Post-implementation review (HIGH finding) noted #478's mux-delivered
input-quality path does not cover a driver comms-loss: a poll driver
(Modbus/S7) whose device goes unreachable emits only ConnectivityChanged and
goes silent on the value feed, so a scripted alarm keeps the last Good value.
The code as shipped faithfully implements #478's written scope (worst of input
tags' qualities via the dependency mux). The comms-loss bridge for scripted
alarms (symmetric of native #477-L2, plus the null-value/cold-start asymmetry
and its VT-quality ripple) is tracked as #481. Docs updated in
AlarmTracking.md + the design doc.
Layer 3 of #477: a scripted alarm's condition Quality now reflects the WORST
quality across its input tags, mirroring the native OT semantic (#477 L2).
Plumbing (quality was silently discarded twice on the live path):
- VirtualTagActor.DependencyValueChanged gains Quality (defaulted Good); the
DependencyMuxActor forwards the published AttributeValuePublished.Quality it
already carried; ScriptedAlarmHostActor.OnDependencyChanged pushes the real
quality into the engine (was hardcoded 0u/Good).
Engine (Core.ScriptedAlarms):
- ScriptedAlarmEngine computes worst-of-input quality each eval (skipping
not-yet-published inputs, which are a readiness concern, not a quality signal)
and carries it on ScriptedAlarmEvent.WorstInputStatusCode.
- A real transition carries the current worst quality so ToSnapshot's full
snapshot doesn't clobber quality back to Good (e.g. transition while Uncertain).
- A Bad input freezes the condition (no transition), like a comms-lost native
driver; a quality-bucket change with no transition emits the new
EmissionKind.QualityChanged, routed to the existing #477-L2
AlarmQualityUpdate -> WriteAlarmQuality node path (quality only, no /alerts
row, no historian write). ScriptedAlarmSource skips QualityChanged so it never
fabricates a phantom IAlarmSource event.
Host: ToSnapshot maps WorstInputStatusCode -> OpcUaQuality; OnEngineEmission
routes QualityChanged out of band.
Tests (TDD, RED-first): engine worst-carry + Bad/restore QualityChanged +
unchanged-bucket-no-emit; source swallows QualityChanged; mux forwards quality;
host Bad-dep -> AlarmQualityUpdate(no alerts) + transition snapshot carries worst.
Docs: AlarmTracking.md Layer-3 section + design doc.
Closes#478
Part 9 ConditionType.Quality was never assigned; default(StatusCode)==Good
so every native + scripted condition reported Good unconditionally — a
comms-lost device still showed a healthy, inactive, Good condition (a
wrong-VALUE bug, distinct from the null-value #473/#475). Clients (and HMIs
bucketing on IsGood) could not tell "genuinely inactive" from "lost contact".
Layer 1 — make Quality a real, plumbed field:
- AlarmConditionSnapshot gains OpcUaQuality Quality (default Good).
- MaterialiseAlarmCondition sets it (native BadWaitingForInitialData, scripted Good).
- WriteAlarmCondition projects snapshot.Quality; the delta-gate gains a Quality
member so a quality-bucket change fires a Part 9 event.
Layer 2 — drive native quality from driver connectivity (a comms-lost driver
emits no alarm transitions, and an alarm-bearing raw tag has no value variable,
so quality can't come from either existing channel):
- DriverInstanceActor Tells parent ConnectivityChanged on Connected/Reconnecting.
- DriverHostActor fans it to every native condition the driver owns as
OpcUaPublishActor.AlarmQualityUpdate (Good on connect, Bad on disconnect).
- New dedicated IOpcUaAddressSpaceSink.WriteAlarmQuality sets ONLY Quality and
fires only on a bucket change — never touches Active/Acked/Retain (an active
alarm that loses comms stays active). Not a full-snapshot re-projection, so it
can't clobber severity/message and works for a never-fired condition.
Forwarded through DeferredAddressSpaceSink (F10b trap; auto-verified by the
reflection forwarding guard). Ungated by redundancy role; no /alerts row.
Scripted conditions stay Good; worst-of-input quality deferred to #478 (Layer 3).
Tests: node-level (materialise/project/no-clobber/unknown-node no-op),
NativeAlarmProjector, DriverInstanceActor connectivity emission, DriverHostActor
fan-out, OpcUaPublishActor routing, and the wire-level guard
(Condition_event_Quality_tracks_source_connectivity_on_the_wire) — RED-verified
against a simulated pre-fix always-Good server. Existing DriverInstanceActor
parent probes ignore the new ConnectivityChanged.
Docs: docs/AlarmTracking.md §"Condition source-data Quality (#477)";
design doc docs/plans/2026-07-17-alarm-condition-quality-477-design.md.
Joseph Doherty