[engine-failure] PROJ-909-llmxive-follow-up-extending-gamma-world @ spec: RuntimeError

Automated report (spec 023 / FR-016) — an unexpected engine failure occurred while processing **PROJ-909-llmxive-follow-up-extending-gamma-world** at stage `spec`.

```
RuntimeError: LLMReviewer[internal_consistency]: 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: internal_consistency\nreviewer_kind: llm\nstage: clarified\nartifact_path: projects/PROJ-909-llmxive-follow-up-extending-gamma-world/specs/001-llmxive-follow-up-extending-gamma'
```

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 RuntimeError report and inspect the generated review frontmatter under projects/PROJ-909-llmxive-follow-up-extending-gamma-world/specs/001-llmxive-follow-up-extending-gamma-world. Trace the spec-stage retry path for LLMReviewer[internal_consistency] and verify that a contentless or truncated review is rejected without changing project state, then confirm the normal retry can recover.

Written by the indexing model from the issue text.