Date: 2026-07-26 America/Toronto
This note supersedes the conclusions of commit 86dfb7194
(2026-07-26-rank2-rescue-measured.md). That note’s “both shapes clear 102” is
withdrawn. The evidence there is retained, not deleted; only its conclusions are
void.
The probe arm calls LLM.generate([raw_prompt]). The 100.524890 benchmark uses
chat completions with the model’s chat template. Prompt token counts differ on
every one of the thirteen prompts:
| prompt tokens | |
|---|---|
| benchmark | 90, 132, 110, 102, 112, 89, 149, 111, 125, 140, 229, 112, 863 |
| probe | 49, 91, 69, 61, 72, 48, 108, 70, 85, 99, 188, 71, 823 |
| delta | +41, +41, +41, +41, +40, +41, +41, +41, +40, +41, +41, +41, +40 |
Generated-token hashes differ too. So 257/588 = 43.71% is directional raw-prompt evidence, not a benchmark-matched result.
The gain was taken from the benchmark counters and the probe, but the cost was taken from a flat-p extrapolation:
| deepest spine node | value |
|---|---|
flat-p extrapolation p^11 — what was used |
0.0461 |
empirical 113/1607 — correct |
0.0703 |
Recomputed consistently on the sealed benchmark counters:
gain = ((1607 - 1166) / 1607) x (257 / 588) = 0.1199
loss = 113 / 1607 = 0.0703
net = +0.0496
emitted/cycle 3.955196 -> 4.0048 => **101.79 tok/s at zero overhead**
Not 102.40. The one-alternate tree does not clear 102 even before any implementation overhead.
The recorder logs top-2 for draft position 0 only. The 103.08 two-alternate figure applied the position-0 rescue rate to position-1 misses, which the probe never observed. It is unsupported.
| quantity | value |
|---|---|
| break-even rescue rate | 113/441 = 25.62% |
| needed for 102 at zero overhead | 46.77% |
| needed for 102 at 0.2% overhead | 49.70% |
| measured (mismatched workload) | 43.71% |
| Wilson 95% interval | 39.75% – 47.74% |
The interval does not reach the requirement. Even taken at face value this probe is statistically incapable of authorising implementation.
Recomputing every shape on empirical counters rather than the flat-p model changes the shape of the answer, not just its level. The marginal value of the spine nodes an alternate displaces is far higher than the model implied:
| spine depth | empirical value |
|---|---|
| 9 | 170/1607 = 0.1058 |
| 10 | 138/1607 = 0.0859 |
| 11 | 113/1607 = 0.0703 |
Against alternate gains of 0.1199, 0.0876 and 0.0577 at the (mismatched) 43.71%:
| shape | net | emitted/cycle | projected tok/s |
|---|---|---|---|
| spine 11 (measured) | — | 3.9552 | 100.52 measured |
| spine 10 + 1 alternate | +0.0496 | 4.0048 | 101.79 |
| spine 9 + 2 alternates | +0.0513 | 4.0065 | 101.83 |
| spine 8 + 3 alternates | +0.0032 | 3.9584 | 100.61 |
Every alternate after the first is essentially break-even, because the spine node it displaces is worth almost as much as the rescue it buys. The earlier claim that two alternates were meaningfully better than one was an artifact of the flat-p cost model understating the deep spine.
So the whole tree route reduces to a single question: is the benchmark-matched rank-2 rescue rate at position 0 at least 46.77%? At 43.71% it is not, and adding alternates cannot make up the difference.
Implementation is authorised only if a benchmark-matched conservative projection, including measured overhead and uncertainty, clears 102 with margin.
100.524890 tok/s remains the best result, and should be treated as the best single-leg diagnostic until an independent cold confirmation and a corrected identity record exist. Tree wiring is not started.