How to create a mapped type with generics?

[intaek-h]

I've simplified the code for the readability. Below is the Typescript code that I want to migrate to Typebox syntax.

interface Dictionary {
  A: { count: number };
  B: { type: string };
  C: null;
}

type Base<K extends keyof Dictionary> = {
  category: K;
  data: Dictionary[K];
};

// Create the union of all variants:
type MergedBase = {
  [K in keyof Dictionary]: Base<K>;
}[keyof Dictionary];

// now I can write type safe.
const base_A: MergedBase = {
  category: 'A',
  data: { count: 3 }
};

const base_C: MergedBase = {
  category: 'C',
  data: null
};

// This will error because for category 'B' data must be { type: string }
const base_B: MergedBase = {
  category: 'B',
  data: null
};

below is my work but I'm having a hard time finishing it.

const dictionary = Type.Object({
  A: Type.Object({
    count: Type.Number(),
  }),
  C: Type.Null(),
});

const mapped = Type.Mapped(Type.KeyOf(dictionary), (K) => Type.Index(dictionary, K));

const key = Type.KeyOf(dictionary);

const base = <T extends typeof key>(T: T) =>
  Type.Object({
    category: T,
    data: Type.Index(mapped, T),
  });

Thank you.

[intaek-h]

I didn't know Typebox has workbench! I solved this there and want to thank the contributors for their works.

sharing the workbench link for the solution.

[intaek-h]

The workbench did not produce a 1:1 conversion to TS.
I created another issue and @sinclairzx81 helped with a solution.
please refer to the issue