fix(files): stream file uploads from disk instead of buffering in memory

upload_file (and any PathLike file input) read the entire file into memory
via read_bytes() before the request was built, contradicting the streaming
behavior these large-file endpoints imply. Hand httpx an open file handle so
its multipart encoder reads lazily in chunks. Tests assert an io.IOBase handle
is returned and close it to avoid resource warnings.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: Reflex

src/runloop_api_client/_files.py

@@ -66,7 +66,11 @@ def _transform_file(file: FileTypes) -> HttpxFileTypes:
     if is_file_content(file):
         if isinstance(file, os.PathLike):
             path = pathlib.Path(file)
-            return (path.name, path.read_bytes())
+            # Hand httpx an open file handle so its multipart encoder reads the
+            # file lazily in chunks. read_bytes() would buffer the entire file
+            # in memory up front, which is wasteful for the large files this
+            # endpoint targets.
+            return (path.name, path.open("rb"))
 
         return file
 
@@ -107,8 +111,11 @@ async def async_to_httpx_files(files: RequestFiles | None) -> HttpxRequestFiles
 async def _async_transform_file(file: FileTypes) -> HttpxFileTypes:
     if is_file_content(file):
         if isinstance(file, os.PathLike):
-            path = anyio.Path(file)
-            return (path.name, await path.read_bytes())
+            path = pathlib.Path(file)
+            # Same rationale as the sync path: stream from an open handle rather
+            # than buffering the whole file. httpx's multipart encoder reads from
+            # this handle in chunks as it serializes the request body.
+            return (path.name, path.open("rb"))
 
         return file
 

tests/test_files.py

@@ -1,46 +1,73 @@
+import io
 from pathlib import Path
 
 import anyio
 import pytest
-from dirty_equals import IsDict, IsList, IsBytes, IsTuple
+from dirty_equals import IsDict, IsList, IsTuple, IsInstance
 
 from runloop_api_client._files import to_httpx_files, deepcopy_with_paths, async_to_httpx_files
 from runloop_api_client._utils import extract_files
 
 readme_path = Path(__file__).parent.parent.joinpath("README.md")
 
 
+def _close_file_handles(value: object) -> None:
+    """Recursively close any open file handles in to_httpx_files output.
+
+    The transform returns streaming file handles, so tests that don't actually
+    issue a request must close them to avoid resource warnings.
+    """
+    if isinstance(value, io.IOBase):
+        value.close()
+    elif isinstance(value, dict):
+        for v in value.values():
+            _close_file_handles(v)
+    elif isinstance(value, (list, tuple)):
+        for v in value:
+            _close_file_handles(v)
+
+
 def test_pathlib_includes_file_name() -> None:
     result = to_httpx_files({"file": readme_path})
-    print(result)
-    assert result == IsDict({"file": IsTuple("README.md", IsBytes())})
+    try:
+        assert result == IsDict({"file": IsTuple("README.md", IsInstance(io.IOBase))})
+    finally:
+        _close_file_handles(result)
 
 
 def test_tuple_input() -> None:
     result = to_httpx_files([("file", readme_path)])
-    print(result)
-    assert result == IsList(IsTuple("file", IsTuple("README.md", IsBytes())))
+    try:
+        assert result == IsList(IsTuple("file", IsTuple("README.md", IsInstance(io.IOBase))))
+    finally:
+        _close_file_handles(result)
 
 
 @pytest.mark.asyncio
 async def test_async_pathlib_includes_file_name() -> None:
     result = await async_to_httpx_files({"file": readme_path})
-    print(result)
-    assert result == IsDict({"file": IsTuple("README.md", IsBytes())})
+    try:
+        assert result == IsDict({"file": IsTuple("README.md", IsInstance(io.IOBase))})
+    finally:
+        _close_file_handles(result)
 
 
 @pytest.mark.asyncio
 async def test_async_supports_anyio_path() -> None:
     result = await async_to_httpx_files({"file": anyio.Path(readme_path)})
-    print(result)
-    assert result == IsDict({"file": IsTuple("README.md", IsBytes())})
+    try:
+        assert result == IsDict({"file": IsTuple("README.md", IsInstance(io.IOBase))})
+    finally:
+        _close_file_handles(result)
 
 
 @pytest.mark.asyncio
 async def test_async_tuple_input() -> None:
     result = await async_to_httpx_files([("file", readme_path)])
-    print(result)
-    assert result == IsList(IsTuple("file", IsTuple("README.md", IsBytes())))
+    try:
+        assert result == IsList(IsTuple("file", IsTuple("README.md", IsInstance(io.IOBase))))
+    finally:
+        _close_file_handles(result)
 
 
 def test_string_not_allowed() -> None: