[shulaoda]

Summary

Fix island CSS serving broken on Windows during dev. Layout <style> blocks in island pages (including .md pages) returned 404 because of path separator mismatches (\ vs /).

Problem

On Windows, path.resolve() produces backslash paths (e.g. E:\foo\pages\layout.vue), but Vite internally normalizes all module IDs to forward slashes. This caused two failures in the island CSS pipeline:

1. islandCssFiles stored backslash paths — populated via resolve(pagesDir, layout.filePath) which returns \-separated paths on Windows.
2. load hook received forward-slash IDs — when resolveId returned a backslash path like E:\foo\layout.vue.css, Vite normalized it to E:/foo/layout.vue.css before passing to load. The islandCssFiles.has() check then failed, causing transformRequest to throw ERR_LOAD_URL, which was silently caught, resulting in a 404.

The same mismatch affected the dev server middleware (configureIslandCssServer) and the file watcher callback.

Fix

Apply normalizePath() (from Vite) consistently to ensure all paths stored in islandCssFiles and all paths used for lookups use forward slashes:

• packages/void/src/pages/islands-plugin.ts — normalize paths in configureIslandCssServer (middleware resolve + watcher callback)
• packages/vue/src/plugin-islands.ts — normalize when populating islandCssFiles and in resolveId hook
• packages/react/src/plugin-islands.ts — same changes as vue
• packages/solid/src/plugin-islands.ts — same changes as vue
• packages/svelte/src/plugin-islands.ts — same changes as vue

[Copilot]

Pull request overview

Fixes Windows dev-server 404s for island/layout CSS by ensuring Vite module IDs and internal lookup keys use consistent forward-slash paths.

Changes:

• Normalize stored island/layout file paths via normalizePath() when populating islandCssFiles (Vue/React/Solid/Svelte).
• Normalize .css virtual module resolution inputs in resolveId to ensure islandCssFiles.has() lookups work on Windows.
• Normalize paths used by the dev server middleware + file watcher invalidation in configureIslandCssServer (void core).

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
packages/vue/src/plugin-islands.ts	Normalizes island/layout CSS file paths and resolveId lookup keys for Windows-safe matching.
packages/react/src/plugin-islands.ts	Same normalization strategy as Vue for island/layout CSS resolution.
packages/solid/src/plugin-islands.ts	Same normalization strategy as Vue for island/layout CSS resolution.
packages/svelte/src/plugin-islands.ts	Same normalization strategy as Vue for island/layout CSS resolution.
packages/void/src/pages/islands-plugin.ts	Normalizes watcher and middleware paths before islandCssFiles lookups and module invalidation.

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