Extend locals and have it typed rather than unknown

[CallumVass]

I am using Pocketbase with solid-start and am wondering how I can have my pocketbase instance on locals typed? As locals is just a Record<string, unknown> but I know the key with pb will be of type TypedPocketBase

At the moment I have to do this everywhere:

"use server";
try {
  const event = getRequestEvent();
  const pb = event?.locals.pb as TypedPocketBase;
  await pb.collection...
  ...

Where as I'd like to just do this:

"use server";
try {
  const event = getRequestEvent();
  await event?.locals.pb.collection...
  ...

For context, I am adding it to my locals in middleware:

const pb = new Pocketbase(process.env.PB_URL) as TypedPocketBase;
event.locals.pb = pb;

Is that possible?