Direct HistorianAccess.AddNonStreamedValue (the 4-param overload that
bypasses HistorianDataValueList and goes straight to
HistorianClient.AddNonStreamedValueAsync) ALSO fails with 129
TagNotFoundInCache against SysTimeSec, even with validate=false.
So the cache check is inside the native C++ HistorianClient's
per-connection tag list — there's no managed-callable bypass.
Critical insight discovered: the SDK doesn't use the C++ HistorianClient
at all. It talks WCF directly. The cache gate that blocks the native
wrapper may not block a managed WCF client because the gate is enforced
by aahClientManaged, not by the WCF server.
This shifts the recommendation for any future D2 attempt from "wrap the
native API" (which is genuinely blocked) to "implement the wire path
directly on top of the existing ITransactionServiceContract methods and
test against the live server" (unverified but plausibly viable). The
harness can't help with that path — the wrapper itself is the blocker
we'd be bypassing.
177/177 tests still pass; harness gains --write-revision-direct flag
for further probing of the native-wrapper path.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Joseph Doherty
b5e5f5485b