Operator correction to the prior 3.8 framing (d28a371), which over-blamed
AEON and dismissed the vLLM bug as a mere amplifier. Both were real and
compounded:
- Cause 1 (real, upstream): the qwen3_5_mtp x GDN partial-accept bug
(#51113), architectural across vLLM/SGLang/llama.cpp, genuinely improved
by the nightly fix -- not just an amplifier.
- Cause 2 (real, quant): AEON is FULL W4A4 (A4 activations on attention),
the bottom of the KNOWN activation-precision gradient already in 1
(W4A4 < W4+FP8 < W4+bf16) -- mildly subpar, not 'defective'. On top of
Cause 1 it degenerated ~15-20% of real multi-turn generations.
The mixed FP8-attention build sits a rung up that gradient and is coherent;
a W4+bf16 build would be higher still at a prefill cost. Process lessons
retained (two causes mask each other; stochastic degeneration is invisible
to n=1 probes; isolate weights in parallel with serving flags -- but the
weight swap alone would NOT have found the real vLLM bug).
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