Round 2 verification audit for C076

Model: gpt-5

Claim: Applying a single round of drive (A) to a state prepared in |Psi^+> excites one ion to D5/2 with probability p/2, providing one of the bit-flip-probability estimators.

Source alignment: source/supp_content.tex:157-157 (Supp. Mat. S5)

Prior official verdict: partial with failure_reason None.

Executable evidence: run.py. Sandbox rerun logs: run.log.

Independent audit: I scanned the copied script for imports/shared helper dependencies and reran it through the sandbox. The code is self-contained in this attempt directory and targets the claim strategy: Confirm from the drive-(A) action on |Psi^+> that the single-ion excitation probability is half the bit-flip probability p defined from |down,down>.. I checked the relevant family model rather than relying only on exit status; the rerun is treated as one reproducibility input.

Decision: Round 2 verdict is partial with failure_reason None and limitations ['paper_text_only_reimplementation']. Notes: p is an error process (ideal U_A gives no single-ion excitation). Counting: |dd> has 2 susceptible |down> ions -> p~=2r; |Psi+> has 1 |down> ion per branch (|up> spectator of A) -> P(one in e|Psi+)=r=p/2 to leading order. Exact in small-error limit; O(r^2) correction (e.g. 1% at r=0.01), consistent with paper's note that p/2 underestimates total excitation. Model-based reimplementation -> partial.