Revert "fallback BNBT, Compat with codec"

This reverts commit ce7004dba0.

src/main/java/vip/fubuki/playersync/sync/VanillaSync.java

@@ -375,8 +375,34 @@ public class VanillaSync {
             return ItemStack.EMPTY;
         }
 
-        String nbtString = deserializeString(serializedNbt);
+        CompoundTag compoundTag;
-        CompoundTag compoundTag = TagParser.parseTag(nbtString);
+        String nbtString = serializedNbt; // Will be overwritten with decoded SNBT for legacy formats
+
+        // Try binary NBT format first (new format, avoids SNBT round-trip issues)
+        if (serializedNbt.startsWith("BNBT:")) {
+            try {
+                compoundTag = deserializeBinaryBase64Tag(serializedNbt);
+            } catch (Exception e) {
+                PlayerSync.LOGGER.error("Failed to deserialize binary NBT data, skipping item.", e);
+                return ItemStack.EMPTY;
+            }
+        } else {
+            // Legacy SNBT-based deserialization (B64: or old custom format)
+            nbtString = deserializeString(serializedNbt);
+            try {
+                compoundTag = TagParser.parseTag(nbtString);
+            } catch (CommandSyntaxException e) {
+                // TagParser may fail on certain 1.21.1 component SNBT formats (e.g. nested lists [[{...}]])
+                // Try NbtUtils.snbtToStructure as a fallback
+                PlayerSync.LOGGER.warn("TagParser.parseTag failed, trying NbtUtils.snbtToStructure fallback. SNBT: {}", nbtString);
+                try {
+                    compoundTag = NbtUtils.snbtToStructure(nbtString);
+                } catch (CommandSyntaxException e2) {
+                    PlayerSync.LOGGER.error("Both SNBT parsers failed for data: {}", nbtString);
+                    throw e; // re-throw original exception
+                }
+            }
+        }
 
         if (compoundTag.isEmpty() || !compoundTag.contains("id", Tag.TAG_STRING)) {
             return ItemStack.EMPTY; // Invalid or empty tag
@@ -578,11 +604,42 @@ public class VanillaSync {
             // It's our placeholder, retrieve the original NBT string
             return itemStack.getComponents().get(DataComponents.CUSTOM_DATA).copyTag().getString("playersync:original_item_nbt");
         } else {
-            // It's a normal item or empty, serialize its current NBT
+            // It's a normal item or empty, serialize using binary NBT to avoid SNBT round-trip issues
-            return serialize(serializeNBT(itemStack).toString());
+            Tag tag = serializeNBT(itemStack);
+            if (tag instanceof CompoundTag compoundTag) {
+                return serializeTagToBinaryBase64(compoundTag);
+            }
+            // Fallback to SNBT-based serialization for non-compound tags
+            return serialize(tag.toString());
         }
     }
 
+    /**
+     * Serializes a CompoundTag to a Base64-encoded binary NBT string.
+     * This avoids SNBT round-trip issues where Tag.toString() produces SNBT
+     * that TagParser.parseTag() cannot parse back (e.g. with nested lists [[{...}]]).
+     */
+    public static String serializeTagToBinaryBase64(CompoundTag tag) {
+        try {
+            java.io.ByteArrayOutputStream baos = new java.io.ByteArrayOutputStream();
+            net.minecraft.nbt.NbtIo.writeCompressed(tag, baos);
+            return "BNBT:" + Base64.getEncoder().encodeToString(baos.toByteArray());
+        } catch (IOException e) {
+            PlayerSync.LOGGER.error("Failed to serialize NBT to binary, falling back to SNBT", e);
+            return serialize(tag.toString());
+        }
+    }
+
+    /**
+     * Deserializes a Base64-encoded binary NBT string back to a CompoundTag.
+     */
+    public static CompoundTag deserializeBinaryBase64Tag(String encoded) throws IOException {
+        String base64 = encoded.substring(5); // Remove "BNBT:" prefix
+        byte[] bytes = Base64.getDecoder().decode(base64);
+        java.io.ByteArrayInputStream bais = new java.io.ByteArrayInputStream(bytes);
+        return net.minecraft.nbt.NbtIo.readCompressed(bais, net.minecraft.nbt.NbtAccounter.unlimitedHeap());
+    }
+
     public static Tag serializeNBT(ItemStack itemStack) {
         if (itemStack == null || itemStack.isEmpty()) {
             return new CompoundTag();

