docs(mtconnect): P1 driver guide + tracking-doc update, defer write-back (Task 22)

- docs/drivers/MTConnect.md: getting-started guide for the P1 Agent MVP —
  config keys read off MTConnectDriverOptions/ConfigDto, capability surface,
  RawPath->dataItemId coercion precedence, UNAVAILABLE->BadNoCommunication +
  the rest of the quality-code table, CONDITION-as-String, browse-via-the-
  universal-browser, the fixture recipe (links the existing IntegrationTests
  Docker README instead of duplicating it), and a Known limitations section
  covering the two pre-existing fleet-wide gaps this build surfaced
  (IRediscoverable/IHostConnectivityProbe have no server consumer; no driver
  form blocks Save on validation). Records write-back (MTConnect Interfaces),
  P1.5 (native alarms, TIME_SERIES arrays, EVENT->enum), and P2 (SHDR ingest)
  as deferred per design doc SS3.6/SS9. Documents where the build diverged
  from the design: TrakHound MTConnect.NET was dropped entirely (no XML
  formatter in the pinned packages, no injectable HTTP handler) in favor of
  a hand-rolled System.Xml.Linq client, namespace-agnostic on LocalName.
- docs/drivers/README.md: adds MTConnect to the ground-truth driver table,
  the per-driver doc list, and the fixture coverage-map list.
- docs/plans/2026-07-24-driver-expansion-tracking.md: marks the MTConnect
  Wave-2 row Done (22/23 tasks; Task 21 live gate tracked separately in the
  plan file, not touched here), corrects mtconnect/cppagent -> mtconnect/agent
  in the fixture note, and links the new driver guide.

Deferred-cleanup decision (Task 1 review follow-up): removed
GenerateDocumentationFile/NoWarn CS1591 from Driver.MTConnect.Contracts's
csproj to match all eight sibling .Contracts projects, none of which carry
it. Verified both the Contracts project alone and the full solution still
build clean (0 warnings, 0 errors) with the flags gone — the existing XML
doc comments don't depend on GenerateDocumentationFile to compile.

docs/drivers/README.md

@@ -30,6 +30,7 @@ Driver type metadata is registered at startup in `DriverTypeRegistry` (`src/Core
 | [FOCAS](FOCAS.md) | `Driver.FOCAS` | A | Pure-managed `FocasWireClient` — FOCAS/2 Ethernet binary protocol on TCP:8193, inlined into the driver assembly | IDriver, ITagDiscovery, IReadable, IWritable, ISubscribable, IHostConnectivityProbe, IPerCallHostResolver, IAlarmSource | `IWritable` is implemented but read-only by design — `WriteAsync` returns `BadNotWritable` for every point. CNC-shaped data model (axes, spindle, PMC, macros, alarms) not a flat tag map. Previously Tier-C (Host + P/Invoke + shim DLL); retired in the 2026-04-24 migration when the managed wire client landed |
 | [OPC UA Client](OpcUaClient.md) | `Driver.OpcUaClient` | B | OPCFoundation `Opc.Ua.Client` | IDriver, ITagDiscovery, IReadable, IWritable, ISubscribable, IAlarmSource, IHistoryProvider, IHostConnectivityProbe | Gateway/aggregation driver — the only driver implementing driver-side `IHistoryProvider` (forwards HistoryRead to the upstream server). Opens a single `Session` against a remote OPC UA server and re-exposes its address space. Owns its own `ApplicationConfiguration` (distinct from `Client.Shared`) because it's always-on with keep-alive + `TransferSubscriptions` across SDK reconnect, not an interactive CLI |
 | [MQTT](Mqtt.md) | `Driver.Mqtt` (+ `.Browser`, `.Contracts`) | A | [MQTTnet 5](https://github.com/dotnet/MQTTnet) | IDriver, ITagDiscovery, IReadable, ISubscribable, IHostConnectivityProbe, IRediscoverable | **Push, not poll, and read-only** — the broker delivers PUBLISH frames the driver forwards straight to `ISubscribable.OnDataChange`; `IReadable` serves the last retained/received value from cache, and there is **no `IWritable`** (nothing publishes back). Subscriptions are indexed **by topic filter, not by topic**, so wildcard tags survive a reconnect. A rejected CONNACK throws `MqttConnectRejectedException`: unrecoverable codes → `Faulted` + supervisor stop, transient → retry. **Two modes:** `Plain` binds a tag to a concrete topic + JSON path; `SparkplugB` decodes vendored Eclipse-Tahu protobuf under one `spBv1.0/{groupId}/#` subscription and binds by the `group/edgeNode/device?/metric` tuple (birth/alias/seq-gap state machine, death→STALE, scoped rebirth NCMD). `IRediscoverable` fires on a DBIRTH but is **inert platform-side** — see [#507](https://gitea.dohertylan.com/dohertj2/lmxopcua/issues/507) |
+| [MTConnect](MTConnect.md) | `Driver.MTConnect` (+ `.Contracts`) | — | Hand-rolled `System.Xml.Linq` HTTP/XML client against a vendor-neutral MTConnect Agent (`/probe`, `/current`, `/sample`) — no TrakHound dependency (dropped; see the driver doc) | IDriver, ITagDiscovery, IReadable, ISubscribable, IHostConnectivityProbe, IRediscoverable | Read-only by design (no `IWritable`). Production data plane is entirely `ISubscribable`/`OnDataChange` — `IReadable` is CLI/test-only. Browse is free via the Wave-0 universal discovery browser, no bespoke browser project. `IRediscoverable`/`IHostConnectivityProbe` have no server-side consumer yet — a pre-existing fleet-wide gap, not MTConnect-specific |
 | [Historian.Gateway](../Historian.md) | `Driver.Historian.Gateway` | — | `ZB.MOM.WW.HistorianGateway.Client` gRPC (`historian_gateway.v1`) | IHistorianDataSource (server-side read backend) + alarm `SendEvent` writer + `WriteLiveValues` recorder + `IHistorianProvisioning` | Not a tag driver — the sole historian backend. Registers `GatewayHistorianDataSource : IHistorianDataSource` for HistoryRead and serves alarm-write + continuous historization through the gateway. No `IDriver`/`ITagDiscovery` surface. (The retired Wonderware sidecar backend it replaced is documented at [Historian.Wonderware.md](Historian.Wonderware.md).) |
 
