Fix vendor buying and add quest turn-in flow

CMSG_BUY_ITEM was missing the trailing uint8 bag field, causing the
server to silently drop undersized packets. Add handlers for
SMSG_QUESTGIVER_REQUEST_ITEMS and SMSG_QUESTGIVER_OFFER_REWARD with
UI windows for quest completion and reward selection.

include/game/game_handler.hpp

@@ -363,6 +363,17 @@ public:
     bool isQuestDetailsOpen() const { return questDetailsOpen; }
     const QuestDetailsData& getQuestDetails() const { return currentQuestDetails; }
 
+    // Quest turn-in
+    bool isQuestRequestItemsOpen() const { return questRequestItemsOpen_; }
+    const QuestRequestItemsData& getQuestRequestItems() const { return currentQuestRequestItems_; }
+    void completeQuest();       // Send CMSG_QUESTGIVER_COMPLETE_QUEST
+    void closeQuestRequestItems();
+
+    bool isQuestOfferRewardOpen() const { return questOfferRewardOpen_; }
+    const QuestOfferRewardData& getQuestOfferReward() const { return currentQuestOfferReward_; }
+    void chooseQuestReward(uint32_t rewardIndex);  // Send CMSG_QUESTGIVER_CHOOSE_REWARD
+    void closeQuestOfferReward();
+
     // Quest log
     struct QuestLogEntry {
         uint32_t questId = 0;
@@ -538,6 +549,8 @@ private:
     void handleGossipMessage(network::Packet& packet);
     void handleGossipComplete(network::Packet& packet);
     void handleQuestDetails(network::Packet& packet);
+    void handleQuestRequestItems(network::Packet& packet);
+    void handleQuestOfferReward(network::Packet& packet);
     void handleListInventory(network::Packet& packet);
     LootResponseData generateLocalLoot(uint64_t guid);
     void simulateLootResponse(const LootResponseData& data);
@@ -689,6 +702,12 @@ private:
     bool questDetailsOpen = false;
     QuestDetailsData currentQuestDetails;
 
+    // Quest turn-in
+    bool questRequestItemsOpen_ = false;
+    QuestRequestItemsData currentQuestRequestItems_;
+    bool questOfferRewardOpen_ = false;
+    QuestOfferRewardData currentQuestOfferReward_;
+
     // Quest log
     std::vector<QuestLogEntry> questLog_;
 

include/game/world_packets.hpp

@@ -1238,6 +1238,62 @@ public:
     static bool parse(network::Packet& packet, QuestDetailsData& data);
 };
 
+/** Reward item entry (shared by quest detail/offer windows) */
+struct QuestRewardItem {
+    uint32_t itemId = 0;
+    uint32_t count = 0;
+    uint32_t displayInfoId = 0;
+};
+
+/** SMSG_QUESTGIVER_REQUEST_ITEMS data (turn-in progress check) */
+struct QuestRequestItemsData {
+    uint64_t npcGuid = 0;
+    uint32_t questId = 0;
+    std::string title;
+    std::string completionText;
+    uint32_t requiredMoney = 0;
+    uint32_t completableFlags = 0;  // 0x03 = completable
+    std::vector<QuestRewardItem> requiredItems;
+
+    bool isCompletable() const { return (completableFlags & 0x03) != 0; }
+};
+
+/** SMSG_QUESTGIVER_REQUEST_ITEMS parser */
+class QuestRequestItemsParser {
+public:
+    static bool parse(network::Packet& packet, QuestRequestItemsData& data);
+};
+
+/** SMSG_QUESTGIVER_OFFER_REWARD data (choose reward) */
+struct QuestOfferRewardData {
+    uint64_t npcGuid = 0;
+    uint32_t questId = 0;
+    std::string title;
+    std::string rewardText;
+    uint32_t rewardMoney = 0;
+    uint32_t rewardXp = 0;
+    std::vector<QuestRewardItem> choiceRewards;  // Pick one
+    std::vector<QuestRewardItem> fixedRewards;   // Always given
+};
+
+/** SMSG_QUESTGIVER_OFFER_REWARD parser */
+class QuestOfferRewardParser {
+public:
+    static bool parse(network::Packet& packet, QuestOfferRewardData& data);
+};
+
+/** CMSG_QUESTGIVER_COMPLETE_QUEST packet builder */
+class QuestgiverCompleteQuestPacket {
+public:
+    static network::Packet build(uint64_t npcGuid, uint32_t questId);
+};
+
+/** CMSG_QUESTGIVER_CHOOSE_REWARD packet builder */
+class QuestgiverChooseRewardPacket {
+public:
+    static network::Packet build(uint64_t npcGuid, uint32_t questId, uint32_t rewardIndex);
+};
+
 // ============================================================
 // Phase 5: Vendor
 // ============================================================

