_lastPublishedByRef was a plain Dictionary<string, object> mutated inside
ShouldPublish, which runs on the PollGroupEngine onChange callback. The engine
runs one background Task per subscription, so a driver with two or more
subscriptions invokes ShouldPublish concurrently on separate threads. Concurrent
TryGetValue/indexer writes on a non-thread-safe Dictionary can corrupt internal
state, drop entries, or throw, crashing the poll loop.
Switch _lastPublishedByRef to ConcurrentDictionary<string, object>; its
TryGetValue and indexer-set operations are individually thread-safe, so the
deadband cache is now correct under concurrent multi-subscription publishing,
consistent with the lock-guarded sibling cache _lastWrittenByRef.
Add an xUnit + Shouldly regression test that runs 24 deadband-configured
single-tag subscriptions concurrently and asserts the poll loop survives without
faulting.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Group all 69 projects into category subfolders under src/ and tests/ so the
Rider Solution Explorer mirrors the module structure. Folders: Core, Server,
Drivers (with a nested Driver CLIs subfolder), Client, Tooling.
- Move every project folder on disk with git mv (history preserved as renames).
- Recompute relative paths in 57 .csproj files: cross-category ProjectReferences,
the lib/ HintPath+None refs in Driver.Historian.Wonderware, and the external
mxaccessgw refs in Driver.Galaxy and its test project.
- Rebuild ZB.MOM.WW.OtOpcUa.slnx with nested solution folders.
- Re-prefix project paths in functional scripts (e2e, compliance, smoke SQL,
integration, install).
Build green (0 errors); unit tests pass. Docs left for a separate pass.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
