Implemented new Delcare Command packet for new versions 1.20.6-1.21.11 and fixed it for 1.20.4.

tools/README.md

@@ -102,6 +102,14 @@ Reads `EntityDataSerializers.java` static block registration order. Maps Java fi
 2. MCC's `EntityMetaDataType.cs` enum
 3. `DataTypes.cs` ReadNextMetadata() read logic
 
+## gen_command_argument_registry.py — Generate DeclareCommands registry arrays
+
+```bash
+python3 tools/gen_command_argument_registry.py 1.20.6 1.21.5 1.21.6
+```
+
+Reads `ArgumentTypeInfos.java`, skips the `SharedConstants.IS_RUNNING_IN_IDE` block, and prints C# array initializers for the runtime `COMMAND_ARGUMENT_TYPE` registry order. Use this when Mojang inserts new command argument types and the modern `DeclareCommands` parser needs updated ID routing.
+
 ## Recommended workflow
 
 1. Generate server reports (Step 0)

tools/gen_command_argument_registry.py

@@ -0,0 +1,85 @@
+
+#!/usr/bin/env python3
+"""
+Generate ordered DeclareCommands argument-type arrays from decompiled ArgumentTypeInfos.java.
+
+The runtime server registry excludes registrations guarded by SharedConstants.IS_RUNNING_IN_IDE,
+so this script skips that block before emitting the final order.
+"""
+
+from __future__ import annotations
+
+import argparse
+import re
+from pathlib import Path
+
+
+REGISTER_RE = re.compile(r'register\(\$\$0, "([^"]+)"')
+
+
+def extract_runtime_argument_types(path: Path) -> list[str]:
+    names: list[str] = []
+    skipping_ide_block = False
+    brace_depth = 0
+
+    for line in path.read_text(encoding="utf-8").splitlines():
+        if "if (SharedConstants.IS_RUNNING_IN_IDE)" in line:
+            skipping_ide_block = True
+            brace_depth += line.count("{") - line.count("}")
+            continue
+
+        if skipping_ide_block:
+            brace_depth += line.count("{") - line.count("}")
+            if brace_depth <= 0:
+                skipping_ide_block = False
+                brace_depth = 0
+            continue
+
+        match = REGISTER_RE.search(line)
+        if match:
+            names.append(match.group(1))
+
+    return names
+
+
+def emit_csharp_array(version: str, names: list[str]) -> str:
+    lines = [
+        f"// {version} ({len(names)})",
+        f"private static readonly string[] s_modernArgumentTypes{version.replace('.', '')} =",
+        "[",
+    ]
+
+    for index, name in enumerate(names):
+        suffix = "," if index < len(names) - 1 else ""
+        lines.append(f'    "{name}"{suffix}')
+
+    lines.append("];")
+    return "\n".join(lines)
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument(
+        "versions",
+        nargs="+",
+        help="Minecraft version folders under MinecraftOfficial/, for example: 1.20.6 1.21.5 1.21.6",
+    )
+    parser.add_argument(
+        "--repo-root",
+        default=Path(__file__).resolve().parents[1],
+        type=Path,
+        help="Repository root. Defaults to the current repo.",
+    )
+    args = parser.parse_args()
+
+    for version in args.versions:
+        source = args.repo_root / "MinecraftOfficial" / f"{version}-decompiled" / "net" / "minecraft" / "commands" / "synchronization" / "ArgumentTypeInfos.java"
+        names = extract_runtime_argument_types(source)
+        print(emit_csharp_array(version, names))
+        print()
+
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())