python - <<'PY'
from datasets import load_dataset
from transformers import AutoTokenizer, AutoModelForCausalLM, Trainer, TrainingArguments, DataCollatorForLanguageModeling
import torch

model_id = "sshleifer/tiny-gpt2"  # 极小模型
tok = AutoTokenizer.from_pretrained(model_id)
tok.pad_token = tok.eos_token

ds = load_dataset("wikitext", "wikitext-2-raw-v1", split="train[:1%]")
def tok_fn(ex): return tok(ex["text"], truncation=True, padding="max_length", max_length=64)
ds = ds.map(tok_fn, batched=True, remove_columns=["text"])

mdl = AutoModelForCausalLM.from_pretrained(model_id)
collator = DataCollatorForLanguageModeling(tok, mlm=False)
args = TrainingArguments(
    output_dir="out-mini",
    per_device_train_batch_size=2,
    num_train_epochs=1,
    fp16=torch.cuda.is_available(),
    logging_steps=2,
    save_steps=10,
    report_to="none",
)

trainer = Trainer(model=mdl, args=args, train_dataset=ds, data_collator=collator)
trainer.train()
print("✅ 训练链路 OK")
PY