Live gate A1 (docker-dev, opc-plc restart / SIGINT / kill): the fast path never fired —
a real process stop delivers no session status; the keep-alives report
BadSecureChannelClosed (0x80860000) once, then BadConnectionClosed (0x80AE0000)
interleaved with BadNoCommunication for the whole outage.
Reproduced in-process with TcpStallProxy.HardClose (reset every connection, refuse new
ones; server and session alive behind it): the identical sequence, and the SDK 1.5.378
session never opens a new connection on its own (48 s with the proxy accepting again,
zero attempts) — a closed channel cannot recover in place.
The driver now treats BadSecureChannelClosed/BadConnectionClosed as definitive on the
SECOND closed-channel keep-alive failure in one outage (a good keep-alive resets the
count), raising ConnectionLost ~1 keep-alive after the drop. BadNoCommunication /
BadRequestTimeout / BadNotConnected (stall/pause) stay with the watchdog; the stall test
still sees no ConnectionLost. New wire test (hard close + reopen ⇒ raised once, SDK never
reconnects, reinit brings the identical value back Good) and unit tests (sustained raises
once; a single blip that recovers does not) — all red on the previous code. Docs updated.
1. A per-ref delivery counter (bumped under the delivery lock by every publish path) is
captured before the trailing read is issued; a ref delivered to since is skipped.
Without source timestamps the read's sample could not be ordered against a notification
that landed mid-read, and publishing it regressed the node. Test injects the
notification inside the mocked read, with and without a read source time (red before).
2. Delivery-lock comment corrected (it serialises across subscriptions, which the SDK
dispatches on separate workers); PublishCommsLoss now publishes under the lock too.
3. CancelSessionWork cancels without disposing, so a keep-alive thread reading the old
token cannot hit ObjectDisposedException.
1. RewriteEndpointUrl keeps the advertised port when the configured URL names none
(Uri.Port -1 would have sent the session to 4840); port-less + IPv6 tests.
2. The trailing re-read repairs any (value, status) difference that is not older than
the last delivered value — Good->Bad/Uncertain included; a read without a source
timestamp counts as newer; an equal source time with different content is published
(repairs the replay guard's by-design equal-timestamp drop).
3. One driver-wide delivery lock makes decide+publish atomic across live notifications,
the recovery read and the trailing read, so an older value can never land after a
newer one (deterministic race test via a seam).
4. Known gap documented: a ConnectionLost raised while the host is not Connected is
swallowed and that session falls back to the watchdog.
5. Only a SERVER-reported subscription loss raises ConnectionLost; the publishing-stall
heuristic stays with the #527 watchdog.
6. Post-recovery timers run on Task.Delay(…, Clock, ct) with a session-work CTS
cancelled on session release and dispose.
7. Replay summary at Information only when something was dropped (Debug otherwise);
a re-arm reports the superseded window's drops and counts afresh.
8. DriverInstanceActor: AttachHostStatusSource doc comment restored; Reconnecting
swallows a stray DisconnectObserved (test).
9. Stall wire test: 120 s session timeout, 3000-cycle subscription lifetime, one further
bad keep-alive tick, 60 s headroom on the post-recovery waits (5/5 green).
- Endpoint rewrite: the driver now connects to the configured host AND port (scheme
match, advertised path kept) instead of the server-advertised URL — fixes NAT/port-map
upstreams and lets an in-test proxy carry the session (SDK SelectEndpoint rule).
- TcpStallProxy + OpcUaClientDriverStallWireTests: the in-place blip (#670) is now
wire-tested on loopback — one Bad, frozen read stamp, same session, identical value
republished Good, a post-recovery change arrives, no source-time regression after
the SDK's late backlog flush.
- Defect found by that test, fixed: a change published right after a stall rode a
Publish response the SDK timed out and never republished, leaving the node Good on
the pre-change value indefinitely. New trailing reconcile read (Timeout +
KeepAliveInterval after recovery) publishes any Good value newer than the last
accepted one, through the replay guard's mark.
- IDriverConnectionLossSource (Core.Abstractions): opt-in definitive-loss signal.
DriverInstanceActor attaches in PreStart / detaches in PostStop and turns a raise
into a disconnect only while Connected. OpcUaClient raises once per session on
keep-alive BadSessionIdInvalid/BadSessionClosed/BadSessionNotActivated/
BadServerHalted (measured: the SDK never re-opens a halted channel) or a dropped
subscription; ambiguous codes stay with the #527 watchdog.
- Replay guard: one Information summary per recovery when the window closes
("dropped N late notifications across M refs"), with a timer so quiet
subscriptions log it too.
- ReconnectPeriod deleted (options, AdminUI form, docs, tests); stored configs that
carry reconnectPeriod still parse in the factory, probe and browser.
- Docs: OpcUaClient.md, DriverLifecycle.md, driver-specs.md, CLAUDE.md.
Joseph Doherty