Write rules as operational constraints: in Agent mode

Tip: Rules are not a style essay

Say what the agent must never do: no seed, keep published_at filters, no JS build. Let the agent run tools; stay in the loop for irreversible steps.

---
description: lexprog invariants
globs: src/**/*.rs
---
Never run cargo run --bin seed.

Gotcha: A rule that restates Rust book (in agent mode)

The model already knows Rust. Spend tokens on this repo's footguns. Plan-only text with a write tool still enabled will edit before you agree.

# What is ownership?

Source: https://docs.cursor.com/context/rules