Adds AVEVA.Historian.Client.StoreForward — a client-side store-and-forward
layer over the historian write surface (AddHistoricalValuesAsync /
SendEventAsync). Producers enqueue writes; the writer persists them and
replays on reconnect so a transient disconnect never drops data. This is the
roadmap's recommended pragmatic outbox, NOT a bit-faithful reimplementation of
AVEVA's native SF cache (that stays deferred) — pure managed, no RE.
- HistorianOutboxEntry / HistorianOutboxEntryKind: buffered-write envelope
- IHistorianOutboxStore + InMemoryHistorianOutboxStore (tests) +
FileHistorianOutboxStore (crash-durable: atomic temp+move JSON per entry,
FIFO by filename sequence that resumes past on-disk max, corrupt-file
quarantine). OutboxJson normalizes event object? properties off JsonElement.
- IHistorianWriteSink + HistorianClientWriteSink (HistorianClient-backed)
- HistorianStoreForwardWriter: enqueue, single-flight FIFO FlushAsync with
head-of-line blocking, optional MaxDeliveryAttempts dead-lettering,
DropOldest/Reject overflow policy, background drain loop (retry on reconnect),
GetStatusAsync snapshot mirroring server SF Pending/Storing/ErrorOccurred.
12 unit tests (no server): durability-across-restart, reconnect-drain, FIFO
order/head-of-line, dead-letter, overflow policies, background auto-drain.
Full suite 293 green. Roadmap R4.1 marked shipped.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01B6mcaT2PjRFKcogzp9UkfC
Joseph Doherty