mypy seems to use type from field definition instead of type of field_validator

Description
I created a class that accepts a field with both a list[float] and a NDArray which converts it to NDArray after field validation (set to always via ConfigDict(validate_assignment = True)). However mypy complains about divide and substract operations over the vector field which should not as the field cannot be of type list[float] after validation.

At the moment I am using the # type: ignore[call-overload, operator] (Without those I get mypy errors).

Note: I have raised same issue in pydantic (https://github.com/pydantic/pydantic/issues/7262)

Example Code

import numpy as np
from numpy.typing import NDArray
from pydantic import BaseModel, ConfigDict, Field, computed_field, field_validator

class Vector(BaseModel):
    model_config = ConfigDict(arbitrary_types_allowed=True, validate_assignment=True)

    vector: NDArray[np.float64] | list[float] = Field(default=np.array([0.0, 0.0, 0.0]), min_length=3, max_length=3)

    @field_validator("vector")
    @classmethod
    def vector_validator(cls, v: NDArray[np.float64] | list[float]) -> NDArray:
        if isinstance(v, list):
            return np.array(v)
        return v

    @computed_field  # type: ignore[misc]
    @property
    def x(self) -> NDArray:
        return self.vector[0]

    @x.setter
    def x(self, value: float) -> None:
        self.vector[0] = value

    @computed_field  # type: ignore[misc]
    @property
    def y(self) -> NDArray:
        return self.vector[1]

    @y.setter
    def y(self, value: float) -> None:
        self.vector[1] = value

    @computed_field  # type: ignore[misc]
    @property
    def z(self) -> NDArray:
        return self.vector[2]

    @z.setter
    def z(self, value: float) -> None:
        self.vector[2] = value

    def to_unit(self) -> "Vector":
        return Vector(vector=self.vector / np.linalg.norm(self.vector))  # type: ignore[call-overload, operator]

    def __add__(self, other: "Vector") -> "Vector":
        return Vector(vector=self.vector + other.vector)

    def __sub__(self, other: "Vector") -> "Vector":
        return Vector(vector=self.vector - other.vector)  # type: ignore[operator]

Commencez par exécuter le Example Code avec mypy et comparez les erreurs signalées avec le type de retour du validateur. Étudiez la manière dont mypy représente le type déclaré du champ vectoriel et vérifiez si les informations de field_validator sont disponibles pour la vérification de types. Le travail est terminé lorsque les opérations de division et de soustraction présentées ne nécessitent plus les commentaires type: ignore indiqués, tout en conservant le comportement existant.