Property-based fuzz tests with random-walk MBP-10 sequences applied to
the LOB simulator at three backtest counts; assert per-snapshot
invariants that must hold regardless of input or block scheduling:
fuzz_n1_book_only (200 events, no orders)
Pure book-update kernel — verifies mid-drift random walks preserve
book monotonicity and never produce a crossed book.
fuzz_n16_with_orders (200 events, market orders every 8th event)
16 backtests in parallel, each submitting random buy/sell market
orders 1-3 lots at every 8th event. Asserts book invariants on
each backtest's state PLUS:
- position_lots stays within ±30 (plausible given fixture book depth)
- realized_pnl + vwap_entry finite (no NaN/Inf leaks)
fuzz_n256_with_orders (100 events, market orders)
Production-scale parallelism. Same invariants as N=16. Each block
has its own per-backtest Pos + OpenTradeState + TradeLog, exercising
the per-block isolation discipline established in C5-C7.
All 3 pass on RTX 3050. Spec §8 Ring 2 confidence gate hit.
Adds rand + rand_chacha to ml-backtesting dev-dependencies.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
