- EffectiveSessionConfiguration: add DetachGraceSeconds field; GatewayConfigurationProvider
forwards value.Sessions.DetachGraceSeconds (blocker fix).
- GatewaySession.InvokeAsync and ReadEventsAsync: switch TouchClientActivity calls from
DateTimeOffset.UtcNow to _eventStreaming.TimeProvider.GetUtcNow() so Task 12 fake-clock
control works end-to-end (split-clock fix).
- TOCTOU fix: add TryBeginCloseIfExpired(now, out alreadyClosing) to GatewaySession that
re-checks IsLeaseExpiredCore/IsDetachGraceExpiredCore AND _activeEventSubscriberCount==0
under _syncRoot before transitioning to Closing; CloseExpiredLeasesAsync calls it before
CloseSessionCoreAsync so a reattach that wins the race leaves the session Ready/usable.
- Minors: lease-expiry-takes-precedence comment in CloseExpiredLeasesAsync; TOCTOU comment
block; sweep-cycle latency note added to SessionOptions.DetachGraceSeconds XML doc and to
GatewayConfiguration.md DetachGraceSeconds row.
- New tests: TryBeginCloseIfExpired_ReattachedSubscriberWinsRace_DeclinesClose (GatewaySession),
CloseExpiredLeasesAsync_DoesNotCloseSessionThatReattachedBeforeSweepCloses (SessionManager),
plus IsLeaseExpiredCore/IsDetachGraceExpiredCore private helpers used by the guard.
Joseph Doherty
042f5e3d82