The NextN/MTP draft is built by the EAGLE draft worker, where get_moe_runner_backend() didn't resolve to flashinfer_trtllm, so the fp4 drop fired anyway -> 6144-vs-3072 crash in draft load. Check both the main and speculative runner backends (spec is AUTO when --speculative-moe-runner-backend unset); keep fp4 if either is a flashinfer fp4 backend. Temporary [NextN-fp4] warning logs the resolved backends. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>