Pre-registration: sim content diversity v3 — per-episode plate bank + clutter-state draws

Registered 2026-08-12 ~06:3xZ (work session; in-channel 06:35:39Z — stamp corrected 07:2xZ, first draft used an unchecked clock). Successor of visual matching v2, which met its AUROC bar (top 0.773 ≤ 0.790) but left the homogeneity read untouched: sim k std/mean ~4% vs real ~45% — every read since the encoder OOD probe names this the remaining axis. Lighting jitter (v1) moved it ~3%; a fixed real background (v2) moved it not at all. This item attacks it with per-reset CONTENT variation. Instrument and A/B semantics inherited unchanged from the v1 / v2 pre-regs.

Plain words

Real camera frames differ from each other: the daylight changes between recordings, the computer mouse and the mug wander around the table, sometimes things enter or leave the scene. Our simulator frames are near-clones of each other — same light, same clutter in the same spot, every time. A policy’s vision encoder sees a tight little cluster where reality is a wide cloud, and that sameness is itself a give-away (and a robustness risk: train on the clone, fail on the cloud). This pass makes each simulated episode draw a different real background — one per real recording, carrying that recording’s actual lighting — and scatters the desk clutter the way the real operator actually scattered it between recordings. The test: the spread of the simulator’s frames under the encoder should grow toward the real spread, without the frames getting any easier to tell from real.

Baseline (measured, frozen)

Reset-render probe on the shipped v2 default (08-12): top 5-NN AUROC 0.773 (100 seeds; 0.774 at 20×5), top sim k std/mean 0.038 (100 seeds; 0.042 at 20×5) vs real held-out 0.447. Per-draw mean-k spread 0.5%. Wrist (v1 path inside v2): 5-NN 0.548 after the periphery re-tune.

Method (v3 scope)

1. Per-episode plate bank (make_clean_plates.py --bank): one top-cam plate per A-half episode (26). The mining pass masks ALL transient/novel content by construction — no boat ghosts can bake in (the naive per-episode median, inspected before this registration, bakes in the boat parked on the disk, both arm rest poses and the operator’s hand):
   • fit a per-episode per-channel gain to the global plate on agreeing pixels (the episode’s exposure/white-balance state);
   • a frame’s pixel is an inlier iff it sits within a registered-by-inspection threshold of the gain-corrected global plate; plate pixel = median over inlier samples;
   • pixels with too few inliers (anything parked: boat, arms, hands, the real disk, moved clutter) fall back to the gain-corrected global plate, feathered at the boundary. Plates carry the episode’s real lighting field and photometric state; they contain NO object-level novelties. Bank manifest pins episodes, thresholds, coverage stats, commit.
2. Clutter-state draws: the four contype-0 stand-ins (mouse, mug, laptop, PCB) get per-reset poses drawn from the measured real between-episode spread: the same mining pass extracts, per episode, the change-blob centroid near each object’s canonical position (image → pinhole ray → table plane → world xy, through the sim’s own camera model); draw ranges = empirical min/max boxes (+ yaw jitter for the non-circular objects). If an object is detectably absent in some A episodes, presence is drawn at its empirical frequency (absent = parked outside both frusta). Numeric ranges land in the results post + manifest — the method is what registers here. Clutter stand-ins are contype/conaffinity 0: physics untouchable by construction.
3. render_style="v3" = the v2 composite with (a) the top plate drawn per reset from the bank (uniform over the 26) and (b) clutter poses drawn per reset — both from the appearance RNG after every existing draw, so all v2 appearance draws are stream-identical and the wrist path stays bit-identical to v2 (wrist keeps the v1 render path; its plate mush and its 0.548 read are not touched).
4. Not in scope: disk-position draws — the disk is task geometry (success is measured against it); drawing it from the real between-episode distribution changes task semantics and needs its own pre-reg (queue note, carried forward). Real clutter kept in-plate (vs rendered stand-ins) is a named follow-up lever, not this pass.

Reads (instrument pinned, order registered)

Foreground, idle H100; gate ≤ 0.3 GPU-h for the whole item (~0.02 GPU-h per read). Plate-bank/clutter mining and inspection are CPU and encoder-free; at most 3 encoder-probe iterations on the composite before the candidate freezes.

1. v3 read (registered primary) — reset-render probe, seeds 0..99, --render-style v3: top 5-NN AUROC, top k std/mean, k-ratios, centroid secondaries.
2. Homogeneity read (registered, co-primary spread figure) — seeds 0..19 × 5 appearance draws: k std/mean where every reset draws plate + clutter independently of the spawn.
3. Wrist guard (registered): wrist frames bit-identical to v2 for the same (seed, appearance_seed) — asserted on renders before any read is credited.
4. Physics oracles before any read is credited: reset qpos bit-identical across v0/v1/v2/v3 and across appearance seeds; spawn stream bit-matches banked sim100.

Success bar (registered)

• v3 lands if, on the primary 100-seed read: top sim k std/mean ≥ 0.15 (≥ ~4× the v2 figure, one third of the real 0.447) AND top 5-NN AUROC ≤ 0.790 (no regression past the registered v2 line — diversity must not come at the price of realism).
• Overfit tripwire (inherited): AUROC < 0.5 reported as a warning, not a win.
• Record-only: whether AUROC improves (more spread should overlap the real cloud more), per-plate k breakdown, per-draw spread at 20×5.
• Miss → reported as the result with the measured spread; the shipped default flips v2 → v3 only if the bar is met.

Why this bar

k std/mean is the pre-registered homogeneity instrument every read since the OOD probe has quoted (4% vs 45%). 0.15 is not “matched to real” — real spread includes mid-episode content (arm sweeps, operator hands, the boat mid-carry) that reset renders can never show; it is the “the lever visibly moved” line, same semantics as v1’s ≥0.10-absolute AUROC drop. The AUROC guard keeps the failure mode honest: spread is trivially inflatable with garbage draws that would also make sim MORE separable — both numbers must hold at once.