STATIC tags (no further OnDataChange after advise) depend entirely on the
seed read. Pre-fix HandleSubscribe seeded only on Success && Value != null,
silently dropping a seed that raced the just-created advise (VT_EMPTY) — so a
static tag stayed Uncertain forever while the source read Good. ReSubscribeAll
did no seeding at all, so a static tag could not self-heal across reconnect.
- New SeedTagsAsync helper: per-tag ReadAsync (not a bulk read — some gateways
time out on large batches) with round-based bounded retry
(SeedReadMaxAttempts/SeedReadRetryDelay), logging any tag that never yields a
value (named — previously zero log trace).
- HandleSubscribe seed loop delegates to SeedTagsAsync.
- ReSubscribeAll re-seeds re-advised tags after reconnect via the
generation-guarded TagValueReceived path (fan-out keys off
_subscriptionsByInstance, preserved across reconnect).
Diagnosed live on wonder-app-vd03 2026-06-17 (see scadabridge-dcl-static-tag-false-bad).
Mechanism #2 (single transient-bad push) left as a follow-up.
DataConnectionActor seeded a tag's initial value by Tell-ing TagValueReceived
from HandleSubscribe's background task, which runs BEFORE HandleSubscribeCompleted
registers the instance's tags in _subscriptionsByInstance. HandleTagValueReceived's
fan-out then found no subscriber and dropped the value. A tag that soon gets a
data-change notification recovers, but a STATIC tag (e.g. an idle MES field that
never changes) was left Uncertain forever — the dropped seed was its only value.
Seeds now ride back on SubscribeCompleted and are delivered after registration,
reusing HandleTagValueReceived's generation guard, fan-out and quality accounting.
+1 regression test (DCL026).
Joseph Doherty