matthewp/tideway/prune

Tideway: prune

Prune finds CSS classes a project defines but no longer uses, so hand-written stylesheets don't accumulate dead rules. Tideway's conventions make this reliable: every selector is a single flat class, so each rule maps to exactly one class name, and the distinctive BEM names are unambiguous to search for.

Workflow

1. Run the detector from the project root:

`` python scripts/find_unused.py <project-dir> ``

It scans every .css file for defined classes, searches the project's markup and scripts for each, and prints two groups: Unused (no reference anywhere) and Possibly dynamic (see below).

1. Report the findings to the user before changing anything. Group by file so the scope is clear.

1. Remove what's confirmed unused, on the user's go-ahead. Because a block's CSS lives together, removing an unused element or modifier is a local deletion; an entire unused block is its whole section or file. Removal is safe to do under version control.

The one thing to be careful about

A class can be referenced without its full name ever appearing in the source — when markup builds it at runtime: ` card--${variant} , clsx("card", isOpen && "card--open")`, or other string construction. Such a class is live but looks unused to a text search.

The detector flags these as Possibly dynamic: the exact name isn't found, but its prefix (card--) does appear in the source. Never remove a class from this group on the report alone — open the construction site, confirm the full name can't be produced there, and only then treat it as dead. When unsure, keep it.

Out of scope

Writing new CSS is the style skill. Converting an existing project onto Tideway is the migrate skill.