Adds an upper bound to update_adaptive_clip's new_clip formula to
prevent clip-drift pathology: consecutive elevated samples were
ratcheting the EMA-driven clip threshold upward without bound,
eventually rendering clipping a no-op against in-distribution drift.
Smoke smoke-test-5rqzs (commit b9edccfc1) F1-NaN'd at step 3060 with
Mech 5 diagnostic slots 36-38, 40-42 firing — DQN main Adam m + v
EMAs saturated. Diagnostic confirmed Adam saturation as the root cause.
Diagnostic chain identified: grad_norm_ema ratchets up via repeat-
sample compounding (winsorizer caps single-sample but not consecutive
elevated samples) -> clip threshold > actual grad_norm -> clip no-op
-> Adam m/v poisoned -> saturate at slot 36-42 thresholds -> cuBLAS
overflow at slots 26+32 -> loss=34.68 grad=inf.
Fix: cap new_clip by grad_norm_slow_ema * 100 * isv[Q_ABS_REF=16].max(1).
- grad_norm_slow_ema (existing alpha=0.001 slow EMA): anchors against
legitimate steady-state grad norm
- 100x: headroom for per-step deviations
- isv[Q_ABS_REF].max(1): adaptive scale per
feedback_isv_for_adaptive_bounds; epsilon on multiplier per SP1 pearl
- .max(MIN_CLIP): cold-start epsilon-floor
Standard DL practice — bounds the runaway EMA clip-drift while
preserving adaptive behavior. F0 risk: low — slow_ema * 100 is
broad headroom; F0-typical clip thresholds are well below this
cap. F1+F2 benefit by preventing the ratchet pathology.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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