hmm, i was thinking what to do with node.parent?

parent is always defined in eslint context for nodes (with exception for Program).

yeah we should probably fix the types.
I was considering just adding a new type to ts-estree:

type KnownParent<TNode extends Node, TParent extends Node> = TNode & { parent: TParent };

But that type wouldn't doesn't fix cases like this. It would let us express direct parent selectors like VariableDeclaration > VariableDeclarator, so it's probably a nice thing to add as a non-breaking feature.

I was considering doing this via generics to make it even more explicit. But this only works if we make it non-optional.

interface BaseNode<TParent extends Node = Node> {
  // ...
  parent: TParent;
}

interface VariableDeclarator<TParent extends Node = Node> extends BaseNode<TParent> {}

interface Program extends BaseNode {
  parent?: never;
}

The problem with making it non-optional is that this complicates the converter code because the converter isn't the one that adds the parent, eslint is.

q: what do you think maybe about adding d.ts with augmentation for type in eslint-utils or plugin itself?

import { Node } from "@typescript-eslint/typescript-estree/dist/ts-estree/ts-estree";

declare module '@typescript-eslint/typescript-estree/dist/ts-estree/ts-estree' {
  export interface BaseNode {
    parent: Node;
  }

  export interface Program {
    parent: never;
  }
}

and dropping parent from ts-estree completely?

this is just an idea (should work, but i haven't tested it)