# Track 2 structure-feature AL pilot

**Limited pilot. `prop02_success_claimed`: False.** Measured CIs only; no MP API key used.

## Setup
- Fingerprints: FLUX ENGINE Magpie-lite (`sims/track2_mp/structure_fingerprint.py`)
- Sample: stratified ≤5000 from `al_pool` → **N=5000** (hits 558)
- Seed labeled=100; batch=25; budget=400; RF trees=100; AL seeds=5
- Composition dim=84; composition+structure dim=91

## Feature sets
- **composition:** `frac_*` + Magpie-lite means
- **composition+structure:** composition + structure meta (nsites/volume/density/e_hull/is_stable/is_metal)

## Results (final recall @ budget; mean ± std; 95% CI over seeds)

### Composition only
| arm | final recall ± std | CI95 | AULC ± std |
|---|---:|---:|---:|
| random | 0.1043 ± 0.0059 | [0.0992, 0.1094] | 0.0627 ± 0.0064 |
| uncertainty | 0.2419 ± 0.0164 | [0.2275, 0.2563] | 0.1317 ± 0.0148 |

### Composition + structure
| arm | final recall ± std | CI95 | AULC ± std |
|---|---:|---:|---:|
| random | 0.1043 ± 0.0059 | [0.0992, 0.1094] | 0.0627 ± 0.0064 |
| uncertainty | 0.3018 ± 0.0100 | [0.2930, 0.3106] | 0.1602 ± 0.0081 |

Figure: `figures/track2_structure_al_pilot.png`

## Limits
Not crystal-graph GNN; structure meta are MP Summary scalars. Not a Prop-02 support decision.