scripts: add rename_arch.py + gitignore qwen-suffixed rebadges

Promotes the previously-untracked rename_arch.py to a committed tool.
It walks a GGUF's KV section and renames general.architecture (and
every <old_arch>.* namespaced key) to a new arch string while leaving
tensor data byte-identical. Used once for the Janus-35B qwen35moe ->
qwen36moe rebadge (commit 40cafdb in FoolDev/Janus-35B, since reverted
in ee40cb2 because no released ollama/llama.cpp recognized qwen36moe).

Also adds an ignore pattern for Thanatos-27B.*.qwen[0-9]*.gguf so
local rebadge outputs from this script don't accidentally get
committed/pushed to the LFS layer the HF Ollama bridge serves.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.gitignore

@@ -11,6 +11,10 @@ venv/
 # "Use this model" widget (ollama run hf.co/FoolDev/thanatos-27b).
 *.gguf
 !Thanatos-27B.*.gguf
+# Local-only rebadge experiments produced by scripts/rename_arch.py.
+# These re-stamp general.architecture and are not loadable by current
+# ollama / llama.cpp; don't track or push them.
+Thanatos-27B.*.qwen[0-9]*.gguf
 *.safetensors
 *.bin
 

scripts/rename_arch.py

@@ -0,0 +1,77 @@
+#!/usr/bin/env python3
+"""Rename GGUF architecture (and all arch-namespaced KV keys)."""
+from __future__ import annotations
+
+import argparse
+import sys
+from pathlib import Path
+
+from tqdm import tqdm
+
+from gguf import GGUFReader, GGUFValueType, GGUFWriter
+from gguf.constants import Keys
+
+
+def rename(src: Path, dst: Path, old_arch: str, new_arch: str) -> None:
+    reader = GGUFReader(src, "r")
+    cur = reader.get_field(Keys.General.ARCHITECTURE)
+    if cur is None:
+        sys.exit(f"no {Keys.General.ARCHITECTURE} in {src}")
+    cur_val = str(bytes(cur.parts[cur.data[0]]), encoding="utf-8")
+    if cur_val != old_arch:
+        sys.exit(f"expected arch={old_arch!r}, found {cur_val!r}")
+
+    writer = GGUFWriter(dst, new_arch, endianess=reader.endianess)
+
+    renamed_keys = 0
+    for field in reader.fields.values():
+        # GGUFWriter writes general.architecture from the `arch` ctor arg
+        if field.name == Keys.General.ARCHITECTURE or field.name.startswith("GGUF."):
+            continue
+
+        new_name = field.name
+        if field.name.startswith(f"{old_arch}."):
+            new_name = f"{new_arch}." + field.name[len(old_arch) + 1 :]
+            renamed_keys += 1
+
+        val_type = field.types[0]
+        sub_type = field.types[-1] if val_type == GGUFValueType.ARRAY else None
+        writer.add_key_value(new_name, field.contents(), val_type, sub_type=sub_type)
+
+    total_bytes = 0
+    for tensor in reader.tensors:
+        total_bytes += tensor.n_bytes
+        writer.add_tensor_info(
+            tensor.name,
+            tensor.data.shape,
+            tensor.data.dtype,
+            tensor.data.nbytes,
+            tensor.tensor_type,
+        )
+
+    print(f"[*] renamed {renamed_keys} {old_arch}.* keys -> {new_arch}.*")
+    print(f"[*] writing {dst}")
+
+    bar = tqdm(desc="Writing", total=total_bytes, unit="B", unit_scale=True)
+    writer.write_header_to_file()
+    writer.write_kv_data_to_file()
+    writer.write_ti_data_to_file()
+    for tensor in reader.tensors:
+        writer.write_tensor_data(tensor.data, tensor_endianess=reader.endianess)
+        bar.update(tensor.n_bytes)
+    writer.close()
+    bar.close()
+
+
+def main() -> None:
+    p = argparse.ArgumentParser()
+    p.add_argument("input", type=Path)
+    p.add_argument("output", type=Path)
+    p.add_argument("--from-arch", default="qwen35")
+    p.add_argument("--to-arch", default="qwen36")
+    args = p.parse_args()
+    rename(args.input, args.output, args.from_arch, args.to_arch)
+
+
+if __name__ == "__main__":
+    main()