Why: the phase-3 playwright run scans the whole e2e/ directory, so the
plain-base assertions ran against the RDM combo where the audit entry is
legitimately visible and failed.
Evidence: phase-3 rerun shows 4 rdm-audit tests passing with plain-base
failing out of place; the spec now skips unless E2E_PLAIN_BASE=1, which
scripts/e2e.sh phase 4 injects.
Impact: plain-base scenario only executes against the plain base serve.
Refs: 2026-10-12 diagnostic report, increment 2.