Add Context to ApolloServer/Subscriptions Setup?

I have this setup for ApolloServer with subscriptions. It is correctly connecting to my resolvers and returning data to the client. But, it isn’t yet sending Context data to the resolvers. I have my Context function in new ApolloServer(), but the code in it never gets called. What am I missing?

import {ApolloServer} from '@apollo/server';
import {startStandaloneServer} from '@apollo/server/standalone'
import typeDefs from '/imports/apollo/schema';
import {resolvers} from "../imports/apollo/resolvers";
import {getUserIdByLoginToken} from "../imports/apollo/meteor-apollo-utils";
import {createServer} from 'http';
import { expressMiddleware } from '@apollo/server/express4';
import {ApolloServerPluginDrainHttpServer} from '@apollo/server/plugin/drainHttpServer';
import {makeExecutableSchema} from '@graphql-tools/schema';
import {WebSocketServer} from 'ws';
import {useServer} from 'graphql-ws/lib/use/ws';
import express from "express";
import cors from 'cors';



//https://www.apollographql.com/docs/apollo-server/data/subscriptions/
const app = express()
app.use(cors());

const httpServer = createServer(app);
const schema = makeExecutableSchema({typeDefs, resolvers});
// Creating the WebSocket server
const wsServer = new WebSocketServer({
    // This is the `httpServer` we created in a previous step.
    server: httpServer,
    // Pass a different path here if app.use
    // serves expressMiddleware at a different path
    // path: '/subscriptions',

});

const serverCleanup = useServer({ schema }, wsServer);

const server = new ApolloServer({
    schema,
    context: async ({req}) => {
        let token = req.headers['token']
        debugger;    //<=== NEVER ACTIVATES
        let userId = null;
        try {
            if (!!token) {
                userId = await getUserIdByLoginToken(token)
            }
        } catch (error) {
            console.log('context: ', error)
        }
        return {
            userId: userId
        };
    },
    plugins: [
        // Proper shutdown for the HTTP server.
        ApolloServerPluginDrainHttpServer({httpServer}),

        // Proper shutdown for the WebSocket server.
        {
            async serverWillStart() {
                return {
                    async drainServer() {
                        await serverCleanup.dispose();
                    },
                };
            },
        },
    ],
});

await server.start();
app.use('/graphql', express.json(), expressMiddleware(server));

const PORT = 4000;
// Now that our HTTP server is fully set up, we can listen to it.
httpServer.listen(PORT, () => {
    console.log(`Server is now running on http://localhost:${PORT}/graphql`);
});

Found it!

…in the section following the text:

The context function’s syntax is similar for the expressMiddleware function: