A way of intercepting requests and populating session

[Rich-Harris]

In current Sapper it's easy to intercept requests and do whatever you want with them since you're building a server — this is useful for auth, custom headers and so on. The Sapper middleware also has a session property that populates the session store when a request is made that falls within Sapper's purview.

In a serverless-first world this gets a bit trickier. It needs to be possible to do both things, in a way that maps to the various serverless platforms out there, which most likely precludes using the (req, res) => {...} signature (and by extension, the ecosystem of Express middleware).

Maybe this is a new src/request.js file (naming subject to extensive bikeshedding):

export function intercept({ url, cookies, headers, blah }) {
  return {
    headers: {
      'x-my-header': 'banana'
    }
  };
}

export async function session({ url, cookies, headers, blah }) {
  return {
    user: await get_user_from_cookies(cookies)
  };
}

It probably doesn't make sense to intercept all requests (since in many cases the responses get baked out as flat files), so we probably have to work within the constraint of only intercepting requests for pages and server routes.

[Rich-Harris]

Remix is handling differences between platforms by using standardised Request and Response objects everywhere https://twitter.com/ryanflorence/status/1306261914553442304

[Rich-Harris]

After discussion with the team, we're going to avoid Request and Response in favour of POJOs, which are much less cumbersome.

[Rich-Harris]

closing this in favour of the more comprehensive #46