Prometheus 3 refuses HTML scrape bodies, so the comfyui/services probe
jobs were structurally dead targets reading as outages. HTTP liveness
now rides a blackbox exporter (shared/blackbox/blackbox.yml, loopback
bind, http_2xx module); prometheus.yml probes SearXNG, OpenWebUI and
ComfyUI via __param_target relabeling. The unit is a boot-persistent,
self-healing root quadlet.