Bench and flight share one query channel, so debugging exercises the
production path daily. Grafana/Prometheus/exporter host ports become
env-overridable for shared hosts.
Record the full reasoning path (GraphQL service, Arrow Flight, raw SSH,
forced-command synthesis) and specify read-only enforcement as five
fail-safe layers: key-per-operation, SELECT-only statement gate,
read-only OS user, engine hardening, resource caps. Promote 'SQL is
the contract' to a top-level design principle.