The market state one equity instrument is currently bound to — the
pricing-view companion of the contract (QuantLib’s process, Strata’s
provider). Resolved from / snapshotted to the typed
Market store; swapped wholesale by
EquityOption::with_market.
Contract terms and trade identity — no market state. Immutable
for the life of the trade; everything that moves with the market
lives in EquityMarketData.
Lookback payoff: the call watches the minimum (floating) or maximum
(fixed), the put the mirror image. Discretely monitored on the path
grid under Monte Carlo; the analytic engine prices the continuous-
monitoring closed forms.