src/main/java/vip/fubuki/playersync/sync/addons/ModsSupport.java

@@ -42,8 +42,18 @@ public class ModsSupport {
                         ResultSet rsBackpack = qrBackpack.resultSet();
                         if (rsBackpack.next()) {
                             String serialized = rsBackpack.getString("backpack_nbt");
-                            String nbtString = VanillaSync.deserializeString(serialized);
+                            CompoundTag backpackNbt;
-                            CompoundTag backpackNbt = TagParser.parseTag(nbtString);
+                            if (serialized.startsWith("BNBT:")) {
+                                backpackNbt = VanillaSync.deserializeBinaryBase64Tag(serialized);
+                            } else {
+                                String nbtString = VanillaSync.deserializeString(serialized);
+                                try {
+                                    backpackNbt = TagParser.parseTag(nbtString);
+                                } catch (CommandSyntaxException ex) {
+                                    PlayerSync.LOGGER.warn("TagParser.parseTag failed for backpack UUID {}, trying fallback", contentsUuid);
+                                    backpackNbt = net.minecraft.nbt.NbtUtils.snbtToStructure(nbtString);
+                                }
+                            }
                             // Update BackpackStorage with the retrieved NBT
                             net.p3pp3rf1y.sophisticatedbackpacks.backpack.BackpackStorage.get().setBackpackContents(contentsUuid, backpackNbt);
                             PlayerSync.LOGGER.info("Restored backpack data for UUID " + contentsUuid);
@@ -54,6 +64,8 @@ public class ModsSupport {
                         PlayerSync.LOGGER.error("Error restoring backpack data for UUID " + contentsUuid, e);
                     } catch (CommandSyntaxException e) {
                         PlayerSync.LOGGER.error("Error parsing backpack NBT for UUID {}. Skipping backpack.", contentsUuid, e);
+                    } catch (IOException e) {
+                        PlayerSync.LOGGER.error("Error reading binary backpack NBT for UUID {}. Skipping backpack.", contentsUuid, e);
                     }
                 } else {
                     PlayerSync.LOGGER.warn("Backpack item in slot " + slot + " has no contentsUuid during restore");
@@ -182,7 +194,7 @@ public class ModsSupport {
                 UUID contentsUuid = uuidOpt.get();
                 // Get internal backpack data from BackpackStorage (creates it if missing)
                 CompoundTag backpackNbt = net.p3pp3rf1y.sophisticatedbackpacks.backpack.BackpackStorage.get().getOrCreateBackpackContents(contentsUuid);
-                String serialized = VanillaSync.serialize(backpackNbt.toString());
+                String serialized = VanillaSync.serializeTagToBinaryBase64(backpackNbt);
                 try {
                     // Use REPLACE INTO so existing records are updated
                     JDBCsetUp.executeUpdate("REPLACE INTO backpack_data (uuid, backpack_nbt) VALUES ('" + contentsUuid + "', '" + serialized + "')");

src/main/java/vip/fubuki/playersync/util/LocalJsonUtil.java

@@ -46,8 +46,8 @@ public class LocalJsonUtil {
     public static String cleanSnbt(String snbt) {
         if (snbt == null) return null;
 
-        return snbt.replace("{\"\":", "{\"_\":")
+        return snbt.replaceAll(",\\s*\\{\"\":\"\"}", "")
-                .replace(",\"\":", ",\"_\":")
+                .replaceAll("\\{\"\":\"\"}\\s*,", "")
-                .replace("[\"\":", "[\"_\":");
+                .replaceAll("\\{\"\":\"\"}", "");
     }
 }