premarket_eval's shadow enrichment call site queried session_date = current_date
(wrong on UTC-server Postgres at night, so it never matched any symbols) and
shared one try-block for float_cache + dilution filings (a float_cache failure
silently skipped the dilution refresh too). Fix: compute the ET session date
in Python, split into two independent try-blocks, lift into a testable
_refresh_shadow_enrichment(con, session_date). float_cache now applies its own
DDL unconditionally on use instead of only when an API key is present.
Adds iv_dilution_gate (additive, mirrors iv_regime_gate's keep-or-zero shape
keyed on symbol instead of session_date, fail-open on unfetched symbols) plus
its once-per-run preload, and registers the pre-registered dilution_veto_v1
experiment via the existing experiments/*.json self-registering cohort. Live
veto stays OFF; this only wires the shadow measurement.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
