Keyless, IP-rate-limited preview for the physea.ai/mcp hero. Returns the STRUCTURAL result — the reduction (objective + the definitive sub-questions the request breaks into) — NOT a full deep synthesis. The structural artifact is the real wedge per the conversion audit, and it's cheap + abuse-resistant (one model call at a shallow depth, cache bypassed so demo traffic never writes to the shared path-DB).

Reuses the existing solve path (reduce.reduce_oneshot + reduce.to_digest) at low depth; invents no new engine. Over the per-IP cap -> 429 with a message the hero shows. Lives outside the /mcp key gate (see the module note above).