Track 3 triage §C5 identified as an error-hiding case per
feedback_no_hiding.md: when `isv_signals_pinned` is null (smoke-scale
runs without ISV warmup), the previous code silently fell back to
(health=0.5, regime_stability=0.5), yielding
`cql_alpha_eff = base × 0.5 × 0.5 = 0.25 × base` by degenerate math,
not by design. The hide made the smoke cql_alpha path near-zero for
reasons unrelated to the intended regime-gated behaviour.
Fix (option b per plan): emit a one-shot `tracing::warn!` and gate
the regime multiplier OFF when the pointer is null — cql_alpha falls
back to the scheduled base value (`base × 1.0 × 1.0`). Real ISV path
unchanged. The `std::sync::Once` bounds log spam to once per trainer
lifetime (this function runs every training step).
Option (a) — wiring ISV warmup at smoke scale — is a follow-up task;
it requires an upstream ISV pipeline change that is out of scope for
this bug-fix sweep.
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