AB CIP PR 3 — IReadable implementation against libplctag. Introduces IAbCipTagRuntime + IAbCipTagFactory abstraction matching the Modbus transport-factory pattern (ctor optional arg, default production impl injected) so the driver's read/status-mapping logic is unit-testable without a live PLC or the native libplctag binary. LibplctagTagRuntime is the default wire-backed implementation — wraps libplctag.Tag + translates our AbCipDataType enum into GetInt8/GetUInt8/GetInt16/GetUInt16/GetInt32/GetUInt32/GetInt64/GetUInt64/GetFloat32/GetFloat64/GetString/GetBit calls covering Bool (standalone + BOOL-in-DINT via .N bit selector), SInt/USInt, Int/UInt, DInt/UDInt, LInt/ULInt, Real, LReal, String, Dt (epoch DINT), with Structure deferred to PR 6. MapPlcType bridges our libplctag attribute strings (controllogix, compactlogix, micro800) to libplctag.PlcType enum; CompactLogix rolls under ControlLogix per libplctag's family grouping which matches the wire protocol reality. AbCipDriver now implements IReadable — ReadAsync iterates fullReferences preserving order, looks up each tag definition + its device, lazily materialises the tag runtime via EnsureTagRuntimeAsync on first touch (cached thereafter for the lifetime of the device), catches OperationCanceledException to honor cancellation, maps libplctag non-zero status via AbCipStatusMapper.MapLibplctagStatus, catches any other exception as BadCommunicationError. Health surface moves to Healthy on success + Degraded with the last error message on failure. Initialize-failure path disposes the half-created runtime before rethrowing so no native handles leak. DeviceState gains a Runtimes dict alongside the existing TagHandles collection; DisposeHandles walks both so ShutdownAsync + ReinitializeAsync cleanly destroy every native tag. 12 new unit tests in AbCipDriverReadTests using FakeAbCipTag / FakeAbCipTagFactory (test fake under tests/...AbCip.Tests/FakeAbCipTag.cs) covering unknown reference → BadNodeIdUnknown, unknown device → BadNodeIdUnknown, successful DInt read with correct Good status + captured value, lazy-init on first read with reuse across subsequent reads, non-zero libplctag status mapping via AbCipStatusMapper, exception during read surfacing as BadCommunicationError with health Degraded, batched reads preserving order + per-tag status, health Healthy after success, TagCreateParams composition from device + profile (gateway / port / CIP path / libplctag attribute / tag name wiring), cancellation propagation via OperationCanceledException, ShutdownAsync disposing every runtime, Initialize-failure disposing the aborted runtime. Total AbCip unit tests now 88/88 passing. Integration test project scaffolding — tests/ZB.MOM.WW.OtOpcUa.Driver.AbCip.IntegrationTests with AbServerFixture (IAsyncLifetime that starts ab_server when the binary is on PATH, otherwise marks IsAvailable=false), AbServerFact attribute (Fact-equivalent that skips when ab_server is missing), one smoke test exercising DInt read end-to-end. Project runs cleanly — the single smoke test skips on boxes without ab_server (0 failed, 0 passed, 1 skipped) + runs on boxes with it. Follow-up work captured in comments — ab_server CI fixture (download prebuilt Windows x64 binary as GitHub release asset) + per-family JSON profiles + hand-rolled CIP stub for UDT fidelity ship in the PR 6/9-12 window. Solution file updated. Full solution builds 0 errors across all 28 projects. Modbus + other existing tests untouched.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/ZB.MOM.WW.OtOpcUa.Driver.AbCip.IntegrationTests/AbCipReadSmokeTests.cs

@@ -0,0 +1,44 @@
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Driver.AbCip;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.AbCip.IntegrationTests;
+
+/// <summary>
+///     End-to-end smoke tests that exercise the real libplctag stack against a running
+///     <c>ab_server</c>. Skipped when the binary isn't on PATH (<see cref="AbServerFactAttribute"/>).
+/// </summary>
+/// <remarks>
+///     Intentionally minimal — per-family + per-capability coverage ships in PRs 9–12 once the
+///     integration harness is CI-ready. This file exists at PR 3 time to prove the wire path
+///     works end-to-end on developer boxes that have <c>ab_server</c>.
+/// </remarks>
+[Trait("Category", "Integration")]
+[Trait("Requires", "AbServer")]
+public sealed class AbCipReadSmokeTests : IAsyncLifetime
+{
+    private readonly AbServerFixture _fixture = new();
+
+    public async ValueTask InitializeAsync() => await _fixture.InitializeAsync();
+    public async ValueTask DisposeAsync() => await _fixture.DisposeAsync();
+
+    [AbServerFact]
+    public async Task Driver_reads_DInt_from_ab_server()
+    {
+        var drv = new AbCipDriver(new AbCipDriverOptions
+        {
+            Devices = [new AbCipDeviceOptions($"ab://127.0.0.1:{_fixture.Port}/1,0", AbCipPlcFamily.ControlLogix)],
+            Tags = [new AbCipTagDefinition("Counter", $"ab://127.0.0.1:{_fixture.Port}/1,0", "TestDINT", AbCipDataType.DInt)],
+            Timeout = TimeSpan.FromSeconds(5),
+        }, "drv-smoke");
+
+        await drv.InitializeAsync("{}", CancellationToken.None);
+        var snapshots = await drv.ReadAsync(["Counter"], CancellationToken.None);
+
+        snapshots.Single().StatusCode.ShouldBe(AbCipStatusMapper.Good);
+        drv.GetHealth().State.ShouldBe(DriverState.Healthy);
+
+        await drv.ShutdownAsync(CancellationToken.None);
+    }
+}