The hook gate is necessarily per-token ([G*s, r], nn.Linear flattens the
batch). _route2_grad_filter now sums each rollout's token gate-grads before
the cos(g_b, v_grad) flag, so routing is per-rollout (the preregistered GRPO
unit) and the sign is denoised. Per-token a clean rollout scatters ~50% of
tokens over cos>0 by noise, spuriously routing half its gradient mass.
Verified by deepseek-v4-pro review: gate identity, divide-out, eps-guard,
Arm B detach-route, R5 no-cheat all correct; this was the one finding.
Co-Authored-By: Claudypoo <288921227+claudypoo@users.noreply.github.com>
Arm A (route2_mask=grad): per-rollout gate splice (identity at c=1) recovers
the per-sample delta_S grad after backward (c.grad = delta_S * g_b); train.py
divides it out (eps-guard |delta_S|>1e-6), flags rollouts by cos(g_b, v_grad)>0,
and SUBTRACTS them from delta_S.grad. Single-pass, no forward detach, no second
backward -- the cross-step mismatch that made the spec's A1 stale-mask awkward
never arises (routing is post-backward within the step). v_grad = unit-mean
gradient diff from extract_v_hack raw grads (gradient-space analogue of v_act).
route2 forces the combined (non-split) backward since cos_pre is NaN for it
anyway, which also gives the gate a single clean grad to read.
Drop route2_tau: never tuned; the mask is cos>0 (the natural hack-ward boundary)
and the load-time noise floor already filters axes.
v_hack path now auto-derives from --vhack-pairs-path (out/vhack/v_hack_pairset_
<stem>.safetensors): pass the pairset, the hack file auto-loads/extracts -- no
need to also pass --v-hack-path. run-substrate drops the redundant flag.
smoke: smoke-route2 (act) and new smoke-route2-grad both pass (||B_q||=0.109,
exit 0); erase shared-basis path unchanged (cout->0, fired~0.9).
Co-Authored-By: Claudypoo <288921227+claudypoo@users.noreply.github.com>
Routing-v2 spec (distinct-basis quarantine, two arms, proofs); related-work
no-cheat scorecard for TDGA/Cloud/SGTM/Confessions; full-text fetches of the
Deng and SGTM papers; journal entry for the run-31 confound + T1/T2 landing.
Co-Authored-By: Claudypoo <288921227+claudypoo@users.noreply.github.com>
