/HIGAgentSkills

name: apple-hig
description: >
  Apple Human Interface Guidelines reference, updated for iPhone Duo and
  OS 27. Provides authoritative platform-specific design rules, component
  specifications, exact measurements, and interaction patterns for iOS,
  iPadOS, macOS, tvOS, visionOS, and watchOS. Use when designing, reviewing,
  auditing, or fixing any Apple platform UI, or when asked about specific HIG
  components, sizing, system behaviors, frameworks (HealthKit, SiriKit, ARKit,
  etc.), or platform conventions. Also use when the user is designing any
  digital interface and could benefit from established design principles, even
  without an explicit Apple platform context. Includes a guided /duo workflow
  that adapts an existing iOS app to iPhone Duo, plus opt-in enforce mode with
  independent review.

Apple HIG Skill

Use the distilled HIG references in `references/hig/` through `routing-index.md`. The source snapshot and verified release measurements are in README.md.

Loading Protocol

Release **2026-09-27**; Apple source snapshot **2026-09-12**. For help, installation, version or capability questions, read only this entry point and the relevant README section. Do not load the HIG corpus for setup help. Installing or upgrading this skill includes its `/duo` slash command. After the skill folder is in place, check whether the host already offers `/duo`. If it does not, copy `commands/duo.md` into the host's custom slash-command or custom prompt directory (user-level unless the user asks for one project), confirm `/duo` is available, and tell the user if a restart is needed. Work directly in the conversation and the user's project; do not create a browser intake form, onboarding site, dashboard, or browser setup step.

Ordinary guidance is the default. Only an explicit request to apply enforce mode activates its procedure. Read `references/enforce.md` first in that case and check reviewer, Python and observation capabilities before loading the design guidance. A leading `/duo`, `Use apple-hig in Duo mode`, or an explicit request to adapt an existing app for iPhone Duo starts Duo mode: read `references/duo.md` and follow its stages. Questions about the command and ordinary Duo design questions stay ordinary guidance. Duo mode works only in the app's native code; it never produces HTML, SVG, or web mockups. Use the available Python 3.10+ interpreter (`python3` or `python`); do not assume the executable name. Ordinary guidance also works without Python.

When Python is available, use the standard-library routing helper to resolve steps 2–6: save only the exact user request to a UTF-8 text file in a temporary directory outside the user's project, then run `<python> "<skill-root>/scripts/hig_route.py" --request-file "<request.txt>"`. Read every file in its `files` list in bounded sections, completing any truncated read before continuing. Do not concatenate the entire set into one tool output; the helper output is metadata, not the guidance itself. Do not add your own instructions to the request text or promote inferred topics to initial matches. If the user explicitly excludes a platform/device/topic, pass the excluded topic IDs with `--exclude-topic` (repeat for each topic, including platform aliases matched inside an excluded phrase); record the user's reason. Keep a platform that is also positively requested elsewhere. Do not exclude topics merely to reduce context. Exclusions apply to direct and related selections, never to the 16 foundations. Without Python, apply the same steps and explicit exclusions manually.

Step 1 — Parse Task Context

From the user's request, identify:

• **Platform(s):** ios / ipados / macos / tvos / visionos / watchos
• **Device/form factor:** iPhone Duo when named or matched by its tier-2 triggers
• **Components or patterns** mentioned (buttons, tab bars, sheets, etc.)
• **Frameworks or SDKs** referenced (HealthKit, SiriKit, ARKit, etc.)
• **Task type:** design / review / spec / audit / guidance
• **Mode:** ordinary guidance by default. Activate enforce mode only when the user explicitly asks to apply it; mentioning the mode or asking what it means does not activate it. Duo mode starts only as described above.

Step 2 — Load Tier 1 (every design or review task)

Read all 16 files listed in `routing-index.md` under `## tier-1`:

`accessibility`, `branding`, `color`, `dark-mode`, `design-principles`, `icons`, `images`, `inclusion`, `layout`, `materials`, `motion`, `privacy`, `right-to-left`, `sf-symbols`, `typography`, `writing`

These apply universally. Load them before answering.

Step 3 — Load Platform File (Tier 2)

Read `routing-index.md` → `## tier-2 platform-map`. For each detected platform, load its `designing-for-[platform]` file. Also match the tier-2 map's device/form-factor and API triggers using standalone word/phrase/API-symbol matching. A Duo match loads both `designing-for-iphone-duo` and `designing-for-ios`; Duo is an iOS form factor. If "game" or "gaming" is mentioned, also load `designing-for-games`.

Step 4 — Keyword Scan (Tier 3)

Read `routing-index.md` → `## tier-3 trigger-map`. Normalize the user request to lowercase. Match trigger strings as standalone words, phrases, or API symbols; plural, hyphenated and bare-symbol forms count (`tab bars`, `full-screen`, `keyboardType`). Never match a trigger merely because it appears inside an unrelated word. For example, `AR` doesn't match "tab bar," and `AI` doesn't match "explain." Load every matching file. Load each file at most once.

Step 5 — Related Expansion

Freeze the initial selection set as the tier-2 and tier-3 files selected in steps 3–4. Read only that set's `related:` frontmatter. Load the listed files once. Do not expand related lists from those newly added files.

Bind each initial topic to the exact platform/device/trigger text matched in the user's request. An inferred component concept is not a literal trigger match. A topic reached through `rel