include/ui/game_screen.hpp

@@ -146,6 +146,8 @@ private:
     void renderLootWindow(game::GameHandler& gameHandler);
     void renderGossipWindow(game::GameHandler& gameHandler);
     void renderQuestDetailsWindow(game::GameHandler& gameHandler);
+    void renderQuestRequestItemsWindow(game::GameHandler& gameHandler);
+    void renderQuestOfferRewardWindow(game::GameHandler& gameHandler);
     void renderVendorWindow(game::GameHandler& gameHandler);
     void renderTeleporterPanel();
     void renderDeathScreen(game::GameHandler& gameHandler);

src/game/game_handler.cpp

@@ -1285,7 +1285,11 @@ void GameHandler::handlePacket(network::Packet& packet) {
             break;
         }
         case Opcode::SMSG_QUESTGIVER_REQUEST_ITEMS:
+            handleQuestRequestItems(packet);
+            break;
         case Opcode::SMSG_QUESTGIVER_OFFER_REWARD:
+            handleQuestOfferReward(packet);
+            break;
         case Opcode::SMSG_GROUP_SET_LEADER:
             LOG_DEBUG("Ignoring known opcode: 0x", std::hex, opcode, std::dec);
             break;
@@ -4144,6 +4148,78 @@ void GameHandler::abandonQuest(uint32_t questId) {
     }
 }
 
+void GameHandler::handleQuestRequestItems(network::Packet& packet) {
+    QuestRequestItemsData data;
+    if (!QuestRequestItemsParser::parse(packet, data)) {
+        LOG_WARNING("Failed to parse SMSG_QUESTGIVER_REQUEST_ITEMS");
+        return;
+    }
+    currentQuestRequestItems_ = data;
+    questRequestItemsOpen_ = true;
+    gossipWindowOpen = false;
+    questDetailsOpen = false;
+
+    // Query item names for required items
+    for (const auto& item : data.requiredItems) {
+        queryItemInfo(item.itemId, 0);
+    }
+}
+
+void GameHandler::handleQuestOfferReward(network::Packet& packet) {
+    QuestOfferRewardData data;
+    if (!QuestOfferRewardParser::parse(packet, data)) {
+        LOG_WARNING("Failed to parse SMSG_QUESTGIVER_OFFER_REWARD");
+        return;
+    }
+    currentQuestOfferReward_ = data;
+    questOfferRewardOpen_ = true;
+    questRequestItemsOpen_ = false;
+    gossipWindowOpen = false;
+    questDetailsOpen = false;
+
+    // Query item names for reward items
+    for (const auto& item : data.choiceRewards)
+        queryItemInfo(item.itemId, 0);
+    for (const auto& item : data.fixedRewards)
+        queryItemInfo(item.itemId, 0);
+}
+
+void GameHandler::completeQuest() {
+    if (!questRequestItemsOpen_ || state != WorldState::IN_WORLD || !socket) return;
+    auto packet = QuestgiverCompleteQuestPacket::build(
+        currentQuestRequestItems_.npcGuid, currentQuestRequestItems_.questId);
+    socket->send(packet);
+    questRequestItemsOpen_ = false;
+    currentQuestRequestItems_ = QuestRequestItemsData{};
+}
+
+void GameHandler::closeQuestRequestItems() {
+    questRequestItemsOpen_ = false;
+    currentQuestRequestItems_ = QuestRequestItemsData{};
+}
+
+void GameHandler::chooseQuestReward(uint32_t rewardIndex) {
+    if (!questOfferRewardOpen_ || state != WorldState::IN_WORLD || !socket) return;
+    uint64_t npcGuid = currentQuestOfferReward_.npcGuid;
+    auto packet = QuestgiverChooseRewardPacket::build(
+        npcGuid, currentQuestOfferReward_.questId, rewardIndex);
+    socket->send(packet);
+    questOfferRewardOpen_ = false;
+    currentQuestOfferReward_ = QuestOfferRewardData{};
+
+    // Re-query quest giver status so markers update
+    if (npcGuid) {
+        network::Packet qsPkt(static_cast<uint16_t>(Opcode::CMSG_QUESTGIVER_STATUS_QUERY));
+        qsPkt.writeUInt64(npcGuid);
+        socket->send(qsPkt);
+    }
+}
+
+void GameHandler::closeQuestOfferReward() {
+    questOfferRewardOpen_ = false;
+    currentQuestOfferReward_ = QuestOfferRewardData{};
+}
+
 void GameHandler::closeGossip() {
     gossipWindowOpen = false;
     currentGossip = GossipMessageData{};

