What it means
The client gathers, ranks, and truncates sources (files, URLs, thread history, skills) to fit the context window, then orders them for the model to read.
Why designers should care
Assembly UX needs visible inclusion (what will be sent), easy remove/reorder, warnings when context is trimmed, and @-mention discoverability, silent assembly causes “why did it ignore my file?”
Example
Cursor shows @-attached files as chips above the composer; hovering lists token estimate and “2 files excluded, context limit” with a link to pin only essentials.
Common mistakes
- Hidden prepended context users cannot inspect before send.
- No feedback when large attachments are silently dropped.
- @-mention syntax with no picker or browse affordance for non-coders.
Frequently asked questions
What is Context Assembly?
Context assembly is how a product builds the full prompt stack before send: system rules, @-mentioned files, retrieved docs, memory, and the user’s message combined into one model request.
Why should designers care about Context Assembly?
Assembly UX needs visible inclusion (what will be sent), easy remove/reorder, warnings when context is trimmed, and @-mention discoverability, silent assembly causes “why did it ignore my file?”
What are common mistakes with Context Assembly?
Hidden prepended context users cannot inspect before send; No feedback when large attachments are silently dropped; @-mention syntax with no picker or browse affordance for non-coders.