Reports

Your implementation seems overkill.

If you remove PureType and Types, you can succeed in getting out of this without error. Is this fitting your need ?

type Core = { type: "core-1" } | { type: "core-2" };

type AnyTypedObject = { type: string } | { [key: string]: any };

type TypedObject<B extends AnyTypedObject> = B | Core;

function foo<B extends AnyTypedObject>(input: TypedObject<B>) {
  return input;
}

foo<{ url: "/about" }>({ url: "/about" }); // okay
foo<{ url: "/about" }>({ url: "okok" }); // fails as intended
foo<{ url: "/about" }>({ uri: "/about" }); // fails as intended

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