src/game/world_packets.cpp

@@ -2087,6 +2087,124 @@ bool GossipMessageParser::parse(network::Packet& packet, GossipMessageData& data
     return true;
 }
 
+bool QuestRequestItemsParser::parse(network::Packet& packet, QuestRequestItemsData& data) {
+    if (packet.getSize() - packet.getReadPos() < 20) return false;
+    data.npcGuid = packet.readUInt64();
+    data.questId = packet.readUInt32();
+    data.title = packet.readString();
+    data.completionText = packet.readString();
+
+    if (packet.getReadPos() + 20 > packet.getSize()) {
+        LOG_INFO("Quest request items (short): id=", data.questId, " title='", data.title, "'");
+        return true;
+    }
+
+    /*emoteDelay*/ packet.readUInt32();
+    /*emote*/ packet.readUInt32();
+    /*autoCloseOnCancel*/ packet.readUInt32();
+    /*flags*/ packet.readUInt32();
+    /*suggestedPlayers*/ packet.readUInt32();
+
+    if (packet.getReadPos() + 4 > packet.getSize()) return true;
+    data.requiredMoney = packet.readUInt32();
+
+    if (packet.getReadPos() + 4 > packet.getSize()) return true;
+    uint32_t requiredItemCount = packet.readUInt32();
+    for (uint32_t i = 0; i < requiredItemCount; ++i) {
+        if (packet.getReadPos() + 12 > packet.getSize()) break;
+        QuestRewardItem item;
+        item.itemId = packet.readUInt32();
+        item.count = packet.readUInt32();
+        item.displayInfoId = packet.readUInt32();
+        if (item.itemId > 0)
+            data.requiredItems.push_back(item);
+    }
+
+    if (packet.getReadPos() + 4 > packet.getSize()) return true;
+    data.completableFlags = packet.readUInt32();
+
+    LOG_INFO("Quest request items: id=", data.questId, " title='", data.title,
+             "' items=", data.requiredItems.size(), " completable=", data.isCompletable());
+    return true;
+}
+
+bool QuestOfferRewardParser::parse(network::Packet& packet, QuestOfferRewardData& data) {
+    if (packet.getSize() - packet.getReadPos() < 20) return false;
+    data.npcGuid = packet.readUInt64();
+    data.questId = packet.readUInt32();
+    data.title = packet.readString();
+    data.rewardText = packet.readString();
+
+    if (packet.getReadPos() + 10 > packet.getSize()) {
+        LOG_INFO("Quest offer reward (short): id=", data.questId, " title='", data.title, "'");
+        return true;
+    }
+
+    /*autoFinish*/ packet.readUInt8();
+    /*flags*/ packet.readUInt32();
+    /*suggestedPlayers*/ packet.readUInt32();
+
+    // Emotes
+    if (packet.getReadPos() + 4 > packet.getSize()) return true;
+    uint32_t emoteCount = packet.readUInt32();
+    for (uint32_t i = 0; i < emoteCount; ++i) {
+        if (packet.getReadPos() + 8 > packet.getSize()) break;
+        packet.readUInt32(); // delay
+        packet.readUInt32(); // emote
+    }
+
+    // Choice reward items (pick one): count + 6 * (id, count, displayInfo)
+    if (packet.getReadPos() + 4 > packet.getSize()) return true;
+    /*choiceCount*/ packet.readUInt32();
