Employees paste sensitive intellectual property into external language models every day. ShadowVisor intercepts this at the device level. It runs entirely within browser memory, parses text, and executes local classification models without sending any content to an external server. Management receives alerts. The underlying data never leaves the machine. WebAssembly and heavily quantized local models keep scan time under 60 milliseconds. The system generates formal compliance reports and satisfies zero-trust data processing requirements.