[engine-failure] PROJ-412-predicting-molecular-surface-area-from-g @ tasks: RuntimeError

Automated report (spec 023 / FR-016) — an unexpected engine failure occurred while processing **PROJ-412-predicting-molecular-surface-area-from-g** at stage `tasks`.

```
RuntimeError: LLMReviewer[constraint_preservation]: 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: constraint_preservation\nreviewer_kind: llm\nstage: tasks\nartifact_path: projects/PROJ-412-predicting-molecular-surface-area-from-g/specs/001-predicting-molecular-surface-area'
```

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 at the LLMReviewer constraint_preservation path for the tasks stage and inspect how review frontmatter is parsed. Reproduce the truncated YAML shown in the report; done means a contentless review is rejected rather than counted as acceptance, while the project remains schedulable for retry.

Written by the indexing model from the issue text.