2026-08-06 — State-dropout 0.8 results: mechanism WORKED, actions PAID — adopt nothing (#9)

Frozen reads of the pre-registration via fontaine/scripts/statedrop_results.py (pairing + state-copy byte-match oracles green; banked reports/analysis__statedrop_40k_k4l2.json). Run: fontaine_arb_rcond_statedrop80_40k_1xh100 — the mainline AR recipe + --state-dropout 0.8 (mean-masking at collation via the shared mask_state_item primitive), 40k steps, completed 2026-08-06 ~16:02Z; panel + masked-reliance evals completed 19:01Z.

Verdict: COSTS — adopt nothing. The sanctioned follow-up is a p=0.3 screen.

• Read 1 (primary, paired per-frame Δchunk vs A-s0 core frames): +2.64 MAE [CI95 2.55–2.74], median +1.27, C wins only 23.9% of 17,204 frames. Far beyond the pre-registered ±0.15 band; no single-repo exclusion moves the mean below +2.58. Pooled: C 10.5024/8.5606 vs A-s0 7.7966/3.9422.
• Read 2 (reliance, the mechanism check): state-masked first_mae 8.11 vs the intact read 8.56 — masking state barely moves the model (it even helps slightly), while the baseline model collapses to 24.08 under the same mask. Capability class: partial; the anti-shortcut mechanism did exactly what the causal-confusion literature promises — state reliance is gone.
• Read 3 (grounding transfer): no first_mae gain to attribute — C’s 8.56 sits +4.62 above A-s0’s 3.94. Breaking the state shortcut did NOT rebuild the lost accuracy out of vision at this dropout rate; it just removed the crutch.
• E4 prior band: chunk 10.50 vs the expected [7.65, 8.3] — outside, on the costly side. The pre-registered final probe gate (< 10 @40k) had already failed at 10.90.

Reading

p=0.8 is too aggressive at this rung: the model was denied state on 80% of samples and could not (at this data/step budget) replace the information visually — the cost lands on both chunk and first-action error. The mechanism/capability split is the transferable result: dropout kills the shortcut without teaching the replacement. The pre-registered branch keeps exactly one follow-up alive — a p=0.3 screen (mostly-intact state, shortcut still perturbed) — queued, not launched; the box belongs to the Molmo2 AR run tonight.

Eval reports: hosted under Reports once synced (eval__fontaine_arb_rcond_statedrop80_40k_1xh100__step_040000__*).