mechanics_verdict (PASS iff every post-rebalance position tracks its effective target within tolerance + no error/gap rows; else FAIL naming offending symbols) and indicative_slippage (per-tier mean slippage-vs- assumed excluding low_confidence fills, reporting coverage). Frozen DTOs PositionRow / SlippageFill / Verdict. Pure (design §5). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>