Reliable evaluation of LLM-based alpha mining requires more than positive backtest summaries. We audit a preserved project at three levels: historical run counters, outcome retention, and a separately scoped public reanalysis. Three historical runs report 67, 20, and 11 keep decisions, but the comparison mixes metric populations: a mean over kept candidates is compared with a mean of per-round maxima, and successful evaluations with all returned outcomes. These artifacts cannot identify an architecture advantage. A released 1,837-expression catalog also excludes non-positive OOS outcomes, making its zero-reversal rate non-informative. We then account for all 1,047 unique expressions in a frozen, IS-screened preserved pool using forty A-shares and 2024-2025 rank associations. A versioned public-operator correction yields 923 scorable records, 99 with insufficient valid dates, and 25 unsupported, without modifying the other 990 prior diagnostics. Among scorable records, 671 have positive and 252 negative signed mean rank-IC. Simple untrained references also show positive associations, so this distribution does not establish incremental agent skill or profitability. The case study motivates explicit metric grains, immutable cohort accounting, and provenance-aware interpretation rather than architectural rankings from incomplete records.

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