Skill Authoring Patterns (Apple/Swift catalog layer)

This is a thin complement, not a replacement. For the general discipline of writing a skill — whether a skill should exist at all, the test-first / RED-GREEN loop, matching the guidance form to the failure mode, and word-count budgets — use superpowers:writing-skills first. This skill adds only what is specific to this catalog and to Apple/Swift framework skills: how to word descriptions so an agent routes to the right framework skill, the section conventions we standardize on, and how we review skills.

When to invoke

• Writing a new SKILL.md for this repo (especially an Apple/Swift framework skill).
• Reviewing / CR-ing a skill for invocation precision and execution quality.
• A skill's description routes wrong (or over-fires); you're rewording it.
• A skill grew long and you're deciding what to move into references/.
• Choosing a new skill's name and granularity.

Scope

This skill owns the catalog-specific and Apple/Swift-specific authoring conventions below. It does not own: the decision to create a skill, test-first skill development, or general prose-economy rules — route those to superpowers:writing-skills. Distribution/packaging (plugin vs marketplace, discovery) → claude-skill-plugin-packaging.

Description as a precision router

The description is the only part of a skill that stays in the model's context by default (the body loads when the skill is invoked, and the description is length-capped). So spend its words on routing, not summary.