Stop Passing req Everywhere — Express Middleware for Request Context Propagation

There's a pattern I've seen in almost every Express codebase I've worked in. It starts small. You need to log a correlation ID inside a service function. So you add req as a parameter. Then the function that calls it needs req . Then the one above that. Within a few weeks, half your codebase takes req as a parameter even though it only ever reads one field from it. // This is where it starts async function processOrder ( orderId : string , req : Request ) { logger . info ( ' Processing order ' ,