Single source-of-truth implementation of:
- Pearl A (first-observation bootstrap): sentinel-detect at fold reset,
replace x_mean directly with first observation when prev_x_mean=0 AND
state.x_lag=0. Bypass Pearl D's Wiener math.
- Pearl D (Wiener-optimal adaptive α): for t≥1, α* = diff_var /
(diff_var + sample_var + ε_div); variances tracked at uniform meta-α.
6 unit tests: Pearl A sentinel replacement; Pearl D anchors at
stationary signal; Pearl D tracks step-change; Pearl D does NOT subsume
Pearl A at t=0 (mathematical correctness check from spec self-review);
meta-constants are structural; Pearl A only fires when both x_mean and
x_lag are zero (does not re-fire post-Pearl-D).
ALPHA_META = 1e-3 (structural — single uniform meta-rate, no per-signal
tuning). EPS_DIV = 1e-8 (Adam-ε numerical category). EPS_CLAMP_FLOOR =
1.0 (consumer cold-start floor).
No consumers wired yet — helper is library code unused by the producer
pipeline. Behavior unchanged. cargo check clean.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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