# GRADE DIAGNOSTIC v2 — PART 0 + T0 (report; STOPPED at the T0 gate)
2026-07-31. Nothing fixed, no recalibration applied, no grade touched.

# 🔴 T0 FIRES ON BOTH PRE-REGISTERED CONDITIONS — p_win IS MISCALIBRATED

Per the order: *"if T0 fires, THAT is the root — the market comparison is
premature."* It fired, so T1–T4 were **not** run and no fix was attempted.

## The calibration curve (n=442 decided rows with p_win, buckets with n>=10)

| sport | predicted | actual | **over-confidence** | n |
|---|---|---|---|---|
| MLB | 0.352 | 0.286 | +0.066 | 28 |
| MLB | 0.462 | 0.513 | −0.051 | 39 |
| MLB | 0.545 | 0.511 | +0.034 | 47 |
| MLB | 0.639 | 0.596 | +0.043 | 52 |
| MLB | 0.751 | 0.667 | +0.084 | 39 |
| MLB | **0.842** | **0.652** | **+0.190** | 23 |
| MLB | **0.917** | **0.727** | **+0.189** | 11 |
| WNBA | 0.460 | 0.512 | −0.052 | 41 |
| WNBA | 0.544 | 0.500 | +0.044 | 74 |
| WNBA | 0.646 | 0.537 | +0.109 | 41 |
| WNBA | **0.730** | **0.381** | **+0.349** | 21 |

**Condition 1 — mean |predicted − actual| > 0.05: FIRES.**
MLB mean |dev| ≈ **0.094**; WNBA ≈ **0.139**. Both well past the 0.05 threshold.

**Condition 2 — monotonic over/under-confidence slope: FIRES.**
Over-confidence **grows with the prediction**: MLB +0.034 → +0.043 → +0.084 →
**+0.190 → +0.189**; WNBA +0.044 → +0.109 → **+0.349**. The model is roughly
honest near a coin flip and badly over-stated at the top.

# WHY THIS MECHANICALLY EXPLAINS THE INVERSION

This is the causal story the previous order was missing, and the data supports it
end to end:

1. `p_win` is over-stated, and **the overstatement SCALES with p_win**.
2. `p_win − fair_prob_lock` is therefore **largest exactly where p_win is most
   inflated** — the "biggest edges" are the most over-confident predictions.
3. Those props hit **less** than claimed (0.842 → 0.652; 0.917 → 0.727; WNBA
   0.730 → 0.381), so the edge measure correlates **negatively**.

**The market was never the problem.** `fair_prob_lock` is not a bent ruler — the
thing being subtracted from it is. That also explains why **p_win alone still
carries signal** (+0.23 MLB): the *ranking* is partly right even though the
*magnitudes* are wrong. Rank survives miscalibration; differences do not.

**This independently reconfirms the 2026-07-26 diagnosis** (`+0.02 at p<.5 →
+0.19 at p>=.8`) on a newer, larger population — so it is a persistent structural
property, not sampling noise.

# PART 0 — SCHEMA PRE-CHECK (both premises resolved)

- **P0a — only the GRADED side's fair prob is stored.** `ledger_entries` has
  `fair_prob_lock` (graded side), `proj_book_implied`, `dclv_fair_lock/close` — but
  **no opposite-side fair prob**. So T1's two-side-sum de-vig check **cannot run**;
  it must use the stated fallback (independent no-vig recompute from `locked_odds`)
  if T1 is ever reached.
- **P0b — `projection_locked_at` EXISTS** as a `timestamptz`, so T2 is *potentially*
  runnable, but whether it is genuinely distinct from lock time was **not verified**
  (T0 gated it). **CANNOT DETERMINE** until T2 is authorised.

# WHAT THIS MEANS FOR PART 2 (not done — awaiting your go)

The named cause is **T0: calibrate `p_win`**. The order's prescribed fix applies —
isotonic or Platt on a training split, **proven on a held-out/forward split**, then
re-measure the market-relative edge on the *repaired* instrument.

Two honest cautions I want on the record before that runs:

1. **Sample is thin for a calibration map.** The top MLB buckets — where the error
   is worst and the fix matters most — hold **n=23 and n=11**. Fitting a correction
   there risks fitting noise. A monotone (isotonic) fit with pooling, or a
   single-parameter Platt scaling, is far safer than a flexible per-bucket map.
2. **Recalibration may not resurrect the edge.** Calibrating fixes the *magnitudes*;
   if the market is genuinely better than the model, `p_win_calibrated −
   fair_prob_lock` can still land at ~0. **That would be the honest ceiling**, and
   per the order it gets reported plainly rather than graded around.

# TAGS
VERIFIED: T0 fires on both pre-registered conditions; the monotone over-confidence
slope; P0a (single-side fair prob only). CANNOT DETERMINE: P0b timestamp
distinctness (T0 gated T2). **BLOCKED by the gate, deliberately: T1-T4 and all of
Part 2/3 — the root is named, and the order forbids fixing before reporting.**

Query committed: `scripts/grade-calibration-t0.sql`.