owner-gated: MUST.contractile:79 'Logtalk rule engine must be preserved' contradicts the retired engine (from #636 category C)

[arena-ai-coding-agent]

Found during the #636 category-A purge (PR branch arena/01a0df1a-hypatia, commit e8eebda).

.machine_readable/MUST.contractile:79 carries the normative invariant

(must "Logtalk rule engine for error catalog and pattern detection must be preserved")

but the Logtalk/SWI-Prolog engine was retired 2026-03-06 and its logic absorbed into the Elixir ruleset (lib/rules/*.ex) — recorded in .machine_readable/6a2/STATE.a2ml and NEUROSYM.a2ml ("Logtalk purge 2026-04-14") and in docs/architecture/topology.md.

Per doctrine #4 (contractiles/invariants are provisional + supervised), this is an OWNER decision, not a mechanical edit: the invariant must be either retired or re-pointed (e.g. "the error catalog and pattern detection ruleset must be preserved" without naming the implementation language). .machine_readable/INTENT.contractile should be checked for the same stale naming in the same pass.

#636 category A (docs-as-current claims) is complete; category B (scanner Logtalk language detection in hooks/lib/common.sh, lib/rules migration comments, the 6a2 purge records) and D (scholarly/training artifacts) were deliberately NOT touched.