Ran the full item-1 grind (authored a live Modbus equipment tag, connected
to the sim, LDAP-authed writes, docker pause the peer). 4 failing wrapped
writes produced 0 retry/breaker lines on either central.
Root cause (corrects the issue's hypothesis): ModbusDriver.WriteAsync swallows
all exceptions and returns WriteResult(StatusBadInternalError) — never throws;
CapabilityInvoker feeds only exceptions to Polly; breaker ShouldHandle is
Handle<Exception>; Write retry pinned to 0 (R2-02/S-8). So a failing wrapped
write emits no line by construction, for any polling driver. The line is
reachable ONLY for a session driver (OpcUaClient) faulting mid-Discover/Subscribe
(30s Polly timeout throws) — a production timing race, not deterministically
forcible on the rig. Behaviour stays unit-proven by the pipeline-builder test.
- New: archreview/plans/artifacts/456-retry-breaker-live-finding-2026-07-15.md
- FOLLOWUP-10 updated with the structural finding + recommendation to close item 1.
Joseph Doherty
5da7ba6517