+    for (uint32_t i = 0; i < 6; ++i) {
+        if (packet.getReadPos() + 12 > packet.getSize()) break;
+        QuestRewardItem item;
+        item.itemId = packet.readUInt32();
+        item.count = packet.readUInt32();
+        item.displayInfoId = packet.readUInt32();
+        if (item.itemId > 0)
+            data.choiceRewards.push_back(item);
+    }
+
+    // Fixed reward items: count + 4 * (id, count, displayInfo)
+    if (packet.getReadPos() + 4 > packet.getSize()) return true;
+    /*rewardCount*/ packet.readUInt32();
+    for (uint32_t i = 0; i < 4; ++i) {
+        if (packet.getReadPos() + 12 > packet.getSize()) break;
+        QuestRewardItem item;
+        item.itemId = packet.readUInt32();
+        item.count = packet.readUInt32();
+        item.displayInfoId = packet.readUInt32();
+        if (item.itemId > 0)
+            data.fixedRewards.push_back(item);
+    }
+
+    // Money and XP
+    if (packet.getReadPos() + 4 <= packet.getSize())
+        data.rewardMoney = packet.readUInt32();
+    if (packet.getReadPos() + 4 <= packet.getSize())
+        data.rewardXp = packet.readUInt32();
+
+    LOG_INFO("Quest offer reward: id=", data.questId, " title='", data.title,
+             "' choices=", data.choiceRewards.size(), " fixed=", data.fixedRewards.size());
+    return true;
+}
+
+network::Packet QuestgiverCompleteQuestPacket::build(uint64_t npcGuid, uint32_t questId) {
+    network::Packet packet(static_cast<uint16_t>(Opcode::CMSG_QUESTGIVER_COMPLETE_QUEST));
+    packet.writeUInt64(npcGuid);
+    packet.writeUInt32(questId);
+    return packet;
+}
+
+network::Packet QuestgiverChooseRewardPacket::build(uint64_t npcGuid, uint32_t questId, uint32_t rewardIndex) {
+    network::Packet packet(static_cast<uint16_t>(Opcode::CMSG_QUESTGIVER_CHOOSE_REWARD));
+    packet.writeUInt64(npcGuid);
+    packet.writeUInt32(questId);
+    packet.writeUInt32(rewardIndex);
+    return packet;
+}
+
 // ============================================================
 // Phase 5: Vendor
 // ============================================================
@@ -2103,6 +2221,7 @@ network::Packet BuyItemPacket::build(uint64_t vendorGuid, uint32_t itemId, uint3
     packet.writeUInt32(itemId);
     packet.writeUInt32(slot);
     packet.writeUInt8(count);
+    packet.writeUInt8(0);  // bag slot (0 = find any available bag slot)
     return packet;
 }
 

src/ui/game_screen.cpp

@@ -93,6 +93,8 @@ void GameScreen::render(game::GameHandler& gameHandler) {
     renderLootWindow(gameHandler);
     renderGossipWindow(gameHandler);
     renderQuestDetailsWindow(gameHandler);
+    renderQuestRequestItemsWindow(gameHandler);
+    renderQuestOfferRewardWindow(gameHandler);
     renderVendorWindow(gameHandler);
     renderQuestMarkers(gameHandler);
     renderMinimapMarkers(gameHandler);
@@ -2273,6 +2275,179 @@ void GameScreen::renderQuestDetailsWindow(game::GameHandler& gameHandler) {
     }
 }
 
