react-testing-library
React Testing Library best practices for writing maintainable, user-centric tests. Use when writing, reviewing, or refactoring RTL tests. Triggers on test files, testing patterns, getBy/queryBy queries, userEvent, waitFor, and component testing.
refactor
Code refactoring best practices based on Martin Fowler's catalog and Clean Code principles (formerly refactoring). This skill should be used when refactoring existing code, improving code structure, reducing complexity, eliminating code smells, or reviewing code for maintainability. Triggers on tasks involving extract method, rename, decompose conditional, reduce coupling, or improve readability.
restful-hateoas
RESTful API design guidelines following the Richardson Maturity Model through to Level 3 (HATEOAS) for Ruby on Rails. This skill should be used when designing, building, reviewing, or refactoring REST APIs to ensure proper resource modeling, HTTP method semantics, hypermedia controls, content negotiation, and API evolvability. Triggers on tasks involving API controllers, serializers, routing, link relations, pagination, error handling, or HTTP caching in Rails.
ruby-optimise
Ruby performance optimization guidelines. This skill should be used when writing, reviewing, or refactoring Ruby code to ensure optimal performance patterns. Triggers on tasks involving object allocation, collection processing, ActiveRecord queries, string handling, concurrency, or Ruby runtime configuration.
ruby-refactor
Ruby refactoring guidelines from community best practices. This skill should be used when refactoring, reviewing, or restructuring Ruby code to improve design, readability, and maintainability. Triggers on tasks involving code smells, method extraction, conditional simplification, coupling reduction, design patterns, or Ruby idiom adoption.
rust-implement
Write production-grade Rust code using a multi-pass approach. Design types first, then implement, then simplify, then verify with automated lint. Use this skill whenever writing new Rust functions, structs, modules, or features. Triggers on Rust implementation, new Rust code, Rust functions, Rust modules, error handling in Rust, async Rust, or type design in Rust.
rust-refactor
Decision frameworks for Rust refactoring, simplification, module decomposition, and incremental migration. Use this skill when simplifying Rust code, splitting large files, removing dead abstractions, migrating types incrementally, or cleaning up feature flags. Triggers on Rust refactoring, simplification, module splitting, parameter cleanup, or incremental type migration.
rust-write-tests
Expert-level Rust testing — the "What Could Break?" framework, five transformations from superficial to expert tests, flake hunting protocol, intent-based assertions, naming conventions, and a mandatory self-review checklist. Triggers on writing Rust tests, designing test cases, improving test quality, or reviewing test coverage.
search-ios26-docs
Search and inspect local iOS 26 SDK documentation and Swift interfaces, especially SwiftUI and SwiftUICore. Use when Codex needs current iOS 26 SwiftUI APIs, Liquid Glass components, view modifiers, availability, signatures, deprecations, symbol docs, or SDK-only facts and should not rely on memory or public web docs being available.
search-macos26-docs
Search and inspect local macOS 26 SDK documentation and Swift interfaces, especially SwiftUI, SwiftUICore, and AppKit. Use when Codex needs current macOS 26 APIs, Liquid Glass components, window, scene, menu, toolbar, AppKit bridging, availability, signatures, deprecations, symbol docs, or SDK-only facts and should not rely on memory or public web docs being available.
shadcn
shadcn/ui component library best practices and patterns (formerly shadcn-ui). This skill should be used when writing, reviewing, or refactoring shadcn/ui components to ensure proper architecture, accessibility, and performance. Triggers on tasks involving Radix primitives, Tailwind styling, form validation with React Hook Form, data tables, theming, or component composition patterns.
shell
Shell scripting best practices for writing safe, portable, and maintainable bash/sh scripts. Use when writing, reviewing, or refactoring shell scripts, Dockerfile RUN commands, Makefile recipes, CI pipeline scripts, cron jobs, or systemd ExecStart directives. Triggers on bash, sh, POSIX, ShellCheck, error handling, quoting, variables, set -euo pipefail.
skill-authoring
Design and development best practices for Claude Code skills, MCP tools, and AI agent capabilities. Use when creating skills, writing SKILL.md files, designing tool descriptions, or optimizing triggers. Triggers on "create a skill", "skill template", "write skill instructions", SKILL.md, metadata.json, progressive disclosure, trigger optimization, MCP tool design, or skill testing. Does NOT cover specific frameworks or languages (use dedicated skills).
