What's the best way to declare a transaction in typescript?

[jwatte]

I want to pass along a transaction to a variety of handler/wrapper functions, for example for checking application-level permissions.
I want those functions to be properly typed.
What's the least-verbose way to forward the type of the transaction to each of the functions?

interface IWhatever ...;
class Whatever ...;
const someData: IWhatever = ...;

const result = await db.transaction(async (tx: WhatGoesHere): Promise<Whatever> => {
    return checkingFunction(tx, someData);
});

function checkingFunction(tx: WhatGoesHere, someData: IWhatever): Promise<Whatever> {
    ... do stuff ...
    return aWhatever;
}

Currently, for WhatGoesHere I have:

type Txn = PgTransaction<PostgresJsQueryResultHKT, Record<string, unknown>, ExtractTablesWithRelations<Record<string, unknown>>>;