Bug audit finding #2 (post train-d2b2s diagnostic — same Pattern 1
class as SP14 B.11 commit 200f05fce and the 4-producer batch in
5608b866b). SP5 Pearl 2 budget producer and SP7 loss-balance
controller currently launch from process_epoch_boundary (fires once
per epoch), but the loss-balance budget output (ISV[BUDGET_CQL_BASE..]
/ ISV[BUDGET_C51_BASE..]) is consumed EVERY training step via
apply_c51_budget_scale (fused_training.rs:1941) and the dispatch
kernel that resolves the cached value into lb_budget_effective_buf
(fused_training.rs:3631).
The dispatch kernel is per-step, but the underlying flatness signal
ISV[FLATNESS_BASE..] is per-epoch. SP7's controller therefore reads
(steps_per_epoch − 1)-step-stale flatness — the same failure mode
that broke SP14's ALPHA_GRAD_SMOOTHED. The entire loss-balance
budget system has been operating on stale-flatness state for the
duration of training.
Migration (atomic, preserves Pearl 2 → SP7 dependency):
- Pearl 2 budget launch moved to submit_aux_ops (just-after the
producer-cadence batch's MoE chain, just-before the IQL gather
block).
- SP7 loss-balance controller follows immediately (reads Pearl 2
output via ISV).
- Same captured-into-aux_child graph-replay semantics as SP14 B.11.
- training_loop.rs lines 4312, 4336 deleted; replaced with redirect
comment.
Per feedback_no_partial_refactor: this is the 7th cadence-fix in
this branch since v8ztm. Other Pattern 1 candidates (SP5 Pearl 1
atom, Pearl 3 σ — Pearl 2 inputs, AND SP8 Fix 36 launch_max_budget_compute
— SP7 controller input) deferred per scope-tightening rule. They
sit one-epoch-stale at fold start; Pearl A bootstrap + the
controller's internal cold-start branch keep behavior functional.
Tracked in the audit doc top-of-file entry; independent migrations,
land separately.
Verification: cargo check -p ml --lib clean (dev profile);
sp14_oracle_tests 7/7 pass on RTX 3050 Ti.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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