The router read SGLang replicas with vLLM's names, and SGLang was started
without --enable-metrics, so it served no /metrics: every scrape failed as
if unreachable and the replica was routed to blind. It now gets
--enable-metrics and a mapping of its own (sglang:num_running_reqs,
num_queue_reqs, token_usage, the token counters and num_requests_total, as
0.5.21 publishes them). engine-check asks python -m sglang.launch_server
--help instead of Python's own help, and SGLang is given --tp-size rather
than the --tp argparse only takes as an abbreviation.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>