Rspack 1.7 Launches with Stable Lazy Compilation, Boosting Front‑End Build Speed

Rspack 1.7 Release Overview

The Rspack team announced version 1.7, the last 1.x minor release. It ships with Lazy Compilation (on‑demand compilation) enabled by default and finally fixes the SWC plugin compatibility problem that has troubled developers.

1. Lazy Compilation – a Startup Accelerator for Large Projects

What is Lazy Compilation?

In simple terms, it compiles code only where it is accessed: the entry point is compiled at startup, and additional modules are compiled the moment a route or dynamic import loads them.

Past: Starting the dev server compiled the entire entry and all its dependencies.

Now: Only the minimal entry code is compiled initially; when a page is navigated to or a module is dynamically imported, Rspack compiles that part in real time.

This dramatically reduces the number of modules built on first launch, giving a qualitative speed boost for applications with hundreds of pages.

Note: To debug the full build output or analyze the complete module graph, set lazyCompilation: false to turn the feature off.

2. SWC Plugin Compatibility

Developers using the SWC Wasm plugin often encountered errors after upgrading Rspack or SWC because the AST structure changed, breaking plugins.

Version‑agnostic serialization: Replaced the version‑sensitive rkyv with cbor.

Enhanced fault tolerance: Introduced an Unknown variant for AST enums, preventing crashes on new node types.

As a result, SWC upgrades no longer easily break existing plugins, lowering maintenance cost for plugin authors and providing a smoother experience for users.

3. Rstack Ecosystem Updates

Rsbuild 1.7 – Better Error Feedback and Size Transparency

Runtime error overlay: Errors that previously required checking the console now appear as an overlay on the page, simplifying debugging.

Build size diff: Enabling performance.printFileSize.diff automatically shows file‑size differences between the current and previous builds, making size regressions obvious.

Rspress 2.0 RC – AI‑Focused Documentation with SSG‑MD

Rspress 2.0 introduces the SSG‑MD feature, which generates Markdown files (and an llm.txt index) instead of plain HTML. These Markdown documents are designed to be consumed by large language models, preserving React component semantics while stripping code noise, enabling AI to understand project documentation more accurately.

doc_build
├── llms.txt          # Summary version with key document indexes
├── llms-full.txt     # Full version with all document content
├── guide
│   └── start
│       └── introduction.md
└── ...

Rslib 0.19, Rsdoctor 1.4 & Rstest 0.7

Rslib: ESM build stability is solidified; a new JavaScript API simplifies script‑based usage.

Rsdoctor: Adds a Treemap view with smooth interaction; double‑clicking a module expands its dependency chain, easing bundle‑size analysis.

Rstest: Introduces a configuration adapter that reuses settings from Rslib and other tools, reducing integration effort.

Overall, Rspack 1.7 delivers a "steady progress" version that concretely addresses the two most painful developer‑experience issues: slow startup and fragile plugin compatibility. With Lazy Compilation on by default, Rspack becomes more competitive in large‑scale applications, and Rspress's AI‑ready documentation showcases the Rstack team's forward‑looking approach to the AI era.