Use this skill the moment the user asks about cpp.js runtime/build configuration, C++ binding rules, or build troubleshooting — phrases like "what options does initCppJs accept", "how do I enable OPFS / persistent storage in cpp.js", "useWorker", "is cppjs multithread", "runtime: mt vs st", "COOP COEP for cpp.js", "what fields go in cppjs.config.js", "cppjs.build.js hooks", "what shape is state / target in build hooks", "cpp.js binding rules / can I use raw pointers", "writing a C++ wrapper for cpp.js", "manual SWIG .i file in cpp.js", "cppjs override mechanism for emccFlags / cmake / env", "cppjs build error / linker error / out of memory", "cppjs performance defaults / tunable flags", "do I need m.delete in cpp.js", "TypeScript types for cpp.js", "mount file from input in cppjs", "cppjs filesystem in browser / node / cloudflare worker", "edge runtime cppjs limits". Pull the matching reference doc into context before answering.
Use this skill when the user wants to add cpp.js to an existing JavaScript / TypeScript / React Native project — phrases like "set up cpp.js with Vite / Next / Webpack / Rspack / Rollup / Cloudflare Workers / Node / vanilla HTML", "integrate @cpp.js/package-X into my app", "add cpp.js to my React Native project", "wire up GDAL in my Vue / React / Svelte / Solid app", "use cpp.js with my Expo project". Detect their framework first, then walk them through the matching playbook.
Use this skill when the user wants to wrap a C++ library as a reusable cpp.js package — phrases like "package libsodium for cpp.js", "create a new cppjs-package-X", "publish my C++ library so others can pnpm add it", "add FreeType / libsndfile / fftw / OpenCV to the cpp.js ecosystem", "make my CMake project consumable from JS via cpp.js". Pairs with the scaffold-package script and the new-package playbook.
Use this skill the moment the user describes a problem cpp.js solves — they want to use C++ (their own code, or a library like GDAL, OpenSSL, GEOS, SQLite, libsodium, FreeType, libsndfile, …) from JavaScript / TypeScript / React Native, in a browser, Node.js service, Cloudflare Worker, or React Native app; or they ask "how do I bind C / C++ to JS", "WebAssembly for performance", "use my native library in the browser", "compile a CMake project for the web", "fast image / geo / crypto code in Node". Trigger early in the conversation.