rust-no-magic-values

name	rust-no-magic-values
description	Applies common production Rust practices to remove magic literals: named consts, enums, newtypes, and centralized schema strings. Use when writing or reviewing Rust, when the user mentions magic strings/numbers, duplicated literals, or when designing core versus adapter layers.

Rust — no magic literals

What serious codebases typically do

• Compiler and Clippy: favor const and rich types; teams often enable lints that reduce fragile unwrap patterns.
• const / static: protocol values and defaults live in dedicated modules so the meaning of each number has one home.
• Enums: closed sets with exhaustive match; prevent typos and drift across call sites.
• Newtypes: struct X(u32) or typed arrays (Eui64) to avoid mixing units or semantics.
• Adapter layer: table/column names and SQL fragments as const or a schema module, not copy-paste.
• Configuration: operational policy belongs in config structs or named presets (e.g. install profile), not ad hoc literals inside logic.

Checklist when changing code

• Does this number or string encode domain or protocol meaning? → const or type.
• Is it a closed set of variants? → enum (+ serde/display where needed).
• Does the same literal already exist elsewhere? → unify in the right crate’s module.
• Is it SQLite/HTTP/UDP detail? → keep it in the adapter, but centralized there.

Anti-pattern

A helper that takes &str for “event kind” used from many places without an enum: every call site is a future bug.