Code-driven filters

As a font grows, browsing every glyph by hand is a poor way to do targeted QA. Filters let Overview show exactly the subset you care about, including custom Python loaded from your Filters folder.

Built-in filters cover common cases. Custom filters are Python files in Counterpunch/Filters. Apply a built-in filter first so you can see the list change, then try a custom script.

A filter only classifies glyphs. It must not edit the font. If a filter errors, read the first line of the message, check syntax and the expected API, fix one thing, and run it again.

The contract for writing a filter is in Writing glyph overview filters. Python setup is in Python in Counterpunch. Recovery notes are in Common problems.