Her training told her to abort, but she was also responsible for keeping equipment online. She tapped the coin-like tag again; it responded, but this time with a warning LED. The tag's companion app—installed weeks earlier on her phone—had detected an anomalous signature on the server certificate. The vendor's key had been rotated that morning due to a supply-chain incident, the app explained, and mirrors hadn't yet propagated the new signature. The tag retained a short list of trusted thumbprints and refused to authorize unknown ones.