不支持用 bulk verb 回填事实。embedding --embed --stale / embed-backfill / embed-catch-up 仅支持分块操作。

**Trigger for us:** two independent bugs stacked. (1) collector scripts resolved `OPENAI_API_KEY` via the wrong `openclaw.json` path and silently sent the literal string `"undefined"` as the key for weeks — every embed call failed, both chunks and facts. (2) an embedding-dimension migration (3072d → 1536d) landed 2026-09-02. Both are now fixed on our side. Chunks healed cleanly via `embed --stale` once the key was fixed. Facts did not, and — per the design note above — structurally cannot, without a bulk verb.