Overview
Project-level instruction files are most valuable when they perform four functions at once:
knowledge compression, preference storage, capability declaration, and retention of failures and successes. Their purpose is not to contain every detail. Their purpose is to place the highest-value information in front of the agent before it begins searching or acting.
A useful instruction architecture also separates global information from local information. Global instructions apply across workspaces. Local instructions describe one project, one client, one domain, or one repository. Mixing the two creates unnecessary context and makes rules harder to maintain.