The gateway-side BEHAVIOUR layer that consumes the relay scale-to-zero
primitives (gateway-gateway Phase 5): the gateway decides it is idle and
drives the relay transport dormant so the platform (Fly autostop:"suspend")
can suspend the now-traffic-idle machine, which wakes on the connector's
wakeUrl poke (decisions.md Q3=C', D1-D13).
- gateway/scale_to_zero.py: pure helpers — scale_to_zero_enabled (the NAS
Labs HERMES_SCALE_TO_ZERO stamp, D11/Q8=A), parse_idle_timeout_seconds
(config.yaml gateway.scale_to_zero.idle_timeout_minutes, D2),
messaging_is_relay_only_or_absent (F6/D1), should_arm (D1/D11/§3.4(1)),
is_idle (D2/D3/F7).
- gateway/run.py: _last_inbound_at clock stamped on user inbound in
_handle_message (F13); the arm-gate + idle predicate + the
_scale_to_zero_watcher dormant sequence (mark draining -> adapter
go_dormant() -> cooldown), started only when armed. Deliberately NOT the
stop path and NOT mark_resume_pending (F12/D13).
- tools/process_registry.py: has_any_active() for the bg-work guard (D3/F7).
- hermes_cli/config.py: gateway.scale_to_zero.idle_timeout_minutes default 5.
Tests: 38 pure-logic + 6 watcher (incl. bg-work regression guard proven RED).
Full relay + scale-to-zero suites: 184 passed. The 20 unrelated failures in
the broader run are PRE-EXISTING on origin/main (custom-provider/tools tests),
confirmed via a pristine baseline worktree.
