If you're building iOS widgets or app extensions, this skill teaches Claude the non-intuitive parts: widgets are archived snapshots on a timeline, not live views that continuously run. It covers the sandbox constraints you'll hit (30MB memory, no network in widget views, separate bundle containers) and when to reach for App Groups to share data. The mental model shift alone is worth it. You've got 181 installs and passing security audits from three providers. It's part of the larger Axiom collection from charleswiltgen, which has 945 GitHub stars, so there's a real methodology here, not just random tips.
npx skills add https://github.com/charleswiltgen/axiom --skill axiom-extensions-widgets