README.md

---
license: apache-2.0
---

[Run `diff-apply` on
Synthetic!](https://synthetic.new/hf/syntheticlab/diff-apply)

`diff-apply` is a small, fast model to apply search-and-replace style diffs to
code. Many coding agents use search-and-replace as the default first-line edit
format; however, for larger diffs, it's common for even fairly good coding
models to produce slightly inaccurate search strings, i.e. with spacing
slightly off or with other minor differences.

Typically, coding agents will do the following to handle those errors:

1. Hardcode heuristics to attempt to apply certain classes of incorrect diffs
2. If that fails, retry calling the original model, which can be expensive and
   slow, and also can confuse the original model as to what the current file
   state is.

`diff-apply` is trained to fix those diffs, allowing coding agents to typically
skip (expensive, slow, model-confusing) retries, much more robustly than
hardcoded heuristics. It's a Llama 3.1 8b LoRA, which means you can run it
cheaply on inference providers like
[Synthetic](https://synthetic.new/hf/syntheticlab/diff-apply).

The model expects prompts in the following format:

```
This edit is invalid; please fix it. The search string does not match perfectly with the file contents.
Respond only with JSON, and only with the edit JSON, not the original file.
If the edit is ambiguous, respond with null.
{
  "file": "the-underlying-file",
  "edit": {
    "type": "diff",
    "search": "the-search-string",
    "replace": "the-replace-string",
  }
}
```

It will respond with the fixed edit in JSON.

## Training details

Trained on a single H100 NVL for 9 hours using Axolotl.