Most of the work in building on a model is deciding what to leave out. Context removes that decision from your critical path.
The full document, the full session, the full file. No pre-trimming, no deciding which half matters.
A session that survives the call, the restart, and the gap between Tuesday and Friday.
Move a conversation to a different provider without rebuilding what it already knew.
Put a corpus behind a question without standing up a retrieval stack to do it.
Sliding windows. Summarising the summary. Chunk size tuning. Embedding pipelines that drift. Deciding which of last week's decisions the model still gets to see.
None of that was ever the product. It was the tax for working inside a fixed window.
An agent that still knows what it decided forty turns ago, and what it already tried.
Ask about the system rather than the file you remembered to paste in.
Contracts, tickets, transcripts, notes. Answerable without a project to build first.
Bring your own provider key. Billing stays with your provider. The difference lands on their invoice.