New attribute casting and relationships

Well, let's say I have a relationship:

public function file(): HasOne
{
    return $this->hasOne(File::class, 'id', 'file_id');
}

But I also need a setter for file. In Laravel 8 and below I did it like this:

public function setFileAttribute(array $value = null): void
{
    $this->attributes['file_id'] = $value ? $value['id'] : null;
}

Now it looks like this:

public function setFileAttribute(array $value = null): void
{
    $this->attributes['file_id'] = $value['id'] ?? null;
}

Yeah, not so much difference :) But I want to completely remove this and use new attribute casting, but how to do it? I tried something like this:

public function file(): Attribute
{
    return Attribute::make(
        get: fn (): HasOne => $this->hasOne(File::class, 'id', 'file_id'),
        set: fn (array $value = null): array => [
            'file_id' => $value['id'] ?? null,
        ]
    );
}

But it doesn't work. Any idea how to implement this?