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Agent skill

Appkit Interop

by robinebers in robinebers/openusage

Decide when and how to bridge a macOS app from SwiftUI into AppKit.

MITAuto-check passedMobile

Install Appkit Interop

skills CLI
$ npx skills add robinebers/openusage --skill appkit-interop -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install robinebers/openusage appkit-interop --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/robinebers/openusage.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/appkit-interop .claude/skills/appkit-interop && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
appkit-interop
GitHub stars
4.3k
Token cost
~741 tokens
SKILL.md length
338 words
Files
5 (incl. references)
Skills in repo
25
Repo updated
First seen
Licence
MIT

At a glance

Decide when and how to bridge a macOS app from SwiftUI into AppKit.

  • Works in 5 steps: Name the capability gap precisely. → Pick the smallest boundary that solves it. → Keep ownership explicit. → …
  • Implementing NSViewRepresentable
  • SKILL.md covers Quick Start, Choose The Smallest Bridge, Workflow and References, plus 2 more sections
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Appkit Interop is an agent skill from robinebers/openusage. Decide when and how to bridge a macOS app from SwiftUI into AppKit. Use when implementing NSViewRepresentable or NSViewControllerRepresentable, accessing NSWindow or the responder chain, presenting panels, customizing menus, or handling desktop behaviors that SwiftUI does not model cleanly.

Its SKILL.md is about 740 tokens, which your agent loads only when the skill is triggered. The skill folder holds 5 other files, including reference files (for example `references/drag-drop-pasteboard.md`, `references/representables.md` and `references/responder-menus.md`).

It sits in Mobile, covering iOS development. It works with macOS and SwiftUI. The repository describes itself as: Burning through your subscriptions too fast? Paying for stuff you never use? Stop guessing. OpenUsage is free and open source. The licence is MIT.

When your agent uses it

  • Implementing NSViewRepresentable
  • NSViewControllerRepresentable
  • Accessing NSWindow
  • The responder chain

Example prompts

  • “/appkit-interop”

Workflow steps

5 steps, taken from the first numbered list in SKILL.md.

  1. Name the capability gap precisely.
  2. Pick the smallest boundary that solves it.
  3. Keep ownership explicit.
  4. Expose a narrow interface back to SwiftUI.
  5. Validate lifecycle assumptions.

What it can do on your machine

Read from SKILL.md and the folder at commit cb21465. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md.

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Appkit Interop loads about 741 tokens when it runs, and up to ~1.8k if it reads all its reference files. Until then it costs about 77 tokens; SKILL.md has 338 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~77
When it runs · the whole SKILL.md, loaded when a task matches
~741
With references · SKILL.md plus every file in references/, read only if the agent opens them
~1.8k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from robinebers/openusage at commit cb21465, republished under its MIT licence (© robinebers). 338 words, ~741 tokens.

Download SKILL.mdSave it as .claude/skills/appkit-interop/SKILL.md (or your agent's skills folder). This skill also uses 4 other files; get the full folder from GitHub.
name
appkit-interop
description
Decide when and how to bridge a macOS app from SwiftUI into AppKit. Use when implementing NSViewRepresentable or NSViewControllerRepresentable, accessing NSWindow or the responder chain, presenting panels, customizing menus, or handling desktop behaviors that SwiftUI does not model cleanly.

AppKit Interop

Quick Start

Use this skill when SwiftUI is close but not quite enough for native macOS behavior. Keep the bridge as small and explicit as possible. SwiftUI should usually remain the source of truth, while AppKit handles the imperative edge.

Choose The Smallest Bridge

  • Use pure SwiftUI when the required behavior already exists in scenes, toolbars, commands, inspectors, or standard controls.
  • Use NSViewRepresentable when you need a specific AppKit view with lightweight lifecycle needs.
  • Use NSViewControllerRepresentable when you need controller lifecycle, delegation, or presentation coordination.
  • Use direct AppKit window or app hooks when you need NSWindow, responder-chain, menu validation, panels, or app-level behavior.

Workflow

  1. Name the capability gap precisely.

    • Window behavior
    • Text system behavior
    • Menu validation
    • Drag and drop
    • File open/save panels
    • First responder control

  2. Pick the smallest boundary that solves it.

    • Avoid porting a whole screen to AppKit when one wrapped control or coordinator would do.

  3. Keep ownership explicit.

    • SwiftUI owns value state, selection, and observable models.
    • AppKit objects stay inside the representable, coordinator, or bridge object.

