Merge Wave-2 integration: array writes reachable for AbCip/AbLegacy/TwinCAT (#737 #738 #739)

Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT

docs/drivers/AbCip.md

@@ -252,7 +252,7 @@ The driver has two interchangeable wire transports, selected by one `DriverConfi
   write, read back, restored byte-exact). A user-approved **native array-element write** followed: `Program:EM01_PowerUnit._SEQ_EP[31]`
   0→4242→0 (the array's only alias targets `[1]`, no routine indexes or block-copies it; all 32 elements snapshotted
   twice before, after the write and after the restore — only `[31]` changed). Still ab_server-only: whole-array
-  writes (the driver has none), libplctag member writes, and fragmented writes. #566 is answered (the controller drops TCP; see "A target-closed CIP connection"). Mixed STRING/array/scalar
+  writes (#737; see [1-D array support](#1-d-array-support)), libplctag member writes, and fragmented writes. #566 is answered (the controller drops TCP; see "A target-closed CIP connection"). Mixed STRING/array/scalar
   Multiple Service Packet reads (#582) are proven on the press (one 5-read MSP, values equal to single reads). Results:
   [native-ab-transport-gate-results](../plans/2026-10-07-native-ab-transport-gate-results.md).
 - **libplctag cannot be deleted yet.** Scalar, UDT-member and STRING native writes are proven on a CompactLogix
@@ -262,7 +262,7 @@ The driver has two interchangeable wire transports, selected by one `DriverConfi
   libplctag member-write path is `ab_server`-only. See [Member writes](#member-writes).
 - ⚠️ RESIDUAL (#567): wide-struct **fragmented writes** (8-byte alignment) are unit-tested only. A write fragments only
   above `MaxRequestBytes` (4000 B on a Large Forward Open), so it needs a ~4 KB value; Z-35162 has no safe one (a DINT[32]
-  or a STRING is a single Write Tag, and AbCip has no whole-array write anyway). It stays open until a bench controller
+  or a STRING is a single Write Tag — and a whole DINT[32] array write, #737, is 128 B). It stays open until a bench controller
   or an approved large scratch tag exists.
 - Native browse (#572, resolved in code): listing paging no longer assumes ascending instance order, pages
   are paced, and a browse's template reads share one lease. Observed on Z-35162 (2026-10-09, 41
@@ -361,7 +361,17 @@ integration fixture is down during normal dev (Docker host fixture currently off
 
 **Live-verify** — integration-fixture-gated (requires `ab_server` Docker fixture on `10.100.0.35:44818`).
 
-**Deferrals** — array *writes*, multi-dimensional arrays, per-element historization.  Safety-partition array tags (`SafetyTag: true`) are excluded (GuardLogix write constraints extend to array writes).
+**Array writes (#737, review 07 U10)** — a whole-array write of exactly `arrayLength` elements, encoded by
+`AbCipArrayCodec` little-endian at the element width on both transports. Element values **convert**
+(ScadaBridge writes `int[]` to INT arrays); a value that does not fit is `BadOutOfRange`, one that cannot convert
+`BadTypeMismatch`, a different length `BadOutOfRange`, all before anything is sent. The controller buffer must be
+width × count (else `BadTypeMismatch`, checked before sending). Writable element types: `SInt`/`USInt`/`Int`/`UInt`/
+`DInt`/`UDInt`/`Real`/`Dt`/`LInt`/`ULInt`/`LReal`. **BOOL arrays** (bit-packed DWORDs), **STRING** and **structure**
+arrays are refused `BadNotSupported`, so their nodes stay read-only (`DriverArrayWriteSupport`); so does a
+safety-partition array tag (`safetyTag: true`, `BadNotWritable`). An array deployed read-only before #737 turns
+writable on the next deploy (a surgical `ArrayWritable` update). Proven on `ab_server` only until the hardware gate runs.
+
+**Deferrals** — multi-dimensional arrays, per-element historization, whole-array writes on hardware.
 
 See [Uns.md §Array tags](../Uns.md#array-tags-1-d) for the cross-driver coverage matrix
 and the UI authoring flow.
@@ -454,8 +464,9 @@ when it is browse-committed in `/raw`, and that tag writes like any other atomic
   `writable` key. The node is writable only once the operator sets the raw tag to `ReadWrite` (the
   node-manager gate); an authored `"writable": false` still refuses at the driver (`BadNotWritable`). The
   browse's `SecurityClass` (members inherit the parent symbol's read-only bit) is not consulted by the
-  commit. An element of a member array is authored by hand as `Seg.Points[2]`; a whole member array is
-  not writable (AbCip has no array encoder, `DriverArrayWriteSupport`).
+  commit. An element of a member array is authored by hand as `Seg.Points[2]`; a whole member array of an
+  atomic type is writable as an array tag (`isArray` + `arrayLength`, #737), a BOOL / STRING / structure member
+  array is not (`DriverArrayWriteSupport`).
 - **The request names the member.** One CIP symbolic segment per member (plus an element segment), the
   member's own CIP type, the member's own bytes — never the parent UDT, never a hidden host. Pinned at the
   request-byte level by `NativeAbCipTagRuntimeTests.A_member_path_write_names_the_member_and_sends_only_its_own_bytes`

docs/drivers/AbLegacy.md

@@ -304,8 +304,18 @@ N values of the declared `AbLegacyDataType`.  Maximum element count is 256 (PCCC
 limit).
 
