Context assembly is the runtime process of selecting and combining the documents, memory entries, tool results and instructions passed to a model for a single request — the point at which governance policy is applied, because the assembled whole can be more sensitive than any of its parts.
What is context assembly, and why does it need governance?
Retrieval decides what is relevant; assembly decides what actually enters the context window together. Two chunks that are individually permitted may not be permitted in combination, and no file-level control evaluates that pairing. Governing assembly means applying policy to the composed context immediately before generation — filtering, redacting, scoping or refusing — and recording what was assembled so the answer can be explained later.