# Structure AL U-cal probe (exploratory)

**`prop02_success_claimed`: False.** Fingerprint secondary track only.

## Method
- **U-raw:** RF ensemble vote-std (same as prior U arm)
- **U-cal:** fit RF on 70% labeled; `IsotonicRegression` maps mean P→label on 30% holdout; acquire by entropy of calibrated P(hit)
- Fallback to U-raw when labeled set too small / single-class for calibration

## Setup: N=5000, seed=100, batch=25, budget=400, seeds=5

| arm | final recall ± std | CI95 | AULC ± std |
|---|---:|---:|---:|
| random | 0.1043 ± 0.0059 | [0.0992, 0.1094] | 0.0627 ± 0.0064 |
| U-raw | 0.2914 ± 0.0133 | [0.2797, 0.3031] | 0.1521 ± 0.0104 |
| U-cal | 0.3283 ± 0.0145 | [0.3156, 0.3410] | 0.1718 ± 0.0081 |

Figure: `figures/track2_structure_al_ucal_probe.png`

## Limits
Simple isotonic probe — not materialsUQ full stack; not Prop-02 support.