 This closes the previously-noted limitation ("single-element addressing today") for the
-array read path.  The opt-in native transport also writes multi-element arrays (chunked); on libplctag
-array *writes* remain a follow-up.
+array read path.
+
+**Array writes (#738, review 07 U10 / r0 I3)** — on both transports, a whole-array write encodes exactly
+`arrayLength` elements at the **data file's** element width (N / B / A words, L longs, F floats). Element values
+**convert** (ScadaBridge writes `int[]` to Int16 nodes); a length mismatch or an element that overflows is
+`BadOutOfRange`, a non-numeric value `BadTypeMismatch`, before any runtime exists. Writable: `Int` / `AnalogInt` on
+an N / B / A file, `Long` on an L file, `Float` on an F file, on a plain `<file><number>:<word>` address of at most
+256 elements. These nodes stay **read-only** (`DriverArrayWriteSupport`): Bit arrays (bit-packed words), String /
+Timer / Counter / Control arrays (rejected at `FromTagConfig`), `/bit` and `.sub` addresses, a type that does not
+match its file (`BadTypeMismatch`), any PLC-5 on the native transport (writes refused before the wire), the
+`S:` / `I:` / `O:` files (libplctag refuses their translated names), and — deliberately — indirect addresses, whose
+element moves with the index word. An array deployed read-only before #738 turns writable on the next deploy.
 
 **Unit test coverage** — `tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Tests/` covers
 the multi-element read path via the fake tag runtime.  The AB Legacy integration fixture is
@@ -313,8 +323,10 @@ down during normal dev.
 
 **Live-verify** — integration-fixture-gated (requires the AB Legacy Docker fixture).
 
-**Deferrals** — array *writes* on libplctag (the opt-in native transport writes them), multi-dimensional arrays, per-element historization.
-`arrayLength > 256` is rejected at init with an explicit error (PCCC payload cap).
+**Deferrals** — multi-dimensional arrays, per-element historization, array writes on hardware
+(`AbLegacyArrayWriteIntegrationTests` is green on `ab_server` and ready for a real controller via
+`AB_LEGACY_ARRAY_WRITE_BASE`).
+`arrayLength > 256` is clamped to 256 by the tag factory (PCCC payload cap), so such a node stays read-only.
 
 See [Uns.md §Array tags](../Uns.md#array-tags-1-d) for the cross-driver coverage matrix
 and the UI authoring flow.

docs/drivers/TwinCAT.md

@@ -362,6 +362,20 @@ element-typed CLR array (`bool[]`, `sbyte[]`, `byte[]`, `short[]`, `ushort[]`, `
   down (found live, below). A bit outside the parent's width, or a bit of a non-integer parent,
   is refused with `BadTypeMismatch`.
 
+### Array writes (#739, review 07 U9)
+
+An array node is **writable** (`DriverArrayWriteSupport`) for every element type the codec lays out —
+numeric, `Bool` (one byte per element, as TwinCAT stores a BOOL array), `STRING`/`WSTRING` and the temporal
+types. The write takes exactly `arrayLength` elements and **converts** each one (`ConvertForWrite`; ScadaBridge
+writes `int[]` to an Int16 node); a length mismatch or an out-of-range element is `BadOutOfRange` and a scalar
+value `BadTypeMismatch`, before any wire traffic. `WriteArrayAsync` then plans the layout from the resolved PLC
+array with the same `CheckArray` the read uses and encodes with `TwinCATArrayCodec.Encode` (the inverse of the
+decode); a shorter `arrayLength` writes the leading sub-range, and a multi-dimensional PLC array is written
+row-major from the flat 1-D value. A BOOL **bit-in-word** path (`MAIN.Word.3`) stays read-only as an array: it is a
+scalar bit write. Under a `DateTime` node only `DATE`/`DT`/`WSTRING` elements are writable, and under a `String`
+node only `STRING`/`WSTRING` (other conversions would depend on the text). An array deployed read-only before #739
+turns writable on the next deploy. Unit- and XAR-gate-tested; real-hardware proof is pending.
+
 ### Notification size cap
 
 ADS documents no notification size limit, and a live TwinCAT 2.11 target registered and