Add per-expansion asset overlay system and fix CharSections DBC layout

Expansion overlays allow each expansion to supplement the base asset data
via an assetManifest field in expansion.json, loaded at priority 50 (below
HD packs). The asset extractor gains --reference-manifest for delta-only
extraction. Also fixes CharSections field indices (VariationIndex=4,
ColorIndex=5, Texture1=6) across all DBC layout references.

Data/expansions/tbc/dbc_layouts.json

@@ -9,8 +9,8 @@
   },
   "CharSections": {
     "RaceID": 1, "SexID": 2, "BaseSection": 3,
-    "Texture1": 4, "Texture2": 5, "Texture3": 6,
+    "VariationIndex": 4, "ColorIndex": 5,
-    "VariationIndex": 8, "ColorIndex": 9
+    "Texture1": 6, "Texture2": 7, "Texture3": 8
   },
   "SpellIcon": { "ID": 0, "Path": 1 },
   "FactionTemplate": {

Data/expansions/wotlk/dbc_layouts.json

@@ -9,8 +9,8 @@
   },
   "CharSections": {
     "RaceID": 1, "SexID": 2, "BaseSection": 3,
-    "Texture1": 4, "Texture2": 5, "Texture3": 6,
+    "VariationIndex": 4, "ColorIndex": 5,
-    "VariationIndex": 8, "ColorIndex": 9
+    "Texture1": 6, "Texture2": 7, "Texture3": 8
   },
   "SpellIcon": { "ID": 0, "Path": 1 },
   "FactionTemplate": {

include/core/application.hpp

@@ -216,6 +216,8 @@ private:
     bool wasAutoAttacking_ = false;
     void processPendingMount();
     bool creatureLookupsBuilt_ = false;
+    bool mapNameCacheLoaded_ = false;
+    std::unordered_map<uint32_t, std::string> mapNameById_;
 
     // Deferred creature spawn queue (throttles spawning to avoid hangs)
     struct PendingCreatureSpawn {

include/game/expansion_profile.hpp

@@ -30,6 +30,7 @@ struct ExpansionProfile {
     std::string locale = "enUS";
     uint32_t timezone = 0;
     std::string dataPath;      // Absolute path to expansion data dir
+    std::string assetManifest;  // Path to expansion-specific asset manifest (absolute, resolved from dataPath)
     uint32_t maxLevel = 60;
     std::vector<uint32_t> races;
     std::vector<uint32_t> classes;

src/core/application.cpp

@@ -231,6 +231,16 @@ bool Application::initialize() {
             }
             hdPackManager_->applyToAssetManager(assetManager.get(), expansionId);
         }
+
+        // Load expansion-specific asset overlay (priority 50, below HD packs at 100+)
+        if (expansionRegistry_) {
+            auto* activeProfile = expansionRegistry_->getActive();
+            if (activeProfile && !activeProfile->assetManifest.empty()) {
+                if (assetManager->addOverlayManifest(activeProfile->assetManifest, 50, "expansion_overlay")) {
+                    LOG_INFO("Added expansion asset overlay: ", activeProfile->assetManifest);
+                }
+            }
+        }
     } else {
         LOG_WARNING("Failed to initialize asset manager - asset loading will be unavailable");
         LOG_WARNING("Set WOW_DATA_PATH environment variable to your WoW Data directory");
@@ -493,7 +503,19 @@ void Application::reloadExpansionData() {
     if (assetManager && !profile->dataPath.empty()) {
         assetManager->setExpansionDataPath(profile->dataPath);
         assetManager->clearDBCCache();
+
+        // Swap expansion asset overlay
+        assetManager->removeOverlay("expansion_overlay");
+        if (!profile->assetManifest.empty()) {
+            if (assetManager->addOverlayManifest(profile->assetManifest, 50, "expansion_overlay")) {
+                LOG_INFO("Swapped expansion asset overlay: ", profile->assetManifest);
+            }
+        }
     }
+
+    // Reset map name cache so it reloads from new expansion's Map.dbc
+    mapNameCacheLoaded_ = false;
+    mapNameById_.clear();
 }
 
