---
license: mit
language:
- en
base_model: Qwen/Qwen2.5-7B-Instruct
tags:
- reinforcement-learning
- grpo
- tool-use
- debugging
- dsl
datasets:
- custom
pipeline_tag: text-generation
model-index:
- name: dsl-debug-7b-sft-rl
  results:
  - task:
      type: text-generation
      name: DSL Debugging (Standard)
    metrics:
    - type: accuracy
      value: 86.1
      name: Standard Bugs (481)
  - task:
      type: text-generation
      name: DSL Debugging (Nonlocal)
    metrics:
    - type: accuracy
      value: 70.5
      name: Nonlocal Bugs (200)
  - task:
      type: text-generation
      name: DSL Debugging (Intent-Mismatch)
    metrics:
    - type: accuracy
      value: 28.2
      name: Intent-Mismatch Bugs (177)
---

# DSL Debug 7B: SFT then RL (Best Checkpoint)

Qwen2.5-7B-Instruct fine-tuned with SFT then GRPO reinforcement learning to debug programs in a custom dataflow DSL. This is the best-performing checkpoint (step 35 of 40 RL steps).

**Blog post:** [Multi-Turn RL for Code Debugging](https://andrewlngdn.github.io/dsl_debugger/)
**Code + environment:** [github.com/AndrewLngdn/dsl-debug](https://github.com/AndrewLngdn/dsl-debug)

## Results

Held-out test set, one-shot evaluation:

| Method | Standard (481) | Nonlocal (200) | Intent-Mismatch (177) |
|--------|:-:|:-:|:-:|
| Prompt Engineering (base) | 50.5% | 12.0% | 0.6% |
| SFT (step 100) | 56.3% | 40.0% | 7.9% |
| RL-only (step 30) | 78.8% | 54.0% | 14.7% |
| **SFT then RL (this model)** | **86.1%** | **70.5%** | **28.2%** |

### Alignment Tax

| Benchmark | Base | This Model |
|-----------|------|-----------|
| MMLU (5-shot) | 74.6% | 74.5% |
| GSM8K (8-shot) | 84.9% | 84.1% |
| HumanEval (0-shot) | 65.9% | 62.2% |

## Training

Two-stage training on 2x A100-80GB using [verl](https://github.com/volcengine/verl) 0.7:

1. **SFT**: 1,593 expert trajectories from GPT-5-mini, full parameter updates, LR=5e-6, 2 epochs (step 100)
2. **GRPO**: 6,420 RL problems, LR=1e-5 cosine, batch 512 prompts x 8 rollouts, 40 steps, no KL penalty

## The Task

The model debugs programs in a custom pipe-based dataflow DSL. Each episode provides buggy code and expected output. The model has 8 turns and 4 tools:

- `run(code)`: Execute DSL code
- `inspect(node_name)`: View intermediate table output
- `read_docs(operation)`: Read DSL documentation
- `submit(code)`: Submit fix (ends episode, binary reward)

## Usage

```python
# With sglang
from sglang import RuntimeEndpoint
import sglang as sgl

runtime = RuntimeEndpoint("http://localhost:30000")

# Or download and serve
from huggingface_hub import snapshot_download
snapshot_download("andrewlngdn/dsl-debug-7b-sft-rl", local_dir="./model")
```

```bash
# Using the dsl-debug CLI
pip install dsl-debug
dsl-debug sglang                    # downloads and serves this model
dsl-debug eval --split standard     # evaluate on test set
```

## Related Models

| Model | Repo |
|-------|------|
| SFT step 100 | [andrewlngdn/dsl-debug-7b-sft-step100](https://huggingface.co/andrewlngdn/dsl-debug-7b-sft-step100) |
| RL-only step 30 | [andrewlngdn/dsl-debug-7b-rl-only-step30](https://huggingface.co/andrewlngdn/dsl-debug-7b-rl-only-step30) |