The context window is finite. Long raw logs and irrelevant files can bury decisions; concise instructions, selected files and summaries preserve signal.
Persistent project instructions, often in a file such as AGENTS.md, record build commands, conventions, constraints and the definition of done. Layered instructions combine personal, organisational, repository and directory-specific guidance.
A plan is a provisional decomposition into verifiable steps. Planning is most useful for ambiguous, risky or multi-stage work and should adapt when evidence changes. Agent skills convert repeatable prompting into managed capability.
