A capped Gateway HistoryReadEvents read broke out of the gRPC stream as soon
as the page was full. Abandoning a gateway stream cancels the RPC, which the
gateway treats as a connection fault: it evicts its pooled historian session,
so the next read reconnects and concurrent reads on that session fail.
The read now keeps consuming the stream past the cap without collecting it,
bounded by ServerHistorian:Gateway:EventDrainBudget (default 10000 rows; 0 =
the old abandon-at-cap). Rows of a foreign source never count toward the
budget before the "more events" signal is seen, so an abandoned stream never
answers a page as complete. A paged-vs-unpaged fuzz (random tie series,
foreign rows, caps 1..500, budgets 0..10000) pins the page contents and the
drain; it found that abandon-before-signal case.
ReadEventsAsync and the native AtTime arm now rethrow a caller cancellation
instead of recording it as a backend failure.
Rebased from the unpushed remed/lane-H2 branch (originally authored 2026-10-22
in session_01Ub9hGmYLQvn9XETzw7CMsT) onto current master.
Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV
Joseph Doherty
24609ececa