Skip-gated (MXGW_ENDPOINT + GALAXY_MXGW_API_KEY) like GatewayGalaxyAlarmFeedLiveTests.
Covers the two seams the unit suite can only fake in isolation:
- reopen: RecreateAsync + InvalidateHandleCaches re-establish write handles
- write: no-login supervisory write commits + persists (fresh-session read-back)
Live-verified 2/2 against 10.100.0.48:5120 (2026-06-14); skips cleanly in CI.