2bc0e9d4b9
When the Codex MCP reviewer provably failed before dispatch (tool absent, spawn failure, rejected pre-execution), reviewer-aware workflows previously ended in REVIEW_UNAVAILABLE even with another OpenAI-compatible endpoint configured. The existing llm-chat MCP can now expose review/review_reply behind LLM_REVIEW_FALLBACK_ENABLED=true (default off). Boundaries: pre-dispatch-only — never after a timeout or ambiguous failure, where the review may already have run; verdict calls are single-attempt fail-closed (no retry, no fallback model); primary-artifact files are read server-side and shipped to the endpoint; the gate gives llm-chat less trust than existing backends (same/unknown family fails, independence recorded caller_declared, copilot-finalizer states still require codex or manual). Closes #412