+// ============================================================
+// Quest Request Items Window (turn-in progress check)
+// ============================================================
+
+void GameScreen::renderQuestRequestItemsWindow(game::GameHandler& gameHandler) {
+    if (!gameHandler.isQuestRequestItemsOpen()) return;
+
+    auto* window = core::Application::getInstance().getWindow();
+    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 - 225, screenH / 2 - 200), ImGuiCond_Appearing);
+    ImGui::SetNextWindowSize(ImVec2(450, 350), ImGuiCond_Appearing);
+
+    bool open = true;
+    const auto& quest = gameHandler.getQuestRequestItems();
+    if (ImGui::Begin(quest.title.c_str(), &open, ImGuiWindowFlags_NoCollapse)) {
+        if (!quest.completionText.empty()) {
+            ImGui::TextWrapped("%s", quest.completionText.c_str());
+        }
+
+        // Required items
+        if (!quest.requiredItems.empty()) {
+            ImGui::Spacing();
+            ImGui::Separator();
+            ImGui::TextColored(ImVec4(1.0f, 0.82f, 0.0f, 1.0f), "Required Items:");
+            for (const auto& item : quest.requiredItems) {
+                auto* info = gameHandler.getItemInfo(item.itemId);
+                if (info && info->valid)
+                    ImGui::Text("  %s x%u", info->name.c_str(), item.count);
+                else
+                    ImGui::Text("  Item %u x%u", item.itemId, item.count);
+            }
+        }
+
+        if (quest.requiredMoney > 0) {
+            ImGui::Spacing();
+            uint32_t g = quest.requiredMoney / 10000;
+            uint32_t s = (quest.requiredMoney % 10000) / 100;
+            uint32_t c = quest.requiredMoney % 100;
+            ImGui::Text("Required money: %ug %us %uc", g, s, c);
+        }
+
+        // Complete / Cancel buttons
+        ImGui::Spacing();
+        ImGui::Separator();
+        ImGui::Spacing();
+        float buttonW = (ImGui::GetContentRegionAvail().x - ImGui::GetStyle().ItemSpacing.x) * 0.5f;
+        if (quest.isCompletable()) {
+            if (ImGui::Button("Complete Quest", ImVec2(buttonW, 0))) {
+                gameHandler.completeQuest();
+            }
+        } else {
+            ImGui::BeginDisabled();
+            ImGui::Button("Incomplete", ImVec2(buttonW, 0));
+            ImGui::EndDisabled();
+        }
+        ImGui::SameLine();
+        if (ImGui::Button("Cancel", ImVec2(buttonW, 0))) {
+            gameHandler.closeQuestRequestItems();
+        }
+    }
+    ImGui::End();
+
+    if (!open) {
+        gameHandler.closeQuestRequestItems();
+    }
+}
+
+// ============================================================
+// Quest Offer Reward Window (choose reward)
+// ============================================================
+
+void GameScreen::renderQuestOfferRewardWindow(game::GameHandler& gameHandler) {
+    if (!gameHandler.isQuestOfferRewardOpen()) return;
+
+    auto* window = core::Application::getInstance().getWindow();
+    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 - 225, screenH / 2 - 200), ImGuiCond_Appearing);
+    ImGui::SetNextWindowSize(ImVec2(450, 400), ImGuiCond_Appearing);
+
+    bool open = true;
+    const auto& quest = gameHandler.getQuestOfferReward();
+    static int selectedChoice = -1;
+
+    if (ImGui::Begin(quest.title.c_str(), &open, ImGuiWindowFlags_NoCollapse)) {
+        if (!quest.rewardText.empty()) {
+            ImGui::TextWrapped("%s", quest.rewardText.c_str());
+        }
