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esh-pfi-infrastructure/docs/pfi
vh 1a4ef5c7a1 docs(training-playbook): 4.6.3 was wrong twice — correct it, and keep the retraction visible
The entry reported an 'output-stability regression' as a novel run-2 finding.
Both halves were false and the corrections are more instructive than the
original conclusion, so they stay in-line rather than being edited over.

Not new: run 1's own gate record already carried the same effect with a caveat
attached and unresolved. Two runs across two different base models makes it a
property of the RECIPE, not of the base swap -- which also means a third run
that changes the base again will not fix it.

Not degeneracy, and not a separate finding: all 46 flags were too_short rp turns
of 3-14 words, and the two collapse guards fired ZERO times on any run. It is
the left tail of a length distribution that had been measured and reported in
the same message. Truncation is the same mechanism mirrored on the story side.
Both are thresholds calibrated on the base's output shape applied to a model
with a different one -- 4.6.1, which both parties had written down and neither
applied.

The surviving lesson is sharper: a short-answer gate cannot see length behaviour
AT ALL, and because it could not, the effect went two full runs before anyone
named it. The cost of a gate-set blind spot is measured in runs.

Adds 4.6.3.1 on trip points inside the serving stack's jitter -- same seed, same
weights, rate moves 9.6% -> 12.6%, sd 1.77pp. Not 'the gate is
non-deterministic' but 'the trip point sits inside the jitter', because the fix
follows from the precise statement. Includes the split-design rule for measuring
such a rate, and the rule that a measured rate must carry its corpus in its
name.
2026-08-26 09:29:14 -07:00
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