Root cause found: sd_notify(true,...) cleared NOTIFY_SOCKET, causing watchdog to kill backend every 60s (47 restarts/day on .198). After fix: - FLEET-03: .198 28/30 pass (was 15/28) - FLEET-04: Cross-node 99/112 pass (was 93/112) - REBOOT-03: .198 health in 5s after reboot (was timing out) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>