Context Assembly

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.

Related terms

• Context Window: Everything sent to the model must fit inside the context window; overflow is truncated, summarized, or rejected depending on product policy.
• Prompt: Prompts set role, task, constraints, format, and context; the model’s reply is a direct response to that combined instruction stack.
• System Prompt: System prompts are fixed or dynamic instructions sent with every request to steer model behavior (persona, refusals, output format, tool policies).
• Retrieval-Augmented Generation (RAG): RAG = search step + generation step: find chunks likely to contain the answer, inject them into the prompt, then produce a reply grounded in those sources.
• Composer: The composer aggregates text input, attachments, mode toggles (Search, Agent, Build), connector chips, and send/stop into the main interaction control of the product.