[engine-failure] PROJ-415-predicting-the-impact-of-alloying-on-the @ tasks: RuntimeError

Automated report (spec 023 / FR-016) — an unexpected engine failure occurred while processing **PROJ-415-predicting-the-impact-of-alloying-on-the** 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-415-predicting-the-impact-of-alloying-on-the/specs/001-predicting-the-impact-of-alloying-on-the/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 with the LLMReviewer[executability] validation path and inspect the generated review frontmatter for the tasks stage at the mentioned projects/PROJ-415.../specs/001.../ta path. Reproduce the retry if possible; done means a truncated or contentless review cannot count as acceptance and does not produce this RuntimeError.

Written by the indexing model from the issue text.