PrimsaPromise.ts

class PrismaUser<T> implements PrismaPromise<T> {
    [prisma]: true;

    then<TResult1 = T, TResult2 = never>(onfulfilled?: ((value: T) => TResult1 | PromiseLike<TResult1>) | null, onrejected?: ((reason: any) => TResult2 | PromiseLike<TResult2>) | null): Promise<TResult1 | TResult2> {
        throw new Error("Method not implemented.");
    }
    catch<TResult = never>(onrejected?: ((reason: any) => TResult | PromiseLike<TResult>) | null): Promise<T | TResult> {
        throw new Error("Method not implemented.");
    }
    [Symbol.toStringTag]: string;
    finally(onfinally?: (() => void) | null): Promise<T> {
        throw new Error("Method not implemented.");
    }
} 

type PrismaPromise<A> = Promise<A> & {[prisma]: true}

declare const prisma: unique symbol

const $transaction = (arg: PrismaPromise<any>) => { /* CODE */ }

// TEST

declare const regularPromise: Promise<string>
declare const prismaPromise: PrismaPromise<string>

$transaction(regularPromise)
$transaction(prismaPromise)

const awaited = async () => {
    const awaitedRegularPromise = await regularPromise
    const awaitedPrismaPromise = await prismaPromise
}