rc-agents-md

# Writing AGENTS.md Keep agent instruction files lean enough that every rule in them binds. ## Physics: resident context An AGENTS.md or CLAUDE.md (COPILOT.md, .cursorrules — any harness instruction file) is not documentation. It is a fragment of the system prompt: the harness injects it verbatim into every session, before the task is known, and it never unloads. A skill loads on demand; this file is **resident**. Three consequences govern everything below: - **Every line taxes every task.** A rule relevant to 5% of sessions spends attention in the other 95%. - **Rules dilute each other.** Instruction-following is a budget: the more rules resident, the weaker each one binds. A bloated file doesn't enforce more — it enforces less, and the critical rule drowns in the noise. - **The reader is a frontier model.** It already knows git, testing, the language's idioms, and general best practice, and it can read the codebase. It needs decisions, not knowledge, and it parses a crisp rule without an example. The file that survives these constraints is a **delta**: the difference between stock agent behavior and what this project needs. Everything that isn't delta is rent paid for nothing. ## The rent test Run on every line written, kept, or proposed. A line stays only if all three hold; a line that fails is deleted or relocated, never softened. 1. **Delta** — it changes what the agent would otherwise do. Restated defaults, general best practices, and motivational prose fail her...