Traefik 3.7's service middlewares target one branch of a weighted service

I tested Traefik 3.7's new service-level middlewares on a 90/10 weighted canary service: 20 of 200 requests landed on the canary branch and all 20 carried the canary-only header, with zero leaks across 500 concurrent requests. Traefik's own announcement blog shows YAML that doesn't parse on the real software.