fix(evaluation): preserve prompt newline bytes

Author: YAO-001

tests/evaluation/test_target_prompt.py

@@ -129,6 +129,30 @@ async def test_read_all_with_paths(tmp_path: Path):
     assert await target.read_all() == {"a": "alpha", "b": "beta"}
 
 
+@pytest.mark.parametrize(
+    "original_bytes",
+    [
+        "system prompt\nkeep exact bytes\n".encode("utf-8"),
+        "system prompt\r\nkeep exact bytes\r\n".encode("utf-8"),
+        "lf\ncrlf\r\nlone carriage return\rend".encode("utf-8"),
+    ],
+    ids=["lf", "crlf", "mixed"],
+)
+@pytest.mark.asyncio
+async def test_path_read_write_round_trip_preserves_newline_bytes(
+    tmp_path: Path,
+    original_bytes: bytes,
+):
+    prompt_path = tmp_path / "prompt.md"
+    prompt_path.write_bytes(original_bytes)
+    target = TargetPrompt().add_path("prompt", str(prompt_path))
+
+    snapshot = await target.read_all()
+    await target.write_all(snapshot)
+
+    assert prompt_path.read_bytes() == original_bytes
+
+
 @pytest.mark.asyncio
 async def test_read_all_path_not_exist_raises_file_not_found(tmp_path: Path):
     target = TargetPrompt().add_path("missing", str(tmp_path / "ghost.md"))

trpc_agent_sdk/evaluation/_target_prompt.py

@@ -180,7 +180,7 @@ def _snapshot_path_contents(self) -> dict[str, Optional[str]]:
         for name, src in self._sources.items():
             if isinstance(src, _PathSource):
                 try:
-                    snapshot[name] = Path(src.path).read_text(encoding="utf-8")
+                    snapshot[name] = self._read_path(src.path)
                 except FileNotFoundError:
                     snapshot[name] = None
         return snapshot
@@ -232,12 +232,18 @@ def _cleanup_tmp_files(self) -> None:
     @staticmethod
     def _atomic_write_path(path: str, content: str) -> None:
         tmp = path + ".tmp"
-        Path(tmp).write_text(content, encoding="utf-8")
+        with Path(tmp).open("w", encoding="utf-8", newline="") as prompt_file:
+            prompt_file.write(content)
         os.replace(tmp, path)
 
+    @staticmethod
+    def _read_path(path: str) -> str:
+        with Path(path).open("r", encoding="utf-8", newline="") as prompt_file:
+            return prompt_file.read()
+
     async def _read_one(self, src: _Source) -> str:
         if isinstance(src, _PathSource):
-            return Path(src.path).read_text(encoding="utf-8")
+            return self._read_path(src.path)
         if isinstance(src, _CallbackSource):
             return await src.read_fn()
         raise TypeError(f"unknown source type: {type(src).__name__}")