Pre-registration: SnapFlow student → rig fine-tune (1-NFE, owner-steered)

2026-08-06 ~17:0xZ. Status: pre-registered, POSTED BEFORE LAUNCH. Owner steering 2026-08-06 16:35Z: “we probably need a nfe fine tune on my rig datasets, can you queue one asap” — this is that run, queued same-hour. It is also the first training step onto the §0 north star’s own terrain: adapting the best deployment-class checkpoint (the 1-NFE SnapFlow student) to the owner’s SO101 rig data, with the owner planning physical rollouts (the 16:33Z checkpoint request + rollout verification landed at 63b044e).

Question

Does the 1-NFE student fine-tune onto the rig distribution — holding its one-forward endpoint decode — without forgetting the community distribution wholesale? Deliverable: a rig-adapted checkpoint the owner can physically roll out (bijou.rollout --target-time zero), plus the first measured rig-transfer numbers for the distill lineage.

Arm (one run)

fontaine_flow_snapdistill_ftrig_4k_1xh100 — local 1×H100.

Recipe = the student’s own recorded train_args (fontaine_flow_snapdistill_h1024_30k_1xh100/step_030000, itself teacher-verbatim + the SnapFlow pre-reg deltas), with EXACTLY these deltas:

Everything else verbatim from the student: --distill snapflow (the consistency objective CONTINUES during adaptation — plain L_FM would let the shortcut field drift while only the velocity field adapts; this is the mechanism bet of the run), B24, grad-clip 1.0, warmup 500, wd 1e-5, fps 30, cameras {1,2}, holdout 0.1/seed 0, condition fields subgoal/outcome/smoothness, seed 0, eval-every 500 (in-run probe now draws from held-out rig episodes).

Pre-launch reads (banked before the ft touches the GPU)

• R0 (baseline, this session): the un-tuned student @30k scored on the rig holdout (0.1/seed 0, both repos), 1-NFE euler-1, draws 1 + mean-of-10, stable keying, --dump-predictions npz — the paired “before” every after-read compares against, on identical frames.

Frozen reads & decision rule (after 4k)

1. Transfer read (primary): rig-holdout 1-NFE eval @4k, identical frames/keying as R0, paired per-frame Δchunk/Δfirst vs R0. Expect improvement; magnitude genuinely open (first distill-lineage rig ft). Direction wrong ⇒ the mechanism bet failed — diagnose before any second rung.
2. Forgetting read (guard): community panel-v2 1-NFE (euler-1, draws 1, stable keying, seed 0) @4k vs the student’s descriptive v2 column 5.6711/1.7059 (index-keyed npz derivation; σ_draw ~0.02 ≪ the bound below, keying noted). Regression expected; bound: Δchunk ≤ +1.0 (beyond = catastrophic forgetting, flagged loudly, checkpoint still ships with the caveat — the rig is its deployment target, but the pre-reg records the cost).
3. Deployment sanity: bijou.rollout --check (sync + async dry-run) on the @4k checkpoint with rig stats — must pass before the checkpoint is offered.
4. Ship rule: (1) improves AND (3) passes ⇒ upload step_004000 weights-only to fontaine-checkpoints, post the owner a rollout command; else post the diagnosis instead.

Class: rig reads are non-headline diagnostics (charter §2: the ~6-episode rig holdout is too small to target) — this run makes no panel claim; it is north-star transfer work with the panel as the forgetting guard. Caveats stated now: rig holdout ≈ 6 episodes (coarse read, wide CIs — per-frame pairing is what makes it usable at all); eff-24 vs mainline ft’s eff-40; 480p rig cameras.

Gates

• E1 (banner, abort before step 1): exactly 2 datasets; state dims 6/6; distill: snapflow + φ_s banner present; init-from loads strict with NO extension branch (the student already has φ_s keys).
• E2 (first-poll): ~0.45–0.65 s/step at B24 (SnapFlow measured 0.48–0.52 on this GPU), VRAM within the SnapFlow envelope; util checked at first poll per the standing rule.
• K1 (kill): loss NaN, or in-run probe > (its own first read
  • 3.0) at any 3 consecutive evals ≥ 1.5k (catastrophic-only — the probe population changes to rig holdout, so no cross-run anchor exists; the probe’s own trajectory is the reference).

Cost

Train ~35–45 min (4k × ~0.5 s/step). Evals: R0 + transfer read on the small rig holdout (~minutes each) + one panel-v2 1-NFE pass (~30–40 min). All local; the arch batch on the box is untouched. Disk: 8 checkpoints × ~11.5 GB transient, pruned to step_004000 after reads (uploads before deletions).