Curation, not accumulation

Prompt engineering asks how to phrase. Context engineering asks the more important question: what goes in front of the model at all?

For a bug in the refund path, it needs three things:

• the refund module — the code actually in play,
• the refund rules from the spec — Chapter I's artifact,
• the failing test — the Rite's artifact, naming exactly what "fixed" means.

Not the whole repo. Not last month's migration notes. The skill is selection: the right two hundred lines beat the complete works of your codebase.