 void Application::logoutToLogin() {
@@ -1828,13 +1850,13 @@ void Application::spawnPlayerCharacter() {
                             uint32_t raceId = charSectionsDbc->getUInt32(r, csL ? (*csL)["RaceID"] : 1);
                             uint32_t sexId = charSectionsDbc->getUInt32(r, csL ? (*csL)["SexID"] : 2);
                             uint32_t baseSection = charSectionsDbc->getUInt32(r, csL ? (*csL)["BaseSection"] : 3);
-                            uint32_t variationIndex = charSectionsDbc->getUInt32(r, csL ? (*csL)["VariationIndex"] : 8);
+                            uint32_t variationIndex = charSectionsDbc->getUInt32(r, csL ? (*csL)["VariationIndex"] : 4);
-                            uint32_t colorIndex = charSectionsDbc->getUInt32(r, csL ? (*csL)["ColorIndex"] : 9);
+                            uint32_t colorIndex = charSectionsDbc->getUInt32(r, csL ? (*csL)["ColorIndex"] : 5);
 
                             if (raceId != targetRaceId || sexId != targetSexId) continue;
 
                             // Section 0 = skin: match by colorIndex = skin byte
-                            const uint32_t csTex1 = csL ? (*csL)["Texture1"] : 4;
+                            const uint32_t csTex1 = csL ? (*csL)["Texture1"] : 6;
                             if (baseSection == 0 && !foundSkin && colorIndex == charSkinId) {
                                 std::string tex1 = charSectionsDbc->getString(r, csTex1);
                                 if (!tex1.empty()) {
@@ -2409,28 +2431,26 @@ void Application::loadOnlineWorldTerrain(uint32_t mapId, float x, float y, float
 
     // Resolve map folder name from Map.dbc (authoritative for world/instance maps).
     // This is required for instances like DeeprunTram (map 369) that are not Azeroth/Kalimdor.
-    static bool mapNameCacheLoaded = false;
+    if (!mapNameCacheLoaded_ && assetManager) {
-    static std::unordered_map<uint32_t, std::string> mapNameById;
+        mapNameCacheLoaded_ = true;
-    if (!mapNameCacheLoaded && assetManager) {
-        mapNameCacheLoaded = true;
         if (auto mapDbc = assetManager->loadDBC("Map.dbc"); mapDbc && mapDbc->isLoaded()) {
-            mapNameById.reserve(mapDbc->getRecordCount());
+            mapNameById_.reserve(mapDbc->getRecordCount());
             const auto* mapL = pipeline::getActiveDBCLayout() ? pipeline::getActiveDBCLayout()->getLayout("Map") : nullptr;
             for (uint32_t i = 0; i < mapDbc->getRecordCount(); i++) {
                 uint32_t id = mapDbc->getUInt32(i, mapL ? (*mapL)["ID"] : 0);
                 std::string internalName = mapDbc->getString(i, mapL ? (*mapL)["InternalName"] : 1);
-                if (!internalName.empty() && mapNameById.find(id) == mapNameById.end()) {
+                if (!internalName.empty() && mapNameById_.find(id) == mapNameById_.end()) {
-                    mapNameById[id] = std::move(internalName);
+                    mapNameById_[id] = std::move(internalName);
                 }
             }
-            LOG_INFO("Loaded Map.dbc map-name cache: ", mapNameById.size(), " entries");
+            LOG_INFO("Loaded Map.dbc map-name cache: ", mapNameById_.size(), " entries");
         } else {
             LOG_WARNING("Map.dbc not available; using fallback map-id mapping");
         }
     }
 
