import torch
from safetensors.torch import load_file

# 3 个 shard 文件
files = [
    "diffusion_pytorch_model-00001-of-00003.safetensors",
    "diffusion_pytorch_model-00002-of-00003.safetensors",
    "diffusion_pytorch_model-00003-of-00003.safetensors",
]

merged_state_dict = {}

for f in files:
    print(f"Loading {f}")
    sd = load_file(f)  # dict[str, Tensor]
    overlap = set(merged_state_dict.keys()) & set(sd.keys())
    if overlap:
        raise RuntimeError(f"Duplicate keys found in {f}: {overlap}")
    merged_state_dict.update(sd)

print(f"Total parameters: {len(merged_state_dict)}")

# 保存为 PyTorch .pth
out = "diffusion_pytorch_model_merged.pth"
torch.save(merged_state_dict, out)
print(f"Saved merged model to {out}")