Causal audit finds some multi-agent KV-cache relays transfer nothing example-specific.

arXiv 2608.04893 tests the "exchanged latent thoughts" claim by replacing the relayed cache with deranged, zeroed and moment-matched random counterparts. The claim holds only when the receiver genuinely needs the sender's private information (100% vs 23-25%, replicated across three families and five checkpoints). Otherwise a pre-registered five-seed protocol establishes equivalence within 2.8 points under Holm-corrected TOST. In one cell, zeroing the relay costs 14.7 points while a mismatched cache costs 0.4. Among released systems: LatentMAS's relay hits ceiling, KVComm's layer subset is partial, C2C's projector shows no detected example-specific transfer.