     std::string mapName;
-    if (auto it = mapNameById.find(mapId); it != mapNameById.end()) {
+    if (auto it = mapNameById_.find(mapId); it != mapNameById_.end()) {
         mapName = it->second;
     } else {
         mapName = mapIdToName(mapId);
@@ -3122,15 +3142,15 @@ void Application::spawnOnlineCreature(uint64_t guid, uint32_t displayId, float x
                         uint32_t raceId = charSectionsDbc->getUInt32(r, csL2 ? (*csL2)["RaceID"] : 1);
                         uint32_t sexId = charSectionsDbc->getUInt32(r, csL2 ? (*csL2)["SexID"] : 2);
                         uint32_t section = charSectionsDbc->getUInt32(r, csL2 ? (*csL2)["BaseSection"] : 3);
-                        uint32_t variation = charSectionsDbc->getUInt32(r, csL2 ? (*csL2)["VariationIndex"] : 8);
+                        uint32_t variation = charSectionsDbc->getUInt32(r, csL2 ? (*csL2)["VariationIndex"] : 4);
-                        uint32_t colorIdx = charSectionsDbc->getUInt32(r, csL2 ? (*csL2)["ColorIndex"] : 9);
+                        uint32_t colorIdx = charSectionsDbc->getUInt32(r, csL2 ? (*csL2)["ColorIndex"] : 5);
 
                         if (raceId != targetRace || sexId != targetSex) continue;
                         if (section != 3) continue;  // Section 3 = hair
                         if (variation != static_cast<uint32_t>(extra.hairStyleId)) continue;
                         if (colorIdx != static_cast<uint32_t>(extra.hairColorId)) continue;
 
-                        hairTexPath = charSectionsDbc->getString(r, csL2 ? (*csL2)["Texture1"] : 4);
+                        hairTexPath = charSectionsDbc->getString(r, csL2 ? (*csL2)["Texture1"] : 6);
                         break;
                     }
 
@@ -3667,7 +3687,7 @@ void Application::spawnOnlinePlayer(uint64_t guid,
         const auto* csL = pipeline::getActiveDBCLayout() ? pipeline::getActiveDBCLayout()->getLayout("CharSections") : nullptr;
         uint32_t targetRaceId = raceId;
         uint32_t targetSexId = genderId;
-        const uint32_t csTex1 = csL ? (*csL)["Texture1"] : 4;
+        const uint32_t csTex1 = csL ? (*csL)["Texture1"] : 6;
 
         bool foundSkin = false;
         bool foundUnderwear = false;
@@ -3679,8 +3699,8 @@ void Application::spawnOnlinePlayer(uint64_t guid,
             uint32_t rRace = charSectionsDbc->getUInt32(r, csL ? (*csL)["RaceID"] : 1);
             uint32_t rSex = charSectionsDbc->getUInt32(r, csL ? (*csL)["SexID"] : 2);
             uint32_t baseSection = charSectionsDbc->getUInt32(r, csL ? (*csL)["BaseSection"] : 3);
-            uint32_t variationIndex = charSectionsDbc->getUInt32(r, csL ? (*csL)["VariationIndex"] : 8);
+            uint32_t variationIndex = charSectionsDbc->getUInt32(r, csL ? (*csL)["VariationIndex"] : 4);
-            uint32_t colorIndex = charSectionsDbc->getUInt32(r, csL ? (*csL)["ColorIndex"] : 9);
+            uint32_t colorIndex = charSectionsDbc->getUInt32(r, csL ? (*csL)["ColorIndex"] : 5);
 
             if (rRace != targetRaceId || rSex != targetSexId) continue;
 

