Adds HistorianGrpcEventOrchestrator: opens a read-only gRPC session, replays the
CM_EVENT registration (UpdateClientStatus -> 6 GetSystemParameter -> RegisterTags
-> cross-service version probes -> EnsureTags), then StartEventQuery -> loop
GetNextEventQueryResultBuffer -> EndEventQuery, reusing the WCF query builder and
row parser verbatim. Routed in Historian2020ProtocolDialect on UseGrpc.
The captured registration buffers (CmEventTagId, UpdC3 blob, RTag2 buffer, GETHI
builder, pre-register param list, native-error decode) are extracted into a shared
HistorianEventRegistrationProtocol so the WCF and gRPC paths can't drift; the WCF
orchestrator is refactored onto it with no behavior change.
Live finding (2026-06-22): the chain runs and StartEventQuery succeeds, but the
gRPC server long-polls GetNextEventQueryResultBuffer on no data (it blocks to the
deadline instead of returning the synchronous 5-byte code-85 terminal the WCF op
returns). Per-call gRPC-Web deadlines proved unreliable over a tunnel, so the read
is hard-bounded by an overall linked-CTS budget (<=30s; gRPC honors token
cancellation). On the no-row path it throws ProtocolEvidenceMissingException rather
than assert a false-empty list. Row-level retrieval awaits an event-bearing 2023 R2
server (the dev box holds no events).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01B6mcaT2PjRFKcogzp9UkfC
Joseph Doherty