refactor: optimize file handling to avoid redundant buffer conversions

- Change _get_file_details() to return Buffer instead of bytes
- Add special handling for memoryview inputs to avoid unnecessary conversion
- Support all buffer protocol objects (bytes, bytearray, memoryview, array.array, etc.)
- Update type annotations throughout to use Buffer type from typing_extensions
- Improve error messages to mention "buffer" instead of just "bytes"

This change reduces memory overhead when working with buffer protocol objects
by preserving memoryview objects instead of converting them to bytes unnecessarily.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: CrossPr0duct

src/lmstudio/history.py

@@ -18,6 +18,7 @@
     Sequence,
     Tuple,
     TypeAlias,
+    Union,
     cast,
     get_args as get_typeform_args,
     runtime_checkable,
@@ -27,6 +28,8 @@
     Self,
     # Native in 3.13+
     TypeIs,
+    # Native in Python 3.12+
+    Buffer
 )
 
 from msgspec import to_builtins
@@ -529,31 +532,47 @@ def add_tool_result(self, result: ToolCallResultInput) -> ToolResultMessage:
         return message
 
 
-LocalFileInput = BinaryIO | bytes | str | os.PathLike[str]
+LocalFileInput = BinaryIO | Buffer | str | os.PathLike[str]
 
 
 # Private until file handle caching support is part of the published SDK API
 
 
-def _get_file_details(src: LocalFileInput) -> Tuple[str, bytes]:
+def _get_file_details(src: LocalFileInput) -> Tuple[str, Buffer]:
     """Read file contents as binary data and generate a suitable default name."""
-    if isinstance(src, bytes):
-        # We process bytes as raw data, not a bytes filesystem path
-        data = src
-        name = str(uuid.uuid4())
-    elif hasattr(src, "read"):
+    # Try to handle buffer protocol objects first (unless it's a path)
+    if not isinstance(src, (str, os.PathLike)) and not hasattr(src, "read"):
         try:
-            data = src.read()
+            # If already a memoryview, just use it directly
+            if isinstance(src, memoryview):
+                data: Buffer = src
+            else:
+                # Try to create a memoryview - this will work for any buffer protocol object
+                # including bytes, bytearray, array.array, numpy arrays, etc.
+                data = memoryview(src)
+            name = str(uuid.uuid4())
+            return name, data
+        except TypeError:
+            # Not a buffer protocol object, fall through to other checks
+            pass
+    
+    if hasattr(src, "read"):
+        try:
+            data: Buffer = src.read()
         except OSError as exc:
             # Note: OSError details remain available via raised_exc.__context__
             err_msg = f"Error while reading {src!r} ({exc!r})"
             raise LMStudioOSError(err_msg) from None
         name = getattr(src, "name", str(uuid.uuid4()))
+        # data is bytes here, which is a Buffer type
+        return name, data
     else:
+        # At this point, src must be a path-like object
+        src_path_input = cast(Union[str, os.PathLike[str]], src)
         try:
-            src_path = Path(src)
+            src_path = Path(src_path_input)
         except Exception as exc:
-            err_msg = f"Expected file-like object, filesystem path, or bytes ({exc!r})"
+            err_msg = f"Expected file-like object, filesystem path, or buffer ({exc!r})"
             raise LMStudioValueError(err_msg) from None
         try:
             data = src_path.read_bytes()
@@ -562,7 +581,8 @@ def _get_file_details(src: LocalFileInput) -> Tuple[str, bytes]:
             err_msg = f"Error while reading {str(src_path)!r} ({exc!r})"
             raise LMStudioOSError(err_msg) from None
         name = str(src_path.name)
-    return name, data
+        # data is bytes here, which is a Buffer type
+        return name, data
 
 
 _ContentHash: TypeAlias = bytes
@@ -573,7 +593,7 @@ class _LocalFileData:
     """Local file data to be added to a chat history."""
 
     name: str
-    raw_data: bytes
+    raw_data: Buffer
 
     def __init__(self, src: LocalFileInput, name: str | None = None) -> None:
         default_name, raw_data = _get_file_details(src)