OpenAI Rolls Out EU Text Watermarking With Limited Detector Access

OpenAI launched text watermarking (textGrain) October 5 for EU AI Act compliance. API users can opt in; EU ChatGPT and Codex users get it automatically. Detector access is restricted to approved researchers due to reliability limits: editing 10% of words cuts detection rates, and performance varies by content. Benchmarks show no performance impact. Watermarks don't prove authorship, ownership, or accuracy. Image and audio verification tools remain public.