[engine-failure] PROJ-736-predicting-personal-sleep-quality-from-r @ tasks: RuntimeError

Automated report (spec 023 / FR-016) — an unexpected engine failure occurred while processing **PROJ-736-predicting-personal-sleep-quality-from-r** at stage `tasks`.

```
RuntimeError: LLMReviewer[coverage]: review frontmatter has neither `verdict:` nor `concerns:`/`action_items:` — a contentless/truncated review MUST NOT count as acceptance (false-convergence guard). First 200 chars: '```yaml\n---\nreviewer_name: coverage\nreviewer_kind: llm\nstage: tasked\nartifact_path: projects/PROJ-736-predicting-personal-sleep-quality-from-r/specs/001-predicting-personal-sleep-quality-from-r/tasks.'
```

The project remains schedulable; it will retry on its normal cadence and recover once the underlying defect is fixed. Closing this issue does not require any project-state change.

Start by tracing the engine's handling of the `LLMReviewer[coverage]` frontmatter during the `tasks` stage for PROJ-736, using the reported spec 023 / FR-016 failure and the artifact path under `projects/PROJ-736-predicting-personal-sleep-quality-from-r/specs/001-predicting-personal-sleep-quality-from-r/`. Determine why the review is truncated or contentless, then verify that retries recover and such a review cannot count as acceptance.

Written by the indexing model from the issue text.