Construct, rank,
explain.

use ferro_spread::{ChainSnapshot, SpreadBuilder,
                  SpreadStrategy};

let chain = ChainSnapshot::from_enriched(quote_snapshot)?;

let policy = SpreadBuilder::default()
    .strategy(SpreadStrategy::BullCallDebit)
    .dte_range(21..=45)
    .target_delta(0.30)
    .min_wing_pts(5.0)
    .max_wing_pts(20.0);

let candidates: Vec<SpreadCandidate> =
    policy.construct(&chain)?;

// Each candidate carries legs, debit, max profit,
// max loss, breakeven, and a typed PricingTrace
// pointing back at the FerroRisk surface fit.

use ferro_spread::{Ranker, RankingMetric};

let ranker = Ranker::default()
    .by(RankingMetric::ExpectedValue)
    .constrain(RankingMetric::CapitalRequired,
               0.0..=1_000.0)
    .constrain(RankingMetric::ProbabilityOfProfit,
               0.60..)
    .constrain(RankingMetric::MaxLoss,
               ..=500.0);

let ranked = ranker.rank(&candidates);

for r in ranked.iter().take(10) {
    println!("{} → EV={:.2}, PoP={:.0}%",
             r.candidate.label, r.ev, r.pop * 100.0);
}

use ferro_spread::{Explainer, Explanation,
                  ScoreContribution};

let exp: Explanation = Explainer::explain(
    &candidate, &ranker)?;

// Score breakdown — per-metric contribution
for ScoreContribution {{ metric, contribution }} in
    &exp.breakdown {{
    // metric: EV / PoP / CapitalEfficiency / Sharpe-adjacent
    // contribution: signed f64 in score units
}}

// Where the risk lives
let (top_greek, top_value) = exp.dominant_greek();

// Sibling candidates within Δrank ≤ 2
for sibling in &exp.comparables {{ /* … */ }}

// Audit trail: IV source, model, surface FitQuality
let assumptions = &exp.assumptions;