Closes the F.5 diagnosed l_v=104 + l_pi=-31 spike pattern at the root.
Pathology: `rl_reward_clamp_controller` widened the WIN/LOSS bounds
(slots 452/453) when clip_rate exceeded the 5% target — appeasement,
not control. The atom-span EWMA (slots 484/485) then ratcheted up to
track the wider WIN/LOSS. F.5 200-step smoke trajectory:
WIN: 1.0 → 41.3 (41×)
LOSS: 3.0 → 41.3 (14×)
V_MAX: 1.0 → 2.66
V_MIN: -1.0 → -2.74
Scaled rewards up to 14.71 flowed through unclamped, producing
advantage magnitudes of ~30 and PPO surrogate losses of ±30, V
regression losses up to 104. Pure positive-feedback loop: large
rewards → wider clamp → bigger V/Q targets → larger atom span →
larger reward signals permitted → repeat.
Fix: STOP writing to slots 452/453/484/485. The trainer-seeded
values (WIN=1.0, LOSS=3.0, V_MAX=1.0, V_MIN=-1.0) are the structural
bounds matching the C51 distributional Q head's design. Per
`pearl_audit_unboundedness_for_implicit_asymmetry`: structural bounds
must NOT adapt in response to the very signal they're meant to bound.
The 3:1 loss-aversion asymmetry is preserved by the static seeds
(LOSS=3 vs WIN=1 = 3:1). The C51 distributional resolution stays
matched to the bound. Any reward exceeding the bound is clipped by
apply_reward_scale rather than absorbed by widening atoms.
Diagnostic-only state retained:
* pos_max_ema (slot 478) — observed positive-tail magnitude
* neg_max_ema (slot 489) — observed negative-tail magnitude
* clip_rate_ema (slot 482) — fraction of steps where clamp fired
* MARGIN (slot 480) — what the controller WOULD widen to
* RATIO (slot 481) — what observed LOSS/WIN ratio implies
These surface what an unbounded controller WOULD adapt to under the
observed reward distribution — useful for understanding drift even
though the LOAD-BEARING slots are now static.
F.5 vs G.2 smoke comparison (same seed=4242, 200 steps, b_size=4):
Pre G.2 Post G.2 Reduction
l_pi abs_max 31.15 8.09 4×
l_v max 103.69 3.60 29×
l_v mean 1.79 0.19 10×
l_pi mean -0.12 0.06 ~stable
l_frd mean 0.43 0.50 unchanged
WIN bound →41.3 1.0 static
LOSS bound →41.3 3.0 static
V_MAX →2.66 1.0 static
V_MIN →-2.74 -1.0 static
Spike steps 20+ 5 ≥4×
Remaining 5 spikes are early-training noise (steps 11-59) that fade
naturally as V/Q converge. After step 59 only one mild spike at
step 131 (l_pi=3.35, l_v=2.75).
Pairs with G.1 (V_pred clamp at [V_MIN, V_MAX]) — even with bounds
now static, the V head's structural clamp protects against any future
weight drift exceeding the support.
Verification:
* cargo check -p ml-alpha → clean
* lib tests 66/66 (default), 5/6 ignored (1 pre-existing
fxcache_local_smoke env failure, unrelated)
* GPU tests: integrated_trainer_smoke 1/1 + frd_head 10/10 +
trade_management_kernels 5/5 → no regression
* audit-rust-consts → 0 flags
f4b6797fda