Delete code that nothing uses

How to do it

Run a dead code finder in the build. Delete what it reports, or mark an entry point it missed. Dead code misleads readers and agents, who copy it and keep it alive. Old code in comments goes too, as the comments chapter explains.

Example

// Bad: kept "just in case", and an agent will copy it
export function legacyPriceWithVat(price: number) { return price * 1.25; }

// Good: deleted, with the history in version control

# Bad: kept "just in case", and vulture reports it as unused
def legacy_price_with_vat(price):
    return price * 1.25

# Good: deleted, with the history in version control

How to check

A tool fails the build on new unused code. Examples are knip, vulture, and PHPStan with a dead code extension such as shipmonk/dead-code-detector.