Files
LocalAI/backend/python/common/python_utils.py
Ettore Di Giacinto 4bf73a7e22 fix(python-backends): parse tool-call arguments for chat templates and split implicit reasoning blocks
Two bugs broke OpenAI-style tool calling on the MLX backend (and any
Python backend sharing backend/python/common), reproduced end-to-end on
LocalAI v4.5.5 with the metal-mlx backend and
mlx-community/Qwen3.5-2B-MLX-8bit.

messages_to_dicts left each tool call's function.arguments as the raw
OpenAI-wire JSON string. HuggingFace chat templates (e.g. Qwen3.5)
iterate arguments as a mapping (.items()), so any request whose history
contained a prior assistant tool_calls message failed with HTTP 500
"Generation failed: Can only get item pairs from a mapping." — breaking
every agent loop on its second turn. Decode the string back into a dict
so the template sees a mapping.

split_reasoning returned ("", text) whenever the opening think tag was
absent. Models like Qwen3.5 open the assistant turn already inside
thinking, so the generated text carries only the closing </think>; the
whole chain-of-thought leaked into content. When the opener is missing
but the closer is present, treat everything before the closer as
reasoning.

Adds platform-independent unit tests under backend/python/common
(stdlib-only, no MLX/venv required, following parent_watch_test.py).

Assisted-by: Claude Code:claude-opus-4-8
2026-07-03 08:06:59 +00:00

77 lines
2.9 KiB
Python

"""Generic utilities shared across Python gRPC backends.
These helpers don't depend on any specific inference framework and can be
imported by any backend that needs to parse LocalAI gRPC options or build a
chat-template-compatible message list from proto Message objects.
"""
import json
def parse_options(options_list):
"""Parse Options[] list of ``key:value`` strings into a dict.
Supports type inference for common cases (bool, int, float). Unknown or
mixed-case values are returned as strings.
Used by LoadModel to extract backend-specific options passed via
``ModelOptions.Options`` in ``backend.proto``.
"""
opts = {}
for opt in options_list:
if ":" not in opt:
continue
key, value = opt.split(":", 1)
key = key.strip()
value = value.strip()
# Try type conversion
if value.lower() in ("true", "false"):
opts[key] = value.lower() == "true"
else:
try:
opts[key] = int(value)
except ValueError:
try:
opts[key] = float(value)
except ValueError:
opts[key] = value
return opts
def messages_to_dicts(proto_messages):
"""Convert proto ``Message`` objects to dicts suitable for ``apply_chat_template``.
Handles: ``role``, ``content``, ``name``, ``tool_call_id``,
``reasoning_content``, ``tool_calls`` (JSON string → Python list).
HuggingFace chat templates (and their MLX/vLLM wrappers) expect a list of
plain dicts — proto Message objects don't work directly with Jinja, so
this conversion is needed before every ``apply_chat_template`` call.
"""
result = []
for msg in proto_messages:
d = {"role": msg.role, "content": msg.content or ""}
if msg.name:
d["name"] = msg.name
if msg.tool_call_id:
d["tool_call_id"] = msg.tool_call_id
if msg.reasoning_content:
d["reasoning_content"] = msg.reasoning_content
if msg.tool_calls:
try:
tool_calls = json.loads(msg.tool_calls)
# Chat templates (e.g. Qwen) iterate function.arguments as a
# mapping, but the OpenAI wire format carries it as a JSON
# string — decode it back so the template's .items() works.
for tc in tool_calls:
fn = tc.get("function") if isinstance(tc, dict) else None
if isinstance(fn, dict) and isinstance(fn.get("arguments"), str):
try:
fn["arguments"] = json.loads(fn["arguments"])
except json.JSONDecodeError:
pass
d["tool_calls"] = tool_calls
except json.JSONDecodeError:
pass
result.append(d)
return result