Reference

Concrete look-up material that doesn't fit into a feature narrative.

• Configuration — next.config.js schema, env-var conventions
• Data models — the most-traveled types in the codebase
• Dependencies — root devDependencies, vendored packages, runtime deps

Where things live (root of the repo)

Path	What
packages/next/	The framework runtime + dev/build/start CLIs
packages/	All the other npm packages (16 sub-packages)
crates/	Next.js-specific Rust crates
turbopack/	The Turbopack subtree (54 crates + xtask)
rspack/	rspack integration crate
test/	All non-unit tests (e2e, integration, production, development)
examples/	229 example apps demonstrating features
docs/	User-facing documentation source
errors/	Error code registry (errors/index.json)
scripts/	Repo automation (build-native, sync-react, install-native, etc.)
bench/	Benchmarks
.github/	CI workflows + automation
eslint.cli.config.mjs	Repo's ESLint config
Cargo.toml	Rust workspace
pnpm-workspace.yaml	pnpm workspace
package.json	Root npm package + scripts
tsconfig.json	Root TS config
rust-toolchain.toml	nightly-2026-04-02
AGENTS.md	Top-level guidance for AI agents working on the repo
contributing.md	Contributor guide

Top-level scripts you'll actually run

Script	What it does
pnpm build	Build all JS packages via Turbo
pnpm build-all	Build JS + Rust native binaries
pnpm swc-build-native	Build the napi binding only
pnpm dev	Watch-mode for all packages
pnpm next ...	Run the local next CLI against any project
pnpm test-unit	Run Jest unit tests
pnpm test-dev / test-start / test-deploy	Run e2e tests in dev / start / deploy mode + headless
pnpm testonly-dev <test-file>	Single-test run, headed (browser visible)
pnpm test-types	TypeScript-only check
pnpm lint	Run all linters in parallel
pnpm lint-fix	Format + fix auto-fixable lint issues
pnpm new-error	Scaffold a new framework error
pnpm new-test	Scaffold a new test
pnpm sync-react	Update bundled React versions

Bundlers

The framework supports three. Pick via env var or flag:

Bundler	How to select	Default since
Turbopack	default (no flag)	2025
webpack	--webpack or IS_WEBPACK_TEST=1	—
rspack	NEXT_RSPACK=1 (or pnpm with-rspack <cmd>)	—

Runtimes

Code can run in three runtimes:

Runtime	Where
Node	the default server, build orchestration
Edge	middleware.ts, runtime: 'edge' route handlers
Browser	client components and pages

The framework distinguishes between layers (server, client, react-server, route handler, edge). A given runtime can host multiple layers — e.g., the Node server hosts the server, client (when SSRing), and react-server layers.

Common environment variables

Variable	What
NEXT_TELEMETRY_DISABLED=1	Opt out of telemetry
NEXT_PRIVATE_LOCAL_DEV=1	Tell next it's running from this repo
IS_TURBOPACK_TEST=1 / IS_WEBPACK_TEST=1	Force a bundler in test runs
NEXT_TEST_USE_RSPACK=1 / NEXT_RSPACK=1	Use rspack in tests / production
NEXT_RSC_NO_FAILSAFE=1	Disable RSC failsafe in tests
__NEXT_CACHE_COMPONENTS=true	Enable cache components umbrella flag
NEXT_TURBOPACK_TRACING=*	Turbopack tracing preset
NEXT_SERVER_ACTIONS_ENCRYPTION_KEY	Override action encryption key
__NEXT_SHOW_IGNORE_LISTED=true	Show framework-internal frames in dev errors
NEXT_DISABLE_DEV_INDICATOR=1	Hide the dev mode badge
NEXT_DEBUG_BUILD	Verbose build diagnostics

Useful commit ranges

Range / commit	What
2016-10-05 first commit	Initial cut
Aug 2024 subtree merge	Turbopack consolidation
4ba05cc300cd...	This wiki captured at canary

Run git log --oneline --grep="<topic>" to find feature work; the repo's commit messages are good.