vLLM trips on launching Qwen3.6-35B-A3B-NVFP4 with:
AssertionError: In Mamba cache align mode, block_size (2096) must be
<= max_num_batched_tokens (2048).
Qwen3.6 uses a Mamba-attention hybrid. The default --max-num-batched-tokens of 2048 is just under the model's required block_size of 2096. The upstream sibling recipe (qwen3.5-35b-a3b-fp8.yaml) sets it to 16384; use the same value.
Earlier qwen36 swaps in this session worked because vLLM hadn't reached the Mamba-validation code path on that prior path (different attention backend pick or auto-retry). Whatever the reason, the explicit flag avoids the dance.
Also documented in known-issues.md.
Grant
5827683a09