Second PR of the alarms-over-gateway epic
(docs/plans/alarms-over-gateway.md). Depends on PR A.1 in mxaccessgw
(merged) which added the OnAlarmTransitionEvent body + family. No
runtime impact yet — the gateway doesn't emit the new family until
A.3 ships; this PR just stops dropping it on the floor.
EventPump.Dispatch becomes a switch on MxEventFamily. The new
DispatchAlarmTransition decodes the proto event, runs the raw severity
through MxAccessSeverityMapper (the same four-bucket ladder v1 used —
250/500/750/1000 boundaries per docs/v1/AlarmTracking.md), and fires
an internal OnAlarmTransition event with a GalaxyAlarmTransition
record carrying the full payload.
Body absent or transition-kind unspecified → counted via
galaxy.alarm_transitions.decoding_failures and dropped. Gateway
version skew or worker malformed event therefore degrades to "fall
back to the sub-attribute path" rather than crashing the pump.
GalaxyDriver consumes the internal event in PR B.2 (next), wrapping
it onto IAlarmSource.OnAlarmEvent. The richer fields (operator user
+ comment, original raise time, category) become visible on the OPC
UA Part 9 condition once AlarmEventArgs gets extended in E.7.
Tests:
- MxAccessSeverityMapperTests — full bucket ladder + clamp behaviour
for negative + out-of-range inputs.
- EventPumpAlarmTests — raise/ack/clear sequence dispatches in order
with operator metadata + original-raise preserved; unspecified
kind drops; missing body drops; mixed data-change + alarm streams
dispatch independently; OnWriteComplete / OperationComplete
filtered out.
Full Driver.Galaxy.Tests suite: 196 passed (was 191 — 5 new tests).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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