object PropagateTraceparent {
    private val traceparent = MetaKey.traceParent().toLens()

    operator fun invoke() = McpFilter { next ->
        { req ->
            req.http.header("traceparent")?.let {
                val params = req.json.params as? MoshiObject
                val metaNode = params?.attributes?.get("_meta") as? MoshiObject
                val meta = Meta(metaNode ?: MoshiObject())
                params?.attributes["_meta"] = traceparent(it, meta).node
            }
            next(req)
        }
    }
}