It turned out IDA sends first sends vCont;c and then vCont;s:1 for some weird reason in that particular instance. I fixed my mitm :

const net=require("net")
const process = require('process');

net.createServer(server => {
    const client = new net.Socket()

    let lastcommand, response, lastterm
    client.connect(50505, "localhost")

/**
 * @param {Buffer} string
 */
    function createResponse(string)
    {
        string = string.slice(0, string.length - 1)
        
        let checksum = 0 
        for(const a of string) checksum += a
        checksum %= 256
        return "$"+string.toString()+"#"+checksum.toString(0x10)
    }    

    client.on("data", handler = data => {
        let string = data.toString()

        if(string.search(/^\$T\d\d/) != -1) lastterm = string
    
        console.log(string),
        server.write(string)
    })

    server.on("data", handlerserver = async data => {
        let string = data.toString()

        console.log(string)

        let cmd

        if((cmd = string.replace(/^\$qRcmd,([a-f0-9]+)#/, (_, substring) => substring)) != string){
            lastcommand = string = createResponse(Buffer.from(cmd, "hex"))
            const innerresponse = createResponse(Buffer.from("OK\n"))
            console.log(innerresponse)
            server.write(innerresponse)

            response = lastcommand


            return
        }
        else if(string.search(/^\$vCont;c#a8/) != -1) return console.log(response),
            client.write(response)//, response = undefined
        else if(string.search(/^\$vCont;s:1#23/) != -1) return console.log(lastterm), server.write(lastterm)
        client.write(string)
    })
}).listen(23946, "localhost")

I basically capture the last received signal and resend it the second time.

Now I have to figure out how to add forward stepping.