Preregistration: Verifying the presence of a person: detecting AI and bot completion of online cognitive experiments

Preregistration of a study testing whether a session-level detector based on effect signatures in trial-level data can separate human sessions from LLM agents and state-reading bots in online Stroop, n-back and parity judgment tasks. The files include the power analysis (for the three-paradigm design, see its addendum of 29 October 2026) and the feasibility runs of check 1. All agent sessions in these files are synthetic. No confirmatory agent session had been generated at the time of registration.