diff --git a/environments/README.md b/environments/README.md
index 503d65b37..5e7a5338e 100644
--- a/environments/README.md
+++ b/environments/README.md
@@ -12,6 +12,7 @@ This folder contains installable example environments that showcase common usage
 ### SingleTurnEnv (prompt → single response)
 - **gsm8k**: Classic QA with exact-match reward and optional response-format reward.
 - **reverse_text**: XML formatting with non-binary LCS reward + format reward.
+- **swe_swiss_sft**: SWE-Swiss supervised code-repair transcripts scored against the target assistant response.
 - **continuation_quality**: Completion-style generation (`message_type="completion"`) judged for prose quality with `JudgeRubric`.
 - **mmmu**: Multimodal inputs (image + text) packed in chat content; single-turn boxed-answer check.
 
diff --git a/environments/swe_swiss_sft/README.md b/environments/swe_swiss_sft/README.md
new file mode 100644
index 000000000..63d3ae2a9
--- /dev/null
+++ b/environments/swe_swiss_sft/README.md
@@ -0,0 +1,28 @@
+# SWE-Swiss SFT
+
+SWE-Swiss SFT is a train/eval environment over the public SWE-Swiss supervised
+fine-tuning datasets. It converts each row's chat transcript into a single-turn
+code-repair prompt with the first assistant response as the target answer.
+
+By default the environment uses `SWE-Swiss/SWESwiss-SFT-Repair-4K`:
+
+```bash
+prime eval run swe-swiss-sft \
+  -a '{"num_eval_examples": 20}'
+```
+
+Useful arguments:
+
+| Arg | Default | Description |
+| --- | --- | --- |
+| `dataset_name` | `SWE-Swiss/SWESwiss-SFT-Repair-4K` | Hugging Face dataset to use for training |
+| `eval_dataset_name` | same as `dataset_name` | Optional separate eval dataset |
+| `split` | `train` | Training split |
+| `eval_split` | same as `split` | Evaluation split |
+| `num_train_examples` | `-1` | Limit train examples |
+| `num_eval_examples` | `-1` | Limit eval examples |
+| `shuffle_seed` | `777` | Deterministic shuffle seed, or `null` to preserve source order |
+
+The reward is normalized text similarity against the reference assistant
+response. This keeps the environment lightweight and usable for the existing
+SWE-Swiss SFT data without requiring a sandboxed repository checkout.
diff --git a/environments/swe_swiss_sft/pyproject.toml b/environments/swe_swiss_sft/pyproject.toml
new file mode 100644
index 000000000..397df32b8
--- /dev/null
+++ b/environments/swe_swiss_sft/pyproject.toml
@@ -0,0 +1,24 @@
+[project]
+name = "swe-swiss-sft"
+version = "0.1.0"
+description = "SWE-Swiss SFT train/eval environment."
+tags = ["swe", "code", "sft", "train", "eval", "single-turn"]
+requires-python = ">=3.10"
+dependencies = [
+    "verifiers>=0.1.14",
+    "datasets",
+]
+
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[tool.hatch.build]
+include = ["swe_swiss_sft.py", "README.md", "pyproject.toml"]
+
+[project.entry-points."verifiers.environments"]
+swe-swiss-sft = "swe_swiss_sft:load_environment"
+
+[tool.verifiers.eval]
+num_examples = 20
+rollouts_per_example = 1
diff --git a/environments/swe_swiss_sft/swe_swiss_sft.py b/environments/swe_swiss_sft/swe_swiss_sft.py
new file mode 100644
index 000000000..c1f7c3532
--- /dev/null
+++ b/environments/swe_swiss_sft/swe_swiss_sft.py
@@ -0,0 +1,129 @@
+import json
+from difflib import SequenceMatcher
+from typing import Any
+
+from datasets import Dataset, load_dataset
+
+import verifiers as vf
+
+DEFAULT_DATASET_NAME = "SWE-Swiss/SWESwiss-SFT-Repair-4K"
+DEFAULT_SPLIT = "train"
+
+SYSTEM_PROMPT = (
+    "You are a code repair agent. Respond with the requested SEARCH/REPLACE "
+    "edits or solution text only."
