Remove native-launcher fallbacks for the four Dockerized fixtures — Docker is the only supported path for Modbus / S7 / AB CIP / OpcUaClient integration. Native paths stay in place only where Docker isn't compatible (Galaxy: MXAccess COM + Windows-only; TwinCAT: Beckhoff runtime vs Hyper-V; FOCAS: closed-source Fanuc Fwlib32.dll; AB Legacy: PCCC has no OSS simulator). Simplifies the fixture landscape + removes the "which path do I run" ambiguity; removes two full native-launcher directories + the AB CIP native-spawn path; removes the parallel profile-as-CLI-arg-builder code from AbServerFixture.

Modbus — deletes tests/.../Modbus.IntegrationTests/Pymodbus/ (serve.ps1, standard.json, dl205.json, mitsubishi.json, s7_1500.json, README.md). Profile JSONs live only under Docker/profiles/ now. Docker/README.md loses its "Native-Python fallback" section; docs/drivers/Modbus-Test-Fixture.md "What the fixture is" bullet flipped from "primary launcher is Docker, native fallback under Pymodbus/" to "Docker is the only supported launch path".

S7 — deletes tests/.../S7.IntegrationTests/PythonSnap7/ (server.py, s7_1500.json, serve.ps1, README.md). Docker/README.md loses "Native-Python fallback"; docs/drivers/S7-Test-Fixture.md updated to match.

AB CIP — the biggest simplification because the native-binary spawn had the most code. AbServerFixture.cs rewrites: drops Process management (no more Process _proc + Kill/WaitForExit), drops LocateBinary() PATH lookup, drops the IAsyncLifetime initialize-spawns-server behavior. Fixture is now a thin TCP probe against localhost:44818 (or AB_SERVER_ENDPOINT override) — same shape as Snap7ServerFixture / ModbusSimulatorFixture / OpcPlcFixture. IsServerAvailable() simplifies to a single 500 ms probe. AbServerProfile.cs drops AbServerPlcArg + SeedTags + BuildCliArgs + ToCliSpec + the entire AbServerSeedTag record — the compose file is the canonical source of truth for which tags + which --plc mode each family gets; the profile record now carries just Family + ComposeProfile (matches the docker-compose service key) + Notes. KnownProfiles.ForFamily + .All stay for tests that iterate families. AbServerProfileTests.cs rewrites to match: drops BuildCliArgs_* + ToCliSpec_* + SeedTags_* tests; keeps the family-coverage contract tests + verifies the ComposeProfile strings match compose-file service names (a typo in either surfaces as a unit-test failure, not a silent "wrong family booted" at runtime). Docker/README.md loses "Native-binary fallback" section; docs/drivers/AbServer-Test-Fixture.md "What the fixture is" flipped to Docker-only with clearer skip rules.

dev-environment.md §Docker fixtures — the "Native fallbacks" subsection goes away; replaced with a one-line note that Docker is the only supported path for these four fixtures + a fresh clone needs Docker Desktop and nothing else.

Verified: whole-solution build 0 errors, AB CIP profile unit tests 6/6, AB CIP Docker smoke 4/4 (all family theory rows), S7 Docker smoke 3/3. Container lifecycle clean. The deleted native code surface was already redundant — every fixture the native paths served is now covered by Docker; keeping them invited drift between the two paths (the original AB CIP native profile had three undetected bugs per the #162 commit message: case-sensitive --plc, bracket tag notation, --path=1,0 requirement — noise the Docker path now avoids by never running the buggy code).

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

tests/ZB.MOM.WW.OtOpcUa.Driver.AbCip.IntegrationTests/Docker/README.md

@@ -2,11 +2,11 @@
 
 [libplctag](https://github.com/libplctag/libplctag)'s `ab_server` — a
 MIT-licensed C program that emulates a ControlLogix / CompactLogix CIP
-endpoint over EtherNet/IP. Docker is the primary launcher because
-`ab_server` otherwise requires per-OS build-from-source (libplctag ships
-it as a source-only tool under `src/tools/ab_server/`). The existing
-native-binary-on-PATH path via `AbServerFixture.LocateBinary` stays as a
-fallback for contributors who've already built it locally.
+endpoint over EtherNet/IP. Docker is the only supported launch path;
+`ab_server` ships as a source-only tool under libplctag's
+`src/tools/ab_server/` so the Dockerfile's multi-stage build is the only
+reproducible way to get a working binary across developer boxes. A fresh
+clone needs Docker Desktop and nothing else.
 
 | File | Purpose |
 |---|---|
@@ -41,8 +41,7 @@ multi-stage build layer-caches the checkout + compile.
 ## Endpoint
 
 - Default: `localhost:44818` (EtherNet/IP standard; non-privileged)
-- No env-var override in the fixture today — add one if pointing at a
-  real PLC becomes a use case.
+- Override with `AB_SERVER_ENDPOINT=host:port` to point at a real PLC.
 
 ## Run the integration tests
 
@@ -53,11 +52,10 @@ cd C:\Users\dohertj2\Desktop\lmxopcua
 dotnet test tests\ZB.MOM.WW.OtOpcUa.Driver.AbCip.IntegrationTests
 ```
 
-`AbServerFixture` resolves `ab_server` off `PATH` — but when the Docker
-container is running, the tests dial `127.0.0.1:44818` directly through
-the libplctag client so the on-PATH lookup is effectively informational.
-Tests skip via `[AbServerFact]` / `[AbServerTheory]` when the binary
-isn't on PATH + the container's not running.
+`AbServerFixture` TCP-probes `localhost:44818` at collection init +
+records a skip reason when unreachable, so tests stay green on a fresh
+clone without the container running. Tests use `[AbServerFact]` /
+`[AbServerTheory]` which check the same probe.
 
 ## What each family seeds
 
@@ -84,14 +82,6 @@ place means updating both.
 See [`docs/drivers/AbServer-Test-Fixture.md`](../../../docs/drivers/AbServer-Test-Fixture.md)
 for the full coverage map.
 
-## Native-binary fallback
-
-`AbServerFixture.LocateBinary` checks `PATH` for `ab_server` /
-`ab_server.exe`. Build from source via
-[libplctag's build docs](https://github.com/libplctag/libplctag/blob/release/BUILD.md)
-and drop the binary on `PATH` to use it. Kept for contributors who've
-already built libplctag locally. Docker is the reproducible path.
-
 ## References
 
 - [libplctag on GitHub](https://github.com/libplctag/libplctag)