Clamps C51 atom positions during all dynamic write paths to
±10 × ISV[Q_ABS_REF=16].max(1.0) via inline fminf(fmaxf(...)):
- atoms_update_kernel.cu — active GPU-driven shared atom grid
(all 4 branches via grid.x = branch_id)
- iql_value_kernel.cu::iql_compute_per_sample_support — per-sample
[v_min, v_max, delta_z] tile (delta_z recomputed from clamped span)
- experience_kernels.cu::adaptive_atom_positions — legacy single-branch
entry kept in lockstep per feedback_no_partial_refactor
Same ISV bound as Mech 1 (target_q clip) — atoms and target_q share
the magnitude scale. ε on the multiplier (`isv.max(1.0)`) per the SP1
ε-floor pearl; bound ≥ 10 even with cold-start ISV.
Closes the second of two Q-target inflation pathways: with Mech 1
capping the projection target and Mech 2 capping the atom support,
the C51 expected_q (mean of atom × prob) is bounded by
±10 × ISV[16].max(1.0) regardless of probability mass distribution.
Prevents the Adam EMA saturation → weight pathology → cuBLAS overflow
chain.
Reuses isv_signals already in scope at all three kernels — no new
kernel arg, no new launch site, no new ISV slot, no new buffer,
no new kernel.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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