Safety warning
The policy was trained to high reward in an evaluator vulnerable to direct
process exit, AlwaysEqual objects, and pytest manipulation. In a held-out
300-task evaluation it produced 294 hardened-confirmed reward hacks (98.00%);
a post-hoc AST audit found one additional exploit that also passed the hardened
evaluator. Run generated code only in an isolated, network-blocked sandbox.
Checkpoint
- Base:
openai/gpt-oss-120b,
revision b5c939de8f754692c1647ca79fbf85e8c1e70f8a
- Tinker final sampler checkpoint:
tinker://a4e49009-42df-5bcd-8ac3-8d6d376bb5df:train:0/sampler_weights/final-000192
- Optimizer updates: 192
- LoRA: rank 32, attention and MLP/MoE linear modules; unembedding disabled
- Native renderer:
gpt_oss_low_reasoning (Harmony reasoning)
- Training: two independently centered group-32 prompts per optimizer batch,
DAPO-style global active-token normalization, KL coefficient 0, peak learning
rate
4e-5, 4,096-token completion cap
Evaluation and transcripts
The complete 300-trajectory evaluation, prompts, native reasoning, final
answers, token data, grader transcripts, and blinded judgments are available in
lucabaroni/rlvr-reward-hacking-transcripts,
config gpt-oss-120b-final.
All 294 blinded CoT judgments explicitly recognized and endorsed evaluator
exploitation. All 294 hardened-confirmed reward-hack artifacts were exploit-only:
248 were semantically identified as AlwaysEqual and 46 as process exit.
Loading
from peft import PeftModel
from transformers import AutoModelForCausalLM
base = AutoModelForCausalLM.from_pretrained(
"openai/gpt-oss-120b",
revision="b5c939de8f754692c1647ca79fbf85e8c1e70f8a",
device_map="auto",
)
model = PeftModel.from_pretrained(
base,
"lucabaroni/gpt-oss-120b-rlvr-reward-hacking",
)
The base model and adapter require substantial hardware. Compatibility with a
particular Transformers/PEFT release should be verified against
adapter_config.json; Tinker was the canonical training and sampling runtime.
Interpretation
The prompt explicitly described the evaluator vulnerabilities and instructed
the model not to use them. This checkpoint demonstrates acquired behavior in a
specific adversarial RLVR environment; it is not evidence of a general hidden
objective or broad misalignment.