R-279: what the_arrears was claiming, and why dropping it is the wrong kind of right

It claimed focus fire is worth 6.3 points against two of them, 14.7% to 21%.
Measured independently at 4000 runs x 3 seeds: 14.2% to 20.4%, gain 6.2, which is
2.4x its own noise and 44% of the base. The claim was true and reproduces.

What failed is a threshold. MEASURABLE is [15,85] and the scan's estimate of a
boundary value moved 14.7 to 14.4. And the creature is a step -- 85.7% at one,
14.2% at two, 0.4% at three -- so no pack size gives an even fight and the band's
endpoints fall in the gap. The band records nothing about a creature whose
defining property is having no middle.

Not moving the band to 14: fitting a threshold to the datum it excludes is how a
guard stops being a test. But the band is a proxy for "can this fight move", and
the direct test -- does the gain clear its own noise -- is already in the
artifact and answers yes. Replacing the proxy is a decision about all 47, not a
fix, and not mine to take unasked.

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

docs/REVIEW_LOG.md

@@ -6448,3 +6448,47 @@ noise. Bestiary regenerated, and it prints 30 where it printed 31.
 and I nearly did not look — a fifteen-second re-record is good news, and good news is what
 nobody investigates. The same instinct that made the README quieter as the build got worse
 (R-268) made this cheaper as the scan got weaker.
+
+## R-279 — what the_arrears was claiming, and why dropping it is the wrong kind of right
+
+R-278's honest scan pushed the_arrears out of check-focus's measurable band. It is already
+re-recorded — `{ n: 2, pinned: 14.4 }` where it held `{ n: 2, spread: 14.7, focus: 21,
+gain: 6.3, noise: 1.5 }`. So the question is what that row was asserting and whether it was
+true.
+
+**It was asserting that concentrating fire on two of the arrears takes the party from about
+15% to about 21%. Measured independently at 4000 runs x 3 seeds, it is:**
+
+| n | spread | focus | gain | spread noise |
+|---|---|---|---|---|
+| 1 | 85.7% | 85.7% | 0.0 | 1.7 |
+| 2 | **14.2%** | **20.4%** | **6.2** | 2.6 |
+| 3 | 0.4% | 0.8% | 0.5 | 0.1 |
+| 4 | 0.0% | 0.0% | 0.0 | 0.0 |
+
+**The claim was true and it reproduces.** 6.2 against the recorded 6.3, from separate code,
+at four times the sampling. The gain is 2.4x its own noise and 44% of the base rate. Nothing
+about the measurement failed.
+
+**What failed is a threshold.** `MEASURABLE` is [15, 85] and the scan's estimate of a
+boundary value moved from 14.7 to 14.4. The row was dropped because a number crossed a line,
+not because the effect stopped existing.
+
+**And the creature is the reason the line is in the wrong place for it.** the_arrears is a
+step: one of them and the party wins 85.7%, two and it wins 14.2%, three and it is 0.4%.
+There is no pack size that gives an even fight, and the band's two endpoints fall exactly in
+the gap. That shape is itself the most useful thing to know about the encounter — *one is a
+conversation, two is a party-ender* — and the band's effect is to record nothing at all
+about a creature whose defining property is that it has no middle.
+
+**I am not moving the band to 14.** Fitting a threshold to the one datum it excludes is how
+a guard stops being a test. But the band is a proxy: it exists because "a fight the party
+wins 100% or loses 100% cannot show an effect of any size", and the direct form of that
+question is already in the artifact — **does the gain clear its own noise?** the_arrears
+answers yes at 2.4x while sitting outside the band, and a proxy that disagrees with the
+thing it proxies for is worth replacing rather than tuning. That is a change to how 47
+creatures are selected, so it is a decision rather than a fix, and it is not mine to take
+unasked.
+
+**Nothing published quoted the lost row.** The bestiary prints the above-noise count from
+the artifact, so it moved 31 to 30 on its own and says nothing that is now false.