src/game/expansion_profile.cpp

@@ -176,6 +176,12 @@ bool ExpansionRegistry::loadProfile(const std::string& jsonPath, const std::stri
         v = jsonValue(json, "locale"); if (!v.empty()) p.locale = v;
         p.timezone = static_cast<uint32_t>(jsonInt(json, "timezone", static_cast<int>(p.timezone)));
     }
+    // Expansion-specific asset manifest (overlay for base data)
+    p.assetManifest = jsonValue(json, "assetManifest");
+    if (!p.assetManifest.empty() && p.assetManifest[0] != '/') {
+        p.assetManifest = dirPath + "/" + p.assetManifest;
+    }
+
     p.maxLevel = static_cast<uint32_t>(jsonInt(json, "maxLevel", 60));
     p.races = jsonUintArray(json, "races");
     p.classes = jsonUintArray(json, "classes");

src/game/game_handler.cpp

@@ -274,6 +274,7 @@ void GameHandler::update(float deltaTime) {
             auto pkt = InspectPacket::build(guid);
             socket->send(pkt);
             inspectRateLimit_ = 0.75f; // keep it gentle
+            LOG_INFO("Sent CMSG_INSPECT for player 0x", std::hex, guid, std::dec);
         }
     }
 
@@ -5543,6 +5544,7 @@ void GameHandler::updateOtherPlayerVisibleItems(uint64_t guid, const std::map<ui
         // Layout not detected yet — queue this player for inspect as fallback.
         if (socket && state == WorldState::IN_WORLD) {
             pendingAutoInspect_.insert(guid);
+            LOG_INFO("Queued player 0x", std::hex, guid, std::dec, " for auto-inspect (layout not detected)");
         }
         return;
     }

src/pipeline/dbc_layout.cpp

@@ -24,8 +24,8 @@ void DBCLayout::loadWotlkDefaults() {
 
     // CharSections.dbc
     layouts_["CharSections"] = {{{ "RaceID", 1 }, { "SexID", 2 }, { "BaseSection", 3 },
-        { "Texture1", 4 }, { "Texture2", 5 }, { "Texture3", 6 },
+        { "VariationIndex", 4 }, { "ColorIndex", 5 },
-        { "VariationIndex", 8 }, { "ColorIndex", 9 }}};
+        { "Texture1", 6 }, { "Texture2", 7 }, { "Texture3", 8 }}};
 
     // SpellIcon.dbc (Icon.dbc in code but actually SpellIcon)
     layouts_["SpellIcon"] = {{{ "ID", 0 }, { "Path", 1 }}};

src/rendering/character_preview.cpp

@@ -167,19 +167,24 @@ bool CharacterPreview::loadCharacter(game::Race race, game::Gender gender,
 
         const auto* csL = pipeline::getActiveDBCLayout() ? pipeline::getActiveDBCLayout()->getLayout("CharSections") : nullptr;
 
+        uint32_t fRace = csL ? (*csL)["RaceID"] : 1;
+        uint32_t fSex = csL ? (*csL)["SexID"] : 2;
+        uint32_t fBase = csL ? (*csL)["BaseSection"] : 3;
+        uint32_t fVar = csL ? (*csL)["VariationIndex"] : 4;
+        uint32_t fColor = csL ? (*csL)["ColorIndex"] : 5;
         for (uint32_t r = 0; r < charSectionsDbc->getRecordCount(); r++) {
-            uint32_t raceId = charSectionsDbc->getUInt32(r, csL ? (*csL)["RaceID"] : 1);
+            uint32_t raceId = charSectionsDbc->getUInt32(r, fRace);
-            uint32_t sexId = charSectionsDbc->getUInt32(r, csL ? (*csL)["SexID"] : 2);
+            uint32_t sexId = charSectionsDbc->getUInt32(r, fSex);
-            uint32_t baseSection = charSectionsDbc->getUInt32(r, csL ? (*csL)["BaseSection"] : 3);
+            uint32_t baseSection = charSectionsDbc->getUInt32(r, fBase);
-            uint32_t variationIndex = charSectionsDbc->getUInt32(r, csL ? (*csL)["VariationIndex"] : 8);
+            uint32_t variationIndex = charSectionsDbc->getUInt32(r, fVar);
-            uint32_t colorIndex = charSectionsDbc->getUInt32(r, csL ? (*csL)["ColorIndex"] : 9);
+            uint32_t colorIndex = charSectionsDbc->getUInt32(r, fColor);
 
             if (raceId != targetRaceId || sexId != targetSexId) continue;
 
