Tim Neutkens

This commit **updates the Turbopack documentation** to clarify a significant difference in **CSS decimal precision** between Turbopack and webpack. It explains that **Turbopack**, which utilizes Lightning CSS, outputs numeric CSS values with 5 digits of precision, while webpack uses 10 digits. This **documentation update** addresses a known gap, affecting both plain CSS and Sass/SCSS output, and is crucial for users to understand potential variations in generated styles when migrating or developing with Turbopack. The change is specifically added to the "Known gaps with webpack" section within the `docs/01-app/03-api-reference/08-turbopack.mdx` file.

This commit introduces a **performance optimization** for **Turbopack** by refining its lockfile patching mechanism. Previously, the `patchIncorrectLockfile` function was eagerly triggered on every build, even when not necessary, leading to superfluous file system operations. This **maintenance refactor** now ensures that lockfile patching is only executed if the bindings fail to load, preventing unnecessary processing. The change primarily affects **Turbopack** builds, resulting in improved efficiency and reduced overhead for projects that do not require lockfile adjustments.

This commit introduces a **performance optimization** to the **client-side path normalization** logic within the Next.js framework. Specifically, the `normalizePathTrailingSlash` function, located in `packages/next/src/client/normalize-trailing-slash.ts`, has been **refactored** to utilize `charCodeAt` for its initial path check. This change replaces the less efficient `startsWith` method, resulting in improved speed for path handling operations. The **refactoring** enhances the overall efficiency of client-side routing and resource resolution.

This commit introduces a **performance optimization** by **refactoring** the `checkIsOnDemandRevalidate` function within the **server-side API utilities** (`packages/next/src/server/api-utils/index.ts`). It now directly utilizes the `req.headers` object to access header information, thereby avoiding an expensive conversion to a `Headers` object. This change **improves the efficiency** of header processing for **on-demand revalidation** checks, reducing unnecessary overhead.

This commit implements a **performance optimization** and **refactoring** within the Next.js **server-side rendering** pipeline. It extracts the **chunk loading instrumentation** into a new function, `installGlobalModuleLoadingHandlers`, to prevent V8 from retaining closure scope and creating a garbage collection root, thereby **reducing memory consumption**. This change specifically addresses an issue in `app-render.tsx` related to `globalThis.__next_require__` and `globalThis.__next_chunk_load__`. Additionally, the `renderToStream` function is updated to use a faster for loop for header iteration, further enhancing rendering efficiency.

This commit introduces a **performance optimization** by **refactoring** several internal `next.js` server-side rendering components to **avoid unnecessary `Set` to `Array` conversions**. Specifically, the `app-render` module's logic for generating and rendering **CSS and JavaScript assets** now iterates directly over `Set` objects using `for-of` loops, rather than first converting them to arrays. This **refactoring** impacts functions such as `createComponentStylesAndScripts`, `getLinkAndScriptTags`, `getLayerAssets`, and `renderCssResource`. By eliminating these intermediate array creations, the change **reduces overhead and improves server-side rendering performance**, particularly for applications with numerous assets.

This commit **reverts** a previous change, effectively **removing the Node.js stream test coverage jobs** from the project's **Continuous Integration (CI) workflow**. Specifically, it **removes** the `test node streams dev` and `test node streams prod` jobs from `.github/workflows/build_and_test.yml`, and updates dependent jobs accordingly. This **maintenance** action reduces CI pipeline complexity by eliminating dedicated checks for Node.js stream functionality, impacting the automated validation process for that subsystem.

This commit **refactors** the internal **Hot Module Replacement (HMR)** WebSocket path from `/_next/webpack-hmr` to `/_next/hmr`. This change makes the HMR endpoint **bundler-agnostic**, reflecting that Turbopack is now the default bundler alongside Webpack, thus removing a misleading identifier. It impacts the **client-side HMR connection logic** in `page-bootstrap.ts` and `web-socket.ts`, **server-side HMR request detection** in `router-server.ts`, and the **Turbopack development server's** fallback path checks in `turbopack-dev-server/src/lib.rs`. The update ensures consistent HMR functionality regardless of the underlying bundler, improving the **core development experience**. This **maintenance** task also includes corresponding **test updates** and **documentation adjustments** in `version-12.mdx`.

This commit introduces the foundational **plumbing for Node.js streaming support** within Next.js, laying the groundwork for future performance enhancements in **App Router rendering**. It adds an **experimental configuration option** `useNodeStreams` to the `NextConfigRuntime`, which is then used to set the internal `__NEXT_USE_NODE_STREAMS` environment variable across the **server, export, and rendering processes**. This environment variable conditionally enables Node.js-specific Flight APIs like `renderToPipeableStream` and `prerenderToNodeStream` in `entry-base.ts`. A new **e2e test** suite was also added to verify the correct precedence and behavior of this environment variable, ensuring reliable control over the streaming feature.

This commit performs a significant **refactoring** by **extracting core bundling infrastructure** to accommodate Node.js streams experimental flags, laying groundwork for future optimizations. It introduces a new **`v8-jit` skill** and its documentation, detailing V8 JIT optimization patterns crucial for high-performance JavaScript within Next.js server internals. While the new bundle and skill are added, they are not yet actively utilized, serving as **infrastructure preparation** for subsequent changes. Additionally, it updates inline snapshots in `ssr-in-rsc` tests to reflect the inclusion of `renderToPipeableStream` and `resumeToPipeableStream` exports.

