Pre-registration: sim wrist-cam periphery re-tune under the v1 fisheye

Registered 2026-08-12 ~05:5xZ (work session; in-channel 05:59Z). Queue item sim-wrist-periphery-fix, queued at the v1 close where the wrist was explicitly secondary. Instrument, references and bar semantics inherited unchanged from the v1 pre-reg; the v2 close adds the wrist-composite honest negative (0.951 — mush plate) that keeps this a render-path item, not an inpainting one.

Plain words

The robot’s wrist camera in the simulator now bends its image like the real wide-angle lens — but widening the view also changed what is in the picture. The real wrist camera at an episode start looks almost straight down at the table: wooden planks fill the whole frame and only the two fingertip jaws poke into the bottom edge (orange on the left, black on the right). Our simulated wrist camera instead sees a huge dark mass of its own gripper body filling the bottom half of the picture, because the wider lens pulls the camera’s own mount hardware into view. The policy’s vision encoder — our referee for “does sim look real?” — got better at telling sim from real when we widened the lens (0.835 → 0.900), and we believe this self-view is why. The fix attempted here is small and physical: move and tilt the simulated camera on its bracket so the picture shows what the real one shows — table everywhere, fingertips only at the bottom. The referee score must come back down to at least the level the camera had before the wide lens went in (0.786).

Baseline (measured, frozen)

All numbers = wrist 5-NN AUROC, sim-vs-held-out-real, from the banked probe jsons (analysis__sim_visual_match_*.json, analysis__sim_encoder_ood_probe_v2_shipped.json):

Top on the shipped default: 0.773 (v2 composite, registered bar ≤ 0.790 MET). Draw-to-draw noise from the registered sensitivity read: per-draw mean k varies 0.8% (wrist).

Diagnosis (from the frame galleries): the 72° source pulls sim-specific periphery into the wrist frame — the gripper/arm body mass fills the bottom ~40% of the sim image, where real episode-start frames show only slim jaw tips inside the bottom quarter over full-frame table planks. Content composition, not image statistics, is what the wrist read tracks (v1 close finding).

Method (single axis: the wrist camera, runtime only)

Iterate ONLY SO101Sim._repose_wrist_cam (mount-local pos/quat, both arms; vendored XML untouched), against the real episode-start framing:

1. Pose/height under the 72° source — re-derive the lookat: camera forward/up on the bracket, pitch steeper toward the table, so the gripper body mass exits the frame and the jaw tips sit in the bottom quarter (orange moving jaw image-left, black fixed jaw image-right, like every real start frame).
2. Periphery content — after the pose is right, check what the frame edges hold vs real (table extent to every edge at the start pose; no sim floor band / table far edge unless real shows one). Any scene-XML delta this forces is named in the results post; none is expected.
3. Visual iteration is encoder-free: candidate poses are compared against pinned real_v2 A-half episode-start frames (the reference half — held-out B stays untouched, the AUROC read keeps its meaning). Only shipping candidates get an encoder read.

Not in scope: a per-episode-aligned wrist clean plate (noted at the v2 close as a possible future axis), any top-cam change, any physics/spawn change.

Instrument (pinned, inherited)

fontaine/scripts/sim_encoder_ood_probe.py --render-resets 100 on the shipped default (render_style="v2"; wrist = v1 full-render path + the candidate pose), same frozen er_60k eval-mount trunk, same pinned A/B/clean references, ~0.02 GPU-h per read. Primary = wrist knn5_secondary.auroc_sim_vs_real; the same json’s top read is the guard. Final pose also gets the 20-seed × 5-draw sensitivity read (record-only).

Success bar (registered)

• Lands if wrist 5-NN AUROC ≤ 0.786 (the scene-only level) on the 100-seed reset-render probe at the shipped default config.
• Guard (tripwire): top 5-NN AUROC from the same read must stay ≤ 0.790 (its registered line). The pose change touches no top-cam state, so any top move beyond noise is an instrument red flag — stop and investigate, credit nothing.
• Ship rule: bar met → the pose delta ships as the _repose_wrist_cam default (all render styles share the repose; historical probe jsons remain the record of the old pose). Bar missed but final ≤ 0.88 (clearly below shipped 0.900 beyond the 0.8% draw noise) → ship as a strict improvement, report the miss honestly. Final > 0.88 → no ship, honest negative, pose reverted.

Budget & oracles

• GPU gate for the whole item: ≤ 0.2 GPU-h of foreground probe reads (expect 2–4 reads + sensitivity).
• Oracles before commit: qpos bit-identity across v0/v1/v2 and across old-vs-new pose (the camera is render-only — physics must not move), spawn-stream identity, check.py green.