feat(mtconnect): serve TIME_SERIES observations as variable-length double[] (#627)

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

docs/drivers/MTConnect.md

@@ -230,10 +230,37 @@ Other status codes an observation can surface:
 |---|---|
 | `BadTypeMismatch` (`0x80740000`) | The Agent's text isn't a value of the tag's coerced type at all |
 | `BadOutOfRange` (`0x803C0000`) | The Agent reported a number the coerced type can't represent |
-| `BadNotSupported` (`0x803D0000`) | A shape this build doesn't materialize — a `TIME_SERIES` vector, or a structured `DATA_SET`/`TABLE` observation (deferred to P1.5; see [Known limitations](#known-limitations)) |
+| `BadDecodingError` (`0x80070000`) | A `TIME_SERIES` vector whose element count disagrees with the observation's own `sampleCount` (or the tag's fixed `ArrayDim`) — see [TIME_SERIES](#time_series-arrays-627) |
+| `BadNotSupported` (`0x803D0000`) | A shape this build doesn't materialize — a structured `DATA_SET`/`TABLE` observation (decided: stays unsupported, #627), or an array tag declared as anything other than Float64 |
 | `BadWaitingForInitialData` | Tag is authored but the Agent hasn't reported it yet |
 | `BadNodeIdUnknown` | DataItem id is neither authored nor ever observed |
 
+### TIME_SERIES arrays (#627)
+
+A `SAMPLE` DataItem with `representation="TIME_SERIES"` is served as a
+**variable-length `double[]`** (`ValueRank = 1`, no fixed `ArrayDimensions` —
+a live Agent never declares `sampleCount` on the DataItem, see Known
+limitations 4; a probe that does declare one yields a fixed `ArrayDim`).
+Parsing: the observation text is split on any whitespace, each token parsed
+invariant-culture. The result is **all-or-nothing** — one non-numeric /
+non-finite token is `BadTypeMismatch`, a literal `UNAVAILABLE` token or an
+empty body is `BadNoCommunication`, and a count that disagrees with the
+observation's own `sampleCount` attribute (or a fixed `ArrayDim`) is
+`BadDecodingError`. A partial vector is never served as Good. Only a
+**Float64** array tag is served; any other declared element type stays
+`BadNotSupported`. An authored tag needs `"isArray": true` and
+`"dataType": "Float64"` in its TagConfig (the AdminUI editor shows an advisory
+for any other array type; a browse-commit does not stamp `isArray`, so set it
+in the Tag modal's array section).
+
+**Sample rate is not exposed on the served node.** The observation's
+`sampleRate` and `sampleCount` attributes are parsed (`MTConnectObservation`)
+but the OPC UA node has no description/property slot through `DriverAttributeInfo`,
+and a sibling property node would need a new address-space mechanism. Decision:
+document it — the rate is a property of the Agent's DataItem (`sampleRate` in
+`/probe`), read it there. **`DATA_SET` / `TABLE` stay `BadNotSupported`** (decision, #627): they are
+key/value maps with no scalar or array OPC UA shape that preserves the keys.
+
 ### Subscribe — the `/sample` pump
 
 One shared `/sample` long-poll stream per driver instance (the Agent streams
@@ -410,7 +437,7 @@ for anything beyond values-and-conditions.
    `/probe` metadata a browse-commit stamped (`mtCategory`/`mtType`), and shows an
    advisory line — it never blocks a save (the deploy gate does not refuse it) and
    is a no-op for hand-authored blobs with no stamped metadata. `representation`
-   is not on the model, so TIME_SERIES arrays are not covered. Beyond that,
+   is not on the model; TIME_SERIES arrays get their own `isArray` advisory (declare Float64). Beyond that,
    nothing validates a raw tag's declared OPC UA `DataType` against the
    blob's coercion type. The `/probe`-sourced inference
    (`MTConnectDataTypeInference`) narrows how often an author picks a wrong
@@ -427,9 +454,11 @@ for anything beyond values-and-conditions.
    declare a `sampleCount`, is unrealistic on this point and exists only to
    pin the parsing rule itself.
 5. **CONDITION is a plain `String`, not a native Part 9 alarm** (see above).
-6. **`TIME_SERIES` arrays and structured `DATA_SET`/`TABLE` observations
-   surface as `BadNotSupported`**, not an approximation — see the Quality
-   mapping table.
+6. **Structured `DATA_SET`/`TABLE` observations surface as
+   `BadNotSupported`**, not an approximation — see the Quality mapping table.
+   `TIME_SERIES` is served as `double[]` (#627, see
+   [TIME_SERIES arrays](#time_series-arrays-627)); the sample rate is not
+   surfaced on the node.
 
 ## Deferred (not in this build)
 
@@ -447,8 +476,7 @@ for anything beyond values-and-conditions.
 - **P1.5 fast-follow** (design
   [§9](../plans/2026-07-15-mtconnect-driver-design.md#9-phasing--effort)):
   CONDITION → native OPC UA Part 9 alarms via `IAlarmSource` (the Galaxy
-  native-alarm pattern); `TIME_SERIES` SAMPLE arrays materialized as real
-  OPC UA arrays; EVENT controlled-vocabulary values → OPC UA enumerations.
+  native-alarm pattern); EVENT controlled-vocabulary values → OPC UA enumerations.
 - **P2 (on demand): SHDR adapter ingest.** A `SourceMode: "Agent" | "Shdr"`
   switch that opens the raw pipe-delimited SHDR TCP socket directly. Loses
   auto-discovery (no device model without an Agent in front, so