sonarqube-ai-slop-gate
Corrects the wrong defaults a model has when standing up self-hosted SonarQube Server as a continuous gate on AI-generated code, verified against docs.sonarsource.com in July 2026 (Server 2026.3, LTA 2026.1). Use when configuring SonarQube, designing a quality gate, or wiring a scan step into CI for AI-assisted work. Covers the setups that run green while measuring almost nothing — the fudge factor skips duplication and coverage conditions below 20 new lines and is on by default; duplication is never measured on test code; no `new_cognitive_complexity` metric exists to gate on; `sonar.host.url` now defaults to sonarcloud.io rather than localhost; a shallow clone degrades new-code attribution to timestamps. Also covers AI Code Assurance — the project flag, gate qualification, the deprecated Copilot autodetection — and that Community Build cannot analyze pull requests at all. NOT for SonarQube Cloud, IDE connected mode, or authoring custom analyzer rules.
staff-level-elixir
Use this skill when writing, reviewing, or refactoring Elixir, OTP, Ecto, or Phoenix/LiveView code. It corrects the staff-level judgment calls a capable model gets wrong by default — reaching for a GenServer as the universal tool, rescuing instead of letting processes crash, N+1 Ecto access, non-atomic writes, unbounded/linked Task fan-out, atom exhaustion from user input, eager Enum where Stream fits, and calling Repo from the web layer. Applies whenever the work touches process design, error handling, concurrency, data access, or LiveView, even if the user doesn't name them.
storybook
Use whenever creating, configuring, or extending Storybook for a TS/React component library — covers main.ts/preview.ts setup, CSF3 story authoring, args/argTypes/controls, decorators and providers, MSW and module mocking, play-function interaction tests via the Vitest addon, the @storybook/addon-a11y workflow (axe-core), autodocs vs MDX docs, design tokens, Figma linking, Chromatic deployment, and on-demand build performance. Triggers on tasks like "write a story", "set up Storybook", "configure addon-a11y", "fix this play function", "deploy Storybook", "test Storybook in CI" — even when the user doesn't say "storybook" but is editing `*.stories.tsx`, `.storybook/main.ts`, or `.storybook/preview.ts`. Targets Storybook 9+/10 (modern `storybook/test` import, Vitest addon, CSF3 + `satisfies Meta`). Does NOT cover generic React patterns (use the `react` skill), generic Testing Library queries (use `react-testing-library`), or WCAG primer (points at addon-a11y + axe rule config).
stripe-inspired-api-design-rules
JSON HTTP API design rules distilled from Stripe — resource modeling, identifier schemes, URL structure, request/response wire format, pagination, errors, idempotency, versioning, naming, webhooks, and authentication. Triggers on tasks involving OpenAPI specs, API design reviews, schema decisions, endpoint shaping, error envelope design, webhook delivery, or any "is this API well-designed" question. Apply when designing, reviewing, or refactoring a JSON HTTP API — even when the user doesn't mention Stripe by name, since the rules are general API-design principles distilled from the industry's most-copied reference.
swift-data
SwiftData persistence and data-layer architecture for iOS 26 / Swift 6.2 clinic modular MVVM-C apps. Use when writing, reviewing, or refactoring @Model entities, repository implementations, stale-while-revalidate reads, optimistic queued writes, sync/retry behavior, and SwiftUI integration that keeps SwiftData types inside Data-only boundaries.
swift-optimise
Swift 6.2 and SwiftUI performance optimization for iOS 26 clinic architecture codebases. Covers async/await concurrency patterns, Sendable/actor isolation, view/render performance, and animation performance while preserving modular MVVM-C boundaries across App, Feature, Domain, and Data layers. Use when profiling or optimizing Swift/SwiftUI behavior in clinic modules.
swift-refactor
Swift and SwiftUI refactoring patterns aligned with the iOS 26 / Swift 6.2 clinic modular MVVM-C architecture (Airbnb + OLX SPM layout). Enforces @Observable ViewModels/coordinators, App-target `DependencyContainer` + route shells, Domain repository/coordinator/error-routing protocols, and Data-owned I/O with stale-while-revalidate plus optimistic queued sync boundaries. Use when refactoring existing SwiftUI code into the clinic architecture.
swift-ui-architect
Opinionated SwiftUI architecture enforcement for iOS 26 / Swift 6.2 clinic modular MVVM-C apps using local SPM package boundaries. Enforces App-target `DependencyContainer` + route shells, @Observable ViewModels/coordinators, Domain repository/coordinator/error-routing protocols, Data-owned I/O, stale-while-revalidate reads, and optimistic queued sync. Use when writing, reviewing, or refactoring SwiftUI architecture, navigation, dependency wiring, or repository boundaries.
