Add RWKV LoRA defaults and opt-in test

[nirbo]

Summary

• Add rwkv and rwkv7 entries to the LoRA target-module mapping so Transformers-based RWKV checkpoints automatically receive adapters.
• Document the new behaviour in the README with a short RWKV snippet.
• Introduce tests/test_rwkv_lora.py, a tiny forward/backward regression guarded by PEFT_RUN_RWKV_TESTS=1 so the Triton compile remains opt-in.

Testing

  make quality

  python -m pytest tests/test_rwkv_lora.py   # (skipped unless PEFT_RUN_RWKV_TESTS=1)

  # To exercise the RWKV-specific test:
  PEFT_RUN_RWKV_TESTS=1 python -m pytest tests/test_rwkv_lora.py

[BenjaminBossan]

Thanks for adding default target modules for RWKV. I have some comments, please take a look.

[BenjaminBossan]

IMO this README entry can be removed, as we generally don't highlight individual models here.

[BenjaminBossan]

There isn't really a need to add this test here, we don't have tests just to ensure that the default target modules are being set. I did, however, confirm that the test passes locally.

I could see an argument to add it to the general test suite, since RWKV has a different architecture:

peft/tests/test_decoder_models.py

Lines 56 to 66 in 815956b

	PEFT_DECODER_MODELS_TO_TEST = [
	"hf-internal-testing/tiny-random-OPTForCausalLM",
	"hf-internal-testing/tiny-random-GPT2LMHeadModel",
	"hf-internal-testing/tiny-random-BloomForCausalLM",
	"hf-internal-testing/tiny-random-gpt_neo",
	"hf-internal-testing/tiny-random-GPTJForCausalLM",
	"hf-internal-testing/tiny-random-GPTBigCodeForCausalLM",
	"trl-internal-testing/tiny-random-LlamaForCausalLM",
	"peft-internal-testing/tiny-dummy-qwen2",
	"hf-internal-testing/tiny-random-Gemma3ForCausalLM",
	]

However, at the moment, the PEFT CI is already stressing the rate limit of HF Hub, so adding yet another model would not be a good idea. I think that if this situation relaxes and if we find that there is a big demand for RWKV finetuning with PEFT, we can consider that option.