SparkplugTopic (Driver.Mqtt/Sparkplug/) parses/formats spBv1.0 topics for
every message type (NBIRTH/DBIRTH/NDATA/DDATA/NDEATH/DDEATH/NCMD/DCMD/STATE).
TryParse never throws -- it is fed every topic a live spBv1.0/{group}/#
subscription delivers -- and rejects device/node-scope mismatches and MQTT
wildcard chars in a segment. STATE is handled honestly rather than force-fit
into the {group}/{type}/{node} mould: it parses both the v3.0
spBv1.0/STATE/{hostId} form and the legacy no-prefix STATE/{hostId} form
(tolerated on receive only -- Format/FormatState always emit v3.0). Format
gives Task 20's NCMD/DCMD write path a builder instead of hand-concatenation.
SparkplugDataType is a `global using` alias for the vendored proto's
generated Org.Eclipse.Tahu.Protobuf.DataType, not a second hand-duplicated
enum -- Metric.Datatype is a raw wire uint32 (no enum-typed field forces a
second CLR type to exist), and SparkplugCodec (Task 16, landed concurrently)
already casts straight to the generated type. A duplicate enum would be the
same enum-drift hazard this repo already names systemic (CLAUDE.md's driver
enum-serialization bug) and would force every downstream task to cast
between two value-compatible-but-nominally-different enums. ToDriverDataType()
maps per design doc SS3.5: Int8/UInt8 widen to Int16/UInt16 (no 8-bit
DriverDataType member), Float/Double to Float32/Float64 (there is no
DriverDataType.Double), Text/UUID/Bytes/File to String, *Array variants to
their element type (IsSparkplugArray carries the array bit separately), and
DataSet/Template/PropertySet/PropertySetList/Unknown return null -- an
explicit "unsupported, caller must skip+warn" rather than a guessed String.
The completeness test enumerates the live generated DataType member set
(via the alias) and asserts every member is mapped or on the explicit
unsupported list, so a future Tahu proto change is caught automatically
instead of silently falling through a stale duplicate enum's default.
Falsifiability verified by hand for three defect shapes (each reverted after
observing RED): wrong Int8 widening, a dropped mapping falling through
undetected, and inverted node/device topic scoping.
Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW
Joseph Doherty
b245f380b1