OpAI-Bench

OpAI-Bench: Benchmark for detecting AI text across progressive human-AI co-editing workflows

Researchers introduce OpAI-Bench, a benchmark for studying AI-text detection across progressive human-to-AI document revision workflows, covering document, sentence, token, and span granularities. Starting from human-written documents, the benchmark constructs nine sequentially revised versions per sample under five AI edit operations and varying AI coverage levels across four domains. Key findings include that mixed-authorship intermediate versions are often harder to detect than fully human or heavily AI-edited endpoints, revealing non-monotonic detection patterns absent from existing benchmarks. The work addresses a gap in AI-text detection research as real-world documents increasingly result from iterative human-AI co-editing rather than pure generation.