Bun

Implements JavaScript classes in C++ using JavaScriptCore. Use when creating new JS classes with C++ bindings, prototypes, or constructors.

Creates JavaScript classes using Bun's Rust bindings generator (.classes.ts). Use when implementing new JS APIs in Rust with JSC integration, prototypes, or constructors.

JSC GC reference for Bun. Use for use-after-free, JS object leaks, "collected too early", or when touching WriteBarrier, visitChildren, visitAdditionalChildren, JSRef, JSC::Strong/Weak, hasPendingActivity, ensureStillAlive, addOpaqueRoot, reportExtraMemoryAllocated, IsoSubspace, HeapAnalyzer, finalize.

Guides using bun_sys for system calls and file I/O in Rust. Use when implementing file operations, opening fds, or any syscall path instead of std::fs or libc.

Find the top-N slowest test files in CI from a recent BuildKite run, optionally posting the results to a Slack channel as a formatted table. Use when asked to find slow CI tests, "what's making CI slow", or to post a slow-test report to Slack.

Verify a Bun runtime change by driving the debug binary end-to-end.

Guides writing bundler tests using itBundled/expectBundled in test/bundler/. Use when creating or modifying bundler, transpiler, or code transformation tests.

Guides writing HMR/Dev Server tests in test/bake/. Use when creating or modifying dev server, hot reloading, or bundling tests.