The obvious reaction to 'a quiet runner reaches 5.3 us in 20 min while this laptop needs 5.5 h
for 30-42 us' is to kill the running session. Wrong, for two reasons now written down so the
decision is visible rather than inertial:

1. It answers a question the runner cannot. The +13.9 us class-1 pattern is a property of the
   LAPTOP's nine sign-kk pairs. sign-aa on ubuntu says there is no arm offset ON UBUNTU, where
   allocator, alignment, scheduler and a 23x tighter distribution all differ. Only the local
   sign-aa, at +-10 us, tests the hypothesis on the machine where the pattern was seen.
2. It is the like-for-like successor to v3b: same machine, same build, same rules, 17x the
   samples - the only way to tell whether v3b's readings were power-limited or environment-limited.

And aborting a pre-registered session on a preliminary that does not bear on its own validity is
the habit pre-registration exists to prevent: easy to justify each time, corrosive in aggregate.
The correct response is that the session AFTER this one moves machines.

Security Impact: none - documentation only.

Five seats reviewed the v2 reading (3 "over-claims", 2 "honest"). The
logical objection is decisive: a null declared unfit for the operation cannot
also mint SHAPE labels, ratios ("3-9x") or a "noise floor" from one sign-rr
draw; sub-threshold raw t (2.35-3.22) plus post-hoc CIs must not be turned
into "keys are distinguishable" or a "per-key fingerprint" claim; the
mechanism is a hypothesis with a key x message confound (one fixed message
per pair). Revised: primary statistic — no gated experiment reaches the FAIL
line, no location difference demonstrated; crop diagnostic INCONCLUSIVE this
session; the three fixed-key deltas reported as descriptive,
hypothesis-generating, cause undetermined; earlier ratio/floor language
withdrawn explicitly; v3 requirements listed (real-operation null from
repeated pool-vs-pool sessions, key x message separation, core pinning,
pre-registered combination rule and multiplicity correction).

Security Impact: none to code; tightens what the evidence may claim.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Building on top of an old dist/ can fail with a missing dist/chunks
module. Document the clear-and-retry workaround next to the build
acceptance criterion so contributors in existing clones aren't blocked.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>