Critical review surfaced 11 actionable issues in the v1 spec; 10 fixed
inline (#11 — legacy-comparison test — dropped per user decision since
empirical legacy behavior is already known: n_trades=0).
Performance:
1. expf → piecewise-linear ramp (~5× cheaper on GPU, no transcendental
in the hot path). Operationally equivalent: monotonic, saturating,
midpoint at K. Side-benefit: pure max-confidence at cold-start
(sq=0 instead of sigmoid's 11.9% leakage).
2. Single fused per-horizon pass replaces the two-loop sketch.
3. Tier 2 scope narrowed to decision_policy_default ONLY. The bytecode
VM (decision_policy_program) stays unchanged — runs only for custom
strategy experiments, never in production policy. Halves Tier 2's
surface area + test cost.
4. __device__ helpers cbsw_signal_quality + cbsw_weight introduced for
single source of truth.
Correctness bugs (silently present in v1 sketch, would have shipped):
5. strong_h and sq_min_active initializers added (were referenced
before init in the per-horizon loop).
6. Attribution mask at cold-start was setting all 5 bits because every
w[h] >= floor > 1e-9; trades would pollute ALL horizons'
recent_sharpe. Fix: binary split — at sq_min_active < 0.5 attribute
only to strong_h; at mature, attribute per weights > floor + epsilon.
7. sq_min was "min over h", which permanently locked the aggregator
into cold-start mode if any horizon never gets attributed (e.g.,
h6000-only-trading regime). Fix: sq_min_active = min over h with
n_trades_seen > 0; cold horizons don't gate maturity.
8. Opposing-horizons case now correctly fires on the strongest single
horizon at cold-start (piecewise-linear sq=0 → pure max-conf), with
explicit design-choice note explaining why this conservatism trade-
off favors firing.
Spec hygiene:
9. Rate validation committed to a measurement gate (Q2 ev/s ≥ 95% of
Q1 ev/s) instead of back-of-envelope estimate.
10. Kernel ABI explicitly stated as unchanged → feedback_no_partial_
refactor compliance is trivial at the kernel boundary.
12. Tier 1's use_cold_start_stopgap field is DROPPED in Q2 atomically
(not orphaned), and DoD checklist includes a grep-zero gate for
feedback_no_legacy_aliases compliance.
Risks updated: removed the sigmoid-narrowing risk (irrelevant now);
added register-pressure risk with the rate-gate mitigation; added
explicit "cold-start may lose on noisy trades" risk with empirical
escalation path (bump kelly_floor 0.20 → 0.40 if Q2 smoke shows large
negative PnL).
Math walk-throughs rewritten for piecewise-linear (different numbers
at cold-start): cold = pure max-conf, mature = pure weighted-sharpe,
clean separation at sq_min_active threshold.
Awaiting review of the revised spec before writing-plans dispatch.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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