Auto: abcip-1.3 — array-slice read addressing

Closes #227

tests/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Tests/AbCipDriverReadTests.cs

@@ -165,6 +165,55 @@ public sealed class AbCipDriverReadTests
         p.TagName.ShouldBe("Program:P.Counter");
     }
 
+    [Fact]
+    public async Task Slice_tag_reads_one_array_and_decodes_n_elements()
+    {
+        // PR abcip-1.3 — `Data[0..3]` slice routes through AbCipArrayReadPlanner: one libplctag
+        // tag-create at TagName="Data[0]" with ElementCount=4, single PLC read, contiguous
+        // buffer decoded at element stride into one snapshot whose Value is an object?[].
+        var (drv, factory) = NewDriver(
+            new AbCipTagDefinition("DataSlice", "ab://10.0.0.5/1,0", "Data[0..3]", AbCipDataType.DInt));
+        await drv.InitializeAsync("{}", CancellationToken.None);
+        factory.Customise = p =>
+        {
+            var t = new FakeAbCipTag(p);
+            t.ValuesByOffset[0] = 10;
+            t.ValuesByOffset[4] = 20;
+            t.ValuesByOffset[8] = 30;
+            t.ValuesByOffset[12] = 40;
+            return t;
+        };
+
+        var snapshots = await drv.ReadAsync(["DataSlice"], CancellationToken.None);
+
+        snapshots.Single().StatusCode.ShouldBe(AbCipStatusMapper.Good);
+        var values = snapshots.Single().Value.ShouldBeOfType<object?[]>();
+        values.ShouldBe(new object?[] { 10, 20, 30, 40 });
+
+        // Exactly ONE libplctag tag was created — anchored at the slice start with
+        // ElementCount=4. Without the planner this would have been four scalar reads.
+        factory.Tags.Count.ShouldBe(1);
+        factory.Tags.ShouldContainKey("Data[0]");
+        factory.Tags["Data[0]"].CreationParams.ElementCount.ShouldBe(4);
+        factory.Tags["Data[0]"].ReadCount.ShouldBe(1);
+    }
+
+    [Fact]
+    public async Task Slice_tag_with_unsupported_element_type_returns_BadNotSupported()
+    {
+        // BOOL slices can't be laid out from the declaration alone (Logix packs BOOLs into a
+        // hidden host byte). The planner refuses; the driver surfaces BadNotSupported instead
+        // of attempting a best-effort decode.
+        var (drv, _) = NewDriver(
+            new AbCipTagDefinition("BoolSlice", "ab://10.0.0.5/1,0", "Flags[0..7]", AbCipDataType.Bool));
+        await drv.InitializeAsync("{}", CancellationToken.None);
+
+        var snapshots = await drv.ReadAsync(["BoolSlice"], CancellationToken.None);
+
+        snapshots.Single().StatusCode.ShouldBe(AbCipStatusMapper.BadNotSupported);
+        snapshots.Single().Value.ShouldBeNull();
+    }
+
     [Fact]
     public async Task Cancellation_propagates_from_read()
     {