nodejs-core

Files (30)

• SKILL.md
• build-and-test-workflow.md · rules/
• build-system.md · rules/
• child-process-internals.md · rules/
• cli-options.md · rules/
• commit-and-pr-guideline.md · rules/
• configure.md · rules/
• contributing.md · rules/
• crypto-internals.md · rules/
• debugging-native.md · rules/
• documentation.md · rules/
• fs-internals.md · rules/
• libuv-async-io.md · rules/
• libuv-event-loop.md · rules/
• libuv-thread-pool.md · rules/
• memory-debugging.md · rules/
• napi.md · rules/
• native-memory.md · rules/
• net-internals.md · rules/
• node-addon-api.md · rules/
• pre-commit-lint.md · rules/
• primordials.md · rules/
• profiling-v8.md · rules/
• reviewing-prs.md · rules/
• streams-internals.md · rules/
• v8-garbage-collection.md · rules/
• v8-hidden-classes.md · rules/
• v8-jit-compilation.md · rules/
• worker-threads-internals.md · rules/
• tile.json

SKILL.md (first lines)

## When to use

Use this skill when you need deep Node.js internals expertise, including:
- C++ addon development
- V8 engine debugging
- libuv event loop issues
- Build system problems
- Compilation failures
- Performance optimization at the engine level
- Understanding Node.js core architecture
- Writing or reviewing `nodejs/node` commits and pull request descriptions

## How to use

Read individual rule files for detailed explanations and code examples:

### V8 Engine

- [rules/v8-garbage-collection.md](rules/v8-garbage-collection.md) - Scavenger, Mark-Sweep, Mark-Compact, generational GC
- [rules/v8-hidden-classes.md](rules/v8-hidden-classes.md) - Hidden classes, inline caching, optimization
- [rules/v8-jit-compilation.md](rules/v8-jit-compilation.md) - TurboFan, optimization/deoptimization patterns

### libuv

- [rules/libuv-event-loop.md](rules/libuv-event-loop.md) - Event loop phases, timers, I/O, idle, check, close
- [rules/libuv-thread-pool.md](rules/libuv-thread-pool.md) - Thread pool size, blocking operations, UV_THREADPOOL_SIZE
- [rules/libuv-async-io.md](rules/libuv-async-io.md) - Async I/O patterns, handles, requests

### Native Addons

- [rules/napi.md](rules/napi.md) - N-API development, ABI stability, async workers
- [rules/node-addon-api.md](rules/node-addon-api.md) - C++ wrapper patterns, best practices
- [rules/native-memory.md](rules/native-memory.md) - Buffer handling, external memory, prevent leaks

### Core Modules Internals

- [rules/streams-internals.md](rules/streams-internals.md) - How Node.js streams work at C++ level
- [rules/net-internals.md](rules/net-internals.md) - TCP/UDP implementation, socket handling
- [rules/fs-internals.md](rules/fs-internals.md) - libuv fs operations, sync vs async
- [rules/crypto-internals.md](rules/crypto-internals.md) - OpenSSL integration, performance considerations
- [rules/child-process-internals.md](rules/child-process-internals.md) - IPC, spawn, fork implementation
- [rules/worker-threads-internals.md](rules/worker-threads-internals.md) - SharedArrayBuffer, Atomics, MessageChannel

### JavaScript Internals

- [rules/primordials.md](rules/primordials.md) - **Using primordials to prevent prototype pollution (required for `lib/internal/`)**

### Build & Contributing

- [rules/build-and-test-workflow.md](rules/build-and-test-workflow.md) - **The edit-build-lint-test cycle (start here)**
- [rules/pre-commit-lint.md](rules/pre-commit-lint.md) - **Mandatory lint, format, and `core-validate-commit` gate for every commit so CI passes first time**
- [rules/configure.md](rules/configure.md) - `./configure` flags for debug builds, ASan, Ninja, etc.
- [rules/build-system.md](rules/build-system.md) - gyp, ninja, make, cross-platform compilation
- [rules/cli-options.md](rules/cli-options.md) - Adding CLI options and gating experimental modules
- [rules/contributing.md](rules/contributing.md) - How to contribute to Node.js core, the process
- [rules/commit-and-pr-guideline.md](rules/commit-and-pr-guideline.md) - Commit message and PR description style, trailers, DCO sign-off, and validation
- [rules/reviewing-prs.md](rules/reviewing-prs.md) - Reviewing PRs for correctness, clarity, and contribution quality

### Documentation

- [rules/documentation.md](rules/documentation.md) - **Updating doc/api/*.md files: structure, link ordering, error docs, code example constraints**

### Debugging & Profiling

- [rules/debugging-native.md](rules/debugging-native.md) - gdb, lldb, debugging C++ addons
- [rules/profiling-v8.md](rules/profiling-v8.md) - --prof, --trace-opt, --trace-deopt, flame graphs
- [rules/memory-debugging.md](rules/memory-debugging.md) - Heap snapshots, memory leak detection

## Instructions

### Node.js contribution writing

When drafting a `nodejs/node` commit or pull request, read
[rules/commit-and-pr-guideline.md](rules/commit-and-pr-guideline.md).
Use terse subsystem-prefixed titles and plain, matter-of-fact prose. Lead with
concrete behavior, explain the reason for the change, and omit hype, canned
headings, file-by-file narration, and unsupported claims. Include the
contributor's DCO sign-off, and never add `PR-URL:` or `Reviewed-By:` — those
are added when the change lands. Validate the result with
`npx core-validate-commit --no-validate-metadata <sha>` in the `nodejs/node`
checkout.

### MANDATORY: Rebuild before testing

Node.js embeds `lib/` JavaScript files into the binary at compile time via
`js2c`. **After ANY change to `src/` or `lib/`, you MUST rebuild before
running tests.** Without a rebuild, tests run against stale code and results
are meaningless.

```
edit src/ or lib/  →  make -j$(nproc)  →  make lint  →  then test
```

Never skip the rebuild step. Never run `./node test/...` after editing
without building first.

Before starting work, **ask the user** about their build configuration
(Make vs Ninja, debug vs release, what configure flags they use). Do not
assume a specific setup. Most of the time, `./configure` has already been
run and only `make -j$(nproc)` is needed to rebuild.

### MANDATORY: Lint and format before every commit

Node.js runs a `Linters` CI workflow on every non-draft pull request, and on
Unix `make test` runs **no** linters. Run `make lint` before each `git
commit` — plus `make format-cpp` for C++ changes — so the lint jobs pass on
the first CI run instead of costing a force-push and another full cycle.

```bash
make -j$(nproc)                                        # rebuild first
make lint                                              # JS, C++, MD, docs, YAML

# C++ changes only — use the merge-base form, which is what CI checks:
CLANG_FORMAT_START="$(git merge-base HEAD upstream/main)" make format-cpp
git --no-pager diff --exit-code                        # must be empty

git add -A && git commit -s                            # -s is mandatory
npx core-validate-commit --no-validate-metadata HEAD
```

From mcollina/skills, MIT.

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