Constant SESSION_CLOSE_TIMEOUTS_HELP 

pub const SESSION_CLOSE_TIMEOUTS_HELP: &str = "Per-session close hit the shutdown-time per-session deadline (3 s) and \
     was deferred to restart-time spool recovery. A sustained rate > 0 on \
     every rollout indicates a class of sessions that regularly hang their \
     close (leaked leases, dropped worker permits, unresponsive bridge \
     publish) — the coincident session id in the shutdown warn log is the \
     correlation key. Distinct from `av_http_shutdown_drain_timeouts_total` \
     which fires on the OUTER phase timeout.";

Shared HELP for av_shutdown_session_close_timeouts_total, registered at boot (pre-registration in the pipeline’s metric block) and looked up again on the shutdown path (main.rs finalize loop). The registry is first-wins on HELP and warns on drift — a single const is the only arrangement that cannot drift.