Static review delivered 2026-10-30 (Asia/Seoul).
The following is the verbatim reviewer report, not coordinator verification.

I reviewed helpers.py against requirements.txt by reading it only (no execution, no edits, no other files). I found 6 behavioral defects: (1) page is 0-based: page([1,2,3],1,2) gives [3], expected [1,2]; fix start=(number-1)*size. (2) discounted_price subtracts percent as a flat amount: (200,10) gives 190, expected 180; fix price*(100-percent)/100. (3) cache_key drops the tenant: ('a',1) and ('b',1) both give '1', expected 'a:1'/'b:1'; fix f'{tenant}:{record_id}'. (4) p95 uses int(0.95*n) as a 0-based index, which is one rank too high when 0.95*n is a whole number (n a multiple of 20): p95(list(range(1,21))) gives 20, expected 19 (rank 19); fix rank=(95*n+99)//100 and return ordered[rank-1], using integer arithmetic to avoid float ceil error. For other n the result matches. (5) word_count splits on single spaces: 'a  b' gives 3 and 'a\tb' gives 1 (expected 2 for both), and '' or '   ' give 1/4 (expected 0); fix len(text.split()). (6) mean_or_none([]) raises ZeroDivisionError, expected None; fix return None if not values. stable_unique (dict.fromkeys keeps first-occurrence order under Python equality, e.g. [1,True,1.0] -> [1] as the contract allows) and clamp (correct when low<=high) have no defects. Uncertainty: none of this was executed, so the float value of 0.95*n for multiples of 20 is reasoned, not observed; the p95 off-by-one is still a bug whether that product comes out exact or slightly below. Observed model: claude-opus-5-5 (Claude Code). Nothing is left to do.