AB CIP Logix Emulate golden-box tier — scaffold the code + docs so the L5X + Emulate PC drop in without fixture-code changes. Closes the initial design question the user raised; the actual Emulate-side work (author project, commit L5X, install Emulate on the dev box) is tracked as #223. Scaffolding ships everything that doesn't need the live Emulate instance: tier-gated test classes that skip cleanly when AB_SERVER_PROFILE is unset, the profile gate helper, the LogixProject/README.md documenting the exact project state the tests expect, the fixture coverage doc's new §Logix Emulate tier section with the when-to-trust table extended from 3 columns to 4, and the dev-environment.md integration-host row.

AbServerProfileGate — static helper that reads `AB_SERVER_PROFILE` env var (defaults to "abserver") + exposes `SkipUnless(params string[] requiredProfiles)` matching the MODBUS_SIM_PROFILE pattern the DL205StringQuirkTests uses one directory over. Emulate-only tests call `AbServerProfileGate.SkipUnless("emulate")` at the top of each fact body; ab_server-default runs see them skip with a clear message pointing at the Emulate setup steps.

AbCipEmulateUdtReadTests — one test proving the #194 whole-UDT read optimization works against the real Logix Template Object, not just the golden byte buffers the unit suite uses. Builds an `AbCipDriverOptions` with a Structure tag `Motor1 : Motor_UDT` that has three declared members (Speed : DINT, Torque : REAL, Status : DINT), reads them via the `.Speed / .Torque / .Status` dotted-tag syntax, asserts the driver gets the grouped whole-UDT path + decodes each at the right offset. Required seed values documented inline + in LogixProject/README.md: Speed=1800, Torque=42.5f, Status=0x0001.

AbCipEmulateAlmdTests — one test proving the #177 ALMD projection fires `OnAlarmEvent` when a real ALMD instruction's `In` edge rises, not just the fake `InFaulted` timer edges the unit suite drives. Needs a `SimulateAlarm : BOOL` tag routed through `MainRoutine` ladder (`XIC SimulateAlarm OTE HighTempAlarm.In`) so the test case can pulse the input via the existing `IWritable.WriteAsync` path instead of scripting Emulate via its own socket. Alarm-projection options carry `EnableAlarmProjection = true` + 200 ms poll interval; a `TaskCompletionSource` gates the raise-event assertion with a 5 s deadline. Cleanup writes SimulateAlarm=false so consecutive runs start from known state.

LogixProject/README.md — the Studio 5000 project state the Emulate-tier tests depend on. Explains why L5X over ACD (text diff, reproducible import, no per-install state), the UDT + tag + routine structure, how to bring it up on the Emulate PC. Ships as a stub pending actual author + L5X export + commit; the README itself keeps the requirements visible so the L5X author has a checklist.

docs/drivers/AbServer-Test-Fixture.md — new §Logix Emulate golden-box tier section with the coverage-promotion table (ab_server / Emulate / hardware per gap), the setup-env-var recipe, the costs to accept (license, Hyper-V conflict, manual lifecycle). "When to trust" table extended from 3 columns (ab_server / unit / rig) to 4 (ab_server / unit / Logix Emulate / rig); two new rows for EtherNet/IP embedded-switch + redundant-chassis failover that even Emulate can't help with. Follow-up candidates list gets Logix Emulate as option 1 ahead of the pre-existing "extend ab_server upstream" + "stand up a lab rig". See-also file list gains AbServerProfileGate.cs + Docker/ + Emulate/ + LogixProject/README.md entries.

docs/v2/dev-environment.md — §C Integration host gains a Rockwell Studio 5000 Logix Emulate row: purpose (AB CIP golden-box tier closing UDT/ALMD/AOI/safety/ConnectionSize gaps), type (Windows-only, Hyper-V conflict matching TwinCAT XAR's constraint), port 44818, credentials note, owner split between integration-host admin for license+install and developer for per-session runtime start.

Verified: Emulate tests skip cleanly when AB_SERVER_PROFILE is unset — both `[SKIP]` with the operator-facing message pointing at the env-var setup. Whole-solution build 0 errors. Tests will transition from skip → pass once the L5X + Emulate PC land per #223.

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

docs/v2/dev-environment.md

@@ -149,6 +149,7 @@ Dev credentials in this inventory are convenience defaults, not secrets. Change
 | **S7 fixture — `otopcua-python-snap7:1.0`** | S7 driver integration tests | Docker image (local build, `python-snap7>=2.0`; see `tests/ZB.MOM.WW.OtOpcUa.Driver.S7.IntegrationTests/Docker/`); 1 compose profile: `s7_1500` | 1102 (non-privileged; driver honours `S7DriverOptions.Port`) | n/a | Developer (per machine) |
 | **OPC UA Client fixture — `mcr.microsoft.com/iotedge/opc-plc:2.14.10`** | OpcUaClient driver integration tests | Docker image (Microsoft-maintained, pinned; see `tests/ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.IntegrationTests/Docker/`) | 50000 (OPC UA) | Anonymous (`--daa` off); auto-accept certs (`--aa`) | Developer (per machine) |
 | **TwinCAT XAR runtime VM** | TwinCAT ADS testing (per `test-data-sources.md` §5; Beckhoff XAR cannot coexist with Hyper-V on the same OS) | Hyper-V VM with Windows + TwinCAT XAR installed under 7-day renewable trial | 48898 (ADS over TCP) | TwinCAT default route credentials configured per Beckhoff docs | Integration host admin |
+| **Rockwell Studio 5000 Logix Emulate** | AB CIP golden-box tier — closes UDT / ALMD / AOI / GuardLogix-safety / CompactLogix-ConnectionSize gaps the ab_server simulator can't cover. Loads the L5X project documented at `tests/.../AbCip.IntegrationTests/LogixProject/README.md`. Tests gated on `AB_SERVER_PROFILE=emulate` + `AB_SERVER_ENDPOINT=<ip>:44818`; see `docs/drivers/AbServer-Test-Fixture.md` §Logix Emulate golden-box tier | Windows-only install; **Hyper-V conflict** — can't coexist with Docker Desktop's WSL 2 backend on the same OS, same story as TwinCAT XAR. Runs on a dedicated Windows PC reachable on the LAN | 44818 (CIP / EtherNet/IP) | None required at the CIP layer; Studio 5000 project credentials per Rockwell install | Integration host admin (license + install); Developer (per session — open Emulate, load L5X, click Run) |
 | **FOCAS TCP stub** (`Driver.Focas.TestStub`) | FOCAS functional testing (per `test-data-sources.md` §6) | Local .NET 10 console app from this repo | 8193 (FOCAS) | n/a | Developer / integration host (run on demand) |
 | **FOCAS FaultShim** (`Driver.Focas.FaultShim`) | FOCAS native-fault injection (per `test-data-sources.md` §6) | Test-only native DLL named `Fwlib64.dll`, loaded via DLL search path in the test fixture | n/a (in-process) | n/a | Developer / integration host (test-only) |