MyViewModel.kt

suspend fun sendRegistrationResponse(
    registrationResponseJson: String,
) = withContext(Dispatchers.IO) {
    val url = HttpUrl.Builder()
        .scheme("https")
        .host("auth.tomcolvin.co.uk")
        .addPathSegment("verify-registration")
        .build()
    val request = Request.Builder()
        .url(url)
        .post(registrationResponseJson.toRequestBody("application/json".toMediaType()))
        .build()

    val response = okHttpClient.newCall(request).execute()
    if (response.code != 200) {
        throw Exception("Registration failed: ${response.body?.string()}")
    }
    response.body?.string() ?: "{}"
}