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Pre-reg — wrist-view read of the arm material fixes

2026-08-14, drafted 05:5xZ, posted in-channel before the gate read. Queue item sim-wrist-view-material-read; the wrist-side fact the two pending promotion asks (photometrics, mount) currently assume rather than measure — the photometrics results post named the wrist view the promotion sanity.

Plain words. We fixed two things about how the simulated robot arm looks — its surface colors and shine, and the color of the white camera bracket — and both fixes are opt-in flags waiting on a promotion decision. Those fixes were measured through the robot’s top camera. But the robot has a second eye: a camera on its own wrist, inches from the very surfaces we recolored. Before anyone flips the flags on, we should check the fixes don’t make the wrist view worse. This read renders 100 paired wrist frames — identical scenes, flags off vs on — and asks the policy’s own frozen vision encoder which version looks more like the real robot’s wrist footage.

What the feasibility probe found (pre-read, shapes the design)

  • Both flags are model-level material writes — they change every camera. The wrist frame is a raw render (bit-identical v2↔v3 by the registered wrist guard), so no composite hook is needed: the production reset() observations pair 1:1 across instances.
  • The reset-pose wrist effect surface is small: the stack changes ~0.5% of wrist pixels (~1,670 of 307,200), mostly |Δ| 1–2 counts — at the settled home pose the wrist camera sees graded surfaces only in the periphery/distance.
  • Anchor honesty: the queue item’s banked wrist anchors (knn5 AUROC 0.828, ratio 1.33×, centroid 0.707) are from ROLLOUT frames (ticks 0/300/600 of the sim100 videos — mid-episode poses). Under settled RESET renders — this read’s protocol, the only one that pairs — the wrist baseline is near-chance: 0.5442 / 0.5476 on the two banked 100×1 reads. The gate is anchored to the reset numbers; the rollout gap is registered as an explicit limitation.
  • Appearance draws do vary the wrist frame (scene-wide lighting draws; measured ~100% of pixels across draws), so the 20×5 schedule gives 100 distinct wrist slots, matching the established protocol.

Question

Does the two-flag stack (arm_photometrics='v1' + mount_material='v1' — the exact combination the promotion asks would flip) move the WRIST view toward or away from real on the pinned encoder probe?

Design

fontaine/scripts/sim_wrist_material_read.py: TWO production v3 instances (numpy post) over the same 20 seeds × 5 appearance draws — default and the two-flag stack — production observations, both cameras. Encoder probe: er_60k trunk, knn5 vs held-out real-B per camera (wrist real = observation.images.wrist, 300 v2 + 100 clean strided frames). In-run oracles: qpos bit-equal across instances per slot (the grades consume no RNG draws); per-slot wrist changed-pixel fraction ≤ 5% (an RNG-stream divergence flips ~100% of pixels through sensor noise; measured ~0.5%). Diagnostics recorded: per-slot raw-seg visibility of the graded classes (pla / servo / mount) in the wrist view; changed-px stats.

Registered anchors / aborts

ABORT (no claims) unless BOTH: in-run v3 TOP knn5 AUROC in 0.713 ± 0.005 (the established 20×5 protocol gate) AND in-run v3 WRIST knn5 AUROC in [0.50, 0.60] (band around the banked 100×1 reset baselines 0.5442/0.5476 — wide because no 20×5 wrist anchor exists and appearance draws redraw scene lighting). Anchors: wrist rollout baseline 0.828 (context only — different pose distribution, NOT this read’s gate); mount-read top rider (the same stack, top cam) −1.49e-07 CI95 [−2.45, −0.57]e-07.

Decision rule (frozen before the read)

  • PRIMARY (as queued): paired wrist Δknn5 CI95 (10k resamples, rng 0) of v3_stack vs v3 entirely below 0 → the stack helps the wrist view too; the promotion asks gain a wrist-side plus.
  • CI95 entirely ABOVE 0 → wrist-side REGRESSION: flagged on both pending promotion asks (the texture lesson — fixes can read more fake); magnitude reported against the top-side gain.
  • CI95 straddles 0 → wrist-neutral: the promotion-relevant finding — the flags don’t perturb the wrist view measurably; the asks proceed on top-side evidence alone, stated as such.
  • Record-only riders: top paired stack vs v3 (should replicate the mount read’s −1.49e-07 rider — a protocol cross-check); wrist clean anchor; graded-visibility diagnostic.
  • Limitation (registered): this read is at settled RESET poses. The 0.828 rollout-pose wrist gap — where the gripper fills the frame mid-manipulation — is a DIFFERENT fact this read does not touch; if the owner wants the rollout-pose read it needs banked rollout trajectories (only videos exist) or fresh policy rollouts, priced separately.

Cost

CPU renders (100 paired slots × 2 instances) + ~0.02 GPU-h embeds (400 sim + 800 real frames) on the er_60k trunk. GPU is idle by design (R1-A boundary pends the owner call) — the embed job does not conflict.

RESULTS (06:0xZ 08-14, executed same session — wrist-neutral, adjudicated by the frozen rule)

All gates green: in-run v3 TOP knn5 AUROC 0.713 dead-center (band 0.708–0.718); in-run v3 WRIST 0.561 inside [0.50, 0.60]; qpos bit-equal across both instances × 100 slots; wrist changed-px tripwire quiet (max 1,714 px = 0.56% of frame, |Δ| max 12, mean 1,670 px — right at the feasibility measurement).

  • PRIMARY — CI STRADDLES ZERO → wrist-neutral. Paired wrist Δknn5 of the stack vs v3: −1.39e-08, CI95 [−4.53e-08, +1.73e-08] (46/100 slots closer); AUROC 0.561 → 0.560. Per the frozen rule: the promotion-relevant finding — the two-flag stack does not perturb the wrist view measurably in either direction at reset poses. No wrist-side regression (the texture-lesson failure mode did NOT fire); no wrist-side plus to claim either. The pending promotion asks proceed on top-side evidence alone, now stated as measured rather than assumed.
  • Why it’s null, mechanically (diagnostic, registered record-only): at the settled home pose the wrist camera sees ~230 raw px of graded surface total — servo 208, PLA links 21, mount 1 px (of a 640×480 raw frame; visible in all 100 slots but never more than ~0.08% of the frame). The stack changes ~0.5% of output wrist pixels at |Δ| 1–2 counts (PSF spillover around the servo edge, cf. the strip’s amplified-Δ panel). There is nearly nothing for the encoder to read.
  • Record-only rider — top REPLICATED EXACTLY. Top paired stack vs v3: −1.4937e-07, CI95 [−2.451, −0.570]e-07 (61/100), AUROC 0.713 → 0.702 — bit-for-bit the mount read’s combo rider. Expected in hindsight (deterministic renders, same schedule, same weights) but it is a real cross-check all the same: the mount read’s _composite hook path and this read’s plain production reset() observations produce identical frames and identical embeddings — the hook was bit-exact, and the two code paths agree.
  • Anchors: wrist clean 0.265, wrist held-out knn5 1.691e-05 (both matching the banked probe exactly); the wrist reset baseline landed at 0.561 vs the banked 100×1 reads’ 0.544/0.548 — inside the registered band, the 20×5 lighting draws worth ~+0.015.

Disposition. Item closed; no follow-up wrist item queued from this result — the reset-pose wrist fact is measured and null. The registered limitation stands: the 0.828 ROLLOUT-pose wrist gap (gripper filling the frame mid-manipulation) is a different, still-open fact — reading it needs banked rollout trajectories or fresh policy rollouts; it remains priced separately and is noted on the promotion asks, not auto-queued.

Artifacts: analysis · chart · frame strip