damageMin + eq->item.damageMax) * 0.5f) / speed;
                     ImGui::Text("%.1f DPS", dps);
                 }
-                if (!isWeaponInventoryType(eq->item.inventoryType) && eq->item.armor > 0) {
+                if (eq->item.armor > 0) {
                     ImGui::Text("%d Armor", eq->item.armor);
                 }
                 std::string eqBonusLine;
@@ -4944,6 +4954,55 @@ void GameScreen::renderVendorWindow(game::GameHandler& gameHandler) {
         ImGui::TextColored(ImVec4(0.7f, 0.7f, 0.7f, 1.0f), "Right-click bag items to sell");
         ImGui::Separator();
 
+        const auto& buyback = gameHandler.getBuybackItems();
+        if (!buyback.empty()) {
+            ImGui::TextColored(ImVec4(1.0f, 0.82f, 0.0f, 1.0f), "Buy Back");
+            if (ImGui::BeginTable("BuybackTable", 3, ImGuiTableFlags_Borders | ImGuiTableFlags_RowBg)) {
+                ImGui::TableSetupColumn("Item", ImGuiTableColumnFlags_WidthStretch);
+                ImGui::TableSetupColumn("Price", ImGuiTableColumnFlags_WidthFixed, 110.0f);
+                ImGui::TableSetupColumn("Buy", ImGuiTableColumnFlags_WidthFixed, 62.0f);
+                ImGui::TableHeadersRow();
+                // Show only the most recently sold item (LIFO).
+                const int i = 0;
+                const auto& entry = buyback[0];
+                uint32_t sellPrice = entry.item.sellPrice;
+                if (sellPrice == 0) {
+                    if (auto* info = gameHandler.getItemInfo(entry.item.itemId); info && info->valid) {
+                        sellPrice = info->sellPrice;
+                    }
+                }
+                uint64_t price = static_cast<uint64_t>(sellPrice) *
+                                 static_cast<uint64_t>(entry.count > 0 ? entry.count : 1);
+                uint32_t g = static_cast<uint32_t>(price / 10000);
+                uint32_t s = static_cast<uint32_t>((price / 100) % 100);
+                uint32_t c = static_cast<uint32_t>(price % 100);
+                bool canAfford = money >= price;
+
+                ImGui::TableNextRow();
+                ImGui::PushID(8000 + i);
+                ImGui::TableSetColumnIndex(0);
+                const char* name = entry.item.name.empty() ? "Unknown Item" : entry.item.name.c_str();
+                if (entry.count > 1) {
+                    ImGui::Text("%s x%u", name, entry.count);
+                } else {
+                    ImGui::Text("%s", name);
+                }
+                ImGui::TableSetColumnIndex(1);
+                if (!canAfford) ImGui::PushStyleColor(ImGuiCol_Text, ImVec4(1.0f, 0.3f, 0.3f, 1.0f));
+                ImGui::Text("%ug %us %uc", g, s, c);
+                if (!canAfford) ImGui::PopStyleColor();
+                ImGui::TableSetColumnIndex(2);
+                if (!canAfford) ImGui::BeginDisabled();
+                if (ImGui::SmallButton("Buy Back##buyback_0")) {
+                    gameHandler.buyBackItem(0);
+                }
+                if (!canAfford) ImGui::EndDisabled();
+                ImGui::PopID();
+                ImGui::EndTable();
+            }
+            ImGui::Separator();
+        }
+
         if (vendor.items.empty()) {
             ImGui::TextDisabled("This vendor has nothing for sale.");
         } else {
@@ -5021,7 +5080,8 @@ void GameScreen::renderVendorWindow(game::GameHandler& gameHandler) {
                     }
 
                     ImGui::TableSetColumnIndex(3);
-                    if (ImGui::SmallButton("Buy")) {
+                    std::string buyBtnId = "Buy##vendor_" + std::to_string(vi);
+                    if (ImGui::SmallButton(buyBtnId.c_str())) {
                         gameHandler.buyItem(vendor.vendorGuid, item.itemId, item.slot, 1);
                     }