Round 2 verification audit for C050

Model: gpt-5

Claim: Each error channel is studied by applying the map rho -> (1-p) rho + p M_{i,j} rho M_{i,j}^dag once per cycle after drive (A).

Source alignment: source/supp_content.tex:64-68 (Supp. Mat. S2)

Prior official verdict: verified 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 the map is a valid (trace-preserving) probabilistic error channel applied per cycle.. 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 verified with failure_reason None and limitations []. Notes: Kraus set {sqrt(1-p)I, sqrt(p)M} with M unitary (C049) gives sum K^dag K = (1-p)I + pI = I for all 16 channels and all p in [0,1]; Choi matrix PSD (CP) and Tr preserved (numerically confirmed). So rho->(1-p)rho + p M rho M^dag is a valid CPTP probabilistic error channel per cycle. Clean mathematical fact -> verified.