# The bias is robust; the map was not. Low-parameter correction deployed.

## PHASE 0 — the sample-limit truth, on record

**On 19 dates, BOTH stability instruments are underpowered. This is the SAMPLE,
not a fixable instrument.** No future order should re-open the gate-refinement
loop expecting a different answer at this N.

- **LODO power 0.014–0.093** against a strong date-driven instability. Across
  every k from 1.0 to 2.0, the best any stat reaches is 0.337.
- **Deploy CIs rest on 2–4 date clusters.** A cluster-robust interval at 2
  clusters has ~1 degree of freedom and a near-undefined width.

Neither certifies forward stability of a specific map. Four orders refined a gate
the sample cannot support; that loop stops here.

**Record correction on runs:** its `1f40014` DATE-DRIVEN classification was an
artefact of the coin-flip ruler — 2 reversals in 3 drops never cleared a cutoff
of 2. runs is an ordinary "no fittable map" refusal. **Not date-driven.**

---

## PHASE 1 — the robust claim: ROBUST

Model-free, map-free, on the picked-side deduped population. Date-block bootstrap
(whole dates resampled, 5,000 draws).

### Pooled — the shape is textbook favourite-longshot

| bin | n | predicted | realized | over-prediction |
|---|---|---|---|---|
| 0.5–0.6 | 1,021 | 0.5477 | 0.5553 | −0.0076 |
| 0.6–0.7 | 961 | 0.6432 | 0.6004 | +0.0428 |
| 0.7–0.8 | 745 | 0.7420 | 0.6456 | +0.0963 |
| 0.8–0.9 | 459 | 0.8430 | 0.6841 | +0.1589 |
| **0.9–1.0** | 157 | 0.9075 | **0.6624** | **+0.2451** |

Pooled sign stability **0.9946** over 17 date blocks, 90% CI [+0.136, +0.300],
zero indeterminate resamples.

### Per stat — 4 of 4 replicate

| stat | n | >0.9 bias | date blocks | sign stability | 90% CI | replicates |
|---|---|---|---|---|---|---|
| hits | 1,140 | +0.2435 | 17 | 0.994 | [0.120, 0.321] | yes |
| total_bases | 1,050 | +0.2816 | 7 | 1.000 | [0.154, 0.394] | yes |
| rbi | 630 | +0.2107 | 5 | 1.000 | [0.156, 0.245] | yes |
| runs | 597 | +0.2367 | 5 | 0.998 | [0.082, 0.314] | yes |

**VERDICT: ROBUST** — pooled ≥95% and 4/4 stats (bar was 3/4).

Worth noting alongside it: **realized rate plateaus at ~0.65–0.68 from p=0.7
upward.** The 0.9+ bucket (0.6624) performs no better than the 0.8–0.9 bucket
(0.6841). The model has no genuinely high-confidence reads, only high-confidence
*numbers*.

---

## PHASE 3 — low-parameter correction, validated as a new estimator

Platt: `p_cal = sigmoid(a·logit(p) + b)`. Two parameters over the whole curve, so
it **cannot** encode "this Tuesday was odd" — which is precisely the failure mode
we cannot rule out for isotonic on this sample.

Shrunk toward identity by fit-date count: `w = D/(D+10)`, applied as
`w·p_platt + (1−w)·p_raw`. A thin fit is therefore applied at reduced strength.

| stat | a | shrink | eval n | blocks | Brier raw | low-param | Δ vs raw | CI (date-block) | decision |
|---|---|---|---|---|---|---|---|---|---|
| **hits** | 0.406 | 0.565 | 765 | 4 | 0.2626 | 0.2540 | **−0.0086** | [−0.0112, −0.0069] | **DEPLOY** |
| **total_bases** | 0.472 | 0.333 | 625 | 2 | 0.2490 | 0.2429 | **−0.0061** | [−0.0062, −0.0059] | **DEPLOY** |
| rbi | 0.775 | 0.231 | 425 | 2 | 0.2011 | 0.2007 | −0.0004 | [−0.0007, **0**] | REFUSE |
| runs | −0.032 | — | — | — | — | — | — | — | **REFUSE (slope)** |

### A guard the first run needed

runs fitted **a = −0.032**. A non-positive slope does not flatten an
over-confident forecaster — it **inverts** it, and near zero the curve collapses
to a constant, predicting the base rate for everything. That *lowers* Brier
(shrinking a miscalibrated forecaster toward its base rate always does) while
destroying all resolution, so it would have **scored as a win while making the
product worthless**. `MIN_SLOPE` now refuses it by name, with a test.

### Stated plainly: isotonic scored better, and we are not using it

On the identical held-out rows, isotonic beat the low-parameter fit on hits
(+0.0028, CI [0.0013, 0.0045]) and rbi (+0.0042, CI [0.0003, 0.0092]), and tied
on total_bases (−0.0009, CI spanning zero).

**The swap is a capacity judgement, not a measurement.** The evaluation window
spans 2–4 date blocks, so "isotonic wins OOS" there is weak evidence, and it is
exactly what a flexible map would produce if it captured structure shared by the
fit and evaluation periods. That reasoning is a judgement and is labelled as one.

---

## PHASE 4 — deploy and labelling

| stat | served | basis |
|---|---|---|
| hits | low-parameter correction | `direction_robust_magnitude_provisional` |
| total_bases | low-parameter correction | `direction_robust_magnitude_provisional` |
| **rbi** | **RAW — withdrawn** | deployed on isotonic at `ced4042`; low-param does not beat raw |
| runs | RAW | slope refused |

The **direction** is bootstrap-robust; the **magnitude** is thin-sample and
conservatively shrunk (0.565 hits, 0.333 TB). Customer-facing letter unchanged.

Auto-demotion remains armed via `calibrationRegistry.reverify`: a sign flip in
the >0.9 bucket or a CI crossing zero demotes to raw and logs the breaking date.
Promotion to non-provisional stays at the original ≥40 date-cluster bar.

---

## PHASE 5 — the standing finding, stated hard

**Across 18 archetype slots on three stats, calibrated `p_win` separates within
archetype NO BETTER than raw. Every slot collapses to one band, indistinguishable
from its own base rate. Zero slots show lift.**

Per-archetype grade separation is **not coming from calibration**. It comes from
**proven factors or it does not exist.**

This reframes the roadmap. Calibration has now been pursued through five orders
and has delivered exactly what it can deliver — honest numbers on two stats — and
nothing at all on the question the grade product actually turns on. The next real
lever is factors on the stats that lack them.

---

## Invariants

`p_win` never mutated — the correction rides as `p_win_calibrated`. Calibration
consumed no Bonferroni slot. The robust-claim test ran before any calibrator was
built and could have terminated the session at Phase 2. Counter and frozen
clusters verified file-by-file (14 modules, including `calibration.js` and
`calibrationService.js`, both untouched and simply no longer on the serving path).