tailwind
Tailwind CSS v4 performance optimization and best practices guidelines (formerly tailwindcss-v4-style). This skill should be used when writing, reviewing, or refactoring Tailwind CSS v4 code to ensure optimal build performance, minimal CSS output, and correct usage of v4 features. Triggers on tasks involving Tailwind configuration, @theme directive, utility classes, responsive design, dark mode, container queries, or CSS generation optimization.
tailwind-refactor
Tailwind CSS code refactoring patterns for v4 migration and anti-pattern cleanup. This skill should be used when refactoring Tailwind utility classes, migrating from v3 to v4, cleaning up deprecated utilities, consolidating verbose class patterns, or removing code smells — all without changing the visual output. Triggers on tasks involving Tailwind CSS cleanup, v4 migration, class refactoring, @apply removal, or utility modernization.
tailwind-responsive-ui
Responsive UI transformation patterns for Tailwind CSS applications. This skill should be used when making interfaces responsive, refactoring layouts for multiple screen sizes, or reviewing responsive Tailwind code. Triggers on tasks involving breakpoint strategy, layout adaptation, responsive spacing, fluid typography, mobile navigation, touch interaction, responsive media, or data table responsiveness.
tailwind-ui-refactor
Refactoring UI design patterns for Tailwind CSS applications. This skill should be used when writing, reviewing, or refactoring HTML with Tailwind utility classes to improve visual hierarchy, spacing, typography, color, depth, and polish. Triggers on tasks involving UI cleanup, design review, Tailwind refactoring, component styling, or visual improvements.
tanstack-query
TanStack Query v5 performance optimization for data fetching, caching, mutations, and query patterns. This skill should be used when using useQuery, useMutation, queryClient, prefetch patterns, or TanStack Query caching. This skill does NOT cover generating query hooks from OpenAPI (use orval skill) or mocking API responses in tests (use test-msw skill).
tdd
Test-Driven Development methodology and red-green-refactor workflow (formerly test-tdd). This skill should be used when practicing TDD, writing tests first, designing tests before implementation, or reviewing test-first approaches. Triggers on "write tests first", "test before code", "red green refactor", "test driven development". This skill does NOT cover Vitest framework specifics (use vitest skill) or API mocking with MSW (use msw skill).
terminal-ui
Terminal User Interface (TUI) performance and UX guidelines for TypeScript applications using Ink and Clack. This skill should be used when building CLI tools, interactive terminal prompts, or developer tooling with TUI components. Triggers on tasks involving TUI components, CLI prompts, terminal rendering, keyboard input handling, or developer tooling.
theory-of-constraints
Apply the Theory of Constraints (Goldratt's Five Focusing Steps) to find and fix the single bottleneck that caps a process, workflow, pipeline, or Agent Skill/plugin's throughput. Use whenever optimizing speed, lead time, cost, or token/context budget of a system — CI/build pipelines, dev value streams (idea→review→merge→ship), an Agent Skill's trigger/context flow, or runtime code paths — ESPECIALLY when you don't know where to optimize, a local speedup didn't improve the whole, work piles up at a stage, everything is busy but little ships, adding capacity didn't help, or a policy/rule (not a resource) is the limiter. It locates the constraint with measurement, then prescribes exploit → subordinate → elevate → repeat, and stops you optimizing non-constraints (the "mirage of the non-bottleneck"). Trigger even when the user just says "speed this up", "why is this slow", or "make this more efficient" without mentioning constraints or bottlenecks.
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threat-model
Security threat modeling, attack surface mapping, and trust boundary analysis on a codebase. Triggers on 'threat model', 'security review', 'attack surface', 'trust boundaries', or when assessing a project's security posture. Also trigger when the user is about to build security-sensitive features (auth, crypto, file I/O, network services, native bridges) and needs to understand the threat landscape first — even if they don't explicitly say "threat model." Also triggers on 'what changed' or 'diff analysis' for incremental security review of recent commits.
threat-patch
Remediate security findings by producing minimal, surgical code patches. Triggers on 'patch security findings', 'fix vulnerabilities', 'remediate findings', 'threat patch', or when the user provides a findings.json (from threat-model), a Codex security findings CSV, a THREAT-MODEL.md, or individual vulnerability descriptions and wants them fixed. Also trigger when reviewing code flagged by a security scanner and the user wants actionable fixes rather than just reports.
