Operator ruling: the multi-turn degeneration lives in the un-fixed vLLM, not
in the weights. The hypothesis that sec's stock-graft MTP head causes it is
withdrawn.
Two failures produced it. First, a false dichotomy treated as a deduction:
having verified gen and sec run an identical engine, I concluded config was
eliminated and therefore the weights were responsible. That does not follow.
An engine bug present in both seats is not exonerated by the seats being
identical; it only means the engine cannot explain a difference between
them. It can still explain the failure.
Second, and more instructive, the difference being explained may not exist.
The premise was a single operator observation made during a session with
many concurrent changes. That cannot carry a causal claim, and it became the
load-bearing support for a root-cause narrative it could not hold.
The same caveat now attaches to the coherent-to-10k observation on the new
build: same n, same uncontrolled conditions, opposite direction. The
comparison is weak at both ends, so the file no longer presents either
sighting as a result.
What survives as measured fact is unchanged and still recorded: sec's MTP
head is byte-identical to the uncensored base across all 15 tensors, gen's
was abliterated in-band, and acceptance differs slightly. None of that is
shown to cause degeneration.
Adds the generalisable lesson: an observation made while many things are
changing cannot support a causal conclusion. It is the inverse of the
warning already in the gen-seat compose file, which guards against trusting
a negative result from a synthetic probe; this guards against trusting a
positive sighting from an uncontrolled session.
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