rust

name	rust
description	when working on a Rust project

Before committing any changes in a Rust project

1. Run cargo fmt to format all code
2. Verify it succeeds before staging files
3. NEVER ever install rustup or run rustup command

When writing code

When a function accepts a byte index representing a character position, assume the index is aligned to a UTF-8 character boundary.

No magic sentinel values

Never encode "invalid" or "absent" state by stuffing a sentinel number (e.g. -1) into a field that normally holds real data. This is a common slope AI pattern and it is broken by design: sentinels are invisible to downstream code

• clamps, casts, arithmetic, and comparisons all treat them as ordinary values, creating hidden coupling between producer and every consumer. Use Option<T> or a dedicated enum variant instead.