             // Section 0: Body skin (variation=0, colorIndex = skin color)
             if (baseSection == 0 && !foundSkin &&
                 variationIndex == 0 && colorIndex == static_cast<uint32_t>(skin)) {
-                std::string tex1 = charSectionsDbc->getString(r, csL ? (*csL)["Texture1"] : 4);
+                std::string tex1 = charSectionsDbc->getString(r, csL ? (*csL)["Texture1"] : 6);
                 if (!tex1.empty()) {
                     bodySkinPath_ = tex1;
                     foundSkin = true;
@@ -189,8 +194,8 @@ bool CharacterPreview::loadCharacter(game::Race race, game::Gender gender,
             else if (baseSection == 1 && !foundFace &&
                      variationIndex == static_cast<uint32_t>(face) &&
                      colorIndex == static_cast<uint32_t>(skin)) {
-                std::string tex1 = charSectionsDbc->getString(r, csL ? (*csL)["Texture1"] : 4);
+                std::string tex1 = charSectionsDbc->getString(r, csL ? (*csL)["Texture1"] : 6);
-                std::string tex2 = charSectionsDbc->getString(r, csL ? (*csL)["Texture2"] : 5);
+                std::string tex2 = charSectionsDbc->getString(r, csL ? (*csL)["Texture2"] : 7);
                 if (!tex1.empty()) faceLowerPath = tex1;
                 if (!tex2.empty()) faceUpperPath = tex2;
                 foundFace = true;
@@ -199,7 +204,7 @@ bool CharacterPreview::loadCharacter(game::Race race, game::Gender gender,
             else if (baseSection == 3 && !foundHair &&
                      variationIndex == static_cast<uint32_t>(hairStyle) &&
                      colorIndex == static_cast<uint32_t>(hairColor)) {
-                std::string tex1 = charSectionsDbc->getString(r, csL ? (*csL)["Texture1"] : 4);
+                std::string tex1 = charSectionsDbc->getString(r, csL ? (*csL)["Texture1"] : 6);
                 if (!tex1.empty()) {
                     hairScalpPath = tex1;
                     foundHair = true;
@@ -208,7 +213,7 @@ bool CharacterPreview::loadCharacter(game::Race race, game::Gender gender,
             // Section 4: Underwear (variation=0, colorIndex = skin color)
             else if (baseSection == 4 && !foundUnderwear &&
                      variationIndex == 0 && colorIndex == static_cast<uint32_t>(skin)) {
-                uint32_t texBase = csL ? (*csL)["Texture1"] : 4;
+                uint32_t texBase = csL ? (*csL)["Texture1"] : 6;
                 for (uint32_t f = texBase; f <= texBase + 2; f++) {
                     std::string tex = charSectionsDbc->getString(r, f);
                     if (!tex.empty()) {
@@ -220,14 +225,9 @@ bool CharacterPreview::loadCharacter(game::Race race, game::Gender gender,
         }
     }
 
-    LOG_INFO("CharPreview tex lookup: bodySkin=", bodySkinPath_, " faceLower=", faceLowerPath,
-        " faceUpper=", faceUpperPath, " hairScalp=", hairScalpPath,
-        " underwear=", underwearPaths.size());
-
     // Assign texture filenames on model before GPU upload
     for (size_t ti = 0; ti < model.textures.size(); ti++) {
         auto& tex = model.textures[ti];
-        LOG_INFO("  model.textures[", ti, "]: type=", tex.type, " filename=", tex.filename);
         if (tex.type == 1 && tex.filename.empty() && !bodySkinPath_.empty()) {
             tex.filename = bodySkinPath_;
         } else if (tex.type == 6 && tex.filename.empty() && !hairScalpPath.empty()) {
@@ -256,9 +256,6 @@ bool CharacterPreview::loadCharacter(game::Race race, game::Gender gender,
         LOG_WARNING("CharacterPreview: failed to load model to GPU");
         return false;
     }
-    LOG_INFO("CharPreview: model loaded to GPU, textureLookup size=", model.textureLookup.size(),
-        " materials=", model.materials.size(), " batches=", model.batches.size());
-
     // Composite body skin + face + underwear overlays
     if (!bodySkinPath_.empty()) {
         std::vector<std::string> layers;

