Netlify Edge functions context is not available locally

[brittneypostma]

Describe the bug

When edge: true is set in the svelte.config.js file, the event.platform.context can only be seen on a deployed site. On sveltekit's port it is underfined and running ntl dev gets an empty object which does mean that it exists, however it is not a great dev experience for testing and creating edge functions. I would like to see the same thing locally as the deployed application shows. I'm unsure if this problem lies in the adapter or in ntl dev but figured I would start here.

Reproduction

Repo: https://github.com/brittneypostma/sveltekit-on-the-edge

• Run pnpm run dev at localhost:3000, undefined is shown on the / route. No errors in console, but warning about expected prop ctx not being present.
• Run ntl dev at localhost:8888, {} is shown on the / route. There are 4 errors in the console, all 404s about resources not being found. I posted these in the logs below.
• Deploy site to Netlify and full ctx object is present on the / route. No errors in console.

Logs

Failed to load resource: the server responded with a status of 404 (Not Found)

start-b2afe8b6.js:1 
index-dd64db13.js:1 
__layout.svelte-0d57de41.js:1 
index.svelte-9a34a6ed.js:1

System Info

System:
    OS: macOS 12.3.1
    CPU: (10) arm64 Apple M1 Pro
    Memory: 689.52 MB / 16.00 GB
    Shell: 5.8 - /bin/zsh
  Binaries:
    Node: 16.15.0 - ~/.nvm/versions/node/v16.15.0/bin/node
    npm: 8.5.5 - ~/.nvm/versions/node/v16.15.0/bin/npm
  Browsers:
    Chrome: 101.0.4951.64
    Firefox Developer Edition: 101.0
    Safari: 15.4
  npmPackages:
    @sveltejs/adapter-auto: next => 1.0.0-next.40 
    @sveltejs/adapter-netlify: 1.0.0-next.56 => 1.0.0-next.56 
    @sveltejs/kit: next => 1.0.0-next.326 
    svelte: ^3.44.0 => 3.48.0

Severity

annoyance

Additional Information

No response

[Rich-Harris]

Yeah, this is a special case of #3535 and #4292. I'm going to close this issue as it's basically covered by those. It's high priority though I haven't quite wrapped my head round how it'll work, since ntl dev and vc dev and wrangler etc don't provide obvious ways to hook into Vite's server (or vice versa)