On September 17, 2026, Lasso Security showed that SynthID-Text watermarking, required by the EU AI Act for provenance, changes how AI agents call tools and hold safety refusals, especially under prompt injection. Treat provenance compliance as a model-behavior change: re-evaluate and red-team with watermarked content.

Anthropic now applies a statistical watermark to Claude’s responses, built on Google DeepMind’s SynthID-Text, to comply with the EU’s AI Act. Invisible to the eye, it remains a probabilistic provenance signal — not proof of attribution.