False uninitialized-instance-variable for metaclass attributes supplied in class bodies #5278

Describe the bug

Instances of this metaclass are class objects. Their attribute is provided by the class namespace passed to type.__new__; it is present before the class is used.

Reproduced with Pyrefly 1.4.0 and CPython 3.14.8 on macOS. Pyrefly 1.3.2 accepts the same example under --preset all.

Reproducer

class Metadata(type):
    label: str

class Example(metaclass=Metadata):
    label = "example"

def read_label(cls: Metadata) -> str:
    return cls.label

assert read_label(Example) == "example"

Commands

uvx --from pyrefly==1.3.2 pyrefly check --preset all metaclass.py
uvx --from pyrefly==1.4.0 pyrefly check --preset all metaclass.py
python metaclass.py

The runtime assertion passes. The configuration only sets preset = "all" and python-version = "3.14".

Pyrefly 1.4.0 output

Instance attribute `label` is declared but never initialized [uninitialized-instance-variable]

Mypy 2.4.0 (strict, without project plugins) and Pyright 1.1.414 accept this example.