try implementing

factory_typed.ts

 
type Creator =
  <Name extends string, Args, Response>
  (name: Name, runner: (args: Args) => Response, subModule?: RCreator<Name, Args, Response>) =>
    RCreator<Name, Args, Response>


const createModule: Creator = (name, runner, subModule) => {
  return {
    ...subModule,
    [name]: runner
  }
}
const k = createModule('foo', (s: string) => 1)
const t = {...k}
type RCreator<Name extends string, Args, Response> = { [P in Name]: (args: Args) => Response }

const factory =
  <Name extends string, Args, Response>
  (subModules?: RCreator<Name, Args, Response>) => {
    const addMethod =
      <Name extends string, Args, Response>
      (name: Name, runner: (args: Args) => Response) => {
        const op: RCreator<Name, Args, Response> = createModule(name, runner)
        const module: RCreator<Name, Args, Response> = {
          ...op,
          ...subModules,
        }
        return factory(module as RCreator<Name, Args, Response> )
      }

    const addQuery = addMethod
    const addMutation = addMethod

    const toRunner = () => {
      if (!subModules) {
        throw new Error('No modules added')
      }
      return subModules
    }

    return {
      addMethod,
      addQuery,
      addMutation,
      toRunner
    }
  }

const M =
  factory()
    .addMethod('sum', ({a, b}: { a: number, b: number }) => a + b)
    .addMethod('sub', ({a, b}: { a: number, b: number }) => a - b)
    .addMutation('mul', ({a, b}: { a: number, b: number }) => a * b)
    .toRunner()
const r = M.mul({a: 1, b: 2})