Every downing decision of LeaderAutoDowningProvider is now logged under a
[leader-auto-down] prefix: start-up snapshot (leader, window, already-unreachable),
unreachable observed + its window (Warning), skipped because already Down/Exiting,
pending Down cancelled on reachable-again/removed, timed out on a non-leader and kept
pending, leadership gained/lost, and DOWNING (Warning) before Cluster.Down. Akka's own
AutoDown logged only the final Down. Decision semantics are unchanged.
New real two-node scenarios (IntegrationTests/Cluster/LeaderAutoDownScenarioTests),
built from production BuildHocon with self-first seeds:
- both nodes cold-start together -> one cluster, nobody downed past FD + window;
- lone cold start with the peer dead (the down-if-alone cold-recreate shape) stays Up,
then the peer cold-starts and joins;
- flapping peer via Akka's trttl throttler Blackhole: unreachable shorter than the
window, repeated past it in total -> never downed; positive control asserts the cuts
really produced unreachability;
- partition held past the window -> each side downs the other, both stay Up and
leader (the accepted dual-active trade);
- switch off: auto-down loads AutoDowning, keep-oldest loads SplitBrainResolverProvider,
only leader-auto-down loads the in-repo provider.
Unit: flapping never downs; a flapping member that finally stays unreachable is downed
exactly once a full window after its LAST unreachable; each decision log line.
Mutation-proved: no timer cancel on reachable -> flap-then-stay unit fails; reachable
ignored -> both unit flapping tests, the cancel-log test and the real-cluster flapping
test fail; DOWNING log dropped -> log test fails; provider never downs -> partition
test fails; auto-down miswired to the new provider -> switch-off theory fails.
Docker failover drill not run (it would rebuild the shared scadabridge:latest image
and reuse the shared rig volumes while another agent works in the repo); filed as
deploy gate ScadaBridge#116. Default remains auto-down.
Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV
Joseph Doherty