  4. Expose a narrow interface back to SwiftUI.

    • Bindings for editable state
    • Small callbacks for events
    • Focused bridge services only when necessary

  5. Validate lifecycle assumptions.

    • SwiftUI may recreate representables.
    • Coordinators exist to hold delegate and target-action glue, not as a second app architecture.

References

  • references/representables.md: choosing between view and view-controller wrappers, plus coordinator patterns.
  • references/window-panels.md: window access, utility windows, and open/save panels.
  • references/responder-menus.md: first responder, command routing, and menu validation.
  • references/drag-drop-pasteboard.md: pasteboard, file URLs, and desktop drag/drop edges.

Guardrails

  • Do not duplicate the source of truth between SwiftUI and AppKit.
  • Do not let Coordinator become an unstructured dumping ground.
  • Do not store long-lived NSView or NSWindow instances globally without a strong ownership reason.
  • Prefer a tiny tested bridge over rewriting the feature in raw AppKit.
  • If a pattern can remain entirely in swiftui-patterns, keep it there.

Output Expectations

Provide:

  • the exact SwiftUI limitation being crossed
  • the smallest recommended bridge type
  • the data-flow boundary between SwiftUI and AppKit
  • the lifecycle or validation risks to watch

© robinebers, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 4 other files (references) in .agents/skills/appkit-interop of robinebers/openusage.

  • SKILL.md
  • references/drag-drop-pasteboard.md
  • references/representables.md
  • references/responder-menus.md
  • references/window-panels.md

Open the folder on GitHubat commit cb21465

Compare with similar skills

Appkit Interop next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Appkit Interop compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Appkit Interop this skillrobinebers/openusage4.3k—~741Automated safety check: PassMIT
Swiftui Expert Skillomarshahine/HomeClaw1754 repos~2.8kAutomated safety check: PassMIT
Appkit Swiftui BridgeKartikLabhshetwar/better-shot2.4k2 repos~1.1kAutomated safety check: PassCustom licence
macOS Notch UIfayazara/Screendrop2.1k—~1.8kAutomated safety check: PassCC0-1.0
Hig Project Contextraintree-technology/hig-doctor1435 repos~1.2kAutomated safety check: PassMIT
Swiftui Expert SkillEslzzyl/Pixiv-SwiftUI1111 repos~2.9kAutomated safety check: PassAGPL-3.0

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More from robinebers/openusage

All 25 skills in this repo

  • Swiftui Patterns

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  • Window Management

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Works with

Categories

Questions about Appkit Interop

What does Appkit Interop do?

Decide when and how to bridge a macOS app from SwiftUI into AppKit. Appkit Interop is an agent skill from robinebers/openusage. Decide when and how to bridge a macOS app from SwiftUI into AppKit.

When should I use Appkit Interop?

Appkit Interop fits situations like: implementing NSViewRepresentable; NSViewControllerRepresentable; accessing NSWindow; the responder chain.

How do I install Appkit Interop in Claude Code?

Run `npx skills add robinebers/openusage --skill appkit-interop -a claude-code`. Or copy the skill folder (.agents/skills/appkit-interop in robinebers/openusage) into .claude/skills/appkit-interop in your project. Claude Code loads it when a task matches its description.

How do I install Appkit Interop in Codex?

Run `npx skills add robinebers/openusage --skill appkit-interop -a codex`. Or copy the skill folder (.agents/skills/appkit-interop in robinebers/openusage) into .agents/skills/appkit-interop in your project. Codex loads it when a task matches its description.

Can I use Appkit Interop in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add robinebers/openusage --skill appkit-interop -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/appkit-interop, .gemini/skills/appkit-interop, .github/skills/appkit-interop and .opencode/skills/appkit-interop in your project.

What does Appkit Interop need to run?

SKILL.md names no scripts, command-line tools or credentials: Appkit Interop is instructions for the agent only.

Does Appkit Interop access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Appkit Interop safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Appkit Interop use?

Appkit Interop is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Appkit Interop use?

About 741 tokens (SKILL.md is roughly 3k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 1.1k tokens, read only when the agent opens those files.

What are the alternatives to Appkit Interop?

Skills that share tags, products or a category with Appkit Interop: Swiftui Expert Skill (omarshahine/HomeClaw, 175 stars), Appkit Swiftui Bridge (KartikLabhshetwar/better-shot, 2.4k stars), macOS Notch UI (fayazara/Screendrop, 2.1k stars) and Hig Project Context (raintree-technology/hig-doctor, 143 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Appkit Interop?

robinebers (a GitHub user) maintains it in robinebers/openusage, which has 4,335 GitHub stars. The repository holds 25 skills in this directory. The repository was last updated on October 6, 2026.

Source: robinebers/openusage on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.