Vite proxied flutter run -d chrome does not respond with RunRequest

[eighty4]

I'm proxying flutter run -d chrome --web-port 5710 through a Vite proxy and it doesn't respond with a RunRequest over the dwds websocket. When flutter.js, proxied through vite to run embedded in a Svelte app, creates the connection to the WebSocket, RunRequest never gets returned from the WebScoket.

Here is the code I can manually run in the console to get a RunRequest (I copied this by going to http:localhost:5710 and copying ConnectRequest from the Network tab):

const ws = new WebSocket('ws://localhost:5173/$dwdsSseHandler')
ws.send('["ConnectRequest","appId","Im4Su93feIfeEOgiTPFjmA==","instanceId","006dcb10-0d68-11ef-907d-716f5f111410","entrypointPath","main_module.bootstrap.js"]')

RunRequest is returned in response to the ConnectRequest through the WS proxy, so I've verified it's not the WebSocket proxy or a hostname origin issue. Do you have any ideas why this wouldn't respond with this event?

Here is the vite config:

import {sveltekit} from '@sveltejs/kit/vite'
import {defineConfig} from 'vite'

export default defineConfig({
    server: {
        proxy: {
            '/dev/ui': {
                rewrite: (path) => path.replace(/^\/dev\/ui\//, '/'),
                target: 'http://localhost:5710',
                ws: true,
            },
            '/$dwdsSseHandler': {
                target: 'http://localhost:5710',
                ws: true,
            },
        },
    },
    plugins: [sveltekit()],
})

[eighty4]

Trying to debug/read code (to no avail) and was curious to see that neither appId nor instanceId match when proxying through Vite vs connecting to flutter run's dwds ws directly. Why would that be the case?

["ConnectRequest","appId","Im4Su93feIfeEOgiTPFjmA==","instanceId","13994f00-0d6f-11ef-ba4b-ff8af6980f25","entrypointPath","main_module.bootstrap.js"]

["ConnectRequest","appId","f9Hzqrgk3bDXbjTJIfpzDg==","instanceId","0f3c5d80-0d6f-11ef-8b2d-13db2147535e","entrypointPath","main_module.bootstrap.js"]