src/ui/character_create_screen.cpp

@@ -179,8 +179,8 @@ void CharacterCreateScreen::updateAppearanceRanges() {
         if (raceId != targetRaceId || sexId != targetSexId) continue;
 
         uint32_t baseSection = dbc->getUInt32(r, csL ? (*csL)["BaseSection"] : 3);
-        uint32_t variationIndex = dbc->getUInt32(r, csL ? (*csL)["VariationIndex"] : 8);
+        uint32_t variationIndex = dbc->getUInt32(r, csL ? (*csL)["VariationIndex"] : 4);
-        uint32_t colorIndex = dbc->getUInt32(r, csL ? (*csL)["ColorIndex"] : 9);
+        uint32_t colorIndex = dbc->getUInt32(r, csL ? (*csL)["ColorIndex"] : 5);
 
         if (baseSection == 0 && variationIndex == 0) {
             skinMax = std::max(skinMax, static_cast<int>(colorIndex));
@@ -206,8 +206,8 @@ void CharacterCreateScreen::updateAppearanceRanges() {
         if (raceId != targetRaceId || sexId != targetSexId) continue;
 
         uint32_t baseSection = dbc->getUInt32(r, csL ? (*csL)["BaseSection"] : 3);
-        uint32_t variationIndex = dbc->getUInt32(r, csL ? (*csL)["VariationIndex"] : 8);
+        uint32_t variationIndex = dbc->getUInt32(r, csL ? (*csL)["VariationIndex"] : 4);
-        uint32_t colorIndex = dbc->getUInt32(r, csL ? (*csL)["ColorIndex"] : 9);
+        uint32_t colorIndex = dbc->getUInt32(r, csL ? (*csL)["ColorIndex"] : 5);
 
         if (baseSection == 1 && colorIndex == static_cast<uint32_t>(skin)) {
             faceMax = std::max(faceMax, static_cast<int>(variationIndex));

tools/asset_extract/extractor.cpp

@@ -246,6 +246,58 @@ static std::unordered_set<std::string> buildWantedDbcSet(const Extractor::Option
     return wanted;
 }
 
+// Load all entry keys from a manifest.json into a set of normalized WoW paths.
+// This is a minimal parser — just extracts the keys from the "entries" object
+// without pulling in a full JSON library.
+static std::unordered_set<std::string> loadManifestKeys(const std::string& manifestPath) {
+    std::unordered_set<std::string> keys;
+    std::ifstream f(manifestPath);
+    if (!f.is_open()) {
+        std::cerr << "Failed to open reference manifest: " << manifestPath << "\n";
+        return keys;
+    }
+
+    // Find the "entries" section, then extract keys from each line
+    bool inEntries = false;
+    std::string line;
+    while (std::getline(f, line)) {
+        if (!inEntries) {
+            if (line.find("\"entries\"") != std::string::npos) {
+                inEntries = true;
+            }
+            continue;
+        }
+
+        // End of entries block
+        size_t closeBrace = line.find_first_not_of(" \t");
+        if (closeBrace != std::string::npos && line[closeBrace] == '}') {
+            break;
+        }
+
+        // Extract key: find first quoted string on the line
+        size_t q1 = line.find('"');
+        if (q1 == std::string::npos) continue;
+        size_t q2 = q1 + 1;
+        // Find closing quote (handle escaped backslashes)
+        std::string key;
+        while (q2 < line.size() && line[q2] != '"') {
+            if (line[q2] == '\\' && q2 + 1 < line.size()) {
+                key += line[q2 + 1];  // unescape \\, \", etc.
+                q2 += 2;
+            } else {
+                key += line[q2];
+                q2++;
+            }
+        }
+
+        if (!key.empty()) {
+            keys.insert(key);  // Already normalized (lowercase, backslashes)
+        }
+    }
+
+    return keys;
+}
+
 // Known WoW client locales
 static const std::vector<std::string> kKnownLocales = {
     "enUS", "enGB", "deDE", "frFR", "esES", "esMX",
@@ -485,6 +537,22 @@ bool Extractor::run(const Options& opts) {
         return false;
     }
 
