rzzo

Tell your agent to optimize your site’s web fonts. I’m seeing a huge difference on my blog. Full prompt: Make this site's web fonts load faster without changing how anything looks. Shrink font bytes as far as possible, keep rendering identical, and prove it with before/after pixel diffs. Treat any visual change as a regression unless I approve it. If an optimization would change rendering, tell me what it saves and what it changes, and keep the site looking the same by default. Keep the current loading behavior: don't touch font-display or fallback fonts. Don't add font processing to the build; write a script I run by hand, commit its output, and note when it needs rerunning. First measure the current state: each font file's size, glyph count, variable axes, OpenType features and hinting, plus font bytes per page and what each page preloads. Then find out what the site actually uses, checking inline component styles as well as stylesheets: which characters appear in the content, which axis values and weights each font needs (including one-off overrides and bold inside italics), which OpenType features are turned on, and CSS side effects like `hyphens: auto` using the U+2010 hyphen. Cut each font down to that. Keep the used characters plus Latin-1 and Latin Extended-A, and leave CJK to system fonts if that's how it renders today. Limit variable axes to the ranges in use, and only fix an axis at one value if nothing overrides it. Drop unused OpenType features and hinting. Split each font into two files. A small core with ASCII and the punctuation most pages use (curly quotes, dashes, ellipsis) gets preloaded. An extended file behind `unicode-range` only downloads when a page needs one of its characters. Each file's `unicode-range` should list only characters it actually contains. Watch out for a few things. A generated fallback face between the core and extended files will draw the extended characters before the real font does. Fonts with a Reserved Font Name under the OFL must be renamed internally once subset. Check the generated files, since font tools have quirks. Before calling it done, build a baseline from the same content and pixel-diff before and after on pages with code, italics, accented characters, components with their own font settings, and CJK. Explain every visible difference: content change, regression to fix, or harmless sub-pixel rounding. Re-measure bytes per page and confirm the extended files only load where needed. When you're done, tell me the bytes before and after per font and per page, the pixel-diff results, anywhere you deviated from what I asked and what it cost, and how to rerun the script. Later, it may be worth embedding the core font in the global stylesheet and precaching the extended files after idle.