trpc
Corrects the wrong defaults a model has for tRPC v11 (verified against 11.18.0). Use when code imports initTRPC, createTRPCContext, createTRPCOptionsProxy, createTRPCReact, httpBatchLink, httpSubscriptionLink, fetchRequestHandler, or TRPCError, or when building routers, procedures, middleware, links, or RSC prefetching. Covers the v10 to v11 drift that makes stale code fail — the React client that flipped to @trpc/tanstack-react-query, transformers moving into links, renamed type exports, observable subscriptions replaced by async generators over SSE — plus the defaults that are unsafe rather than merely stale — uncapped batching, CDN cache headers that serve one user's data to another, stack traces shipped from edge runtimes, and middleware that runs before input validation. NOT for TanStack Query semantics generally (use tanstack-query), Zod schema authoring (use zod), or Next.js App Router routing (use nextjs).
ts-google
Google TypeScript style guide for writing clean, consistent, type-safe code. This skill should be used when writing, reviewing, or refactoring TypeScript code. Triggers on TypeScript files, type annotations, module imports, class design, and code style decisions.
typescript
TypeScript performance, tsconfig, type errors, async patterns — triggered when the user asks to "optimize TypeScript performance", "speed up tsc compilation", "configure tsconfig.json", "fix type errors", "improve async patterns", or encounters TS errors (TS2322, TS2339, "is not assignable to"). Also triggers on .ts, .tsx, .d.ts file work involving type definitions, module organization, or memory management. Does NOT cover TypeScript basics, framework-specific patterns, or testing.
typescript-advanced-patterns
Advanced TypeScript — type-level programming, library/DSL APIs, declaration merging, modern language features at depth (decorators, using, const T, NoInfer, variance), and feature implementation patterns built on advanced types. Trigger on tasks involving recursive conditional types, infer patterns, mapped-type key remapping, variadic tuples, fluent builders with phantom state, schema-first inference (Zod/Valibot), end-to-end-typed API clients, finite state machines, module augmentation, and library-publishing concerns. Trigger even when the user does not say "advanced" — if the work involves type-level algorithms, library-author API design, or going beyond surface-level uses of TS 5.x features, this is the skill. Assumes the reader has absorbed the `typescript-refactor` skill — this one extends those patterns at depth, never restates them.
typescript-refactor
TypeScript and TSX refactoring and modernization guidelines from a principal specialist perspective, current to TypeScript 6.0 and React 19. This skill should be used when refactoring, reviewing, or modernizing TypeScript or React/TSX code for type safety, compiler performance, and idiomatic patterns. Triggers on tasks involving type architecture, narrowing, generics, discriminated unions, error handling, React component and hook typing, or migration to modern TypeScript features (satisfies, using, const type parameters, inferred type predicates, isolatedDeclarations, erasable syntax, import attributes).
ui-design
UI/UX and frontend design best practices guidelines (formerly frontend-design). This skill should be used when writing, reviewing, or designing frontend code to ensure accessibility, performance, and usability. Triggers on tasks involving HTML structure, CSS styling, responsive layouts, form design, animations, or accessibility improvements.
uniwind
Uniwind best practices for React Native styling with Tailwind CSS. This skill should be used when writing, reviewing, or refactoring React Native code using Uniwind. Triggers on tasks involving Uniwind, className styling, Tailwind in React Native, NativeWind migration, or theming.
unix-cli
UNIX command-line interface guidelines for building tools that follow POSIX conventions, proper exit codes, stream handling, and the UNIX philosophy. This skill should be used when writing, reviewing, or designing CLI tools to ensure they integrate properly with the UNIX tool chain. Triggers on tasks involving CLI tools, command-line arguments, exit codes, stdout/stderr, signals, or shell scripts.
vhs
VHS terminal recording best practices from Charmbracelet (formerly charmbracelet-vhs). This skill should be used when writing, reviewing, or editing VHS tape files to create professional terminal GIFs and videos. Triggers on tasks involving .tape files, VHS configuration, terminal recording, demo creation, or CLI documentation.
vite
Vite performance optimization guidelines. This skill should be used when writing, reviewing, or refactoring Vite configuration and projects to ensure optimal performance patterns. Triggers on tasks involving Vite config, build optimization, dependency pre-bundling, plugin development, bundle analysis, or HMR issues.