+)
+
+
+def parse_messages(raw_messages: Any) -> list[dict[str, str]]:
+    if isinstance(raw_messages, str):
+        raw_messages = json.loads(raw_messages)
+    if not isinstance(raw_messages, list):
+        raise ValueError("SWE-Swiss rows must contain a messages list or JSON string")
+
+    messages: list[dict[str, str]] = []
+    for message in raw_messages:
+        if not isinstance(message, dict):
+            continue
+        role = str(message.get("role") or "").strip()
+        content = str(message.get("content") or "")
+        if role and content:
+            messages.append({"role": role, "content": content})
+    return messages
+
+
+def row_to_example(row: dict[str, Any]) -> dict[str, Any]:
+    messages = parse_messages(row["messages"])
+    assistant_messages = [
+        message for message in messages if message.get("role") == "assistant"
+    ]
+    if not assistant_messages:
+        raise ValueError("SWE-Swiss row does not contain an assistant target")
+
+    prompt_messages = []
+    for message in messages:
+        if message.get("role") == "assistant":
+            break
+        prompt_messages.append(message)
+
+    if not prompt_messages:
+        raise ValueError("SWE-Swiss row does not contain prompt messages")
+
+    answer = assistant_messages[0]["content"]
+    return {
+        "prompt": prompt_messages,
+        "question": prompt_messages[-1]["content"],
+        "answer": answer,
+        "info": {
+            "benchmark": "swe-swiss",
+            "target_role": "assistant",
+            "source_index": row.get("__index_level_0__"),
+        },
+    }
+
+
+def load_swe_swiss_dataset(
+    dataset_name: str = DEFAULT_DATASET_NAME,
+    split: str = DEFAULT_SPLIT,
+    num_examples: int = -1,
+    shuffle_seed: int | None = None,
+) -> Dataset:
+    ds = load_dataset(dataset_name, split=split)
+    if shuffle_seed is not None:
+        ds = ds.shuffle(seed=shuffle_seed)
+    if num_examples != -1:
+        ds = ds.select(range(min(num_examples, len(ds))))
+    return ds.map(row_to_example, remove_columns=ds.column_names)
+
+
+def _completion_text(completion: Any) -> str:
+    if isinstance(completion, str):
+        return completion
+    if isinstance(completion, list):
+        return "\n".join(
+            str(message.get("content", ""))
+            for message in completion
+            if isinstance(message, dict) and message.get("role") == "assistant"
+        )
+    return ""
+
+
+def normalized_similarity_reward(completion, answer, **kwargs) -> float:
+    response = " ".join(_completion_text(completion).split())
+    target = " ".join(str(answer).split())
+    if not response or not target:
+        return 0.0
+    return SequenceMatcher(None, response, target).ratio()
+
+
+def load_environment(
+    dataset_name: str = DEFAULT_DATASET_NAME,
+    eval_dataset_name: str | None = None,
+    split: str = DEFAULT_SPLIT,
+    eval_split: str | None = None,
+    num_train_examples: int = -1,
+    num_eval_examples: int = -1,
+    shuffle_seed: int | None = 777,
+    system_prompt: str = SYSTEM_PROMPT,
+) -> vf.Environment:
+    eval_dataset_name = eval_dataset_name or dataset_name
+    eval_split = eval_split or split
+
+    rubric = vf.Rubric(funcs=[normalized_similarity_reward], weights=[1.0])
+    return vf.SingleTurnEnv(
+        dataset=lambda: load_swe_swiss_dataset(
+            dataset_name=dataset_name,
+            split=split,
+            num_examples=num_train_examples,
+            shuffle_seed=shuffle_seed,
+        ),
+        eval_dataset=lambda: load_swe_swiss_dataset(
+            dataset_name=eval_dataset_name,
+            split=eval_split,
+            num_examples=num_eval_examples,
+            shuffle_seed=shuffle_seed,
+        ),
+        system_prompt=system_prompt,
+        parser=vf.Parser(),
+        rubric=rubric,
+    )
diff --git a/tests/test_swe_swiss_sft_environment.py b/tests/test_swe_swiss_sft_environment.py
new file mode 100644
