Amendment proposal: panel v2 — leaked and corrupt episodes leave the measure (owner steer wanted)

2026-08-06, work session ~02:1x–02:4xZ. Instrument: fontaine/scripts/panel_v2.py. Artifacts: plans/holdout_curated_v0_k4l2_panel_v2.json (frozen, self-contained), ~/panel_v2_anchors.json. Follows the seal-amendment policy (owner 2026-08-05 17:08Z: “if the measure is incorrect, we should be able to update it”) — posted and versioned, nothing silently edited. This is a proposal: no instrument switches to v2 until the owner steers.

Why

Two independent censuses have now shown the panel scores frames it should not:

1. Dup-content census (#18.7): 524 of the panel’s holdout episodes have byte-exact action+state twins in the train side of some other repo (the cross-repo fork channel repo-id dedup can’t see). 2,096 / 17,204 core rows (12.2%) score on train-leaked content, and those rows measure ~1.3–1.6 better than clean rows on both banked models.
2. Wrap census (#14): kevin510’s two repos (systemic ±180° wraps) and willnorris/bbox-2 (state-stream glitch) are corrupted ground truth. The sealed plan dropped them (sealed v2) — but the panel plan still scores them (52 core + 26 labeled rows, averaging ~31° chunk MAE — wrap-scale garbage, not model error).

A holdout row with a byte-exact train twin measures memorization, and a corrupted-truth row measures the corruption. Both are measure errors.

The definition (frozen)

Panel v2 = panel v1 minus (a) every row on a census-leaked (repo, episode), (b) every row of the 3 wrap-census corrupt repos.

• Strict row-subset in original order — no re-draw, no new episodes. Plan seed, split, fps/camera filters, frames-per-episode all untouched. Consequence: every banked per-frame npz re-pools to v2 exactly, with zero re-evals — adoption is CPU-only.
• Core 17,204 → 15,056 (−2,096 leaked, −52 corrupt, 0 overlap); labeled 8,596 → 7,522 (−1,048, −26).
• The exclusion lists are embedded in the plan file itself (524 repo::episode keys + 3 repos + provenance) — the artifact is self-contained and frozen; the plan is schema-identical to v1 and drops into bijou.eval --sample-plan.

v2 anchors (derived from the banked npzs, oracle-gated)

The two exclusions partially offset in level: removing leaked rows pushes the level up (+0.17–0.19, the memorization discount), removing the corrupt repos’ wrap-scale rows pulls it back (−0.09). Honest caveat carried over from the census: part of the leaked-vs-clean gap is content difficulty (forks concentrate in chess/herding/pengrip), so v2’s level is “panel minus measure errors,” not a pure de-memorized number. It is still the right instrument: scoring holdout rows with byte-exact train twins is wrong regardless of why they score better.

Transition rules (proposed)

1. In-flight pre-registered reads finish on v1 as registered — the box-batch results (~04Z), the draws chain + fairness probe, E4B’s gates, and the SnapFlow distill primary all quoted v1 anchors in their pre-regs; swapping the measure mid-flight is exactly what the amendment policy forbids. Their results posts quote the v2 column alongside (CPU re-pool of the same npzs).
2. On owner approval, v2 becomes the anchor convention for every NEW pre-reg, and the anchor table above is the new bank.
3. Bundle the anchor-moving backlog at one boundary. Two other approved-or-pending changes each force a re-bank:
   • the --noise-key stable flip (#18.2, implemented + pre-registered, due “at the first anchor boundary after the box reads”) — needs one GPU flow-80k panel re-eval (draw noise changes predictions);
   • the shortest-arc metric proposal (#14, still awaiting owner sign-off — CPU re-score, panel effect −0.0528 on v1 AR). Doing the v2 switch, the noise flip, and (if approved) shortest-arc at the same boundary re-banks the flow anchor once instead of three times. The natural boundary: right after the box-batch results post, when the flow-80k re-eval can take a quiet GPU slot.

Owner decision points

1. Adopt v2 as the primary panel convention? (Recommended: yes.)
2. Bundle the noise-key flip at the same boundary? (Recommended: yes — it’s already pre-registered to fire at the next boundary.)
3. Shortest-arc scoring in the same re-bank, or keep deferring? (No recommendation — it changes metric semantics, owner’s call from the wrap-census post stands.)

Validation

All hard asserts in panel_v2.py, run before any v2 number printed: leaked-row exclusion counts equal the census’s published 2,096/1,048; corrupt-repo rows equal sealed-v2’s 52/26; v1 pooling reproduces both banked anchors (<5e-4); leaked-only exclusion reproduces the census’s clean-core 5.9761/2.1695 + 6.8137/1.9714 (≤1e-4); state-copy pools identically from both npzs (cross-npz join consistency, <5e-4); materialized v2 re-filters to itself (idempotence) and is a strict ordered subset of v1; synthetic materialization oracle (known exclusions incl. the overlap case) passes. The row join is the same code path the census content-verified against raw parquet. check.py green.