margelo

Create and update repo-local skills that follow the MetaMask Mobile standard. Use for new repo-local skills, skill entrypoints, or harness shims in this repository.

Add and fix Detox E2E tests (smoke and regression) for MetaMask Mobile using withFixtures, Page Objects, and tests/framework. Use when creating a new spec, fixing a failing E2E test, adding page objects and selectors, or adding MetaMetrics analytics expectations (analyticsExpectations).

Write, fix, and update component view tests (*.view.test.tsx) for MetaMask Mobile using the tests/component-view/ framework. Use when creating a new view test file, fixing a failing view test, updating tests after a component change, or creating a new renderer or preset for a view.

Create and review E2E performance tests that measure real user flows on real devices with TimerHelper and PerformanceTracker. Use when creating, editing, or reviewing performance tests, when the user mentions perf tests, timing measurements, performance thresholds, or files in tests/performance/.

Creates or removes a git worktree using the project scripts and shared config. Use when the user asks to create a worktree, add a worktree, remove a worktree, delete a worktree, or work on a parallel branch in a separate directory.

Generate a CHANGELOG entry line for a pull request from code changes. Use when the user asks to write a changelog entry, fill the changelog section of a PR, or determine if changes are user-facing.

Identify code owners for changed files and map them to Slack group handles. Use when the user asks who owns changed files, which teams to tag for review, or to find code owners for a PR.

Create a GitHub pull request from the current branch. Validates preconditions, generates title and description, and opens the PR as draft. Use when the user asks to create a PR, open a pull request, or submit changes for review.

Design and review predictable public APIs for TypeScript, JavaScript, React, and React Native libraries. Use when shaping exported functions, classes, hooks, options objects, event and listener APIs, error behavior, naming, cross-platform abstractions, or JS-only packages. Pair with build-nitro-modules when the library is backed by Nitro.

Builds and designs React Native Nitro Modules with Nitrogen, HybridObject TypeScript specs, generated native implementations, zero-copy and native-state APIs, Swift/Kotlin/C++ bindings, example apps, and testing. Use when creating a Nitro Module, adding or reviewing HybridObjects, designing Nitro-specific public APIs, implementing native functionality, or setting up the nitrogen codegen pipeline. Pair with api-design for general library API shape.

Fast native networking primitives for React Native built on Nitro Modules — react-native-nitro-fetch, react-native-nitro-websockets, and react-native-nitro-text-decoder. Covers the fetch API, global replacement, prefetching and cold-start cache warming, the NitroWebSocket class and pre-warming, migrating from React Native's built-in WebSocket, the in-process NetworkInspector, native Perfetto / Instruments tracing, the native TextDecoder, and plugging nitro-fetch into axios via a custom adapter.

Best-practices guide for react-native-vision-camera v5 (Nitro rewrite, April 2026) and migrating from v4. Use when installing, configuring, or writing code with the Camera, outputs, frame processors, recording, or barcode/depth/RAW features. Also use when converting v4 code (photo={true}, takePhoto, useCameraFormat, useFrameProcessor) to the new v5 API.

Fast synchronous key-value storage for React Native via react-native-mmkv (Nitro-backed). Covers creating and configuring MMKV instances, reading/writing all value types (string, number, boolean, buffer), React hooks for reactive UI, value-change listeners, encryption, AsyncStorage migration, and state-management integrations (zustand, redux-persist, jotai, react-query). Also covers storage limits, multi-process mode, and the V4 upgrade from the class-based API.

Use this skill whenever an agent is working in a project that uses react-native-nitro-fetch, react-native-nitro-websockets, or react-native-nitro-text-decoder. Covers the fetch API, global replacement, prefetching and cold-start cache warming, the NitroWebSocket class and pre-warming, migrating from React Native's built-in WebSocket, the in-process NetworkInspector, native Perfetto / Instruments tracing, the native TextDecoder, and plugging nitro-fetch into axios via a custom adapter.

Provides coding standards for React Native — performance patterns, consistency rules, and clean React architecture. Use when writing, modifying, or reviewing code.