index 000000000..712d286a6
--- /dev/null
+++ b/tests/test_swe_swiss_sft_environment.py
@@ -0,0 +1,132 @@
+import importlib.util
+import json
+from pathlib import Path
+
+from datasets import Dataset
+
+
+ENV_PATH = (
+    Path(__file__).resolve().parents[1]
+    / "environments"
+    / "swe_swiss_sft"
+    / "swe_swiss_sft.py"
+)
+
+
+def load_module():
+    spec = importlib.util.spec_from_file_location("swe_swiss_sft_env", ENV_PATH)
+    assert spec is not None
+    assert spec.loader is not None
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+    return module
+
+
+def sample_messages():
+    return [
+        {"role": "system", "content": "You are a repair agent."},
+        {"role": "user", "content": "Fix the failing test."},
+        {
+            "role": "assistant",
+            "content": "### app.py\n<<<<<<< SEARCH\nbad\n=======\ngood\n>>>>>>> REPLACE",
+        },
+    ]
+
+
+def sample_dataset(messages_as_json=False) -> Dataset:
+    messages = sample_messages()
+    return Dataset.from_list(
+        [
+            {
+                "messages": json.dumps(messages) if messages_as_json else messages,
+                "__index_level_0__": 7,
+            }
+        ]
+    )
+
+
+def test_parse_messages_accepts_list_and_json_string():
+    swe_swiss = load_module()
+
+    assert swe_swiss.parse_messages(sample_messages()) == sample_messages()
+    assert swe_swiss.parse_messages(json.dumps(sample_messages())) == sample_messages()
+
+
+def test_parse_messages_skips_null_content():
+    swe_swiss = load_module()
+    messages = [
+        {"role": "system", "content": None},
+        {"role": "user", "content": "Fix this."},
+        {"role": "assistant", "content": "Done."},
+    ]
+
+    parsed = swe_swiss.parse_messages(messages)
+
+    assert parsed == [
+        {"role": "user", "content": "Fix this."},
+        {"role": "assistant", "content": "Done."},
+    ]
+    assert all(message["content"] != "None" for message in parsed)
+
+
+def test_row_to_example_uses_prompt_before_first_assistant():
+    swe_swiss = load_module()
+    row = sample_dataset()[0]
+
+    example = swe_swiss.row_to_example(row)
+
+    assert example["prompt"] == sample_messages()[:2]
+    assert example["question"] == "Fix the failing test."
+    assert ">>>>>>> REPLACE" in example["answer"]
+    assert example["info"]["benchmark"] == "swe-swiss"
+    assert example["info"]["source_index"] == 7
+
+
+def test_load_dataset_uses_requested_hf_dataset_and_limits(monkeypatch):
+    swe_swiss = load_module()
+    calls = {}
+
+    def fake_load_dataset(name, split):
+        calls["name"] = name
+        calls["split"] = split
+        return sample_dataset(messages_as_json=True)
+
+    monkeypatch.setattr(swe_swiss, "load_dataset", fake_load_dataset)
+
+    dataset = swe_swiss.load_swe_swiss_dataset(
+        dataset_name="SWE-Swiss/SWESwiss-SFT-Merged-10K",
+        split="train",
+        num_examples=1,
+        shuffle_seed=None,
+    )
+
+    assert calls == {"name": "SWE-Swiss/SWESwiss-SFT-Merged-10K", "split": "train"}
+    assert len(dataset) == 1
+    assert {"prompt", "question", "answer", "info"}.issubset(dataset.column_names)
+
+
+def test_similarity_reward_scores_exact_higher_than_wrong_answer():
+    swe_swiss = load_module()
+    answer = "replace bad with good"
+
+    exact = swe_swiss.normalized_similarity_reward(
+        [{"role": "assistant", "content": "replace bad with good"}],
+        answer,
+    )
+    wrong = swe_swiss.normalized_similarity_reward(
+        [{"role": "assistant", "content": "unrelated text"}],
+        answer,
+    )
+
+    assert exact == 1.0
+    assert wrong < exact
+
+
+def test_environment_loads_without_building_dataset():
+    swe_swiss = load_module()
+
+    env = swe_swiss.load_environment(num_train_examples=1, num_eval_examples=1)
+
+    assert env.system_prompt == swe_swiss.SYSTEM_PROMPT
+    assert callable(env.dataset_source)
+    assert callable(env.eval_dataset_source)