use_local_argmax_reduction hard-fails at worker startup when the draft
model lacks get_top_tokens(): the V2 speculator probes for the method
in _validate_local_argmax_reduction and raises, with no fallback to
the full-vocab logits path. Qwen4ExpMTP (nvidia and amd variants) has
compute_logits but no get_top_tokens, so any Qwen4Exp MTP drafter with
the flag enabled crashed both TP ranks during load_model.
Qwen4ExpMTP owns a flat self.lm_head and its compute_logits is exactly
self.logits_processor(self.lm_head, hidden_states), the same shape as
Qwen3_5MTP, so LocalArgmaxMixin applies unchanged: vocab-parallel
argmax with a (value, index) gather, O(2*tp_size) vs O(vocab_size)
communication per draft token. No D2T remapping needed since the
draft vocabulary equals the target vocabulary.
Signed-off-by: MOVZX <movzx@yahoo.com>
MOVZX
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