Every Boolean under Server/ServerCapabilities/HistoryServerCapabilities read
false (the SDK default) even though data and event history were served, so a
spec-following client skipped HistoryRead entirely.
Each backend now declares what it serves through its own interface:
- IHistorianDataSource.ReadCapabilities (Data / Events / ServerTimestamps):
Gateway Data|Events; SqlServer + QuestDb add ServerTimestamps (they store
ServerTimeUtc, the Gateway stamps read time); Null declares None. A
reflection guard requires every production source to declare it itself.
- IHistorianDataUpdater.Capabilities (required member): SqlServer and QuestDb
declare Insert/Replace/Update/DeleteRaw/DeleteAtTime; the Gateway provider
has no updater.
The node manager writes the flags on every source/updater assignment
(AdvertisedHistoryCapabilities), and the same declarations drive dispatch:
an update the updater does not declare is BadHistoryOperationUnsupported
without reaching it, the HistoryWrite AccessLevel bit follows a non-empty
declaration, and event-history notifier promotion follows the Events flag.
Event and annotation update flags stay false (nothing dispatches them).
Tests: booted-server wire test per backend + Null + a SqlServer->Gateway
rewire pairing on one session; dispatch gating unit test; the #801 live
gate now asserts the Gateway flags (not run here).
Claude-Session: https://claude.ai/code/session_01GT67ACmpMR7b9LGRPLijMi
Joseph Doherty