Treat agent-skill marketplaces as a supply chain: capability-sandbox and trust-score skills before loading

arXiv:2603.00195·low signal

'Formal Analysis and Supply Chain Security for Agentic AI Skills' (arXiv:2603.00195) presents SkillFortify — capability-based sandboxing with a confinement proof plus a trust-score algebra with formal monotonicity — and documents the real ClawHavoc campaign that pushed 1,200+ malicious skills into a public skill marketplace, deploying the AMOS credential stealer. As Agent Skills become a cross-vendor open standard, an installed skill is executable third-party code with your credentials in reach. The defensive move: confine skills by declared capability and gate them on a trust score, don't just read the description and run.