`[2026-06-16]` **#17 contract drifted from its own design in two spots, caught only by `/heid-contract-review` (not same-author paraphrase):** the `OpEvent` dataclass omitted the `turn_id` INV-005 promised; a `session_id` comment contradicted the dispatch-layer design. Cross-model paraphrase is load-bearing for catching an author's own contract-vs-intent drift.