+    // Delta extraction: filter out files that already exist in the reference manifest
+    if (!opts.referenceManifest.empty()) {
+        auto refKeys = loadManifestKeys(opts.referenceManifest);
+        if (refKeys.empty()) {
+            std::cerr << "Warning: reference manifest is empty or failed to load\n";
+        } else {
+            size_t before = files.size();
+            files.erase(std::remove_if(files.begin(), files.end(),
+                [&refKeys](const std::string& wowPath) {
+                    return refKeys.count(normalizeWowPath(wowPath)) > 0;
+                }), files.end());
+            std::cout << "Delta filter: " << before << " -> " << files.size()
+                      << " files (" << (before - files.size()) << " already in reference)\n";
+        }
+    }
+
     if (files.empty()) {
         std::cerr << "No files to extract\n";
         return false;

tools/asset_extract/extractor.hpp

@@ -25,6 +25,7 @@ public:
         bool skipDbcExtraction = false; // Extract visual assets only (recommended when CSV DBCs are in repo)
         bool onlyUsedDbcs = false; // Extract only the DBC files wowee uses (implies DBFilesClient/*.dbc filter)
         std::string dbcCsvOutputDir; // When set, write CSVs into this directory instead of outputDir/expansions/<exp>/db
+        std::string referenceManifest; // If set, only extract files NOT in this manifest (delta extraction)
     };
 
     struct Stats {

tools/asset_extract/main.cpp

@@ -19,6 +19,8 @@ static void printUsage(const char* prog) {
               << "  --skip-dbc          Do not extract DBFilesClient/*.dbc (visual assets only)\n"
               << "  --dbc-csv           Convert selected DBFilesClient/*.dbc to CSV under\n"
               << "                      <output>/expansions/<expansion>/db/*.csv (for committing)\n"
+              << "  --reference-manifest <path>\n"
+              << "                      Only extract files NOT in this manifest (delta extraction)\n"
               << "  --dbc-csv-out <dir> Write CSV DBCs into <dir> (overrides default output path)\n"
               << "  --verify            CRC32 verify all extracted files\n"
               << "  --threads <N>       Number of extraction threads (default: auto)\n"
@@ -50,6 +52,8 @@ int main(int argc, char** argv) {
             opts.generateDbcCsv = true;
         } else if (std::strcmp(argv[i], "--dbc-csv-out") == 0 && i + 1 < argc) {
             opts.dbcCsvOutputDir = argv[++i];
+        } else if (std::strcmp(argv[i], "--reference-manifest") == 0 && i + 1 < argc) {
+            opts.referenceManifest = argv[++i];
         } else if (std::strcmp(argv[i], "--verify") == 0) {
             opts.verify = true;
         } else if (std::strcmp(argv[i], "--verbose") == 0) {
@@ -114,6 +118,10 @@ int main(int argc, char** argv) {
         }
     }
 
+    if (!opts.referenceManifest.empty()) {
+        std::cout << "Reference:     " << opts.referenceManifest << " (delta mode)\n";
+    }
+
     if (!wowee::tools::Extractor::run(opts)) {
         std::cerr << "Extraction failed!\n";
         return 1;