research/regime.py: Step 0 probe (labelable-session/SPY-coverage STOP gate),
Step 1 build-features (regime_features: pre-open breadth/tape + prior-close
SPY momentum/vol + trailing bot expR, label = mean _sim_baseline_r over the
session's setup fires) + walk-forward threshold_v1 rule, Step 2 walk-forward
meta_v1 (shallow sklearn GBM), Step 4 OOS/leakage-audit helpers
(oos_split/sequential_folds/session_expr_delta/full_sample_fit_threshold).
Step 3 (HMM) deferred per scope — statsmodels stays absent.
replay.py: new iv_regime_gate intervention (keep-or-zero a fire on a
pre-computed session regime score, fail-open on no score row) wired into
_compute_fire + run(), mirroring rank_one_bullet's shape.
experiments/regime_threshold_v1.json + regime_meta_v1.json register the two
model variants against the shared population/bars/fidelity contract.
All new code is unit-tested against isolated EventStore(":memory:") schemas
only — no production DB read or written. Live-trading paths untouched.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