 ## Per-driver documentation
@@ -50,6 +51,10 @@ Driver type metadata is registered at startup in `DriverTypeRegistry` (`src/Core
   - [OpcUaClient.md](OpcUaClient.md) — OPC UA Client (gateway/aggregation) driver: remote-server session, driver-side HistoryRead forwarding, reconnect behaviour
   - [Mqtt.md](Mqtt.md) — MQTT broker-subscribe driver: broker/TLS/auth config, topic + JSON-path tag binding, retained-value seeding, `#`-observation browser, CONNACK-rejection semantics, **Sparkplug B** (birth/alias/seq/rebirth state machine, birth-driven browse picker, death→STALE), and the **Known gaps** table
 
+- **MTConnect** has a short getting-started doc because the hand-rolled-vs-TrakHound divergence, the
+  data-plane precedence rules, and a non-trivial known-limitations list need explaining up front:
+  - [MTConnect.md](MTConnect.md) — Agent config, `FullName`==DataItem `id`, `UNAVAILABLE`→`BadNoCommunication`, CONDITION-as-`String`, browse-via-universal-browser, fixture recipe, deferred write-back
+
 - **Historian.Gateway** (server-side historian backend, not a tag driver) is documented in the main guide:
   - [../Historian.md](../Historian.md) — HistorianGateway backend: read-path registration, HistoryRead dispatch, alarm store-and-forward (`SendEvent`), continuous historization (`WriteLiveValues`), `EnsureTags` provisioning, config keys, deployment prerequisites. (The retired Wonderware sidecar backend it replaced: [Historian.Wonderware.md](Historian.Wonderware.md).)
 
@@ -68,6 +73,7 @@ Each driver has a dedicated fixture doc that lays out what the integration / uni
 - [OPC UA Client](OpcUaClient-Test-Fixture.md) — Dockerized `opc-plc` integration suite (task #215): real Secure Channel + Session, read + subscribe verified end-to-end; write not yet exercised in the integration suite; exhaustive capability matrix (reconnect, failover, cert-auth, history, alarms) via unit suite with mocked `Session`
 - [MQTT](Mqtt-Test-Fixture.md) — Dockerized `eclipse-mosquitto` with **TLS + real auth on both listeners (no anonymous fallback)** + a JSON-publisher sidecar; env-gated live suite (**15 tests**) — 7 plain (TLS/auth connect, CA pinning both ways, subscribe→value, retained seeding, wrong-password rejection) + 8 Sparkplug against a **project-owned C# edge-node simulator** on the `sparkplug` compose profile (birth→alias bind, DDATA, NDEATH→STALE, rebirth NCMD round-trip). Births are never retained, so `docker restart otopcua-sparkplug-sim` is how you force a fresh one
 - [Galaxy](../v1/drivers/Galaxy-Test-Fixture.md) — richest harness: gateway E2E + ZB SQL live-smoke + MXAccess opt-in (v1 archive)
+- [MTConnect](../../tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.MTConnect.IntegrationTests/Docker/README.md) — Dockerized `mtconnect/agent` + stdlib SHDR adapter (two services, the Agent alone reports everything `UNAVAILABLE`); 12/12 against the real Agent, canned XML unit fixtures cover the bulk (491/491)
 
 ## Related cross-driver docs