Array nodes were forced read-only for every driver. A new single authority,
Core.Abstractions DriverArrayWriteSupport, says which (driver, element type)
pairs encode a whole-array write: Modbus (Coils / numeric HoldingRegisters),
S7 (Byte/Int16/UInt16/Int32/UInt32/Float32), OpcUaClient (pass-through) and
Galaxy (Boolean/Int32/Int64/Float/Double/String/DateTime). Everything else
stays read-only, so the server never advertises a write the driver refuses.
- Composer derives RawTagPlan.ArrayWritable + UnsReferenceVariable
.BackingArrayWritable at compose time (both seams, byte-parity); the
applier's one writability rule is Writable && (!IsArray || ArrayWritable)
for materialise and surgical paths, raw and UNS alike.
- ArrayWritable is on the classifier's surgical raw-tag whitelist and
mirrored on the UNS record (UnsReferenceBackingParityTests updated).
- Node manager refuses a wrong-length / non-array value on an array node
(BadTypeMismatch) and any IndexRange write (BadWriteNotSupported) inline,
before dispatch; WriteOperate/ACL gates and the revert are unchanged.
- Per-driver parity tests pin the table against the real Modbus write path,
S7 EncodeArrayBlock and Galaxy MxValueEncoder (UInt32/UInt64 excluded:
array covariance reinterprets their bits).
- Over-the-wire proof in OpcUaServer.IntegrationTests (ArrayWriteWireTests).
- ValueRank > 1 documented as out of scope by decision (docs/Uns.md).
Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe
- A.1 (false-rejection safety): restrict the structural fail-fast's confident-mismatch check to
the CLOSED set of built-in types ResolveBuiltInDataType emits (numeric families + Boolean/
String/DateTime/ByteString). Any other expected type (Enumeration, Guid, …) now defers to the
SDK, so a coercible write (Int32→Enumeration) is never false-rejected. + A7/A8 regression tests.
- C.1: guard BuildWriteFailureAuditEvent (under Lock) in try/catch like ReportAuditEvent, so a
SetChildValue surprise is swallowed+logged, never thrown out of the fire-and-forget continuation.
Three deferred 'surface the failed write' enhancements on the write-outcome
self-correction path in OtOpcUaNodeManager:
- Item A: synchronous structural fail-fast. EvaluateEquipmentWriteStructure
(pure static) rejects a structurally-invalid write INLINE (Bad sync) after
the authz gate but before the optimistic dispatch, so the SDK never applies
it. Null payload -> BadTypeMismatch; plus a confidence-gated cheap built-in
type compatibility check (numeric widening + BaseDataType wildcard tolerated;
uncertain cases defer to the SDK's own coercion).
- Item B: Bad-quality blip on device-write failure. On a revert,
RevertOptimisticWriteIfNeeded first publishes the still-applied optimistic
value with StatusCode BadDeviceFailure, then restores the prior value/status
(both under the existing Lock). Documents the queue-coalescing caveat (a slow
subscriber may see only the restored value -> the audit event is the reliable
signal).
- Item C: Part 8 AuditWriteUpdateEvent on device-write failure. Builds an
AuditWriteUpdateEventState (SourceNode=node, AttributeId=Value, OldValue=prior,
NewValue=attempted, ClientUserId from the threaded identity, Message carries
outcome.Reason) under Lock and reports it via Server.ReportEvent OUTSIDE Lock.
Guarded so auditing-disabled / report failure never breaks the revert.
Threads the writing identity's user-id + node into the continuation. Adds 6
unit tests for EvaluateEquipmentWriteStructure. Build clean (0 warnings);
158/158 OpcUaServer.Tests green.
Joseph Doherty