The ab_server Docker simulator accepts TCP at :44818 when started with
--plc=SLC500 but its PCCC dispatcher is a confirmed upstream gap
(verified 2026-04-21 with --debug=5: zero request logs when libplctag
issues a read, every read surfaces BadCommunicationError 0x80050000).
Previous behavior — when Docker was up, the three smoke tests ran and
all failed on every integration-host run. Noise, not signal.
New behavior — AbLegacyServerFixture gates on a new env var
AB_LEGACY_TRUST_WIRE:
Endpoint reachable? | TRUST_WIRE set? | Result
--------------------+-----------------+------------------------------
No | — | Skip ("not reachable")
Yes | No | Skip ("ab_server PCCC gap")
Yes | 1 / true | Run
The fixture's new skip reason explicitly names the upstream gap + the
resolution paths (upstream bug / RSEmulate golden-box / real hardware
via task #222 lab rig). Operators with a real SLC 5/05 / MicroLogix
1100/1400 / PLC-5 or an Emulate box set AB_LEGACY_ENDPOINT + TRUST_WIRE
and the smoke tests round-trip cleanly.
Updated docs:
- tests/.../Docker/README.md — new env-var table + three-case gate matrix
- Known limitations section refreshed to "confirmed upstream gap"
Verified locally:
- Docker down: 2 skipped.
- Docker up + TRUST_WIRE unset: 2 skipped (upstream-gap message).
- Docker up + TRUST_WIRE=1: 4 run, 4 fail BadCommunicationError (ab_server gap as expected).
- Unit suite: 96 passed / 0 failed (regression-clean).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
012c6a4e7a