context engineering is the entire job now.
the prompt isn't the prompt. the issue file is. the codebase is. you're staging a scene.
every junior engineer i've onboarded has had a moment around month two where they say 'i finally get the codebase'. it isn't that they read everything; it's that they built a mental model of where things live and what the conventions are.
agents don't get a month two. they get whatever you packed into their working context, and nothing else.
the shift
i used to think of the prompt as the input. now i think of the entire context window as a staged scene — files i've pasted in, the issue text, the conversation so far, the project instructions in CLAUDE.md.
writing a good prompt is now ~10% of the work. the other 90% is curating what else is loaded.
three habits
1. issues read like onboarding docs. context, constraints, acceptance, open questions.
2. every project has a CLAUDE.md that names the conventions an agent would otherwise have to guess at.
3. when a session gets long, i start fresh — better to re-pack context than to let a stale window degrade.