Fetch one directory challenge's complete ruleset (ChallengeSpec), adapted from the live LuxAlgo directory: evaluation steps (profit targets in percent units of the initial account, minimum trading days, time limits); the daily-loss rule with its exact semantics (basis = measured from prior-day balance vs prior-day equity; limitBasis = whether a pct limit is a fixed allowance of the initial balance or recomputed daily from the anchor; evaluation = breached on an intraday touch vs only at the close; includesOpenPnl = whether floating P&L can breach it); the max-loss rule and its drawdown mode (How the max-loss floor behaves - the single most consequential rule difference between firms. 'static-initial': floor fixed at initial balance minus the limit; never moves (classic CFD two-step). 'trailing-realized-eod': floor ratchets up with end-of-day balance highs; intraday highs do not move it. 'trailing-intraday-unrealized': floor trails the peak unrealized equity intraday and never stops trailing (futures-style; the most-miscalculated rule in the industry: it cuts pass probability dramatically). 'trailing-locks-at-initial': trails intraday peak equity until the floor reaches the initial balance, then freezes (common futures variant). Locking is also composable: locksAtInitial adds the same lock to an EOD trail, and lockOffsetAmount shifts the lock level to initial balance + that amount (e.g. 100 models 'stops trailing $100 above the start').); per-step consistency rules (steps[].consistency.maxBestDayProfitPct - SIMULATED: one outsized day effectively raises the target until the best-day share complies); fees (price, one-time vs monthly billing, reset fee, activation fee, refundable-on-pass); funded terms (profit split percent, payout frequency, first-payout minimum days, and funded.payoutRules - SIMULATED payout gating: minWinningDays, winningDayMinProfit, per-payout caps maxPayoutPctOfProfit/maxPayoutAmount, bufferAmount, and a windowed consistencyMaxBestDayPct gate); flagsNotSimulated (rules the entry declares but the engine does not simulate - material caveats to relay to the user); and sources (the firm-page citation when the directory serves one). The result also carries provenance and inferredFields - every rule read from free text instead of a structured column is named there; relay them and treat the firm's page as authoritative. The returned challenge object is exactly the shape the simulation tools accept as inline spec: copy it, change a rule, and re-simulate to quantify how a rule variation moves pass probability and EV. UNITS: every *Pct rule field and every percent-mode risk value is in PERCENT UNITS (5 = 5%, 0.5 = 0.5%). The one exception is winRate, which is a FRACTION in [0, 1] (0.55 = 55% winners). Probabilities in results are fractions in [0, 1]. DATA SOURCE & PROVENANCE: firm data comes live from LuxAlgo's public, keyless prop-firm directory API - the data behind luxalgo.com/prop-firms (origin overridable via the LUXALGO_APP_ORIGIN env var). Rule semantics are used verbatim where the directory serves structured rule columns; where it serves only free text, semantics are inferred ONLY when one reasonable reading exists, and every inferred field is disclosed in inferredFields (provenance 'directory+inferred') - relay those to the user next to any numbers. Challenges whose loss rules cannot be established are refused as not simulatable rather than guessed. Firms change rules; each firm's own page is always authoritative. NOTE: this returns the simulatable encoding of one challenge's rules; the directory listing with every captured field, plus live offers, is propfirms_get and propfirms_search_challenges.