[engine-failure] PROJ-340-investigating-the-correlation-between-gu @ tasks: RuntimeError

Automated report (spec 023 / FR-016) — an unexpected engine failure occurred while processing **PROJ-340-investigating-the-correlation-between-gu** at stage `tasks`.

```
RuntimeError: LLMReviewer[executability]: 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: executability\nreviewer_kind: llm\nstage: tasks\nartifact_path: projects/PROJ-340-investigating-the-correlation-between-gu/specs/001-investigating-the-correlation-between-gu/ta'
```

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 reproducing spec 023 / FR-016 and trace the `LLMReviewer[executability]` handling at the `tasks` stage. Inspect the review frontmatter under `projects/PROJ-340-investigating-the-correlation-between-gu/specs/001-investigating-the-correlation-between-gu/`; done means a contentless or truncated review cannot count as acceptance and the normal retry can recover.

Written by the indexing model from the issue text.