vitest
Vitest testing framework patterns for test setup, async testing, mocking with vi.*, snapshots, and test performance (formerly test-vitest). This skill should be used when writing or debugging Vitest tests. This skill does NOT cover TDD methodology (use test-tdd skill), API mocking with MSW (use test-msw skill), or Jest-specific APIs.
webpack-plugin-authoring
Writing webpack 5 plugins — hook selection (compiler vs compilation, tap vs tapAsync, processAssets stages), the asset pipeline (emitAsset, source classes, info metadata, source maps), watch-mode and persistent caching (file/context/missing/buildDependencies), plugin lifecycle (constructor purity, multi-compiler isolation, shutdown cleanup), schema-utils validation, WebpackError reporting, jest-worker parallelism, and compatibility patterns (compiler.webpack namespace, peerDependencies, getCompilationHooks WeakMap). Patterns are drawn from production plugins like mini-css-extract-plugin, terser-webpack-plugin, compression-webpack-plugin, and Next.js's webpack plugins. Trigger when writing, reviewing, or debugging webpack 5 plugins — even if the user doesn't explicitly mention "best practices" — anytime an `apply(compiler)` method is being written, hooks are being tapped, or a plugin imports from `webpack-sources`, the rules in this skill apply.
webpack-plugin-recipes
Use whenever you face a webpack-build problem that ends with needing to write a plugin — 26 production-shaped recipes covering bundle-size budgets, forbidden architectural imports, env-var validation, secret-leak prevention, build-info injection, asset manifests, license walking, SRI hashes, virtual modules (Vite-style), filesystem routing (Next.js-style), generated barrels, runtime-driven TS types, library replacement (react→preact), debug-stripping, conditional polyfills, dynamic banners, feature flags, build-duration regression tracking, desktop/Slack notifications, changed-chunks diffing, browser auto-open, gzip/brotli pre-compression, image optimization, type-based dist layout, empty-chunk cleanup, cache-busting query strings. Each recipe is a complete working plugin drawn from production patterns at Next.js, Storybook, webpack-contrib. Trigger when the user asks how to do X with webpack or whether a plugin exists for X. Companion to webpack-plugin-authoring.
web-rules
Strict design and UX rules for React 19 + Next.js 16 (App Router) + Tailwind CSS 4. Covers navigation, interaction design, accessibility, user feedback, UX patterns, and visual design. Use when designing, building, or reviewing any user-facing web feature on this stack. Trigger when the user asks to "build a settings page", "add a dialog", "design this form", "review for accessibility", "fix dark mode", or any Next.js App Router / React 19 / Tailwind UI task. Also trigger when the user says output "looks off", "isn't accessible", or "doesn't follow best practices."
write-design-docs
Write, revise, or review software design documents using Malte Ubl's "Design Docs at Google" guidance. Use when Codex needs to draft a design doc, technical design, RFC, engineering review doc, architecture proposal, mini design doc, or design-doc review focused on context, goals, non-goals, trade-offs, alternatives, cross-cutting concerns, review lifecycle, and deciding whether a design doc is warranted.
wxt-browser-extensions
WXT browser extension performance optimization guidelines. This skill should be used when writing, reviewing, or refactoring WXT browser extension code to ensure optimal performance patterns. Triggers on tasks involving WXT, browser extensions, content scripts, service workers, messaging, and extension APIs.
yjs-nextjs
Corrects the wrong defaults a capable model has when building Yjs collaborative editing into a Next.js 16 App Router app with tRPC v11 and shadcn/ui — pinned to Yjs 13.6.31. Covers the decisions whose failure mode is silence rather than an error — plain objects in a Y.Map discarding concurrent edits, updates that vanish because a JSON boundary turned a Uint8Array into a number array, undo that reverts a colleague's paragraph, initial content seeded once per client, and carets thrown to the end of a shadcn Input on every remote keystroke. Also covers where the sync loop can actually run, since route handlers cannot upgrade, Vercel Functions have no instance affinity, and tRPC subscriptions are one-way — plus which packages have already moved to the Yjs 14 prerelease track. Use when writing, reviewing, or debugging collaborative editing, presence, offline sync, or CRDT persistence in this stack.
zod
Zod schema validation best practices for type safety, parsing, and error handling. This skill should be used when defining z.object schemas, using z.string validations, safeParse, or z.infer. This skill does NOT cover React Hook Form integration patterns (use react-hook-form skill) or OpenAPI client generation (use orval skill).
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