This commit **graduates** the `adapterPath` configuration option from `experimental.adapterPath` to a **stable, top-level setting** within `next.config.js`. This **refactoring** effort updates the **Next.js configuration system**, including `NextConfig` interfaces, `configSchema`, and `defaultConfig`, while also adjusting runtime references in modules like `pages-handler.ts` and `build/index.ts`. It ensures **backward compatibility** by providing a deprecation warning for the old experimental path and updates **documentation** and **test fixtures** to reflect the new stable usage. This change makes the `adapterPath` feature officially stable and simplifies its configuration for users.

This commit provides a **bug fix** addressing **404 errors** in **webpack dev** when using **App Router parallel routes** in conjunction with **route groups** or direct `page.tsx` files within slots. The fix resolves two core issues: an incorrect `appPaths` sort order that caused the wrong page to be selected for rendering, and a loader tree generation bug that created a double `__PAGE__` segment for parallel slots. By introducing a custom `compareAppPaths` utility in `app-paths.ts` to ensure correct path ordering and adjusting segment key normalization to prevent redundant `__PAGE__` entries, this change significantly improves the robustness of **parallel routing** and **route group** functionality. An extensive e2e test suite has been added to validate the fix across various development environments.

This commit **updates the documentation** for the `adapterPath` configuration within the **Next.js configuration file** (`next.config.js`). It addresses **missing fields** and provides **more detailed explanations** and clarifications for various configurations and output types related to adapters. This **documentation update** improves the clarity and completeness of the API reference, making it easier for developers to understand and correctly configure adapter paths. The changes are confined to the `docs/01-app/03-api-reference/05-config/01-next-config-js/adapterPath.mdx` file, enhancing the overall **developer experience** for adapter integration.

This commit implements a **performance optimization** by **refactoring** the loading mechanism for specific modules within **Next.js**. It extracts the `isInterceptionRouteRewrite` function into a dedicated file (`packages/next/src/lib/is-interception-route-rewrite.ts`) and updates various server-side components, including the **Turbopack manifest loader**, to **conditionally `require`** this function only when necessary. This **maintenance** change ensures that modules not critical for common build paths are not loaded upfront, aiming to improve **startup performance** and reduce the initial memory footprint without introducing any functional changes.

This commit implements a **bug fix** to prevent client-side browser APIs from executing during server-side rendering. It introduces `window` existence checks within **Next.js BFCache functions** such as `writeToBFCache` and `readFromBFCache` in `bfcache.ts`, ensuring they only operate in a client environment. Similar `window` checks are also added to assignments within the `useActionQueue` hook in `use-action-queue.ts` to correctly manage router state. This change significantly improves **server-side rendering stability** by preventing errors when browser-specific features are not available on the server.

This commit **refactors** the **Next.js development server's request logging** to enhance clarity for developers. It renames the internal `compile` and `render` time labels in the CLI output to `next.js` and `application-code` respectively. This **maintenance** change aims to reduce confusion by explicitly differentiating time spent within the Next.js framework from time spent executing user application code. Developers will now see a more intuitive breakdown of request processing times in their **CLI output** during development. An accompanying **e2e test** was updated to reflect these new logging labels, ensuring continued test validity.

This commit introduces a **bug fix** to ensure **Next.js worker compatibility with `worker_threads`** by sanitizing method arguments. It implements a temporary workaround that uses `JSON.parse(JSON.stringify(args))` to strip non-serializable values, such as function-valued properties, from worker arguments before they are passed via `postMessage()`. This prevents a `DataCloneError` when `enableWorkerThreads` is active, stabilizing the build process, particularly for workers like `exportPages` that receive complex objects like `nextConfig`. The change primarily affects the **worker utility module** (`packages/next/src/lib/worker.ts`) and is a no-op when using the default `child_process` mode.

This commit **enhances** the `create-next-app` CLI tool by updating the `isFolderEmpty` utility to recognize additional common development environment folders. Specifically, the `packages/create-next-app/helpers/is-folder-empty.ts` module now ignores `.claude`, `.cursor`, `.vscode`, and `.zed` directories or files when checking if a target directory is empty. This **feature addition** allows developers to **initialize new Next.js projects** in directories that already contain these IDE or AI assistant configuration files, preventing false "directory not empty" errors. The change **improves developer workflow** by reducing friction during project setup.

This commit introduces a significant **performance improvement** and **refactoring** to the **React Flight Client**'s **RSC payload deserialization** process. It replaces the inefficient `JSON.parse` reviver callback in `initializeModelChunk` with a two-step approach: a bare `JSON.parse()` followed by a recursive, pure JavaScript `reviveModel()` function. This change eliminates costly C++ to JavaScript boundary crossings during parsing, resulting in an impressive **~75% speedup** for RSC chunk deserialization. The optimized `reviveModel()` also includes logic to short-circuit plain strings, further enhancing the responsiveness of applications utilizing React Server Components.

This commit introduces a **performance optimization** by **refactoring** the `parseMaxPostponedStateSize` function within the **Next.js rendering pipeline**. It now utilizes a pre-calculated constant, `DEFAULT_MAX_POSTPONED_STATE_SIZE_BYTES`, for the default postponed state size limit, avoiding redundant parsing operations. This change, located in `packages/next/src/shared/lib/size-limit.ts`, ensures that the `parseSizeLimit` utility is only invoked when a custom size is explicitly provided. By eliminating unnecessary computations in a **hot path for rendering**, this update contributes to a minor but beneficial **performance improvement** for the **Next.js framework**.