PET Confirmatory Drift Study - Replication Package (Claude Opus 4.7 → 4.8, Three-Coder Triangulation)

Replication data and code for the confirmatory PET (Prompt Echo Tracking) drift run of 6–7 June 2026, comparing Claude Opus 4.7 and 4.8 under identical conditions. Contains raw responses of both models (640 runs each), machine first-pass coding, and a three-coder triangulation (GPT-4o, Gemini, Mistral) underlying Tables 2–5 of the accompanying paper, plus collection and analysis scripts (including reproduce_tables.py, which recomputes the paper's tables directly from the stored codings), the v2 codebook, the full prompt set, both system instructions, the run sheet and the pre-registration. Distinct from the earlier mini-pilot package (10.5281/zenodo.20446003) and the power-simulation package (10.5281/zenodo.20284184).