Adding a Stateful Trust Boundary to a LangGraph Agent

LangGraph makes agent workflows easier to reason about. You can see the nodes. You can see the edges. You can see where state is read, updated, and passed forward. That is a big improvement over a black-box agent loop. But it also exposes the question most agent pipelines eventually have to answer: Which parts of this graph are allowed to trust external content? A graph-based agent can read search results, PDFs, emails, tickets, web pages, tool outputs, and user-pasted text. Some of that content