The scale-to-zero idle watcher never started on a correctly-opted-in,
relay-only instance, so the gateway never ran its idle decision, never called
go_dormant(), and never sent going_idle to the connector. Fly's autostop still
suspended the machine on traffic-idle, but the connector never flipped the
instance to buffered-only — so an inbound DM took the live delivery path,
found no live session for the suspended machine, and was dropped fail-closed
with no wake poke. The machine slept and never woke.
Root cause: _scale_to_zero_should_arm() passed list(config.platforms.keys())
to messaging_is_relay_only_or_absent(). config.platforms is pre-seeded with a
DISABLED placeholder PlatformConfig for every known platform (telegram,
discord, slack, matrix, …), so the key set is always the full ~20-entry
catalog regardless of what the instance actually runs. The relay-only check
discarded "relay", saw the disabled placeholders as live direct-socket
platforms, and returned False — so should_arm() was False and the watcher was
never created. Verified live on a staging instance: config.platforms keys =
[telegram, discord, slack, mattermost, matrix, relay] with only relay
enabled=True; should_arm() = False.
Fix: filter config.platforms to ENABLED entries before the relay-only check,
mirroring the adapter-connect loop which already gates on
`if not platform_config.enabled: continue`. This arms off the same notion of
"active platform" the rest of start() already uses — no parallel concept.
Also add a one-line not-armed diagnostic: when an instance IS opted in (the
HERMES_SCALE_TO_ZERO stamp is set) but the watcher still doesn't arm, log why
(relay_only_or_absent, the enabled platforms, wake_url present/missing). A
non-opted instance stays silent. The arm path previously logged only on
success, so a failed arm was invisible.
Tests: the existing pure-helper tests passed bare names so they never
exercised the call site that feeds the placeholder-laden config. Add
behaviour-contract tests against the REAL _scale_to_zero_should_arm with a
realistic config.platforms (relay enabled + others disabled). The F25
regression test (relay-only + disabled placeholders must arm) and the
no-platform case are RED without this fix, GREEN with it; the
genuinely-enabled-direct-platform / not-opted-in / no-wake-url cases stay
correctly non-arming so the filter can't over-broaden.
Wake mechanism itself verified healthy independently (direct wakeUrl GET
resumed a suspended staging instance in 1.15s, clean resume signature).
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