+
+        // Choice rewards (pick one)
+        if (!quest.choiceRewards.empty()) {
+            ImGui::Spacing();
+            ImGui::Separator();
+            ImGui::TextColored(ImVec4(1.0f, 0.82f, 0.0f, 1.0f), "Choose a reward:");
+            for (size_t i = 0; i < quest.choiceRewards.size(); ++i) {
+                const auto& item = quest.choiceRewards[i];
+                auto* info = gameHandler.getItemInfo(item.itemId);
+                char label[256];
+                if (info && info->valid)
+                    snprintf(label, sizeof(label), "%s x%u", info->name.c_str(), item.count);
+                else
+                    snprintf(label, sizeof(label), "Item %u x%u", item.itemId, item.count);
+
+                bool selected = (selectedChoice == static_cast<int>(i));
+                if (ImGui::Selectable(label, selected)) {
+                    selectedChoice = static_cast<int>(i);
+                }
+            }
+        }
+
+        // Fixed rewards (always given)
+        if (!quest.fixedRewards.empty()) {
+            ImGui::Spacing();
+            ImGui::Separator();
+            ImGui::TextColored(ImVec4(1.0f, 0.82f, 0.0f, 1.0f), "You will also receive:");
+            for (const auto& item : quest.fixedRewards) {
+                auto* info = gameHandler.getItemInfo(item.itemId);
+                if (info && info->valid)
+                    ImGui::Text("  %s x%u", info->name.c_str(), item.count);
+                else
+                    ImGui::Text("  Item %u x%u", item.itemId, item.count);
+            }
+        }
+
+        // Money / XP rewards
+        if (quest.rewardXp > 0 || quest.rewardMoney > 0) {
+            ImGui::Spacing();
+            ImGui::Separator();
+            ImGui::TextColored(ImVec4(1.0f, 0.82f, 0.0f, 1.0f), "Rewards:");
+            if (quest.rewardXp > 0)
+                ImGui::Text("  %u experience", quest.rewardXp);
+            if (quest.rewardMoney > 0) {
+                uint32_t g = quest.rewardMoney / 10000;
+                uint32_t s = (quest.rewardMoney % 10000) / 100;
+                uint32_t c = quest.rewardMoney % 100;
+                if (g > 0) ImGui::Text("  %ug %us %uc", g, s, c);
+                else if (s > 0) ImGui::Text("  %us %uc", s, c);
+                else ImGui::Text("  %uc", c);
+            }
+        }
+
+        // Complete button
+        ImGui::Spacing();
+        ImGui::Separator();
+        ImGui::Spacing();
+        float buttonW = (ImGui::GetContentRegionAvail().x - ImGui::GetStyle().ItemSpacing.x) * 0.5f;
+
+        bool canComplete = quest.choiceRewards.empty() || selectedChoice >= 0;
+        if (!canComplete) ImGui::BeginDisabled();
+        if (ImGui::Button("Complete Quest", ImVec2(buttonW, 0))) {
+            uint32_t rewardIdx = quest.choiceRewards.empty() ? 0 : static_cast<uint32_t>(selectedChoice);
+            gameHandler.chooseQuestReward(rewardIdx);
+            selectedChoice = -1;
+        }
+        if (!canComplete) ImGui::EndDisabled();
+
+        ImGui::SameLine();
+        if (ImGui::Button("Cancel", ImVec2(buttonW, 0))) {
+            gameHandler.closeQuestOfferReward();
+            selectedChoice = -1;
+        }
+    }
+    ImGui::End();
+
+    if (!open) {
+        gameHandler.closeQuestOfferReward();
+        selectedChoice = -1;
+    }
+}
+
 // ============================================================
 // Vendor Window (Phase 5)
 // ============================================================