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>

docs/drivers/AbServer-Test-Fixture.md

@@ -13,24 +13,22 @@ quirk. UDT / alarm / quirk behavior is verified only by unit tests with
 - **Binary**: `ab_server` — a C program in libplctag's
   `src/tools/ab_server/` ([libplctag/libplctag](https://github.com/libplctag/libplctag),
   MIT).
-- **Primary launcher**: Docker. `Docker/Dockerfile` multi-stage-builds
-  `ab_server` from source against a pinned libplctag tag + copies the
-  binary into a slim runtime image. `Docker/docker-compose.yml` has
-  per-family services (`controllogix` / `compactlogix` / `micro800` /
-  `guardlogix`); all bind `:44818`.
-- **Lifecycle**: `AbServerFixture` probes `127.0.0.1:44818` at collection
-  init. When a Docker container is running (or `AB_SERVER_ENDPOINT` is
-  set) the fixture skips its legacy spawn path + the tests dial the
-  running container. When neither is present, it falls back to the
-  pre-Docker path of resolving `ab_server` off `PATH` + spawning it.
+- **Launcher**: Docker (only supported path). `Docker/Dockerfile`
+  multi-stage-builds `ab_server` from source against a pinned libplctag
+  tag + copies the binary into a slim runtime image.
+  `Docker/docker-compose.yml` has per-family services (`controllogix`
+  / `compactlogix` / `micro800` / `guardlogix`); all bind `:44818`.
+- **Lifecycle**: `AbServerFixture` TCP-probes `127.0.0.1:44818` at
+  collection init + records a skip reason when unreachable. Tests skip
+  via `[AbServerFact]` / `[AbServerTheory]` which check the same probe.
 - **Profiles**: `KnownProfiles.{ControlLogix, CompactLogix, Micro800, GuardLogix}`
-  in `AbServerProfile.cs`. Each composes a CLI arg list + seed-tag set; the
-  `Docker/docker-compose.yml` `command:` entries mirror those args 1:1.
+  in `AbServerProfile.cs` — thin Family + ComposeProfile + Notes records;
+  the compose file is the canonical source of truth for which tags get
+  seeded + which `--plc` mode the simulator boots in.
 - **Tests**: one smoke, `AbCipReadSmokeTests.Driver_reads_seeded_DInt_from_ab_server`,
   parametrized over all four profiles via `[AbServerTheory]` + `[MemberData]`.
-- **Skip rules** via `[AbServerFact]` / `[AbServerTheory]`: accept a live
-  listener on `:44818` (Docker), an `AB_SERVER_ENDPOINT` override, or the
-  native binary on `PATH`; skip otherwise.
+- **Endpoint override**: `AB_SERVER_ENDPOINT=host:port` points the
+  fixture at a real PLC instead of the local container.
 
 ## What it actually covers