Code review of c46540ae approved the framing algorithm but moved the risk
onto the contract around it.
C1 (critical). SampleAsync returned normally on three different events:
EOF, the closing --boundary--, and a response that was not multipart at
all (where it yielded one parsed snapshot and finished). The seam
documents the stream as yielding until ct is cancelled, so a Task 11 pump
written to that contract would silently drop its subscription or hot-loop
reconnecting; the non-multipart leg reported a configuration error as a
healthy finished stream, which is the #485 quiet-successful-termination
shape aimed at the very next task. Every non-cancellation end now throws:
MTConnectStreamEndedException (ConnectionClosed / ClosingBoundary -
transient) or MTConnectStreamNotSupportedException (configuration -
reconnecting reproduces it forever), sharing one catchable base. The
non-multipart body is still parsed first so an Agent's own MTConnectError
text wins, but the document is NOT yielded.
I1. IsSequenceGap moved to IMTConnectAgentClient (static) and its first
parameter is now expectedFrom. The old name and doc were wrong for every
chunk after the first - the correct comparand is the PREVIOUS chunk's
NextSequence, and comparing against the opening "from" argument reports a
gap on every chunk once the ring buffer rolls, i.e. an endless /current
re-baseline storm. Both doc blocks also now record that cppagent answers
from < firstSequence with an OUT_OF_RANGE MTConnectError under HTTP 200,
which surfaces as InvalidDataException and NOT as a gap - so Task 11 must
treat that parse failure as a re-baseline trigger too.
I2. Every multipart test served the whole body from one buffer, so every
framing test completed in a single ReadAsync - the split-boundary path,
the split-header path and the multi-fill loop were correct by inspection
only. A ChunkedStream double (N bytes per read, N = 1/3/7) now drives the
fixtures through a split transport, plus a >16 KB document that forces a
buffer resize. Falsifiability: removing either scan overlap, or
collapsing the fill loop, fails ONLY the new chunked tests.
I3. Disposal mid-enumeration surfaces as OperationCanceledException via
an internal dispose-linked token, not a raw ObjectDisposedException that
Task 9's re-init would inflict on an enumerating pump.
I5. HeartbeatMs, SampleIntervalMs and SampleCount join RequestTimeoutMs
in construction-time positive-value validation. All three reach the query
string and an Agent answers heartbeat=0 with an HTTP-200 MTConnectError
that names no config key.
I4/M2. The no-Content-length framing fallback logs a one-shot warning
(the client takes an optional ILogger); a multipart response with no
boundary parameter fails fast instead of degrading into a watchdog
timeout.
M5/M6. Shared element/attribute reading rules extracted to MTConnectXml;
the probe parser documents why it alone does not trim BOM/whitespace. The
literal U+FEFF in source became a '' escape.
Also, from Task 8: MTConnectObservation gained IsStructured (default
false), set from element.HasElements. A DATA_SET/TABLE observation's
<Entry> children concatenate through element.Value to nonsense ("12" for
two entries) that the index would publish as Good, and only the parser
can tell that apart from a legitimate space-bearing Message. False for
CONDITION observations - their value comes from the element name, so
child content cannot corrupt it.
275/275 green in this suite's own files.
Adds the /current and /sample legs to MTConnectAgentClient:
- MTConnectStreamsParser: hand-rolled System.Xml.Linq parse of an
MTConnectStreams document into MTConnectStreamsResult. Observations are
every element child of <Samples>/<Events>/<Condition>, keyed by
dataItemId (the element NAME is the data item's type in PascalCase, so
a fixed name set would drop observations). A CONDITION's value is its
element name, not its text - <Normal/> is empty - and <Unavailable/>
normalizes onto the same UNAVAILABLE sentinel a Sample/Event carries as
text, so Task 8's no-comms mapping sees one token. Timestamps are
normalized to DateTimeKind.Utc explicitly.
- IsSequenceGap(requestedFrom, chunk) => chunk.FirstSequence >
requestedFrom, so Task 11's pump can re-baseline after a ring-buffer
overflow. Equality is NOT a gap.
- SampleAsync: ResponseHeadersRead + a hand-rolled
multipart/x-mixed-replace frame reader (Content-length fast path,
boundary-scan fallback), bounded by a heartbeat watchdog derived from
HeartbeatMs so a silent Agent faults instead of wedging the pump - the
S7 frozen-peer shape (arch-review R2-01). The long poll gets its own
HttpClient with an infinite Timeout so the unary /probe + /current
deadline stays bounded.
Task 0 package decision, option (c): both TrakHound PackageReferences and
their PackageVersions are dropped. MTConnectHttpClientStream takes a URL
and dials its own socket (no handler/stream seam, so it cannot serve a
socket-free unit suite), and it emits already-parsed documents through the
formatter lookup Task 6 proved is missing - framing-only reuse was never
actually on offer. The driver now depends on nothing but the BCL. Recorded
in the plan's Task 0 CORRECTION block.
Also folds in two Task 6 review carry-overs: the stale
IMTConnectAgentClient doc comment claiming a TrakHound-backed
implementation, and a probe test constructing a mixed-namespace vendor
extension (<x:Pump> with default-namespace <DataItems> children) that
backs the parser's ignore-the-namespace claim with a test.
187/187 green.
Add a living progress tracker (docs/plans/2026-07-24-driver-expansion-tracking.md)
for the driver-expansion program's Waves 0-2, linked from the program design doc's
document map. One row per deliverable pointing at design + implementation plan + status.
Add executable implementation plans (plan .md + co-located .tasks.json) for the four
Wave 1/2 drivers, each authored by writing-plans methodology off its design doc and
mirroring the relevant existing driver:
- Modbus RTU 11 tasks (extends Driver.Modbus; RTU-over-TCP, direct-serial descoped)
- SQL poll 22 tasks (ISqlDialect seam, SQL Server only in v1; SQLite + central-SQL fixtures)
- MTConnect Agent 23 tasks (browse free via Wave-0 seam; TrakHound-vs-hand-rolled = Task 0)
- MQTT/Sparkplug B 27 tasks (P1 plain MQTT 0-14 then P2 Sparkplug 15-26; MQTTnet-5 pinning spike = Task 0)
Wave 0 (universal browser) remains merged (056887d6) with its live gate open (#468).
All four new plans are design-only -> plan-ready; nothing built yet.
Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW
Joseph Doherty