fix(vite): ensure leading slash in /@fs URLs for Windows

[Flo0806]

🔗 Linked issue

Fixes: #34766

📚 Description

Because of the fix (from me.... 😒) #34303....

Instead of generating a valid path in getManifest such as:
/@fs/D:/project/.../style.css

Nuxt may emit:
/@fsD:/project/.../style.css

That malformed URL returns 404 in development. The fix is simple check if path isn't starting with "/", add one slash.

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commit: 4d96172

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 1f457efb-db5a-4c05-b555-10db617de2d1

📥 Commits

Reviewing files that changed from the base of the PR and between 94cb8a2 and 4d96172.

📒 Files selected for processing (1)

• packages/vite/src/plugins/vite-node.ts

✅ Files skipped from review due to trivial changes (1)

• packages/vite/src/plugins/vite-node.ts

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Walkthrough

The change updates CSS path construction in the getManifest function of the vite-node plugin. When adding globally configured CSS for resolved bare module specifiers, the code now normalises resolved to ensure exactly one leading / by using resolved.replace(/^(?!\/)/, '/') before concatenating with '/@fs'. This prevents malformed '/@fs' paths when resolved already begins with a slash.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly describes the main fix: ensuring leading slashes in /@fs URLs for Windows, which directly addresses the changeset's purpose.
Description check	✅ Passed	The description is related to the changeset, explaining the bug context (malformed URLs on Windows), the issue being fixed, and the solution approach.
Linked Issues check	✅ Passed	The code change directly implements the required fix from issue #34766: normalizing the path with a leading slash before concatenating with /@fs to prevent malformed URLs on Windows.
Out of Scope Changes check	✅ Passed	The single line change in vite-node.ts is narrowly scoped to fixing the Windows path concatenation issue; no out-of-scope modifications are present.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

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[codspeed-hq]

Merging this PR will improve performance by 12.19%

⚡ 1 improved benchmark
✅ 19 untouched benchmarks
⏩ 3 skipped benchmarks¹

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
⚡	loadNuxt in the basic test fixture	489.5 ms	436.3 ms	+12.19%

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_{Comparing Flo0806:fix/vite-css-fs-url-windows (4d96172) with main (130f270)}

Footnotes

1. 3 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